Question:
My application needs to display properties (width, height, color depth) of bitmaps in a selected directory. How can I obtain such properties?
Answer:
Bitmap files have two headers of type TBitmapinfoheader. Simply open the file and read them as shown in the example below.
procedure TForm1.Button1Click(Sender: TObject);
var
FileHeader: TBitmapfileheader;
InfoHeader: TBitmapinfoheader;
sBmpFile : TFilestream;
begin { TForm1.Button1Click }
sBmpFile := TFilestream.Create('C:\Bild.bmp', fmOpenRead);
sBmpFile.Read(FileHeader, SizeOf(FileHeader));
sBmpFile.Read(InfoHeader, SizeOf(InfoHeader));
sBmpFile.Free;
with ListBox1.Items do
begin
Clear;
Add('File Size: ' + IntToStr(FileHeader.bfSize));
Add('Width: ' + IntToStr(InfoHeader.biWidth));
Add('Height: ' + IntToStr(InfoHeader.biHeight));
Add('Color Depth: ' + IntToStr(InfoHeader.biBitCount)); // bits per color
// e.g. 8 means 2^8 = 256 colors
// 24 = true color (16 Mio colors)
end; { with ListBox1.Items }
end; { TForm1.Button1Click }