[SOLVED] How do deal with "Warning: Symbol "ScanLine" is not portable"

[TTL]

Hello,
I found a way to improve the performance of my code using scanline, but now I get a warning about missing portability. Are there any information available under which circumstances my code might fail? And is there a way to use my slower code as fallbacks for such platforms like using some {$IfDef <platform>}

Snippet from the slow code (Xorg uses 90% CPU, and my application 20% while executing):

Code: Pascal  [Select][+][-]

1.       sourcedata := obj.FirstChild.FirstChild.NodeValue;
2.       InputStream := TStringStream.Create(sourcedata);
3.       Decoder := TBase64DecodingStream.Create(InputStream);
4.       readerPicture := TPortableNetworkGraphic.Create;
5.       readerPicture.LoadFromStream(Decoder);
6.       inputmaxX := readerPicture.Width;
7.       inputmaxY := readerPicture.Height;
8.       wptr := 0;
9.       for y := 0 to (py-1) do begin
10.         for x := 0 to (px-1) do begin
11.           if (x < sx) and (y < sy) and (x < inputmaxX) and (y < inputmaxY) then begin
12.             tempdata[wptr] := readerPicture.Canvas.pixels[x, y]; //more than 10x slower
13.           end else begin //source image is smaller than target image -> fill with zeros
14.             tempdata[wptr] := 0;
15.           end;
16.           inc(wptr);
17.           if (wptr >= maxmem) then begin
18.             showmessage('Error, Image' +getnodeident(obj)+ ' too big');
19.             break;
20.           end;
21.         end;
22.         if (wptr >= maxmem) then begin
23.           break;
24.         end;
25.       end;
26.  

And ~28x faster (when running multiple instances at the same time):

Code: Pascal  [Select][+][-]

1.       sourcedata := obj.FirstChild.FirstChild.NodeValue;
2.       InputStream := TStringStream.Create(sourcedata);
3.       Decoder := TBase64DecodingStream.Create(InputStream);
4.       readerPicture := TPortableNetworkGraphic.Create;
5.       readerPicture.LoadFromStream(Decoder);
6.       inputmaxX := readerPicture.Width;
7.       inputmaxY := readerPicture.Height;
8.       wptr := 0;
9.       for y := 0 to (py-1) do begin
10.         if (y < inputmaxY) then begin
11.           ScanData := readerPicture.ScanLine[y];
12.         end;
13.         for x := 0 to (px-1) do begin
14.           if (x < sx) and (y < sy) and (x < inputmaxX) and (y < inputmaxY) then begin
15.             if (scanData <> nil) then begin
16.               r := ScanData^.rgbRed;
17.               g := ScanData^.rgbGreen;
18.               b := ScanData^.rgbBlue;
19.               inc(ScanData);
20.               tempdata[wptr] := (b shl 16) or (g shl 8) or r;
21.             end else begin //fallback
22.               tempdata[wptr] := readerPicture.Canvas.pixels[x, y]; //more than 10x slower
23.             end;
24.           end else begin //source image is smaller than target image -> fill with zeros
25.             tempdata[wptr] := 0;
26.           end;
27.           inc(wptr);
28.           if (wptr >= maxmem) then begin
29.             showmessage('Error, Image' +getnodeident(obj)+ ' too big');
30.             break;
31.           end;
32.         end;
33.         if (wptr >= maxmem) then begin
34.           break;
35.         end;
36.       end;
37.  

[jamie]

The Tbitmap has a RasterImge .. RawImage..

The RawImage is direct access to the memory

Using GetLinePoitner or something like that is the same as Scanline.
https://wiki.freepascal.org/Developing_with_Graphics

[TTL]

Thanks for pointing me to the differences between native and non native image classes.
As I dont want to show the result on a screen anyway (at least not on the image processing computer), I think I should only use the non native classes. By more or less try and error (I found an example how to connect a TLazReaderXPM in the source of intfgraphics.pas), I managed to get pixel Data, but the colors dont fit. It seems like lRawImage.Description. changes the format - at least I can change the image to black/white there. So which format should I use? Which format does TLazReaderPNG deliver?

Code: Pascal  [Select][+][-]

1.  
2.     pngConverter: TLazReaderPNG;
3.     t: TLazIntfImage;
4.     lRawImage: TRawImage;  
5.  
6. ...
7.  
8.       sourcedata := obj.FirstChild.FirstChild.NodeValue;
9.       InputStream := TStringStream.Create(sourcedata);
10.       Decoder := TBase64DecodingStream.Create(InputStream);
11.       pngConverter := TLazReaderPNG.Create;
12.       t := TLazIntfImage.Create(0,0);
13.       lRawImage.Init;
14.       lRawImage.Description.Init_BPP24_B8G8R8_BIO_TTB(0, 0);
15.       lRawImage.CreateData(True);
16.       t.SetRawImage(lRawImage);
17.       t.LoadFromStream(Decoder, pngConverter);
18.       inputmaxX := t.Width;
19.       inputmaxY := t.height;
20.  
21. ....
22.  
23.             r := t.Colors[x, y].red;
24.             g := t.Colors[x, y].green;
25.             b := t.Colors[x, y].blue;
26.             temppixel := (b shl 16) or (g shl 8) or r;
27.             tempdata[wptr] := temppixel;
28.  
29.  

[winni]

Hi!
I don't quiet understand what you want to achieve.

You get the picture data from a base64 stream. And then??

Save it to a file ? Display it on the screen?

Write a little about it.

Winni

[jamie]

I too am not sure what you really want but!

TPicture will let you do all sorts of things with files and streams and it supports PNG, JPG etc...

[TTL]

Today i found my error. t.Colors[x, y].red; gives me a 16bit value, but I expected 8.
So with

Code: Pascal  [Select][+][-]

1.             tempColor := internalImage.Colors[x, y];
2.             r := tempColor.red shr 8;
3.             g := tempColor.green shr 8;
4.             b := tempColor.blue shr 8;
5.  

its now working without warnings, no pointer usage, proper colors and satisfying speed. 

I am still wondering what the different type of image formats are meaning:
https://lazarus-ccr.sourceforge.io/docs/lazutils/graphtype/trawimagedescription-3.html
There is no description. I can only guess R, G, B are the number of used bits for each color and A is transparency. But M1 and BIO? Whats the difference?

I am using the data later to further process them to different image formats and then write them to a binary which is finally flashed into a microcontroller. If you are curious: https://sourceforge.net/projects/menudesigner/