将Imagelist里的图像复制到TCanvas上的指定区域

function Tdmd.Draw_Image_In_Rect(C:TCanvas;R:TRect;i:integer):boolean;
var
  tr:TRect;
begin
    if i<ML.Count then
    begin
      if tempImage=nil then tempImage:=TBitMap.Create;
      ML.GetBitmap(i,tempimage);
      tr.Top:=R.Top+(((R.Bottom-R.Top)-24) div 2)+1;
      tr.Left:=R.Left+(((R.Right-R.Left)-24) div 2+1);
      tr.Right:=tr.Left+23;
      tr.Bottom:=tr.Top+23;
      C.CopyRect(TR,tempimage.Canvas,rect(0,0,24,24));
      result:=true;
    end else result:=false;
end ;

图像复制方式：

TCopyMode values describe how to combine the colors of a source bitmap and a destination bitmap.

The Windows unit defines the following constants for TCopyMode values:

Value	Meaning
cmBlackness	Fills the destination rectangle on the canvas with black.
cmDstInvert	Inverts the image on the canvas and ignores the source.
cmMergeCopy	Combines the image on the canvas and the source bitmap by using the Boolean AND operator.
cmMergePaint	Combines the inverted source bitmap with the image on the canvas by using the Boolean OR operator.
cmNotSrcCopy	Copies the inverted source bitmap to the canvas.
cmNotSrcErase	Combines the image on the canvas and the source bitmap by using the Boolean OR operator, and inverts the result.
cmPatCopy	Copies the source pattern to the canvas.
cmPatInvert	Combines the source pattern with the image on the canvas using the Boolean XOR operator
cmPatPaint	Combines the inverted source bitmap with the source pattern by using the Boolean OR operator. Combines the result of this operation with the image on the canvas by using the Boolean OR operator.
cmSrcAnd	Combines the image on the canvas and source bitmap by using the Boolean AND operator.
cmSrcCopy	Copies the source bitmap to the canvas.
cmSrcErase	Inverts the image on the canvas and combines the result with the source bitmap by using the Boolean AND operator.
cmSrcInvert	Combines the image on the canvas and the source bitmap by using the Boolean XOR operator.
cmSrcPaint	Combines the image on the canvas and the source bitmap by using the Boolean OR operator.
cmWhiteness	Fills the destination rectangle on the canvas with white.

http://blog.sina.com.cn/s/blog_56294d0a0100tnsd.html