找到了缩放的代码。
出自： 咸菜蛋炒饭
//保存JPEG的缩略图
procedure SavePic(SourceFileName,DescFileName: String);
const
MaxWidth = 200 ;
MaxHigth = 200 ;
var
jpg: TJPEGImage;
bmp: TBitmap;
SourceJpg: TJPEGImage;
Width, Height,tmpInt: Integer;
begin
try
bmp := TBitmap.Create;
SourceJpg := TJPEGImage.Create;
Jpg:= TJPEGImage.Create;
//读取源文件
SourceJpg.LoadFromFile(SourceFileName);
//计算缩小比例
if SourceJpg.Width >= SourceJpg.Height then
tmpInt := Round(SourceJpg.Width div MaxWidth)
else
tmpInt := Round(SourceJpg.Height div MaxHigth) ;
Width := SourceJpg.Width div tmpInt ;
Height := SourceJpg.Height div tmpInt ;
//缩小
bmp.Width := Width;
bmp.Height := Height;
bmp.PixelFormat := pf24bit;
bmp.Canvas.StretchDraw(Rect(0,0,Width,Height), SourceJpg);
//保存
jpg.Assign(bmp);
jpg.SaveToFile(DescFileName);
finally
bmp.Free;
jpg.Free;
SourceJpg.Free;
end;
end;
