An abstract, device-independent, interface to bitmapped graphics contexts. More...

#include <gdi.h>

Inheritance diagram for CBitmapContext:

Public Member Functions
virtual void	Clear ()=0
	Clears the whole bitmap.

virtual void	Clear (const TRect &aRect)=0
	Clears a rectangular area of a bitmap.

virtual void	CopyRect (const TPoint &aOffset, const TRect &aRect)=0
	Copies a rectangle.

virtual void	BitBlt (const TPoint &aPoint, const CFbsBitmap *aBitmap)=0
	Performs a bitmap block transfer.

virtual void	BitBlt (const TPoint &aPoint, const CFbsBitmap *aBitmap, const TRect &aRect)=0
	Performs a bitmap block transfer of a rectangular piece of a bitmap.

virtual void	BitBltMasked (const TPoint &aPoint, const CFbsBitmap aBitmap, const TRect &aSourceRect, const CFbsBitmap aMaskBitmap, TBool aInvertMask)=0
	Performs a masked bitmap block transfer.

virtual void	SetFaded (TBool aFaded)=0
	Sets whether the graphics context is faded.

virtual void	SetFadingParameters (TUint8 aBlackMap, TUint8 aWhiteMap)=0
	Sets the fading parameters.

virtual TInt	AlphaBlendBitmaps (const TPoint &aDestPt, const CFbsBitmap aSrcBmp, const TRect &aSrcRect, const CFbsBitmap aAlphaBmp, const TPoint &aAlphaPt)=0
	Performs an alpha blending of the source data, aSrcBmp, with the CBitmapContext, using the data from aAlphaBmp as an alpha blending factor.

virtual TInt	AlphaBlendBitmaps (const TPoint &aDestPt, const CWsBitmap aSrcBmp, const TRect &aSrcRect, const CWsBitmap aAlphaBmp, const TPoint &aAlphaPt)=0
	The method performs an alpha blending of the source data, aSrcBmp, with the CBitmapContext, using the data from aAlphaBmp as an alpha blending factor.

Public Member Functions inherited from CGraphicsContext
virtual CGraphicsDevice *	Device () const =0
	Gets a pointer to the graphics context's graphics device.

virtual void	SetOrigin (const TPoint &aPos=TPoint(0, 0))=0
	Sets the position of the co-ordinate origin.

virtual void	SetDrawMode (TDrawMode aDrawingMode)=0
	Sets the drawing mode.

virtual void	SetClippingRect (const TRect &aRect)=0
	Sets the clipping rectangle.

virtual void	CancelClippingRect ()=0
	Cancels any clipping rectangle.

virtual void	Reset ()=0
	Resets the graphics context to its default settings:

virtual void	UseFont (const CFont *aFont)=0
	Sets the device font to be used for text drawing.

virtual void	DiscardFont ()=0
	Discards a font.

virtual void	SetUnderlineStyle (TFontUnderline aUnderlineStyle)=0
	Sets the underline style.

virtual void	SetStrikethroughStyle (TFontStrikethrough aStrikethroughStyle)=0
	Sets the strikethrough style.

virtual void	SetWordJustification (TInt aExcessWidth, TInt aNumGaps)=0
	Adjusts the spaces between words to stretch or squeeze to a certain width.

virtual void	SetCharJustification (TInt aExcessWidth, TInt aNumChars)=0
	Sets character justification.

virtual void	SetPenColor (const TRgb &aColor)=0
	Sets the pen colour.

virtual void	SetPenStyle (TPenStyle aPenStyle)=0
	Sets the line drawing style for the pen.

virtual void	SetPenSize (const TSize &aSize)=0
	Sets the line drawing size for the pen.

virtual void	SetBrushColor (const TRgb &aColor)=0
	Sets the brush colour.

virtual void	SetBrushStyle (TBrushStyle aBrushStyle)=0
	Sets the brush style.

virtual void	SetBrushOrigin (const TPoint &aOrigin)=0
	Sets the brush pattern origin.

virtual void	UseBrushPattern (const CFbsBitmap *aBitmap)=0
	Sets the brush pattern to the specified bitmap.

virtual void	DiscardBrushPattern ()=0
	Discards a non-built-in brush pattern.

virtual void	MoveTo (const TPoint &aPoint)=0
	Sets the drawing point relative to the co-ordinate origin.

virtual void	MoveBy (const TPoint &aVector)=0
	Sets the drawing point relative to the current co-ordinates.

virtual void	Plot (const TPoint &aPoint)=0
	Draws a single point.

virtual void	DrawArc (const TRect &aRect, const TPoint &aStart, const TPoint &aEnd)=0
	Draws an arc.

virtual void	DrawLine (const TPoint &aPoint1, const TPoint &aPoint2)=0
	Draws a straight line between two points.

virtual void	DrawLineTo (const TPoint &aPoint)=0
	Draws a straight line from the current drawing point to a specified point.

virtual void	DrawLineBy (const TPoint &aVector)=0
	Draws a straight line relative to the current drawing point, using a vector.

virtual void	DrawPolyLine (const CArrayFix< TPoint > *aPointList)=0
	Draws a polyline from a set of points in an array.

virtual void	DrawPolyLine (const TPoint *aPointList, TInt aNumPoints)=0
	Draws a polyline from a set of points in a list.

virtual void	DrawPie (const TRect &aRect, const TPoint &aStart, const TPoint &aEnd)=0
	Draws and fills a pie slice.

virtual void	DrawEllipse (const TRect &aRect)=0
	Draws and fills an ellipse.

virtual void	DrawRect (const TRect &aRect)=0
	Draws and fills a rectangle.

virtual void	DrawRoundRect (const TRect &aRect, const TSize &aCornerSize)=0
	Draws and fills a rectangle with rounded corners.

virtual TInt	DrawPolygon (const CArrayFix< TPoint > *aPointList, TFillRule aFillRule=EAlternate)=0
	Draws and fills a polygon defined using an array of points.

virtual TInt	DrawPolygon (const TPoint *aPointList, TInt aNumPoints, TFillRule aFillRule=EAlternate)=0
	Draws and fills a polygon defined using a list of points.

virtual void	DrawBitmap (const TPoint &aTopLeft, const CFbsBitmap *aSource)=0
	Draws a bitmap at the specified point.

virtual void	DrawBitmap (const TRect &aDestRect, const CFbsBitmap *aSource)=0
	Draws a bitmap to fit a given rectangle.

virtual void	DrawBitmap (const TRect &aDestRect, const CFbsBitmap *aSource, const TRect &aSourceRect)=0
	Draws a specified rectangle of a source bitmap to fit into a given destination rectangle.

virtual void	DrawBitmapMasked (const TRect &aDestRect, const CFbsBitmap aBitmap, const TRect &aSourceRect, const CFbsBitmap aMaskBitmap, TBool aInvertMask)=0
	Draws a specified rectangle of a source bitmap to fit into a given rectangle using a given mask.

virtual void	DrawBitmapMasked (const TRect &aDestRect, const CWsBitmap aBitmap, const TRect &aSourceRect, const CWsBitmap aMaskBitmap, TBool aInvertMask)=0
	Draws a specified rectangle from a wserv bitmap and its mask into another rectangle.

virtual void	DrawText (const TDesC &aText, const TPoint &aPosition)=0
	Draws text without a surrounding box.

virtual void	DrawText (const TDesC &aText, const TRect &aBox, TInt aBaselineOffset, TTextAlign aAlignment=ELeft, TInt aLeftMargin=0)=0
	Draws text inside a box.

virtual IMPORT_C void	DrawText (const TDesC &aText, const TPoint &aPosition, const TDrawTextParam &aParam)
	Draws the specified text at the given position using the parameters supplied.

virtual IMPORT_C void	Reserved ()
	Reserved function for future use.

IMPORT_C TInt	DrawTextExtended (const TDesC &aText, const TPoint &aPosition, const TDrawTextExtendedParam &aParam)
	Draws text, optionally changing its direction (right-to-left / left-to-right).

virtual void	MapColors (const TRect &aRect, const TRgb *aColors, TInt aNumPairs, TBool aMapForwards)=0
	Maps pixels in the specified rectangle.

virtual TInt	SetClippingRegion (const TRegion &aRegion)=0
	Sets the clipping region, any items that fall outside the extent of the clipping region will not be drawn.

virtual void	CancelClippingRegion ()=0
	Cancels the current clipping region.

virtual void	DrawTextVertical (const TDesC &aText, const TPoint &aPos, TBool aUp)=0
	Draws vertical text in the specified direction.

virtual void	DrawTextVertical (const TDesC &aText, const TRect &aBox, TInt aBaselineOffset, TBool aUp, TTextAlign aVert=ELeft, TInt aMargin=0)=0
	Draws text vertically in the specified direction, within a box of the specified size.

IMPORT_C TInt	GetUnderlineMetrics (TInt &aTop, TInt &aBottom)

IMPORT_C TInt	SetShadowColor (const TRgb &aShadowColor)
	Set the font's shadow colour.

IMPORT_C TInt	GetShadowColor (TRgb &aShadowColor)
	Get the font's shadow colour.

IMPORT_C TBool	IsFbsBitGc () const
	Determine if the Gc is a CFbsBitGc.

IMPORT_C void	DrawText (const TDesC &aText, const TTextParameters *iParam, const TPoint &aPosition)

IMPORT_C void	DrawText (const TDesC &aText, const TTextParameters *iParam, const TRect &aBox, TInt aBaselineOffset, TTextAlign aHrz=ELeft, TInt aMargin=0)

IMPORT_C void	DrawText (const TDesC &aText, const TTextParameters *iParam, const TPoint &aPosition, const TDrawTextParam &aParam)

IMPORT_C void	DrawTextVertical (const TDesC &aText, const TTextParameters *iParam, const TPoint &aPos, TBool aUp)

IMPORT_C void	DrawTextVertical (const TDesC &aText, const TTextParameters *iParam, const TRect &aBox, TInt aBaselineOffset, TBool aUp, TTextAlign aVert=ELeft, TInt aMargin=0)

IMPORT_C TInt	DrawTextExtended (const TDesC &aText, const TTextParameters *iParam, const TPoint &aPosition, const TDrawTextExtendedParam &aParam)
	Draws text, optionally changing its direction (right-to-left / left-to-right).

Public Member Functions inherited from CBase
	CBase ()
	Default constructor.

virtual IMPORT_C	~CBase ()
	Virtual destructor.

TAny *	operator new (TUint aSize, TAny *aBase) __NO_THROW
	Initialises the object to binary zeroes.

TAny *	operator new (TUint aSize) __NO_THROW
	Allocates the object from the heap and then initialises its contents to binary zeroes.

TAny *	operator new (TUint aSize, TLeave)
	Allocates the object from the heap and then initialises its contents to binary zeroes.

TAny *	operator new (TUint aSize, TUint aExtraSize) __NO_THROW
	Allocates the object from the heap and then initialises its contents to binary zeroes.

TAny *	operator new (TUint aSize, TLeave, TUint aExtraSize)
	Allocates the object from the heap and then initialises its contents to binary zeroes.

Protected Member Functions
IMPORT_C TInt	APIExtension (TUid aUid, TAny &aOutput, TAny aInput)

IMPORT_C void	Reserved_CGraphicsContext_2 ()
	A reserved virtual function for future use.

virtual IMPORT_C void	Reserved_CBitmapContext_1 ()

virtual IMPORT_C void	Reserved_CBitmapContext_2 ()

virtual IMPORT_C void	Reserved_CBitmapContext_3 ()

Protected Member Functions inherited from CBase
virtual IMPORT_C TInt	Extension_ (TUint aExtensionId, TAny &a0, TAny a1)
	Extension function.

Additional Inherited Members
Public Types inherited from CGraphicsContext
enum	TTextAlign { ELeft , ECenter , ERight }
	Text alignment. More...

enum	TDrawModeComponents { EInvertScreen =1 , EXor =2 , EOr =4 , EAnd =8 , ELogicalOp =14 , EInvertPen =16 , EPenmode =32 , EWriteAlpha =64 }

enum	TDrawMode { EDrawModeAND =EAnd , EDrawModeNOTAND =EInvertScreen\|EAnd , EDrawModePEN =EPenmode , EDrawModeANDNOT =EAnd\|EInvertPen , EDrawModeXOR =EXor , EDrawModeOR =EOr , EDrawModeNOTANDNOT =EInvertScreen\|EAnd\|EInvertPen , EDrawModeNOTXOR =EInvertScreen\|EXor , EDrawModeNOTSCREEN =EInvertScreen , EDrawModeNOTOR =EInvertScreen\|EOr , EDrawModeNOTPEN =EInvertPen\|EPenmode , EDrawModeORNOT =EOr\|EInvertPen , EDrawModeNOTORNOT =EInvertScreen\|EOr\|EInvertPen , EDrawModeWriteAlpha =EWriteAlpha }

enum	TPenStyle { ENullPen , ESolidPen , EDottedPen , EDashedPen , EDotDashPen , EDotDotDashPen }

enum	TBrushStyle { ENullBrush , ESolidBrush , EPatternedBrush , EVerticalHatchBrush , EForwardDiagonalHatchBrush , EHorizontalHatchBrush , ERearwardDiagonalHatchBrush , ESquareCrossHatchBrush , EDiamondCrossHatchBrush }

enum	TFillRule { EAlternate , EWinding }

Static Public Member Functions inherited from CGraphicsContext
static IMPORT_C TInt	JustificationInPixels (TInt aExcessPixels, TInt aTotalUnits, TInt aFirstUnit, TInt aNumUnits)
	Gets the amount of space in pixels by which to adjust letter or word spacing, given the total number of words and spaces, a start space, and the number of units to be adjusted.

static IMPORT_C TInt	JustificationInPixels (TInt &aExcessPixels, TInt &aTotalUnits)
	Gets the amount of space in pixels by which to adjust the current letter or word spacing, and also retrieves the number of excess pixels and word spaces remaining after the adjustment is performed.

Static Public Member Functions inherited from CBase
static IMPORT_C void	Delete (CBase *aPtr)
	Deletes the specified object.

Detailed Description

An abstract, device-independent, interface to bitmapped graphics contexts.

This holds the setting used to draw to a CBitmapDevice.

The default settings of a CBitmapContext object immediately after construction are:

drawing mode is EDrawModePen (pen and brush colours used as they are)

no clipping rectangle

pen settings are: black, solid, single pixel width

brush style is null

no text font selected

The classes CFbsBitGc and CWindowGc are derived from this class.

See also: CFbsBitGc

API status: Published to all clients. Released API.

Definition at line 3180 of file gdi.h.

Member Function Documentation

◆ AlphaBlendBitmaps() [1/2]

virtual TInt CBitmapContext::AlphaBlendBitmaps	(	const TPoint &	aDestPt,
		const CFbsBitmap *	aSrcBmp,
		const TRect &	aSrcRect,
		const CFbsBitmap *	aAlphaBmp,
		const TPoint &	aAlphaPt
	)

pure virtual

Performs an alpha blending of the source data, aSrcBmp, with the CBitmapContext, using the data from aAlphaBmp as an alpha blending factor.

The formula used is: (S * A + W * (255 - A)) / 255, where:

S - a pixel from aSrcBmp;
W - a pixel from the window;

A - a pixel from aAlphaBmp; The contents of source and alpha bitmap are preserved. The calculated alpha blended pixels are written to the destination CBitmapContext.

Parameters

aDestPt	Position in the target the result should be drawn to.
aSrcBmp	A pointer to the source bitmap.
aSrcRect	The part of the source bitmap that should be used.
aAlphaBmp	A pointer to the bitmap used as an alpha blending factor.
aAlphaPt	Position of the first pixel in the alpha bitmap that should be used as a source for the alpha blending. The size of the area is the same as the source bitmap area - aSrcRect parameter.

Implemented in CWindowGc.

◆ AlphaBlendBitmaps() [2/2]

virtual TInt CBitmapContext::AlphaBlendBitmaps	(	const TPoint &	aDestPt,
		const CWsBitmap *	aSrcBmp,
		const TRect &	aSrcRect,
		const CWsBitmap *	aAlphaBmp,
		const TPoint &	aAlphaPt
	)

pure virtual

The method performs an alpha blending of the source data, aSrcBmp, with the CBitmapContext, using the data from aAlphaBmp as an alpha blending factor.

For information on how this function works, see the other overload.

Parameters

aDestPt	Position in the target the result should be drawn to.
aSrcBmp	A pointer to the source bitmap.
aSrcRect	The part of the source bitmap that should be used.
aAlphaBmp	A pointer to the bitmap used as an alpha blending factor.
aAlphaPt	Position of the first pixel in the alpha bitmap that should be used as a source for the alpha blending. The size of the area is the same as the source bitmap area - aSrcRect parameter.

Implemented in CWindowGc.

◆ APIExtension()

IMPORT_C TInt CBitmapContext::APIExtension	(	TUid	aUid,
		TAny *&	aOutput,
		TAny *	aInput
	)

protectedvirtual

Parameters

aOutput	is for output
aInput	is for input

(generated from Symbian Developer Library)

Reimplemented from CGraphicsContext.

Reimplemented in CWindowGc.

◆ BitBlt() [1/2]

virtual void CBitmapContext::BitBlt	(	const TPoint &	aPoint,
		const CFbsBitmap *	aBitmap
	)

pure virtual

Performs a bitmap block transfer.

This pure virtual function is implemented in derived classes.

Parameters

aPoint	The destination for the top left corner of the transferred bitmap. It is relative to the top left corner of the destination bitmap, which may be the screen.
aBitmap	A memory-resident bitmap.

Implemented in CWindowGc.

◆ BitBlt() [2/2]

virtual void CBitmapContext::BitBlt	(	const TPoint &	aPoint,
		const CFbsBitmap *	aBitmap,
		const TRect &	aRect
	)

pure virtual

Performs a bitmap block transfer of a rectangular piece of a bitmap.

If the specified rectangle is larger than the bitmap then the bitmap is padded with white.

This pure virtual function is implemented in derived classes.

Parameters

aPoint	The destination for the top left corner of the transferred bitmap. It is relative to the top left corner of the destination bitmap, which may be the screen.
aBitmap	A memory-resident bitmap
aRect	A rectangle defining the portion of the bitmap to transfer. Its coordinates are relative to the top left corner of the source bitmap.

Implemented in CWindowGc.

◆ BitBltMasked()

virtual void CBitmapContext::BitBltMasked	(	const TPoint &	aPoint,
		const CFbsBitmap *	aBitmap,
		const TRect &	aSourceRect,
		const CFbsBitmap *	aMaskBitmap,
		TBool	aInvertMask
	)

pure virtual

Performs a masked bitmap block transfer.

The mask bitmap can be used as either a positive or negative mask. Masked pixels are not mapped to the destination rectangle.

This function uses either a black and white (binary) mask bitmap, or if aMaskBitmap's display mode is EGray256, alpha blending is used. Use of any other mode may result in unpredictable results

With aInvertMask=EFalse, black pixels in the mask bitmap stop corresponding pixels in the source bitmap from being transferred to the destination rectangle. With aInvertMask=ETrue, white pixels in the mask bitmap stop corresponding pixels in the source bitmap from being transferred to the destination rectangle.

Note�that if the mask bitmap is smaller than the source bitmap, then it is tiled across the bitmap. Note that the mask is applied before the piece of the bitmap is defined - the mask is tiled relative to the top left of the original source bitmap rather than the top left of the bitmap piece.

This pure virtual function is implemented in derived classes.

Parameters

aPoint	The destination for the top left corner of the transferred bitmap. It is relative to the top left corner of the destination bitmap, which may be the screen.
aBitmap	A memory-resident source bitmap.
aSourceRect	A rectangle defining the piece of the bitmap to be drawn, with co-ordinates relative to the top left corner of the bitmap.
aMaskBitmap	A mask bitmap
aInvertMask	If EFalse, a source pixel that is masked by a black pixel is not transferred to the destination rectangle. If ETrue, then a source pixel that is masked by a white pixel is not transferred to the destination rectangle.

Implemented in CWindowGc.

◆ Clear() [1/2]

virtual void CBitmapContext::Clear ( )

pure virtual

Clears the whole bitmap.

The cleared area is filled with the current brush colour.

This pure virtual function is implemented in derived classes.

Implemented in CWindowGc.

◆ Clear() [2/2]

virtual void CBitmapContext::Clear ( const TRect & aRect )

pure virtual

Clears a rectangular area of a bitmap.

The cleared area is filled with the current brush colour.

This pure virtual function is implemented in derived classes.

Parameters

aRect The rectangle to clear.

Implemented in CWindowGc.

◆ CopyRect()

virtual void CBitmapContext::CopyRect	(	const TPoint &	aOffset,
		const TRect &	aRect
	)

pure virtual

Copies a rectangle.

This pure virtual function is implemented in derived classes.

Parameters

aOffset	The offset from the top left corner of the rectangle to be copied to the top left corner of the copy.
aRect	The rectangular area to be copied.

Implemented in CWindowGc.

◆ Reserved_CBitmapContext_1()

virtual IMPORT_C void CBitmapContext::Reserved_CBitmapContext_1 ( )

protectedvirtual

◆ Reserved_CBitmapContext_2()

virtual IMPORT_C void CBitmapContext::Reserved_CBitmapContext_2 ( )

protectedvirtual

◆ Reserved_CBitmapContext_3()

virtual IMPORT_C void CBitmapContext::Reserved_CBitmapContext_3 ( )

protectedvirtual

◆ Reserved_CGraphicsContext_2()

IMPORT_C void CBitmapContext::Reserved_CGraphicsContext_2 ( )

protectedvirtual

A reserved virtual function for future use.

Reimplemented from CGraphicsContext.

◆ SetFaded()

virtual void CBitmapContext::SetFaded ( TBool aFaded )

pure virtual

Sets whether the graphics context is faded.

Parameters

aFaded ETrue to fade the GC; EFalse to unfade it.

Implemented in CWindowGc.

◆ SetFadingParameters()

virtual void CBitmapContext::SetFadingParameters	(	TUint8	aBlackMap,
		TUint8	aWhiteMap
	)

pure virtual

Sets the fading parameters.

This function allows you to override the map used when drawing with a faded graphics context (GC). However if you draw to a faded window with a faded GC, then fading on the GC is ignored and the fading of the window is used.

Fading is used to change the colour of a window to make other windows stand out. Fading can either make a faded window closer to white or closer to black.

Fading re-maps colours in the faded GC to fall between the specified black and white map values. If aBlackMap=0 and aWhiteMap=255 then the colours are mapped unchanged. As the values converge the colours are mapped to a smaller range - so the differences between colours in the faded GC decrease. If the values are reversed then the colours are inverted (i.e. where the GC would be black, it is now white).

Parameters

aBlackMap	Black map fading parameter. Unfaded this is 0.
aWhiteMap	White map fading parameter. Unfaded this is 255.

Implemented in CWindowGc.

The documentation for this class was generated from the following files:

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ AlphaBlendBitmaps() [1/2]

◆ AlphaBlendBitmaps() [2/2]

◆ APIExtension()

◆ BitBlt() [1/2]

◆ BitBlt() [2/2]

◆ BitBltMasked()

◆ Clear() [1/2]

◆ Clear() [2/2]

◆ CopyRect()

◆ Reserved_CBitmapContext_1()

◆ Reserved_CBitmapContext_2()

◆ Reserved_CBitmapContext_3()

◆ Reserved_CGraphicsContext_2()

◆ SetFaded()

◆ SetFadingParameters()