TPNGImage help

TPNGImage

Converting from TBitmap to TPNGObject


TPNGObject provides flexibility by allowing to convert from a Bitmap file format to Portable Network Graphics format.
This is easily done like in the same way as any graphic class in delphi.
IMPORTANT: Always remember to add pngimage to the unit uses.

Converting from Windows bitmap file to PNG file
This method loads a bitmap and saves it using png format

procedure BitmapFileToPNG(const Source, Dest: String);
var
  Bitmap: TBitmap;
  PNG: TPNGObject;
begin
 
Bitmap := TBitmap.Create;
  PNG := TPNGObject.Create;
 
{In case something goes wrong, free booth Bitmap and PNG}
  try
   
Bitmap.LoadFromFile(Source);
   
PNG.Assign(Bitmap);    //Convert data into png
    PNG.SaveToFile(Dest);
  finally
   
Bitmap.Free;
    PNG.Free;
  end
end;

Converting from PNG file to Windows bitmap file
The above inverse. Loads a png and saves into a bitmap

procedure PNGFileToBitmap(const Source, Dest: String);
var
  Bitmap: TBitmap;
  PNG: TPNGObject;
begin
  PNG := TPNGObject.Create;
 
Bitmap := TBitmap.Create;
 
{In case something goes wrong, free booth PNG and Bitmap}
  try
   
PNG.LoadFromFile(Source);
   
Bitmap.Assign(PNG);    //Convert data into bitmap
    Bitmap.SaveToFile(Dest);
  finally
    PNG.Free;
   
Bitmap.Free;
  end
end;

Converting from TImage to PNG file
This method converts from TImage to PNG. It has full exception handling and allows
converting from file formats other than TBitmap (since they allow assigning to a TBitmap)

procedure TImageToPNG(Source: TImage; const Dest: String);
var
  PNG: TPNGObject;
  BMP: TBitmap;
begin
  PNG := TPNGObject.Create;

 
{In case something goes wrong, free PNG}
  try
   
//If the TImage contains a TBitmap, just assign from it
    if
Source.Picture.Graphic is TBitmap then
     
PNG.Assign(TBitmap(Source.Picture.Graphic))    //Convert bitmap data into png
    else begin

     
//Otherwise try to assign first to a TBimap
      BMP := TBitmap.Create;
      try
       
BMP.Assign(Source.Picture.Graphic);
       
PNG.Assign(BMP);
      finally
       
BMP.Free;
      end;

    end;

   
//Save to PNG format
   
PNG.SaveToFile(Dest);
  finally
    PNG.Free;
  end
end;