Hello friends,

I'm trying to extract the color data and alpha from a PNG image. In PHP it is very easy to implement, but in FPC I don't know how to do it. I tried to do it via "chunk.data", "ZData" etc., but, without success.

Attached two files to test it. To test the PHP code run this command in your terminal:

php -f fpdf.php

The in FPC code is partially complete.

Thank you!

ps. can ZData be public?

Oops, files attached.

2013/2/5 silvioprog

Have you tried fpimage?

uses
  fpreadpng, fpimage;
var
  image: TFPCustomImage;
  reader: TFPCustomImageReader;
  x,y: integer;
  c: TFPColor;
begin
  Image := TFPMemoryImage.Create(0, 0);
  Reader := TFPReaderPNG.Create;
  Image.LoadFromFile(AFileName, Reader);
  for y:=0 to Image.Height-1 do
    for x:=0 to Image.Width-1 do begin
      c:=Image.Colors[x,y];
      writeln(c.Alpha,' ',c.Blue);
    end;
  //...

Mattias

2013/2/5 Mattias Gaertner

Yes, I tried it too, but, without success. :(

See my new code in attached. It generates the data, but with wrong content.

silvioprog hat am 5. Februar 2013 um 16:08 geschrieben:

c.Alpha, c.Blue are word, not byte.

BTW, reading and writing to/from Filestream should be done in chunks, not in bytes. That's dog slow.
Use a TMemoryStream as cache.

Mattias