这可以通过创建一个附加位图 (Intrans) 来完成,其 alpha 通道设置为
0。Intrans 用于 ImageList。将原始位图作为图像添加为掩码。
这个例子应该反映你的。
type
pRGBQuadArray = ^TRGBQuadArray;
TRGBQuadArray = ARRAY [0 .. 0] OF TRGBQuad;
Procedure GenIntransparentBitmap(bmp, Intrans: TBitmap);
var
pscanLine32: pRGBQuadArray;
i, j: Integer;
begin
Intrans.Assign(bmp);
for i := 0 to Intrans.Height - 1 do
begin
pscanLine32 := Intrans.Scanline[i];
for j := 0 to Intrans.Width - 1 do
begin
pscanLine32[j].rgbReserved := 0;
end;
end;
end;
procedure TForm3.Button1Click(Sender: TObject);
var
Bitmap, Intransp: TBitmap;
begin
Bitmap := TBitmap.Create;
try
Bitmap.PixelFormat := pf32bit;
Bitmap.Transparent := true;
Bitmap.AlphaFormat := afIgnored;
SetBkMode(Bitmap.Canvas.Handle, BKMODE_LAST);
Bitmap.SetSize(100, 42);
ImageList1.Draw(Bitmap.Canvas, 5, 5, 0, dsTransparent, itImage);
Bitmap.Canvas.Brush.Style := bsClear;
Bitmap.Canvas.RoundRect(0, 0, 99, 41, 5, 5);
Bitmap.Canvas.TextOut(50, 5, 'Test string');
BitmapImageList.Width := Bitmap.Width;
BitmapImageList.Height := Bitmap.Height;
// Create intransparent bitmap from transparent bitmap
Intransp := TBitmap.Create;
try
GenIntransparentBitmap(Bitmap, Intransp);
// add intransparent bitmap as image and transparent bitmap as mask
BitmapImageList.Add(Intransp, Bitmap);
finally
Intransp.Free;
end;
BitmapImageList.Draw(Canvas, 100, 100, 0);
finally
Bitmap.Free;
end;
end;
一个较短的版本是
Procedure GenIntransparentBitmap(bmp, Intrans: TBitmap);
begin
Intrans.Assign(bmp);
Intrans.PixelFormat := pf24bit;
end;
procedure TForm3.Button1Click(Sender: TObject);
var
Bitmap, Intransp: TBitmap;
begin
Bitmap := TBitmap.Create;
try
Bitmap.PixelFormat := pf32bit;
SetBkMode(Bitmap.Canvas.Handle, TRANSPARENT);
Bitmap.SetSize(100, 42);
ImageList1.Draw(Bitmap.Canvas, 5, 5, 0, dsTransparent, itImage);
Bitmap.Canvas.Brush.Style := bsClear;
Bitmap.Canvas.RoundRect(0, 0, 99, 41, 5, 5);
Bitmap.Canvas.TextOut(50, 5, 'Test string');
BitmapImageList.Width := Bitmap.Width;
BitmapImageList.Height := Bitmap.Height;
// Create intransparent bitmap from transparent bitmap
Intransp := TBitmap.Create;
try
GenIntransparentBitmap(Bitmap, Intransp);
// add intransparent bitmap as image and transparent bitmap as mask
BitmapImageList.Add(Intransp, Bitmap);
finally
Intransp.Free;
end;
BitmapImageList.Draw(Canvas, 100, 100, 0);
finally
Bitmap.Free;
end;
end;