More info for PTCGraph users - bitmap data layout
lazarus / 39-Graphics

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TBMan · 2025-11-25 04:21

I guess I live under a rock, but I took the time tonight to figure out
how ptcgraph (on a windows system) stores the bitmap for getimage and
put image.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
typeTPackedsprite= packed record      width,height,      extra:dword; 
    colors:array of word;    end;                            
  varworkingbitmap :pointer = NIL; // and assuming you set the sprite
to the size you want and the colors is set to your imagedata...//  You
could probably use a multi dimensional array also, but I didn't work
with that procedure namehere(x,y:integer;sprite:TPackedSprite);beginif
workingbitmap = nil then  begin     sz :=
imagesize(0,0,sprite.width-1,sprite.height-1);   
 getmem(Workingbitmap,sz);   
 getimage(0,0,sprite.width-1,sprite.height-1,Workingbitmap^);  end; mo
ve(sprite.colors,pointer(PtrUint(Workingbitmap)+4*sizeof(dword)-
sizeof(word)*2)^, (sprite.height*sprite.width)*sizeof(word));putimage(
x,y,workingbitmap^,0);     end; 
So what I do is use the workingbitmap through the app without
allocating memory everytime I want to use it. I will just freemem the
image at the end of the app. (I make the sz variable global);

I was using this to display my playing cards:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i index :=
0;for r := 0 to sprite.height-1 do  for c := 0 to sprite.width-1 do  
 begin        putpixel(x+c,y+r,sprite.colors[index]);       
inc(index);end; 
Which is more than 10 times slower than using the putimage example
above.