Title: Bitmap crossfade
Question: Well I have two pictures and I want to put the second on the first but with transparence. This could be usefull in many situations.
Answer:
The function combines two images in a crossfade image and returns it.
function returncross(srcbit, markbit:TBitmap; srcleft, srctop, markleft, marktop:integer):TBitmap;
var x, y : integer;
psrc, pmark : PByteArray;
begin
srcbit.PixelFormat := pf24bit;
markbit.PixelFormat := pf24bit;
for y := 0 to markbit.Height - 1 do begin
if y+srctop psrc := srcbit.ScanLine[y+srctop];
pmark := markbit.ScanLine[y+marktop];
for x := 0 to srcbit.Width - 1 do begin
if (y+srctop psrc^[(x+srcleft)*3] := (psrc^[(x+srcleft)*3] + pmark^[(x+markleft)*3]) div 2;
psrc^[(x+srcleft)*3 + 1] := (psrc^[(x+srcleft)*3 + 1] + pmark^[(x+markleft)*3 + 1]) div 2;
psrc^[(x+srcleft)*3 + 2] := (psrc^[(x+srcleft)*3 + 2] + pmark^[(x+markleft)*3 + 2]) div 2;
end;
end;
end;
result := srcbit;
end;
srcbit - the first picture, on the foreground
markbit - the second picture, this picture is drawed transparently
srcleft - the left coordinate of the drawed markbit
srctop - the top coordinate ...
markleft and marktop are used if you want to take only a part of the picture (by default you can use 0)
Usage example:
Put on a form two tpicture objects (image1, image2). Load some bitmaps in them. In a button click event you can place the next line.
image1.Picture.Bitmap := putwatermark(image1.Picture.Bitmap,image2.Picture.Bitmap,0,0,0,0);