我必须从
XML文件加载一个图像.
XML文件中没有关于图像是JPG / GIF / BMP的信息.加载图像后,我需要将其转换为Bitmap.
有没有人知道如何将图像转换为Bitmap而不知道实际的文件格式？我正在使用Delphi 2007/2009
谢谢.
解决方法
Delphi 2009内置支持JPEG,BMP,GIF和PNG.
对于早期版本的Delphi,您可能需要找到PNG和GIF的第三方实现,但在Delphi 2009中,您只需将Jpeg,pngimage和GIFImg单元添加到您的uses子句中即可.
如果文件具有扩展名,则可以使用以下代码,如其他人所述,TPicture.LoadFromFile查看继承的类注册的扩展名,以确定要加载的映像.
uses
Graphics,Jpeg,pngimage,GIFImg;
procedure TForm1.Button1Click(Sender: TObject);
var
Picture: TPicture;
Bitmap: TBitmap;
begin
Picture := TPicture.Create;
try
Picture.LoadFromFile('C:\imagedata.dat');
Bitmap := TBitmap.Create;
try
Bitmap.Width := Picture.Width;
Bitmap.Height := Picture.Height;
Bitmap.Canvas.Draw(0,Picture.Graphic);
Bitmap.SaveToFile('C:\test.bmp');
finally
Bitmap.Free;
end;
finally
Picture.Free;
end;
end;
如果文件扩展名不知道,一个方法是查看前几个字节来确定图像类型.
procedure DetectImage(const InputFileName: string; BM: TBitmap);
var
FS: TFileStream;
FirstBytes: AnsiString;
Graphic: TGraphic;
begin
Graphic := nil;
FS := TFileStream.Create(InputFileName,fmOpenRead);
try
SetLength(FirstBytes,8);
FS.Read(FirstBytes[1],8);
if Copy(FirstBytes,1,2) = 'BM' then
begin
Graphic := TBitmap.Create;
end else
if FirstBytes = #137'PNG'#13#10#26#10 then
begin
Graphic := TPngImage.Create;
end else
if Copy(FirstBytes,3) = 'GIF' then
begin
Graphic := TGIFImage.Create;
end else
if Copy(FirstBytes,2) = #$FF#$D8 then
begin
Graphic := TJPEGImage.Create;
end;
if Assigned(Graphic) then
begin
try
FS.Seek(0,soFromBeginning);
Graphic.LoadFromStream(FS);
BM.Assign(Graphic);
except
end;
Graphic.Free;
end;
finally
FS.Free;
end;
end;