I am working with Delphi. I am usin开发者_如何学Gog bmp.ScanLine[]
in my code. My code is as follows :
bmp := TBitmap.Create;
bmp.Height := imgMain.Height;
bmp.Width := imgMain.Width;
for i := 0 to imgMain.Height - 1 do begin
prgb := bmp.ScanLine[i];
p1 := imgMain.ScanLine[i];
for j := 0 to imgMain.Width - 1 do begin
//Some code
end;
end;
Here, imgMain is of TBitmap type. My problem is when I execute this code, it takes too much time on the lines
prgb := bmp.ScanLine[i];
p1 := imgMain.ScanLine[i];
Please, tell me where I am wrong?
Hmm, something can be gained (introducing rowpitch, see below) but that is not too much. Probably changing the for loop to a while loop that does pointer increment and compares with a pointer value of the last pixel
// from memory, might need an additional typecast here or there.
// will typically be negative
scanline0:=imga.scanline[0];
rowpitchimga:=integer(imga.scanline[1])-integer(scanline0); // bytes to jump row.
prgb1 :=scanline0;
for i:=0 to imgmain.height-1;
begin
prgbend:=prgb1;
inc(prgbend,width); // if prgbend, it will be with sizeof(prgb1^)
while(prgb1<prbend) do // smaller then, since prgb1[] is 0 based.
begin
// do your thing
inc(prgb1);
end;
prgb1:=prgbend;
inc(pointer(prgb1),rowpitch-width*sizeof(prgb1^)); // skip alignmentbytes
inc(pointer(prgbend),rowpitch);
end;
See also rotating bitmaps. In code for a routine that does things like this to rotate an image fast.
Allocating bmps all the time can be expensive too, specially if they are large, use pools to avoid repeated allocation.
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