delphi图象三旋转 (2001年4月2日).txt

delphi 编程技巧

delphi图象三旋转 (2001年4月2日) 

网友更新  分类:图形图象   作者:ice_ren  推荐:ice_ren   阅读次数:303  
(http://www.codesky.net)  

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将uv平面上的图象中的所有点相对坐标原点反时针旋转一定角度的变换表达式为：
|cos(a) sin(a) 0| 
[x,y,1]=[u,v,1]|-sin(a) cos(a) 0|
|0 0 1|
当a=90度(pi/2)时，上式简化为：
|0 1 0|
[x,y,1]=[u,v,1]|-1 0 0| 
|0 0 1|
即：x=-v,y=u
同理，我们也可以计算出旋转180度，270度的情况。
下面是用delphi实现的过程：
1、旋转90度操作
var
x,y:integer;
myimage:timage;
srcrect,dstrect:trect;
begin
myimage:=timage.Create(self);
myimage.Width:=image1.picture.Height;
myimage.height:=image1.picture.Width;
srcrect:=rect(0,0,image1.picture.width,image1.picture.height);
dstrect:=rect(0,0,image1.picture.height,image1.picture.width);
for x:=0 to image1.picture.Width do
begin
for y:=0 to image1.picture.Height do
begin
myimage.Canvas.Pixels[-y+image1.picture.Height,x]:=image1.Canvas.Pixels[x,y];
end;
progressbar1.Position:=x;
end;
myimage.Canvas.CopyRect(dstrect,myimage.Canvas,srcrect);
image1.Picture:=myimage.Picture;
myimage.Free;
end;
2、旋转180度
var
x,y:integer;
myimage:timage;
srcrect,dstrect:trect;
begin
myimage:=timage.Create(self);
myimage.Width:=image1.Picture.Width;
myimage.Height:=image1.Picture.Height;
srcrect:=rect(0,0,image1.picture.width,image1.picture.height);
dstrect:=rect(0,0,image1.picture.width,image1.picture.height);
for x:=0 to image1.Picture.Width do
begin
for y:=0 to image1.Picture.Height do
begin
myimage.Canvas.Pixels[-x+image1.Picture.Width,- y+image1.Picture.Height]:=image1.Canvas.Pixels[x,y];
end;
end;
myimage.Canvas.CopyRect(dstrect,myimage.canvas,srcrect);
image1.Picture:=myimage.Picture;
myimage.Free;
end;
3、旋转270度
var
x,y:integer;
myimage:timage;
srcrect,dstrect:trect;
begin
myimage:=timage.Create(self);
myimage.Width:=image1.Picture.height;
myimage.Height:=image1.Picture.width;
srcrect:=rect(0,0,image1.picture.width,image1.picture.height);
dstrect:=rect(0,0,image1.picture.height,image1.picture.width);
for x:=0 to image1.Picture.Width do
begin
for y:=0 to image1.Picture.Height do
begin
myimage.Canvas.Pixels[y,-x+image1.Picture.width]:=image1.Canvas.Pixels[x,y];
end;
progressbar1.Position:=x;
end;
myimage.Canvas.CopyRect(dstrect,myimage.canvas,srcrect);
image1.Picture:=myimage.Picture;
myimage.Free;
end;
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