Resize Image 2

uses Windows, SysUtils, Graphics;

procedure ResizeImage(Src, Dst: TBitmap);
type
TRGBArray = array[Word] of TRGBTriple;
pRGBArray = ^TRGBArray;

var
x, y: Integer;
xP, yP: Integer;
xP2, yP2: Integer;
SrcLine1, SrcLine2: pRGBArray;
t3: Integer;
z, z2, iz2: Integer;
DstLine: pRGBArray;
DstGap: Integer;
w1, w2, w3, w4: Integer;
begin
Src.PixelFormat := pf24Bit;
Dst.PixelFormat := pf24Bit;

if (Src.Width = Dst.Width) and (Src.Height = Dst.Height) then
Dst.Assign(Src)
else
begin
DstLine := Dst.ScanLine[0];
DstGap := Integer(Dst.ScanLine[1]) - Integer(DstLine);

xP2 := MulDiv(pred(Src.Width), $10000, Dst.Width);
yP2 := MulDiv(pred(Src.Height), $10000, Dst.Height);
yP := 0;

for y := 0 to pred(Dst.Height) do
begin
xP := 0;

SrcLine1 := Src.ScanLine[yP shr 16];

if (yP shr 16 < pred(Src.Height)) then
SrcLine2 := Src.ScanLine[succ(yP shr 16)]
else
SrcLine2 := Src.ScanLine[yP shr 16];

z2 := succ(yP and $FFFF);
iz2 := succ((not yp) and $FFFF);
for x := 0 to pred(Dst.Width) do
begin
t3 := xP shr 16;
z := xP and $FFFF;
w2 := MulDiv(z, iz2, $10000);
w1 := iz2 - w2;
w4 := MulDiv(z, z2, $10000);
w3 := z2 - w4;
DstLine[x].rgbtRed := (SrcLine1[t3].rgbtRed * w1 +
SrcLine1[t3 + 1].rgbtRed * w2 +
SrcLine2[t3].rgbtRed * w3 + SrcLine2[t3 + 1].rgbtRed * w4) shr 16;
DstLine[x].rgbtGreen :=
(SrcLine1[t3].rgbtGreen * w1 + SrcLine1[t3 + 1].rgbtGreen * w2 +

SrcLine2[t3].rgbtGreen * w3 + SrcLine2[t3 + 1].rgbtGreen * w4) shr 16;
DstLine[x].rgbtBlue := (SrcLine1[t3].rgbtBlue * w1 +
SrcLine1[t3 + 1].rgbtBlue * w2 +
SrcLine2[t3].rgbtBlue * w3 +
SrcLine2[t3 + 1].rgbtBlue * w4) shr 16;
Inc(xP, xP2);
end;
Inc(yP, yP2);
DstLine := pRGBArray(Integer(DstLine) + DstGap);
end;
end;
end;