Mega Code Archive
Scanline implementation of stretchblt-delete_scans
<![CDATA[
unit DeleteScans;
//Renate Schaaf
//renates@xmission.com
interface
uses Windows, Graphics;
procedure DeleteScansRect(Src, Dest: TBitmap; rs, rd: TRect);
//scanline implementation of Stretchblt/Delete_Scans
//about twice as fast
//Stretches Src to Dest, rs is source rect, rd is dest. rect
//The stretch is centered, i.e the center of rs is mapped to the center of rd.
//Src, Dest are assumed to be bottom up
implementation
uses Classes, math;
type
TRGBArray = array[0..64000] of TRGBTriple;
PRGBArray = ^TRGBArray;
TQuadArray = array[0..64000] of TRGBQuad;
PQuadArray = ^TQuadArray;
procedure DeleteScansRect(Src, Dest: TBitmap; rs, rd: TRect);
var
xsteps, ysteps: array of Integer;
intscale: Integer;
i, x, y, x1, x2, bitspp, bytespp: Integer;
ts, td: PByte;
bs, bd, WS, hs, w, h: Integer;
Rows, rowd: PByte;
j, c: Integer;
pf: TPixelFormat;
xshift, yshift: Integer;
begin
WS := rs.Right - rs.Left;
hs := rs.Bottom - rs.Top;
w := rd.Right - rd.Left;
h := rd.Bottom - rd.Top;
pf := Src.PixelFormat;
if (pf <> pf32Bit) and (pf <> pf24bit) then
begin
pf := pf24bit;
Src.PixelFormat := pf;
end;
Dest.PixelFormat := pf;
if not (((w <= WS) and (h <= hs)) or ((w >= WS) and (h >= hs))) then
//we do not handle a mix of up-and downscaling,
//using threadsafe StretchBlt instead.
begin
Src.Canvas.Lock;
Dest.Canvas.Lock;
try
SetStretchBltMode(Dest.Canvas.Handle, STRETCH_DELETESCANS);
StretchBlt(Dest.Canvas.Handle, rd.Left, rd.Top, w, h,
Src.Canvas.Handle, rs.Left, rs.Top, WS, hs, SRCCopy);
finally
Dest.Canvas.Unlock;
Src.Canvas.Unlock;
end;
Exit;
end;
if pf = pf24bit then
begin
bitspp := 24;
bytespp := 3;
end
else
begin
bitspp := 32;
bytespp := 4;
end;
bs := (Src.Width * bitspp + 31) and not 31;
bs := bs div 8; //BytesPerScanline Source
bd := (Dest.Width * bitspp + 31) and not 31;
bd := bd div 8; //BytesPerScanline Dest
if w < WS then //downsample
begin
//first make arrays of the skipsteps
SetLength(xsteps, w);
SetLength(ysteps, h);
intscale := round(WS / w * $10000);
x1 := 0;
x2 := (intscale + $7FFF) shr 16;
c := 0;
for i := 0 to w - 1 do
begin
xsteps[i] := (x2 - x1) * bytespp;
x1 := x2;
x2 := ((i + 2) * intscale + $7FFF) shr 16;
if i = w - 2 then
c := x1;
end;
xshift := min(max((WS - c) div 2, - rs.Left), Src.Width - rs.Right);
intscale := round(hs / h * $10000);
x1 := 0;
x2 := (intscale + $7FFF) shr 16;
c := 0;
for i := 0 to h - 1 do
begin
ysteps[i] := (x2 - x1) * bs;
x1 := x2;
x2 := ((i + 2) * intscale + $7FFF) shr 16;
if i = h - 2 then
c := x1;
end;
yshift := min(max((hs - c) div 2, - rs.Top), Src.Height - rs.Bottom);
if pf = pf24bit then
begin
Rows := @PRGBArray(Src.Scanline[rs.Top + yshift])^[rs.Left + xshift];
rowd := @PRGBArray(Dest.Scanline[rd.Top])^[rd.Left];
for y := 0 to h - 1 do
begin
ts := Rows;
td := rowd;
for x := 0 to w - 1 do
begin
pRGBTriple(td)^ := pRGBTriple(ts)^;
Inc(td, bytespp);
Inc(ts, xsteps[x]);
end;
Dec(rowd, bd);
Dec(Rows, ysteps[y]);
end;
end
else
begin
Rows := @PQuadArray(Src.Scanline[rs.Top + yshift])^[rs.Left + xshift];
rowd := @PQuadArray(Dest.Scanline[rd.Top])^[rd.Left];
for y := 0 to h - 1 do
begin
ts := Rows;
td := rowd;
for x := 0 to w - 1 do
begin
pRGBQuad(td)^ := pRGBQuad(ts)^;
Inc(td, bytespp);
Inc(ts, xsteps[x]);
end;
Dec(rowd, bd);
Dec(Rows, ysteps[y]);
end;
end;
end
else
begin
//first make arrays of the steps of uniform pixels
SetLength(xsteps, WS);
SetLength(ysteps, hs);
intscale := round(w / WS * $10000);
x1 := 0;
x2 := (intscale + $7FFF) shr 16;
c := 0;
for i := 0 to WS - 1 do
begin
xsteps[i] := x2 - x1;
x1 := x2;
x2 := ((i + 2) * intscale + $7FFF) shr 16;
if x2 > w then
x2 := w;
if i = WS - 1 then
c := x1;
end;
if c < w then //>is now not possible
begin
xshift := (w - c) div 2;
yshift := w - c - xshift;
xsteps[WS - 1] := xsteps[WS - 1] + xshift;
xsteps[0] := xsteps[0] + yshift;
end;
intscale := round(h / hs * $10000);
x1 := 0;
x2 := (intscale + $7FFF) shr 16;
c := 0;
for i := 0 to hs - 1 do
begin
ysteps[i] := (x2 - x1);
x1 := x2;
x2 := ((i + 2) * intscale + $7FFF) shr 16;
if x2 > h then
x2 := h;
if i = hs - 1 then
c := x1;
end;
if c < h then
begin
yshift := (h - c) div 2;
ysteps[hs - 1] := ysteps[hs - 1] + yshift;
yshift := h - c - yshift;
ysteps[0] := ysteps[0] + yshift;
end;
if pf = pf24bit then
begin
Rows := @PRGBArray(Src.Scanline[rs.Top])^[rs.Left];
rowd := @PRGBArray(Dest.Scanline[rd.Top])^[rd.Left];
for y := 0 to hs - 1 do
begin
for j := 1 to ysteps[y] do
begin
ts := Rows;
td := rowd;
for x := 0 to WS - 1 do
begin
for i := 1 to xsteps[x] do
begin
pRGBTriple(td)^ := pRGBTriple(ts)^;
Inc(td, bytespp);
end;
Inc(ts, bytespp);
end;
Dec(rowd, bd);
end;
Dec(Rows, bs);
end;
end
else
begin
Rows := @PQuadArray(Src.Scanline[rs.Top])^[rs.Left];
rowd := @PQuadArray(Dest.Scanline[rd.Top])^[rd.Left];
for y := 0 to hs - 1 do
begin
for j := 1 to ysteps[y] do
begin
ts := Rows;
td := rowd;
for x := 0 to WS - 1 do
begin
for i := 1 to xsteps[x] do
begin
pRGBQuad(td)^ := pRGBQuad(ts)^;
Inc(td, bytespp);
end;
Inc(ts, bytespp);
end;
Dec(rowd, bd);
end;
Dec(Rows, bs);
end;
end;
end;
end;
end.
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