TIEBitmap.MergeAlphaRectTo

Declaration

procedure MergeAlphaRectTo(Dest: TIEBitmap; SrcX, SrcY, DstX, DstY: integer; RectWidth, RectHeight: integer
MergeMethod: TIEMergeMethod = iemMax; MergePercent: Double = 1);

Description

Merges the alpha channel to the Dest bitmap alpha channel using the specified method.

Merge Method	Effect
iemmMax	Maximum alpha of source and dest is used
iemmMin	Minimum alpha of source and dest is used
iemmAdd	Alpha of dest is increased by that in source (effect can be reduced by specifying a lower value for MergePercent)
iemmSubtract	Alpha of dest is reduced by that in source (effect can be reduced by specifying a lower value for MergePercent)
iemmReplaceWithSrc	Replaces alpha of dest, with that of source pixels where alpha > 0

Note:
◼Dest must be the same PixelFormat as the image
◼This method only affects the alpha channel (transparency) of the two images, it does not affect the color channels

TIEBitmap Assignment and Drawing Methods

TIEBitmap Methods

Method	Mode	Purpose
Assign	From TIEBitmap/TBitmap/TGraphic/TIcon	Copy whole image
AssignImage	From TIEBitmap	Like assign, but does not copy the alpha channel
AssignRect	From TIEBitmap/TBitmap	Copy a specified rect
CopyAndConvertFormat	From TIEBitmap	Copy whole image
CopyRectTo	To TIEBitmap	Copy rect to another image (without scaling)
CopyWithMask1	To TIEBitmap	Copy image using a mask to specify what is copied from the source
CopyWithMask2	To TIEBitmap	Copy image using a mask to specify what is replaced in the destintation
DrawToTIEBitmap	To TIEBitmap	Copies all or part of the image to a specified position and/or size
JoinBitmaps	From two TIEBitmaps	Draws two bitmaps to a single bitmap
MergeAlphaRectTo	With TIEBitmap	Merges the alpha channels of two TIEBitmaps using merge rules
MergeWithAlpha	With TIEBitmap	Merges all or part of two TIEBitmaps with alpha channels to a specified position
RenderToTIEBitmapEx	To TIEBitmap	Extended drawing of content to a TIEBitmap
StretchRectTo	To TIEBitmap	Copy rect to dest rect in another image (with scaling)
SwitchTo	To TIEBitmap	Move content from one TIEBitmap to another

TBitmap Methods

Method	Mode	Purpose
Assign	From TIEBitmap/TBitmap/TGraphic/TIcon	Copy whole image
AssignTo	To TIEBitmap/TBitmap	Copy whole image with optional scaling
AssignRect	From TIEBitmap/TBitmap	Copy a specified rect
CopyFromTBitmap	From TBitmap	Copy whole image
CopyToTBitmap	To TBitmap	Copy whole image
RenderToTBitmapEx	To TBitmap	Extended drawing of content to a TBitmap

TCanvas Methods

Method	Mode	Purpose
DrawToCanvas	To TCanvas	Copies whole image to canvas at specified position (ignoring the alpha channel)
DrawToCanvasWithAlpha	To TCanvas	Copies whole image to canvas at specified position (honoring the alpha channel)
RenderToCanvas	To TCanvas	Extended drawing of content to a TCanvas (ignoring the alpha channel)
RenderToCanvasWithAlpha	To TCanvas	Extended drawing of content to a TCanvas (honoring the alpha channel)

Example

// 50% merge of alpha in Source to dest alpha
bmp.MergeAlphaRectTo( ImageEnView1.IEBitmap, 0, 0, 0, 0, bmp.Width, bmp.Height, iemmSubtract, 0.50 );
ImageEnView1.IEBitmap.SyncFull();

TIEBitmap.MergeAlphaRectTo