位图旋转后失真

位图旋转后失真

xiaong
晓雄
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可用分等级：乞丐
总技术分：455
总技术分排名：34898
结帖率：92.73%

发表于：2008-08-21 15:53:04 楼主

procedure TForm1.bmp_rotate(Srcbmp, DestBmp: Tbitmap; angle: extended);
var
c1x, c1y, c2x, c2y: integer;
p1x, p1y, p2x, p2y: integer;
radius, n: integer;
alpha: extended;
c0, c1, c2, c3: tcolor;
begin
if SrcBmp.Width > SrcBmp.Height then
begin
DestBmp.width := SrcBmp.Width;
DestBmp.height := SrcBmp.Width;
end
else
DestBmp.Width := SrcBmp.Height;
DestBmp.Height := SrcBmp.Height;
//将角度转换为PI值
angle := (angle / 180) * pi;
// 计算中心点，你可以修改它
c1x := SrcBmp.width div 2;
c1y := SrcBmp.height div 2;
c2x := DestBmp.width div 2;
c2y := DestBmp.height div 2;
// 步骤数值number
if c2x < c2y then
n := c2y
else
n := c2x;
dec(n, 1);
// 开始旋转
for p2x := 0 to n do
begin
for p2y := 0 to n do
begin
if p2x = 0 then
alpha := pi / 2
else
alpha := arctan2(p2y, p2x);
radius := round(sqrt((p2x * p2x) + (p2y * p2y)));
p1x := round(radius * cos(angle + alpha));
p1y := round(radius * sin(angle + alpha));

c0 := SrcBmp.canvas.pixels[c1x + p1x, c1y + p1y];
c1 := SrcBmp.canvas.pixels[c1x - p1x, c1y - p1y];
c2 := SrcBmp.canvas.pixels[c1x + p1y, c1y - p1x];
c3 := SrcBmp.canvas.pixels[c1x - p1y, c1y + p1x];

DestBmp.Canvas.pixels[c2x + p2x, c2y + p2y] := c0;
DestBmp.canvas.pixels[c2x - p2x, c2y - p2y] := c1;
DestBmp.canvas.pixels[c2x + p2y, c2y - p2x] := c2;
DestBmp.canvas.pixels[c2x - p2y, c2y + p2x] := c3;
end;
application.processmessages
end;
end;

这是在网上找的一段算法，但是出现很严重的失真，有没有好的办法避免？急！

问题点数：100 回复次数：3 修改删除举报引用回复

uses Gdiplus; ... var Image: TGpImage; Matrix: TGpMatrix; g: TGpGraphics; cp: TGpPointF; begin Image := TGpImage.Create('d:\1-2.jpg'); g := TGpGraphics.Create(Canvas.Handle); g.DrawImage(Image, 0, 0, Image.Width, Image.Height); Matrix := TGpMatrix.Create; cp.X := Image.Width / 2; cp.Y := Image.Height / 2; Matrix.Translate(Image.Width, 0); Matrix.RotateAt(90, cp); g.SetTransform(Matrix); g.DrawImage(Image, 0, 0, Image.Width, Image.Height); g.Free; Matrix.Free; Image.Free; end;