wxDC Class Reference

#include <wx/dc.h>

Inheritance diagram for wxDC:

Detailed Description

A wxDC is a "device context" onto which graphics and text can be drawn.

It is intended to represent different output devices and offers a common abstract API for drawing on any of them.

wxWidgets offers an alternative drawing API based on the modern drawing backends GDI+, CoreGraphics and Cairo. See wxGraphicsContext, wxGraphicsRenderer and related classes. There is also a wxGCDC linking the APIs by offering the wxDC API on top of a wxGraphicsContext.

wxDC is an abstract base class and cannot be created directly. Use wxPaintDC, wxClientDC, wxWindowDC, wxScreenDC, wxMemoryDC or wxPrinterDC. Notice that device contexts which are associated with windows (i.e. wxClientDC, wxWindowDC and wxPaintDC) use the window font and colours by default (starting with wxWidgets 2.9.0) but the other device context classes use system-default values so you always must set the appropriate fonts and colours before using them.

In addition to the versions of the methods documented below, there are also versions which accept single wxPoint parameter instead of the two wxCoord ones or wxPoint and wxSize instead of the four wxCoord parameters.

Beginning with wxWidgets 2.9.0 the entire wxDC code has been reorganized. All platform dependent code (actually all drawing code) has been moved into backend classes which derive from a common wxDCImpl class. The user-visible classes such as wxClientDC and wxPaintDC merely forward all calls to the backend implementation.

Device and logical units

In the wxDC context there is a distinction between logical units and device units.

Device units are the units native to the particular device; e.g. for a screen, a device unit is a pixel. For a printer, the device unit is defined by the resolution of the printer (usually given in DPI: dot-per-inch).

All wxDC functions use instead logical units, unless where explicitly stated. Logical units are arbitrary units mapped to device units using the current mapping mode (see wxDC::SetMapMode).

This mechanism allows to reuse the same code which prints on e.g. a window on the screen to print on e.g. a paper.

Support for Transparency / Alpha Channel

In general wxDC methods don't support alpha transparency and the alpha component of wxColour is simply ignored and you need to use wxGraphicsContext for full transparency support. There are, however, a few exceptions: first, under Mac OS X colours with alpha channel are supported in all the normal wxDC-derived classes as they use wxGraphicsContext internally. Second, under all platforms wxSVGFileDC also fully supports alpha channel. In both of these cases the instances of wxPen or wxBrush that are built from wxColour use the colour's alpha values when stroking or filling.

for Transformation Matrix

On some platforms (currently only under MSW and only on Windows NT, i.e. not Windows 9x/ME, systems) wxDC has support for applying an arbitrary affine transformation matrix to its coordinate system. Call CanUseTransformMatrix() to check if this support is available and then call SetTransformMatrix() if it is. If the transformation matrix is not supported, SetTransformMatrix() always simply returns false and doesn't do anything.

Library:  wxCore

Category:  Device Contexts, Graphics Device Interface (GDI)

See Also

Device Contexts, wxGraphicsContext, wxDCFontChanger, wxDCTextColourChanger, wxDCPenChanger, wxDCBrushChanger, wxDCClipper

Todo:

Precise definition of default/initial state.

Pixelwise definition of operations (e.g. last point of a line not drawn).

Public Member Functions
void	CopyAttributes (const wxDC &dc)
	Copy attributes from another DC.
int	GetDepth () const
	Returns the depth (number of bits/pixel) of this DC.
wxPoint	GetDeviceOrigin () const
	Returns the current device origin.
wxRasterOperationMode	GetLogicalFunction () const
	Gets the current logical function.
wxMappingMode	GetMapMode () const
	Gets the current mapping mode for the device context.
bool	GetPixel (wxCoord x, wxCoord y, wxColour *colour) const
	Gets in colour the colour at the specified location.
wxSize	GetPPI () const
	Returns the resolution of the device in pixels per inch.
void	GetSize (wxCoord *width, wxCoord *height) const
	Gets the horizontal and vertical extent of this device context in device units.
wxSize	GetSize () const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	GetSizeMM (wxCoord *width, wxCoord *height) const
	Returns the horizontal and vertical resolution in millimetres.
wxSize	GetSizeMM () const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	GetUserScale (double *x, double *y) const
	Gets the current user scale factor.
bool	IsOk () const
	Returns true if the DC is ok to use.
void	SetAxisOrientation (bool xLeftRight, bool yBottomUp)
	Sets the x and y axis orientation (i.e. the direction from lowest to highest values on the axis).
void	SetDeviceOrigin (wxCoord x, wxCoord y)
	Sets the device origin (i.e. the origin in pixels after scaling has been applied).
void	SetLogicalFunction (wxRasterOperationMode function)
	Sets the current logical function for the device context.
void	SetMapMode (wxMappingMode mode)
	The mapping mode of the device context defines the unit of measurement used to convert logical units to device units.
void	SetPalette (const wxPalette &palette)
	If this is a window DC or memory DC, assigns the given palette to the window or bitmap associated with the DC.
void	SetUserScale (double xScale, double yScale)
	Sets the user scaling factor, useful for applications which require 'zooming'.
void *	GetHandle () const
	Returns a value that can be used as a handle to the native drawing context, if this wxDC has something that could be thought of in that way.
wxBitmap	GetAsBitmap (const wxRect *subrect=NULL) const
	If supported by the platform and the type of DC, fetch the contents of the DC, or a subset of it, as a bitmap.
void	SetLogicalScale (double x, double y)
void	GetLogicalScale (double *x, double *y) const
void	SetLogicalOrigin (wxCoord x, wxCoord y)
void	GetLogicalOrigin (wxCoord *x, wxCoord *y) const
wxPoint	GetLogicalOrigin () const
Coordinate conversion functions
wxCoord	DeviceToLogicalX (wxCoord x) const
	Convert device X coordinate to logical coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
wxCoord	DeviceToLogicalXRel (wxCoord x) const
	Convert device X coordinate to relative logical coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.
wxCoord	DeviceToLogicalY (wxCoord y) const
	Converts device Y coordinate to logical coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
wxCoord	DeviceToLogicalYRel (wxCoord y) const
	Convert device Y coordinate to relative logical coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.
wxCoord	LogicalToDeviceX (wxCoord x) const
	Converts logical X coordinate to device coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
wxCoord	LogicalToDeviceXRel (wxCoord x) const
	Converts logical X coordinate to relative device coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.
wxCoord	LogicalToDeviceY (wxCoord y) const
	Converts logical Y coordinate to device coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
wxCoord	LogicalToDeviceYRel (wxCoord y) const
	Converts logical Y coordinate to relative device coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.
Drawing functions
void	Clear ()
	Clears the device context using the current background brush.
void	DrawArc (wxCoord xStart, wxCoord yStart, wxCoord xEnd, wxCoord yEnd, wxCoord xc, wxCoord yc)
	Draws an arc from the given start to the given end point.
void	DrawArc (const wxPoint &ptStart, const wxPoint &ptEnd, const wxPoint &centre)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawBitmap (const wxBitmap &bitmap, wxCoord x, wxCoord y, bool useMask=false)
	Draw a bitmap on the device context at the specified point.
void	DrawBitmap (const wxBitmap &bmp, const wxPoint &pt, bool useMask=false)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawCheckMark (wxCoord x, wxCoord y, wxCoord width, wxCoord height)
	Draws a check mark inside the given rectangle.
void	DrawCheckMark (const wxRect &rect)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawCircle (wxCoord x, wxCoord y, wxCoord radius)
	Draws a circle with the given centre and radius.
void	DrawCircle (const wxPoint &pt, wxCoord radius)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawEllipse (wxCoord x, wxCoord y, wxCoord width, wxCoord height)
	Draws an ellipse contained in the rectangle specified either with the given top left corner and the given size or directly.
void	DrawEllipse (const wxPoint &pt, const wxSize &size)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawEllipse (const wxRect &rect)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawEllipticArc (wxCoord x, wxCoord y, wxCoord width, wxCoord height, double start, double end)
	Draws an arc of an ellipse.
void	DrawEllipticArc (const wxPoint &pt, const wxSize &sz, double sa, double ea)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawIcon (const wxIcon &icon, wxCoord x, wxCoord y)
	Draw an icon on the display (does nothing if the device context is PostScript).
void	DrawIcon (const wxIcon &icon, const wxPoint &pt)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawLabel (const wxString &text, const wxBitmap &bitmap, const wxRect &rect, int alignment=wxALIGN_LEFT|wxALIGN_TOP, int indexAccel=-1, wxRect *rectBounding=NULL)
	Draw optional bitmap and the text into the given rectangle and aligns it as specified by alignment parameter; it also will emphasize the character with the given index if it is != -1 and return the bounding rectangle if required.
void	DrawLabel (const wxString &text, const wxRect &rect, int alignment=wxALIGN_LEFT|wxALIGN_TOP, int indexAccel=-1)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawLine (wxCoord x1, wxCoord y1, wxCoord x2, wxCoord y2)
	Draws a line from the first point to the second.
void	DrawLine (const wxPoint &pt1, const wxPoint &pt2)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawLines (int n, const wxPoint points[], wxCoord xoffset=0, wxCoord yoffset=0)
	Draws lines using an array of points of size n adding the optional offset coordinate.
void	DrawLines (const wxPointList *points, wxCoord xoffset=0, wxCoord yoffset=0)
	This method uses a list of wxPoints, adding the optional offset coordinate.
void	DrawPoint (wxCoord x, wxCoord y)
	Draws a point using the color of the current pen.
void	DrawPoint (const wxPoint &pt)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawPolygon (int n, const wxPoint points[], wxCoord xoffset=0, wxCoord yoffset=0, wxPolygonFillMode fill_style=wxODDEVEN_RULE)
	Draws a filled polygon using an array of points of size n, adding the optional offset coordinate.
void	DrawPolygon (const wxPointList *points, wxCoord xoffset=0, wxCoord yoffset=0, wxPolygonFillMode fill_style=wxODDEVEN_RULE)
	This method draws a filled polygon using a list of wxPoints, adding the optional offset coordinate.
void	DrawPolyPolygon (int n, const int count[], const wxPoint points[], wxCoord xoffset=0, wxCoord yoffset=0, wxPolygonFillMode fill_style=wxODDEVEN_RULE)
	Draws two or more filled polygons using an array of points, adding the optional offset coordinates.
void	DrawRectangle (wxCoord x, wxCoord y, wxCoord width, wxCoord height)
	Draws a rectangle with the given top left corner, and with the given size.
void	DrawRectangle (const wxPoint &pt, const wxSize &sz)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawRectangle (const wxRect &rect)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawRotatedText (const wxString &text, wxCoord x, wxCoord y, double angle)
	Draws the text rotated by angle degrees (positive angles are counterclockwise; the full angle is 360 degrees).
void	DrawRotatedText (const wxString &text, const wxPoint &point, double angle)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawRoundedRectangle (wxCoord x, wxCoord y, wxCoord width, wxCoord height, double radius)
	Draws a rectangle with the given top left corner, and with the given size.
void	DrawRoundedRectangle (const wxPoint &pt, const wxSize &sz, double radius)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawRoundedRectangle (const wxRect &rect, double radius)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawSpline (int n, const wxPoint points[])
	Draws a spline between all given points using the current pen.
void	DrawSpline (const wxPointList *points)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawSpline (wxCoord x1, wxCoord y1, wxCoord x2, wxCoord y2, wxCoord x3, wxCoord y3)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	DrawText (const wxString &text, wxCoord x, wxCoord y)
	Draws a text string at the specified point, using the current text font, and the current text foreground and background colours.
void	DrawText (const wxString &text, const wxPoint &pt)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	GradientFillConcentric (const wxRect &rect, const wxColour &initialColour, const wxColour &destColour)
	Fill the area specified by rect with a radial gradient, starting from initialColour at the centre of the circle and fading to destColour on the circle outside.
void	GradientFillConcentric (const wxRect &rect, const wxColour &initialColour, const wxColour &destColour, const wxPoint &circleCenter)
	Fill the area specified by rect with a radial gradient, starting from initialColour at the centre of the circle and fading to destColour on the circle outside.
void	GradientFillLinear (const wxRect &rect, const wxColour &initialColour, const wxColour &destColour, wxDirection nDirection=wxRIGHT)
	Fill the area specified by rect with a linear gradient, starting from initialColour and eventually fading to destColour.
bool	FloodFill (wxCoord x, wxCoord y, const wxColour &colour, wxFloodFillStyle style=wxFLOOD_SURFACE)
	Flood fills the device context starting from the given point, using the current brush colour, and using a style:
bool	FloodFill (const wxPoint &pt, const wxColour &col, wxFloodFillStyle style=wxFLOOD_SURFACE)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	CrossHair (wxCoord x, wxCoord y)
	Displays a cross hair using the current pen.
void	CrossHair (const wxPoint &pt)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Clipping region functions
void	DestroyClippingRegion ()
	Destroys the current clipping region so that none of the DC is clipped.
void	GetClippingBox (wxCoord *x, wxCoord *y, wxCoord *width, wxCoord *height) const
	Gets the rectangle surrounding the current clipping region.
void	SetClippingRegion (wxCoord x, wxCoord y, wxCoord width, wxCoord height)
	Sets the clipping region for this device context to the intersection of the given region described by the parameters of this method and the previously set clipping region.
void	SetClippingRegion (const wxPoint &pt, const wxSize &sz)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	SetClippingRegion (const wxRect &rect)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	SetDeviceClippingRegion (const wxRegion &region)
	Sets the clipping region for this device context.
Text/character extent functions
wxCoord	GetCharHeight () const
	Gets the character height of the currently set font.
wxCoord	GetCharWidth () const
	Gets the average character width of the currently set font.
wxFontMetrics	GetFontMetrics () const
	Returns the various font characteristics.
void	GetMultiLineTextExtent (const wxString &string, wxCoord *w, wxCoord *h, wxCoord *heightLine=NULL, const wxFont *font=NULL) const
	Gets the dimensions of the string using the currently selected font.
wxSize	GetMultiLineTextExtent (const wxString &string) const
	Gets the dimensions of the string using the currently selected font.
bool	GetPartialTextExtents (const wxString &text, wxArrayInt &widths) const
	Fills the widths array with the widths from the beginning of text to the corresponding character of text.
void	GetTextExtent (const wxString &string, wxCoord *w, wxCoord *h, wxCoord *descent=NULL, wxCoord *externalLeading=NULL, const wxFont *font=NULL) const
	Gets the dimensions of the string using the currently selected font.
wxSize	GetTextExtent (const wxString &string) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Text properties functions
int	GetBackgroundMode () const
	Returns the current background mode: wxPENSTYLE_SOLID or wxPENSTYLE_TRANSPARENT.
const wxFont &	GetFont () const
	Gets the current font.
wxLayoutDirection	GetLayoutDirection () const
	Gets the current layout direction of the device context.
const wxColour &	GetTextBackground () const
	Gets the current text background colour.
const wxColour &	GetTextForeground () const
	Gets the current text foreground colour.
void	SetBackgroundMode (int mode)
	mode may be one of wxPENSTYLE_SOLID and wxPENSTYLE_TRANSPARENT.
void	SetFont (const wxFont &font)
	Sets the current font for the DC.
void	SetTextBackground (const wxColour &colour)
	Sets the current text background colour for the DC.
void	SetTextForeground (const wxColour &colour)
	Sets the current text foreground colour for the DC.
void	SetLayoutDirection (wxLayoutDirection dir)
	Sets the current layout direction for the device context.
Bounding box functions
void	CalcBoundingBox (wxCoord x, wxCoord y)
	Adds the specified point to the bounding box which can be retrieved with MinX(), MaxX() and MinY(), MaxY() functions.
wxCoord	MaxX () const
	Gets the maximum horizontal extent used in drawing commands so far.
wxCoord	MaxY () const
	Gets the maximum vertical extent used in drawing commands so far.
wxCoord	MinX () const
	Gets the minimum horizontal extent used in drawing commands so far.
wxCoord	MinY () const
	Gets the minimum vertical extent used in drawing commands so far.
void	ResetBoundingBox ()
	Resets the bounding box: after a call to this function, the bounding box doesn't contain anything.
Page and document start/end functions
bool	StartDoc (const wxString &message)
	Starts a document (only relevant when outputting to a printer).
void	StartPage ()
	Starts a document page (only relevant when outputting to a printer).
void	EndDoc ()
	Ends a document (only relevant when outputting to a printer).
void	EndPage ()
	Ends a document page (only relevant when outputting to a printer).
Bit-Block Transfer operations (blit)
bool	Blit (wxCoord xdest, wxCoord ydest, wxCoord width, wxCoord height, wxDC *source, wxCoord xsrc, wxCoord ysrc, wxRasterOperationMode logicalFunc=wxCOPY, bool useMask=false, wxCoord xsrcMask=wxDefaultCoord, wxCoord ysrcMask=wxDefaultCoord)
	Copy from a source DC to this DC.
bool	StretchBlit (wxCoord xdest, wxCoord ydest, wxCoord dstWidth, wxCoord dstHeight, wxDC *source, wxCoord xsrc, wxCoord ysrc, wxCoord srcWidth, wxCoord srcHeight, wxRasterOperationMode logicalFunc=wxCOPY, bool useMask=false, wxCoord xsrcMask=wxDefaultCoord, wxCoord ysrcMask=wxDefaultCoord)
	Copy from a source DC to this DC possibly changing the scale.
Background/foreground brush and pen
const wxBrush &	GetBackground () const
	Gets the brush used for painting the background.
const wxBrush &	GetBrush () const
	Gets the current brush.
const wxPen &	GetPen () const
	Gets the current pen.
void	SetBackground (const wxBrush &brush)
	Sets the current background brush for the DC.
void	SetBrush (const wxBrush &brush)
	Sets the current brush for the DC.
void	SetPen (const wxPen &pen)
	Sets the current pen for the DC.
Transformation matrix
See the notes about the availability of these functions in the class documentation.
bool	CanUseTransformMatrix () const
	Check if the use of transformation matrix is supported by the current system.
bool	SetTransformMatrix (const wxAffineMatrix2D &matrix)
	Set the transformation matrix.
wxAffineMatrix2D	GetTransformMatrix () const
	Return the transformation matrix used by this device context.
void	ResetTransformMatrix ()
	Revert the transformation matrix to identity matrix.
query capabilities
bool	CanDrawBitmap () const
	Does the DC support drawing bitmaps?
bool	CanGetTextExtent () const
	Does the DC support calculating the size required to draw text?
Public Member Functions inherited from wxObject
	wxObject ()
	Default ctor; initializes to NULL the internal reference data.
	wxObject (const wxObject &other)
	Copy ctor.
virtual	~wxObject ()
	Destructor.
virtual wxClassInfo *	GetClassInfo () const
	This virtual function is redefined for every class that requires run-time type information, when using the wxDECLARE_CLASS macro (or similar).
wxObjectRefData *	GetRefData () const
	Returns the wxObject::m_refData pointer, i.e. the data referenced by this object.
bool	IsKindOf (const wxClassInfo *info) const
	Determines whether this class is a subclass of (or the same class as) the given class.
bool	IsSameAs (const wxObject &obj) const
	Returns true if this object has the same data pointer as obj.
void	Ref (const wxObject &clone)
	Makes this object refer to the data in clone.
void	SetRefData (wxObjectRefData *data)
	Sets the wxObject::m_refData pointer.
void	UnRef ()
	Decrements the reference count in the associated data, and if it is zero, deletes the data.
void	UnShare ()
	This is the same of AllocExclusive() but this method is public.
void	operator delete (void *buf)
	The delete operator is defined for debugging versions of the library only, when the identifier WXDEBUG is defined.
void *	operator new (size_t size, const wxString &filename=NULL, int lineNum=0)
	The new operator is defined for debugging versions of the library only, when the identifier WXDEBUG is defined.

Additional Inherited Members
Protected Member Functions inherited from wxObject
void	AllocExclusive ()
	Ensure that this object's data is not shared with any other object.
virtual wxObjectRefData *	CreateRefData () const
	Creates a new instance of the wxObjectRefData-derived class specific to this object and returns it.
virtual wxObjectRefData *	CloneRefData (const wxObjectRefData *data) const
	Creates a new instance of the wxObjectRefData-derived class specific to this object and initializes it copying data.
Protected Attributes inherited from wxObject
wxObjectRefData *	m_refData
	Pointer to an object which is the object's reference-counted data.

Member Function Documentation

bool wxDC::Blit	(	wxCoord	xdest,
		wxCoord	ydest,
		wxCoord	width,
		wxCoord	height,
		wxDC *	source,
		wxCoord	xsrc,
		wxCoord	ysrc,
		wxRasterOperationMode	logicalFunc = wxCOPY,
		bool	useMask = false,
		wxCoord	xsrcMask = wxDefaultCoord,
		wxCoord	ysrcMask = wxDefaultCoord
	)

Copy from a source DC to this DC.

With this method you can specify the destination coordinates and the size of area to copy which will be the same for both the source and target DCs. If you need to apply scaling while copying, use StretchBlit().

Notice that source DC coordinates xsrc and ysrc are interpreted using the current source DC coordinate system, i.e. the scale, origin position and axis directions are taken into account when transforming them to physical (pixel) coordinates.

Parameters

xdest	Destination device context x position.
ydest	Destination device context y position.
width	Width of source area to be copied.
height	Height of source area to be copied.
source	Source device context.
xsrc	Source device context x position.
ysrc	Source device context y position.
logicalFunc	Logical function to use, see SetLogicalFunction().
useMask	If true, Blit does a transparent blit using the mask that is associated with the bitmap selected into the source device context. The Windows implementation does the following if MaskBlt cannot be used: Creates a temporary bitmap and copies the destination area into it. Copies the source area into the temporary bitmap using the specified logical function. Sets the masked area in the temporary bitmap to BLACK by ANDing the mask bitmap with the temp bitmap with the foreground colour set to WHITE and the bg colour set to BLACK. Sets the unmasked area in the destination area to BLACK by ANDing the mask bitmap with the destination area with the foreground colour set to BLACK and the background colour set to WHITE. ORs the temporary bitmap with the destination area. Deletes the temporary bitmap. This sequence of operations ensures that the source's transparent area need not be black, and logical functions are supported. Note: on Windows, blitting with masks can be speeded up considerably by compiling wxWidgets with the wxUSE_DC_CACHEING option enabled. You can also influence whether MaskBlt or the explicit mask blitting code above is used, by using wxSystemOptions and setting the no-maskblt option to 1.
xsrcMask	Source x position on the mask. If both xsrcMask and ysrcMask are -1, xsrc and ysrc will be assumed for the mask source position. Currently only implemented on Windows.
ysrcMask	Source y position on the mask. If both xsrcMask and ysrcMask are -1, xsrc and ysrc will be assumed for the mask source position. Currently only implemented on Windows.

Remarks

There is partial support for Blit() in wxPostScriptDC, under X.

See Also

StretchBlit(), wxMemoryDC, wxBitmap, wxMask

void wxDC::CalcBoundingBox	(	wxCoord	x,
		wxCoord	y
	)

Adds the specified point to the bounding box which can be retrieved with MinX(), MaxX() and MinY(), MaxY() functions.

See Also

ResetBoundingBox()

bool wxDC::CanDrawBitmap

(

)

const

Does the DC support drawing bitmaps?

bool wxDC::CanGetTextExtent

(

)

const

Does the DC support calculating the size required to draw text?

bool wxDC::CanUseTransformMatrix

(

)

const

Check if the use of transformation matrix is supported by the current system.

Currently this function always returns false for non-MSW platforms and may return false for old (Windows 9x/ME) Windows systems. Normally support for the transformation matrix is always available in any relatively recent Windows versions.

Since

2.9.2

void wxDC::Clear

(

)

Clears the device context using the current background brush.

void wxDC::CopyAttributes

(

const wxDC &

dc

)

Copy attributes from another DC.

The copied attributes currently are:

• Font
• Text foreground and background colours
• Background brush
• Layout direction

Parameters

dc	A valid (i.e. its IsOk() must return true) source device context.

void wxDC::CrossHair	(	wxCoord	x,
		wxCoord	y
	)

Displays a cross hair using the current pen.

This is a vertical and horizontal line the height and width of the window, centred on the given point.

void wxDC::CrossHair

(

const wxPoint &

pt

)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DestroyClippingRegion

(

)

Destroys the current clipping region so that none of the DC is clipped.

See Also

SetClippingRegion()

wxCoord wxDC::DeviceToLogicalX

(

wxCoord

x

)

const

Convert device X coordinate to logical coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.

wxCoord wxDC::DeviceToLogicalXRel

(

wxCoord

x

)

const

Convert device X coordinate to relative logical coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.

Use this for converting a width, for example.

wxCoord wxDC::DeviceToLogicalY

(

wxCoord

y

)

const

Converts device Y coordinate to logical coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.

wxCoord wxDC::DeviceToLogicalYRel

(

wxCoord

y

)

const

Convert device Y coordinate to relative logical coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.

Use this for converting a height, for example.

void wxDC::DrawArc	(	wxCoord	xStart,
		wxCoord	yStart,
		wxCoord	xEnd,
		wxCoord	yEnd,
		wxCoord	xc,
		wxCoord	yc
	)

Draws an arc from the given start to the given end point.

Note

DrawEllipticArc() has more clear semantics and it is recommended to use it instead of this function.

The arc drawn is an arc of the circle centered at (xc, yc). Its start point is (xStart, yStart) whereas its end point is the point of intersection of the line passing by (xc, yc) and (xEnd, yEnd) with the circle passing by (xStart, yStart).

The arc is drawn in a counter-clockwise direction between the start and the end points.

The current pen is used for the outline and the current brush for filling the shape. Notice that unless the brush is transparent, the lines connecting the centre of the circle to the end points of the arc are drawn as well.

void wxDC::DrawArc	(	const wxPoint &	ptStart,
		const wxPoint &	ptEnd,
		const wxPoint &	centre
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawBitmap	(	const wxBitmap &	bitmap,
		wxCoord	x,
		wxCoord	y,
		bool	useMask = false
	)

Draw a bitmap on the device context at the specified point.

If transparent is true and the bitmap has a transparency mask, the bitmap will be drawn transparently.

When drawing a mono-bitmap, the current text foreground colour will be used to draw the foreground of the bitmap (all bits set to 1), and the current text background colour to draw the background (all bits set to 0).

See Also

SetTextForeground(), SetTextBackground(), wxMemoryDC

void wxDC::DrawBitmap	(	const wxBitmap &	bmp,
		const wxPoint &	pt,
		bool	useMask = false
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawCheckMark	(	wxCoord	x,
		wxCoord	y,
		wxCoord	width,
		wxCoord	height
	)

Draws a check mark inside the given rectangle.

void wxDC::DrawCheckMark

(

const wxRect &

rect

)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawCircle	(	wxCoord	x,
		wxCoord	y,
		wxCoord	radius
	)

Draws a circle with the given centre and radius.

See Also

DrawEllipse()

void wxDC::DrawCircle	(	const wxPoint &	pt,
		wxCoord	radius
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawEllipse	(	wxCoord	x,
		wxCoord	y,
		wxCoord	width,
		wxCoord	height
	)

Draws an ellipse contained in the rectangle specified either with the given top left corner and the given size or directly.

The current pen is used for the outline and the current brush for filling the shape.

See Also

DrawCircle()

void wxDC::DrawEllipse	(	const wxPoint &	pt,
		const wxSize &	size
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawEllipse

(

const wxRect &

rect

)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawEllipticArc	(	wxCoord	x,
		wxCoord	y,
		wxCoord	width,
		wxCoord	height,
		double	start,
		double	end
	)

Draws an arc of an ellipse.

The current pen is used for drawing the arc and the current brush is used for drawing the pie.

x and y specify the x and y coordinates of the upper-left corner of the rectangle that contains the ellipse.

width and height specify the width and height of the rectangle that contains the ellipse.

start and end specify the start and end of the arc relative to the three-o'clock position from the center of the rectangle. Angles are specified in degrees with 0 degree angle corresponding to the positive horizontal axis (3 o'clock) direction. Positive values mean counter-clockwise motion. If start is equal to end, a complete ellipse will be drawn.

Notice that unlike DrawArc(), this function does not draw the lines to the arc ends, even when using non-transparent brush.

void wxDC::DrawEllipticArc	(	const wxPoint &	pt,
		const wxSize &	sz,
		double	sa,
		double	ea
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawIcon	(	const wxIcon &	icon,
		wxCoord	x,
		wxCoord	y
	)

Draw an icon on the display (does nothing if the device context is PostScript).

This can be the simplest way of drawing bitmaps on a window.

void wxDC::DrawIcon	(	const wxIcon &	icon,
		const wxPoint &	pt
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawLabel	(	const wxString &	text,
		const wxBitmap &	bitmap,
		const wxRect &	rect,
		int	alignment = wxALIGN_LEFT|wxALIGN_TOP,
		int	indexAccel = -1,
		wxRect *	rectBounding = NULL
	)

Draw optional bitmap and the text into the given rectangle and aligns it as specified by alignment parameter; it also will emphasize the character with the given index if it is != -1 and return the bounding rectangle if required.

void wxDC::DrawLabel	(	const wxString &	text,
		const wxRect &	rect,
		int	alignment = wxALIGN_LEFT|wxALIGN_TOP,
		int	indexAccel = -1
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawLine	(	wxCoord	x1,
		wxCoord	y1,
		wxCoord	x2,
		wxCoord	y2
	)

Draws a line from the first point to the second.

The current pen is used for drawing the line. Note that the point (x2, y2) is not part of the line and is not drawn by this function (this is consistent with the behaviour of many other toolkits).

void wxDC::DrawLine	(	const wxPoint &	pt1,
		const wxPoint &	pt2
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawLines	(	int	n,
		const wxPoint	points[],
		wxCoord	xoffset = 0,
		wxCoord	yoffset = 0
	)

Draws lines using an array of points of size n adding the optional offset coordinate.

The current pen is used for drawing the lines.

wxPerl Note: Not supported by wxPerl.

void wxDC::DrawLines	(	const wxPointList *	points,
		wxCoord	xoffset = 0,
		wxCoord	yoffset = 0
	)

This method uses a list of wxPoints, adding the optional offset coordinate.

The programmer is responsible for deleting the list of points.

wxPerl Note: The wxPerl version of this method accepts as its first parameter a reference to an array of wxPoint objects.

void wxDC::DrawPoint	(	wxCoord	x,
		wxCoord	y
	)

Draws a point using the color of the current pen.

Note that the other properties of the pen are not used, such as width.

void wxDC::DrawPoint

(

const wxPoint &

pt

)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawPolygon	(	int	n,
		const wxPoint	points[],
		wxCoord	xoffset = 0,
		wxCoord	yoffset = 0,
		wxPolygonFillMode	fill_style = wxODDEVEN_RULE
	)

Draws a filled polygon using an array of points of size n, adding the optional offset coordinate.

The first and last points are automatically closed.

The last argument specifies the fill rule: wxODDEVEN_RULE (the default) or wxWINDING_RULE.

The current pen is used for drawing the outline, and the current brush for filling the shape. Using a transparent brush suppresses filling.

wxPerl Note: Not supported by wxPerl.

void wxDC::DrawPolygon	(	const wxPointList *	points,
		wxCoord	xoffset = 0,
		wxCoord	yoffset = 0,
		wxPolygonFillMode	fill_style = wxODDEVEN_RULE
	)

This method draws a filled polygon using a list of wxPoints, adding the optional offset coordinate.

The first and last points are automatically closed.

The last argument specifies the fill rule: wxODDEVEN_RULE (the default) or wxWINDING_RULE.

The current pen is used for drawing the outline, and the current brush for filling the shape. Using a transparent brush suppresses filling.

The programmer is responsible for deleting the list of points.

wxPerl Note: The wxPerl version of this method accepts as its first parameter a reference to an array of wxPoint objects.

void wxDC::DrawPolyPolygon	(	int	n,
		const int	count[],
		const wxPoint	points[],
		wxCoord	xoffset = 0,
		wxCoord	yoffset = 0,
		wxPolygonFillMode	fill_style = wxODDEVEN_RULE
	)

Draws two or more filled polygons using an array of points, adding the optional offset coordinates.

Notice that for the platforms providing a native implementation of this function (Windows and PostScript-based wxDC currently), this is more efficient than using DrawPolygon() in a loop.

n specifies the number of polygons to draw, the array count of size n specifies the number of points in each of the polygons in the points array.

The last argument specifies the fill rule: wxODDEVEN_RULE (the default) or wxWINDING_RULE.

The current pen is used for drawing the outline, and the current brush for filling the shape. Using a transparent brush suppresses filling.

The polygons maybe disjoint or overlapping. Each polygon specified in a call to DrawPolyPolygon() must be closed. Unlike polygons created by the DrawPolygon() member function, the polygons created by this method are not closed automatically.

void wxDC::DrawRectangle	(	wxCoord	x,
		wxCoord	y,
		wxCoord	width,
		wxCoord	height
	)

Draws a rectangle with the given top left corner, and with the given size.

The current pen is used for the outline and the current brush for filling the shape.

void wxDC::DrawRectangle	(	const wxPoint &	pt,
		const wxSize &	sz
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawRectangle

(

const wxRect &

rect

)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawRotatedText	(	const wxString &	text,
		wxCoord	x,
		wxCoord	y,
		double	angle
	)

Draws the text rotated by angle degrees (positive angles are counterclockwise; the full angle is 360 degrees).

Notice that, as with DrawText(), the text can contain multiple lines separated by the new line ('\n') characters.

Note

Under Win9x only TrueType fonts can be drawn by this function. In particular, a font different from wxNORMAL_FONT should be used as the latter is not a TrueType font. wxSWISS_FONT is an example of a font which is.

See Also

DrawText()

void wxDC::DrawRotatedText	(	const wxString &	text,
		const wxPoint &	point,
		double	angle
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawRoundedRectangle	(	wxCoord	x,
		wxCoord	y,
		wxCoord	width,
		wxCoord	height,
		double	radius
	)

Draws a rectangle with the given top left corner, and with the given size.

The corners are quarter-circles using the given radius. The current pen is used for the outline and the current brush for filling the shape.

If radius is positive, the value is assumed to be the radius of the rounded corner. If radius is negative, the absolute value is assumed to be the proportion of the smallest dimension of the rectangle. This means that the corner can be a sensible size relative to the size of the rectangle, and also avoids the strange effects X produces when the corners are too big for the rectangle.

void wxDC::DrawRoundedRectangle	(	const wxPoint &	pt,
		const wxSize &	sz,
		double	radius
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawRoundedRectangle	(	const wxRect &	rect,
		double	radius
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::DrawSpline	(	int	n,
		const wxPoint	points[]
	)

Draws a spline between all given points using the current pen.

wxPerl Note: Not supported by wxPerl.

void wxDC::DrawSpline

(

const wxPointList *

points

)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

wxPerl Note: The wxPerl version of this method accepts as its first parameter a reference to an array of wxPoint objects.

void wxDC::DrawSpline	(	wxCoord	x1,
		wxCoord	y1,
		wxCoord	x2,
		wxCoord	y2,
		wxCoord	x3,
		wxCoord	y3
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

wxPerl Note: Not supported by wxPerl.

void wxDC::DrawText	(	const wxString &	text,
		wxCoord	x,
		wxCoord	y
	)

Draws a text string at the specified point, using the current text font, and the current text foreground and background colours.

The coordinates refer to the top-left corner of the rectangle bounding the string. See GetTextExtent() for how to get the dimensions of a text string, which can be used to position the text more precisely and DrawLabel() if you need to align the string differently.

Starting from wxWidgets 2.9.2 text parameter can be a multi-line string, i.e. contain new line characters, and will be rendered correctly.

Note

The current logical function is ignored by this function.

void wxDC::DrawText	(	const wxString &	text,
		const wxPoint &	pt
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::EndDoc

(

)

Ends a document (only relevant when outputting to a printer).

void wxDC::EndPage

(

)

Ends a document page (only relevant when outputting to a printer).

bool wxDC::FloodFill	(	wxCoord	x,
		wxCoord	y,
		const wxColour &	colour,
		wxFloodFillStyle	style = wxFLOOD_SURFACE
	)

Flood fills the device context starting from the given point, using the current brush colour, and using a style:

• wxFLOOD_SURFACE: The flooding occurs until a colour other than the given colour is encountered.
• wxFLOOD_BORDER: The area to be flooded is bounded by the given colour.

Currently this method is not implemented in wxOSX and does nothing there.

Returns

false if the operation failed.

Note

The present implementation for non-Windows platforms may fail to find colour borders if the pixels do not match the colour exactly. However the function will still return true.

This method shouldn't be used with wxPaintDC under non-Windows platforms as it uses GetPixel() internally and this may give wrong results, notably in wxGTK. If you need to flood fill wxPaintDC, create a temporary wxMemoryDC, flood fill it and then blit it to, or draw as a bitmap on, wxPaintDC. See the example of doing this in the drawing sample and wxBufferedPaintDC class.

bool wxDC::FloodFill	(	const wxPoint &	pt,
		const wxColour &	col,
		wxFloodFillStyle	style = wxFLOOD_SURFACE
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

wxBitmap wxDC::GetAsBitmap

(

const wxRect *

subrect = NULL

)

const

If supported by the platform and the type of DC, fetch the contents of the DC, or a subset of it, as a bitmap.

const wxBrush& wxDC::GetBackground

(

)

const

Gets the brush used for painting the background.

See Also

wxDC::SetBackground()

int wxDC::GetBackgroundMode

(

)

const

Returns the current background mode: wxPENSTYLE_SOLID or wxPENSTYLE_TRANSPARENT.

See Also

SetBackgroundMode()

const wxBrush& wxDC::GetBrush

(

)

const

Gets the current brush.

See Also

wxDC::SetBrush()

wxCoord wxDC::GetCharHeight

(

)

const

Gets the character height of the currently set font.

wxCoord wxDC::GetCharWidth

(

)

const

Gets the average character width of the currently set font.

void wxDC::GetClippingBox	(	wxCoord *	x,
		wxCoord *	y,
		wxCoord *	width,
		wxCoord *	height
	)		const

Gets the rectangle surrounding the current clipping region.

int wxDC::GetDepth

(

)

const

Returns the depth (number of bits/pixel) of this DC.

See Also

wxDisplayDepth()

wxPoint wxDC::GetDeviceOrigin

(

)

const

Returns the current device origin.

See Also

SetDeviceOrigin()

const wxFont& wxDC::GetFont

(

)

const

Gets the current font.

Notice that even although each device context object has some default font after creation, this method would return a wxNullFont initially and only after calling SetFont() a valid font is returned.

wxFontMetrics wxDC::GetFontMetrics

(

)

const

Returns the various font characteristics.

This method allows to retrieve some of the font characteristics not returned by GetTextExtent(), notably internal leading and average character width.

Currently this method returns correct results only under wxMSW, in the other ports the internal leading will always be 0 and the average character width will be computed as the width of the character 'x'.

Since

2.9.2

void* wxDC::GetHandle

(

)

const

Returns a value that can be used as a handle to the native drawing context, if this wxDC has something that could be thought of in that way.

(Not all of them do.)

For example, on Windows the return value is an HDC, on OSX it is a CGContextRef and on wxGTK it will be a GdkDrawable. If the DC is a wxGCDC then the return value will be the value returned from wxGraphicsContext::GetNativeContext. A value of NULL is returned if the DC does not have anything that fits the handle concept.

Since

2.9.5

wxLayoutDirection wxDC::GetLayoutDirection

(

)

const

Gets the current layout direction of the device context.

On platforms where RTL layout is supported, the return value will either be wxLayout_LeftToRight or wxLayout_RightToLeft. If RTL layout is not supported, the return value will be wxLayout_Default.

See Also

SetLayoutDirection()

wxRasterOperationMode wxDC::GetLogicalFunction

(

)

const

Gets the current logical function.

See Also

SetLogicalFunction()

void wxDC::GetLogicalOrigin	(	wxCoord *	x,
		wxCoord *	y
	)		const

wxPoint wxDC::GetLogicalOrigin

(

)

const

void wxDC::GetLogicalScale	(	double *	x,
		double *	y
	)		const

wxMappingMode wxDC::GetMapMode

(

)

const

Gets the current mapping mode for the device context.

See Also

SetMapMode()

void wxDC::GetMultiLineTextExtent	(	const wxString &	string,
		wxCoord *	w,
		wxCoord *	h,
		wxCoord *	heightLine = NULL,
		const wxFont *	font = NULL
	)		const

Gets the dimensions of the string using the currently selected font.

string is the text string to measure, heightLine, if non NULL, is where to store the height of a single line.

The text extent is set in the given w and h pointers.

If the optional parameter font is specified and valid, then it is used for the text extent calculation, otherwise the currently selected font is used.

Note

This function works with both single-line and multi-line strings.

wxPerl Note: In wxPerl this method is implemented as GetMultiLineTextExtent(string, font = undef) returning a 3-element list (width, height, line_height)

See Also

wxFont, SetFont(), GetPartialTextExtents(), GetTextExtent()

wxSize wxDC::GetMultiLineTextExtent

(

const wxString &

string

)

const

Gets the dimensions of the string using the currently selected font.

string is the text string to measure, heightLine, if non NULL, is where to store the height of a single line.

Returns

The text extent as a wxSize object.

Note

This function works with both single-line and multi-line strings.

wxPerl Note: Not supported by wxPerl.

See Also

wxFont, SetFont(), GetPartialTextExtents(), GetTextExtent()

bool wxDC::GetPartialTextExtents	(	const wxString &	text,
		wxArrayInt &	widths
	)		const

Fills the widths array with the widths from the beginning of text to the corresponding character of text.

The generic version simply builds a running total of the widths of each character using GetTextExtent(), however if the various platforms have a native API function that is faster or more accurate than the generic implementation then it should be used instead.

wxPerl Note: In wxPerl this method only takes the text parameter and returns the widths as a list of integers.

See Also

GetMultiLineTextExtent(), GetTextExtent()

const wxPen& wxDC::GetPen

(

)

const

Gets the current pen.

See Also

SetPen()

bool wxDC::GetPixel	(	wxCoord	x,
		wxCoord	y,
		wxColour *	colour
	)		const

Gets in colour the colour at the specified location.

Not available for wxPostScriptDC or wxMetafileDC.

Note

Setting a pixel can be done using DrawPoint().

This method shouldn't be used with wxPaintDC as accessing the DC while drawing can result in unexpected results, notably in wxGTK.

wxSize wxDC::GetPPI

(

)

const

Returns the resolution of the device in pixels per inch.

void wxDC::GetSize	(	wxCoord *	width,
		wxCoord *	height
	)		const

Gets the horizontal and vertical extent of this device context in device units.

It can be used to scale graphics to fit the page.

For example, if maxX and maxY represent the maximum horizontal and vertical 'pixel' values used in your application, the following code will scale the graphic to fit on the printer page:

wxCoord w, h;
dc.GetSize(&w, &h);
double scaleX = (double)(maxX / w);
double scaleY = (double)(maxY / h);
dc.SetUserScale(min(scaleX, scaleY),min(scaleX, scaleY));

wxPerl Note: In wxPerl there are two methods instead of a single overloaded method:

• GetSize(): returns a Wx::Size object.
• GetSizeWH(): returns a 2-element list (width, height).

wxSize wxDC::GetSize

(

)

const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::GetSizeMM	(	wxCoord *	width,
		wxCoord *	height
	)		const

Returns the horizontal and vertical resolution in millimetres.

wxSize wxDC::GetSizeMM

(

)

const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

const wxColour& wxDC::GetTextBackground

(

)

const

Gets the current text background colour.

See Also

SetTextBackground()

void wxDC::GetTextExtent	(	const wxString &	string,
		wxCoord *	w,
		wxCoord *	h,
		wxCoord *	descent = NULL,
		wxCoord *	externalLeading = NULL,
		const wxFont *	font = NULL
	)		const

Gets the dimensions of the string using the currently selected font.

string is the text string to measure, descent is the dimension from the baseline of the font to the bottom of the descender, and externalLeading is any extra vertical space added to the font by the font designer (usually is zero).

The text extent is returned in w and h pointers or as a wxSize object depending on which version of this function is used.

If the optional parameter font is specified and valid, then it is used for the text extent calculation. Otherwise the currently selected font is.

Note

This function only works with single-line strings.

wxPerl Note: In wxPerl this method is implemented as GetTextExtent(string, font = undef) returning a 4-element list (width, height, descent, externalLeading)

See Also

wxFont, SetFont(), GetPartialTextExtents(), GetMultiLineTextExtent()

wxSize wxDC::GetTextExtent

(

const wxString &

string

)

const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

wxPerl Note: Not supported by wxPerl.

const wxColour& wxDC::GetTextForeground

(

)

const

Gets the current text foreground colour.

See Also

SetTextForeground()

wxAffineMatrix2D wxDC::GetTransformMatrix

(

)

const

Return the transformation matrix used by this device context.

By default the transformation matrix is the identity matrix.

Since

2.9.2

void wxDC::GetUserScale	(	double *	x,
		double *	y
	)		const

Gets the current user scale factor.

wxPerl Note: In wxPerl this method takes no arguments and return a two element array (x, y).

See Also

SetUserScale()

void wxDC::GradientFillConcentric	(	const wxRect &	rect,
		const wxColour &	initialColour,
		const wxColour &	destColour
	)

Fill the area specified by rect with a radial gradient, starting from initialColour at the centre of the circle and fading to destColour on the circle outside.

The circle is placed at the centre of rect.

Note

Currently this function is very slow, don't use it for real-time drawing.

void wxDC::GradientFillConcentric	(	const wxRect &	rect,
		const wxColour &	initialColour,
		const wxColour &	destColour,
		const wxPoint &	circleCenter
	)

Fill the area specified by rect with a radial gradient, starting from initialColour at the centre of the circle and fading to destColour on the circle outside.

circleCenter are the relative coordinates of centre of the circle in the specified rect.

Note

Currently this function is very slow, don't use it for real-time drawing.

void wxDC::GradientFillLinear	(	const wxRect &	rect,
		const wxColour &	initialColour,
		const wxColour &	destColour,
		wxDirection	nDirection = wxRIGHT
	)

Fill the area specified by rect with a linear gradient, starting from initialColour and eventually fading to destColour.

The nDirection specifies the direction of the colour change, default is to use initialColour on the left part of the rectangle and destColour on the right one.

bool wxDC::IsOk

(

)

const

Returns true if the DC is ok to use.

wxCoord wxDC::LogicalToDeviceX

(

wxCoord

x

)

const

Converts logical X coordinate to device coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.

wxCoord wxDC::LogicalToDeviceXRel

(

wxCoord

x

)

const

Converts logical X coordinate to relative device coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.

Use this for converting a width, for example.

wxCoord wxDC::LogicalToDeviceY

(

wxCoord

y

)

const

Converts logical Y coordinate to device coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.

wxCoord wxDC::LogicalToDeviceYRel

(

wxCoord

y

)

const

Converts logical Y coordinate to relative device coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.

Use this for converting a height, for example.

wxCoord wxDC::MaxX

(

)

const

Gets the maximum horizontal extent used in drawing commands so far.

wxCoord wxDC::MaxY

(

)

const

Gets the maximum vertical extent used in drawing commands so far.

wxCoord wxDC::MinX

(

)

const

Gets the minimum horizontal extent used in drawing commands so far.

wxCoord wxDC::MinY

(

)

const

Gets the minimum vertical extent used in drawing commands so far.

void wxDC::ResetBoundingBox

(

)

Resets the bounding box: after a call to this function, the bounding box doesn't contain anything.

See Also

CalcBoundingBox()

void wxDC::ResetTransformMatrix

(

)

Revert the transformation matrix to identity matrix.

Since

2.9.2

void wxDC::SetAxisOrientation	(	bool	xLeftRight,
		bool	yBottomUp
	)

Sets the x and y axis orientation (i.e. the direction from lowest to highest values on the axis).

The default orientation is x axis from left to right and y axis from top down.

Parameters

xLeftRight	True to set the x axis orientation to the natural left to right orientation, false to invert it.
yBottomUp	True to set the y axis orientation to the natural bottom up orientation, false to invert it.

void wxDC::SetBackground

(

const wxBrush &

brush

)

Sets the current background brush for the DC.

void wxDC::SetBackgroundMode

(

int

mode

)

mode may be one of wxPENSTYLE_SOLID and wxPENSTYLE_TRANSPARENT.

This setting determines whether text will be drawn with a background colour or not.

void wxDC::SetBrush

(

const wxBrush &

brush

)

Sets the current brush for the DC.

If the argument is wxNullBrush (or another invalid brush; see wxBrush::IsOk), the current brush is selected out of the device context (leaving wxDC without any valid brush), allowing the current brush to be destroyed safely.

See Also

wxBrush, wxMemoryDC (for the interpretation of colours when drawing into a monochrome bitmap)

void wxDC::SetClippingRegion	(	wxCoord	x,
		wxCoord	y,
		wxCoord	width,
		wxCoord	height
	)

Sets the clipping region for this device context to the intersection of the given region described by the parameters of this method and the previously set clipping region.

The clipping region is an area to which drawing is restricted. Possible uses for the clipping region are for clipping text or for speeding up window redraws when only a known area of the screen is damaged.

Notice that you need to call DestroyClippingRegion() if you want to set the clipping region exactly to the region specified.

Also note that if the clipping region is empty, any previously set clipping region is destroyed, i.e. it is equivalent to calling DestroyClippingRegion(), and not to clipping out all drawing on the DC as might be expected.

See Also

DestroyClippingRegion(), wxRegion

void wxDC::SetClippingRegion	(	const wxPoint &	pt,
		const wxSize &	sz
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::SetClippingRegion

(

const wxRect &

rect

)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void wxDC::SetDeviceClippingRegion

(

const wxRegion &

region

)

Sets the clipping region for this device context.

Unlike SetClippingRegion(), this function works with physical coordinates and not with the logical ones.

void wxDC::SetDeviceOrigin	(	wxCoord	x,
		wxCoord	y
	)

Sets the device origin (i.e. the origin in pixels after scaling has been applied).

This function may be useful in Windows printing operations for placing a graphic on a page.

void wxDC::SetFont

(

const wxFont &

font

)

Sets the current font for the DC.

If the argument is wxNullFont (or another invalid font; see wxFont::IsOk), the current font is selected out of the device context (leaving wxDC without any valid font), allowing the current font to be destroyed safely.

See Also

wxFont

void wxDC::SetLayoutDirection

(

wxLayoutDirection

dir

)

Sets the current layout direction for the device context.

Parameters

dir	May be either wxLayout_Default, wxLayout_LeftToRight or wxLayout_RightToLeft.

See Also

GetLayoutDirection()

void wxDC::SetLogicalFunction

(

wxRasterOperationMode

function

)

Sets the current logical function for the device context.

It determines how a source pixel (from a pen or brush colour, or source device context if using Blit()) combines with a destination pixel in the current device context. Text drawing is not affected by this function.

See wxRasterOperationMode enumeration values for more info.

The default is wxCOPY, which simply draws with the current colour. The others combine the current colour and the background using a logical operation. wxINVERT is commonly used for drawing rubber bands or moving outlines, since drawing twice reverts to the original colour.

void wxDC::SetLogicalOrigin	(	wxCoord	x,
		wxCoord	y
	)

void wxDC::SetLogicalScale	(	double	x,
		double	y
	)

void wxDC::SetMapMode

(

wxMappingMode

mode

)

The mapping mode of the device context defines the unit of measurement used to convert logical units to device units.

Note that in X, text drawing isn't handled consistently with the mapping mode; a font is always specified in point size. However, setting the user scale (see SetUserScale()) scales the text appropriately. In Windows, scalable TrueType fonts are always used; in X, results depend on availability of fonts, but usually a reasonable match is found.

The coordinate origin is always at the top left of the screen/printer.

Drawing to a Windows printer device context uses the current mapping mode, but mapping mode is currently ignored for PostScript output.

void wxDC::SetPalette

(

const wxPalette &

palette

)

If this is a window DC or memory DC, assigns the given palette to the window or bitmap associated with the DC.

If the argument is wxNullPalette, the current palette is selected out of the device context, and the original palette restored.

See Also

wxPalette

void wxDC::SetPen

(

const wxPen &

pen

)

Sets the current pen for the DC.

If the argument is wxNullPen (or another invalid pen; see wxPen::IsOk), the current pen is selected out of the device context (leaving wxDC without any valid pen), allowing the current pen to be destroyed safely.

See Also

wxMemoryDC for the interpretation of colours when drawing into a monochrome bitmap.

void wxDC::SetTextBackground

(

const wxColour &

colour

)

Sets the current text background colour for the DC.

void wxDC::SetTextForeground

(

const wxColour &

colour

)

Sets the current text foreground colour for the DC.

See Also

wxMemoryDC for the interpretation of colours when drawing into a monochrome bitmap.

bool wxDC::SetTransformMatrix

(

const wxAffineMatrix2D &

matrix

)

Set the transformation matrix.

If transformation matrix is supported on the current system, the specified matrix will be used to transform between wxDC and physical coordinates. Otherwise the function returns false and doesn't change the coordinate mapping.

Since

2.9.2

void wxDC::SetUserScale	(	double	xScale,
		double	yScale
	)

Sets the user scaling factor, useful for applications which require 'zooming'.

bool wxDC::StartDoc

(

const wxString &

message

)

Starts a document (only relevant when outputting to a printer).

message is a message to show while printing.

void wxDC::StartPage

(

)

Starts a document page (only relevant when outputting to a printer).

bool wxDC::StretchBlit	(	wxCoord	xdest,
		wxCoord	ydest,
		wxCoord	dstWidth,
		wxCoord	dstHeight,
		wxDC *	source,
		wxCoord	xsrc,
		wxCoord	ysrc,
		wxCoord	srcWidth,
		wxCoord	srcHeight,
		wxRasterOperationMode	logicalFunc = wxCOPY,
		bool	useMask = false,
		wxCoord	xsrcMask = wxDefaultCoord,
		wxCoord	ysrcMask = wxDefaultCoord
	)

Copy from a source DC to this DC possibly changing the scale.

Unlike Blit(), this method allows to specify different source and destination region sizes, meaning that it can stretch or shrink it while copying. The same can be achieved by changing the scale of the source or target DC but calling this method is simpler and can also be more efficient if the platform provides a native implementation of it.

The meaning of its other parameters is the same as with Blit(), in particular all source coordinates are interpreted using the source DC coordinate system, i.e. are affected by its scale, origin translation and axis direction.

Parameters

xdest	Destination device context x position.
ydest	Destination device context y position.
dstWidth	Width of destination area.
dstHeight	Height of destination area.
source	Source device context.
xsrc	Source device context x position.
ysrc	Source device context y position.
srcWidth	Width of source area to be copied.
srcHeight	Height of source area to be copied.
logicalFunc	Logical function to use, see SetLogicalFunction().
useMask	If true, Blit does a transparent blit using the mask that is associated with the bitmap selected into the source device context. The Windows implementation does the following if MaskBlt cannot be used: Creates a temporary bitmap and copies the destination area into it. Copies the source area into the temporary bitmap using the specified logical function. Sets the masked area in the temporary bitmap to BLACK by ANDing the mask bitmap with the temp bitmap with the foreground colour set to WHITE and the bg colour set to BLACK. Sets the unmasked area in the destination area to BLACK by ANDing the mask bitmap with the destination area with the foreground colour set to BLACK and the background colour set to WHITE. ORs the temporary bitmap with the destination area. Deletes the temporary bitmap. This sequence of operations ensures that the source's transparent area need not be black, and logical functions are supported. Note: on Windows, blitting with masks can be speeded up considerably by compiling wxWidgets with the wxUSE_DC_CACHEING option enabled. You can also influence whether MaskBlt or the explicit mask blitting code above is used, by using wxSystemOptions and setting the no-maskblt option to 1.
xsrcMask	Source x position on the mask. If both xsrcMask and ysrcMask are wxDefaultCoord, xsrc and ysrc will be assumed for the mask source position. Currently only implemented on Windows.
ysrcMask	Source y position on the mask. If both xsrcMask and ysrcMask are wxDefaultCoord, xsrc and ysrc will be assumed for the mask source position. Currently only implemented on Windows.

There is partial support for Blit() in wxPostScriptDC, under X.

See wxMemoryDC for typical usage.

Since

2.9.0

See Also

Blit(), wxMemoryDC, wxBitmap, wxMask