Image2.Canvas.CopyRect(Image2.Canvas.ClipRect,Image1.Canvas,SrcRect);出错！！！

Question

我想在Image1上截取一部分到Image2上。
结果出错：Can only Modify an image if it contains a bitmap

Answer 1

提供一段代码给你参考：procedure TFrmDesktop.FixSize(const vFileName: String);
var
  vBitmap3: TBitmap;
  vImage: TImage;
begin
  try
    vImage := TImage.Create(self);
    vImage.Visible := False;
    vImage.AutoSize := true;
    vBitmap3 := TBitmap.Create;
    if CompareText(vExt, 'Bmp') = 0 then vImage.Picture.LoadFromFile(OpenDialog1.FileName);
    if CompareText(vExt, 'Jpg') = 0 then vImage.Picture.LoadFromFile(vFileName);
    if vImage.Picture.Bitmap.Height / vImage.Picture.Bitmap.Width > 0.75 then
    begin
      if vImage.Picture.Bitmap.Height >= ScreenY then
      begin
        vImage.Canvas.StretchDraw(Rect(0,0,round(vImage.Picture.Bitmap.Width * ScreenY/vImage.Picture.Bitmap.Height),ScreenY),vImage.Picture.Bitmap);
        vImage.Center := True;
        vBitmap3.Width := round(vImage.Picture.Bitmap.Width * ScreenY/vImage.Picture.Bitmap.Height);
        vBitmap3.Height := ScreenY;
        vBitmap3.Canvas.CopyRect(Rect(0,0,vBitmap3.Width,vBitmap3.Height), vImage.Canvas, Rect(0,0,round(vImage.Picture.Bitmap.Width * ScreenY/vImage.Picture.Bitmap.Height),ScreenY));
Image2.Canvas, Rect(0,0,Image2.Width,Image2.Height));
      end
      else
        vImage.Picture.Bitmap.SaveToFile(vFileName);
    end
    else if vImage.Picture.Bitmap.Height / vImage.Picture.Bitmap.Width < 0.75 then
    begin
      if vImage.Picture.Bitmap.Width >= ScreenX then
      begin
        vImage.Canvas.StretchDraw(Rect(0,0,ScreenX,round(vImage.Picture.Bitmap.Height * ScreenX/vImage.Picture.Bitmap.Width)),vImage.Picture.Bitmap);
        vImage.Center := True;
        vBitmap3.Height := round(vImage.Picture.Bitmap.Height * ScreenX/vImage.Picture.Bitmap.Width);
        vBitmap3.Width := ScreenX;
        vBitmap3.Canvas.CopyRect(Rect(0,0,vBitmap3.Width,vBitmap3.Height), vImage.Canvas, Rect(0, 0, ScreenX, round(vImage.Picture.Bitmap.Height * ScreenX/vImage.Picture.Bitmap.Width)));
        vBitmap3.SaveToFile(vFileName);
      end
      else
        vImage.Picture.Bitmap.SaveToFile(vFileName);
    end
    else
    begin
      if vImage.Picture.Bitmap.Height >= ScreenY then
      begin
        vImage.Canvas.StretchDraw(Rect(0,0,ScreenX,ScreenY),vImage.Picture.Bitmap);
        vImage.Center := True;
        vBitmap3.Width := ScreenX;
        vBitmap3.Height := ScreenY;
        vBitmap3.Canvas.CopyRect(Rect(0,0,vBitmap3.Width,vBitmap3.Height), vImage.Canvas, Rect(0,0,ScreenX,ScreenY));
        vBitmap3.SaveToFile(vFileName);
      end
      else
        vImage.Picture.Bitmap.SaveToFile(vFileName);
    end;
  finally
    vImage.free;
  end;
end;

Answer 2

估计你的Image1载入的不是BMP文件，要BMP才可以。

Answer 3

image只能载入bmp文件，如果是jpg文件要进行响应的转化。

Answer 4

同意sysu(死树) 和weibz0525(小虫) ，TCanvas只能对位图进行操作

Answer 5

谢谢各位。我的数码相机照的照片要进行处理后转化成Jpeg。已经收钱了。在此谢谢。