ImageEn, unit iexBitmaps

TIEBitmap.CanvasCurrentAlpha

TIEBitmap.CanvasCurrentAlpha


Declaration


property CanvasCurrentAlpha: integer


Description


Setting this property to a value >=0, makes the alpha channel an 8 bit gray scale paintable bitmap.
This means that you can draw on the alpha channel using TCanvas object.
The value (0..255) specifies the transparency, 0=fully transparent, 255=fully opaque.

Default: -1


Examples


ImageEnView1.IEBitmap.AlphaChannel.CanvasCurrentAlpha := 128;
with ImageEnView1.IEBitmap.AlphaChannel.Canvas do
begin
  FillRect(0, 0, 100, 100);
  Ellipse(10, 10, 200, 200);
end;

// Draw a line on the IEBitmap canvas and ensure it also make opaque on the transparency
With ImageEnView1 do
begin
  IEBitmap.Canvas.Pen.Color := clRed;
  IEBitmap.Canvas.MoveTo( 10, 10 ) ;
  IEBitmap.Canvas.LineTo( 100, 100 );

  IEBitmap.AlphaChannel.CanvasCurrentAlpha := 255;
  IEBitmap.AlphaChannel.Canvas.MoveTo( 10, 10 ) ;
  IEBitmap.AlphaChannel.Canvas.LineTo( 100, 100 );

  Update;
end