I've seen many sh***y things coming from MS through the years, but I
you really saying that their stretch (down) algorithm is worst than
"copy every Nth pixel"??? This is something I'll have to see before my
eyes ;-)
BTW, there's a WinAPI function to set the stretch quality... I don't
remember its name right now, unfortunately :-(
-Flávio
On 9/7/06, Albert Zeyer <[EMAIL PROTECTED]> wrote:
Hi
Are you using Windows? I recognized that the StretchBlt in the Windows API
sometimes results in crappy effects while scaling down a picture. On GTK, I
don't have this effects.
To avoid such effect, I coded a very simple own Stretch-Function:
Excerpt from my little sample game Robot:
procedure TMainForm.CopyRect(DstCanvas: TCanvas; const Dest: TRect;
SrcCanvas: TCanvas; const Source: TRect);
procedure OwnCopyRect();
var
x,y: Integer;
w,h: Integer;
sw, sh: Integer;
begin
w := Dest.Right - Dest.Left;
h := Dest.Bottom - Dest.Top;
sw := Source.Right - Source.Left;
sh := Source.Bottom - Source.Top;
for x := 0 to w do
for y := 0 to h do
begin
DstCanvas.Pixels[Dest.Left + x, Dest.Top + y] :=
SrcCanvas.Pixels[Source.Left + (x * sw) div w,
Source.Top + (y * sh) div h];
end;
end;
begin
{$IFDEF win32}
// WIN API StretchBlt is shit !
OwnCopyRect();
{$ELSE}
// on something else, we have already a good copyrect ...
DstCanvas.CopyRect(Dest, SrcCanvas, Source);
{$ENDIF win32}
end;
Regards,
Albert
Am Donnerstag, den 07.09.2006, 14:45 +0300 schrieb Ewald Horn:
Hi,
when I stretch a PNG file (256 colours) to fit a smaller window the new
image quality is extremely poor. Am I doing something wrong here ? In
Lazarus I use a TImage component and set the Stretch property to true. Maybe
there is another way to make an image fit the constraints of the component ?
If I resize the image with XnView and the load it it works, but that defeats
the purpose of being able to browse images on the fly.
Kind regards
Ewald Horn
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