advice on handling vector graphs, svg in my case
lazarus / 39-Graphics

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Thaddy · 2025-04-15 07:30

What is the general opinion on the best way to handle vector graph
formats like svg in FPC?

Background is the cards discussion and I tested several solutions for
svg formats, but I still have to render the individual cards from the
cards tile in the background to reach acceptable performance on
somewhat slower hardware.

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zamtmn · 2025-04-15 08:49

You'll have to write it all yourself. I have only general
recommendations - OpenGL\Vulcan, tree-like data storage structures

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Thaddy · 2025-04-15 08:58

Not very helpful.
Of course not, something like this snippet works: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 uses 
BGRABitmap, BGRABitmapTypes; var  Bitmap: TBGRABitmap;begin  Bitmap :=
TBGRABitmap.Create;  try    Bitmap.LoadFromFile('example.svg'); //
Load your SVG file    Bitmap.Draw(Canvas, 0, 0, True);    // Draw it
on a canvas  finally    Bitmap.Free;  end;end;The question is if there
are more efficient options?

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zamtmn · 2025-04-15 09:06

For money yes http://delphihtmlcomponents.com/FileBrowser.zip
https://delphihtmlcomponents.com/MapView.zip

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Thaddy · 2025-04-15 11:14

OK, then I write it myself. Money is for difficult code, not for such
things.

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zamtmn · 2025-04-15 11:17

I'm going to upset you - vector graphics are quite difficult. But in
any case, we are waiting for your results.

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Lulu · 2025-04-15 18:37

Hi, I don't know if I understand well, but i post what I use to manage
svg file with BGRABitmap.

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 // return a
TBGRABitmap from an SVG file.// aWidth and aHeight = -1 => return an
image with original size as described in svg.// aWidth and aHeight <>
-1 => return a streched image that fit in the given rectangle (don't
keep aspect ratio).// Only aImageWidth = '-1' => returned image width
is computed from aHeight to keep aspect ratio.// Only aImageHeight =
'-1' => returned image height is computed from aWidth to keep aspect
ratio.// the drawing is centered in the returned bitmapfunction
LoadBitmapFromSVG(const aSVGFilename: string; aWidth, aHeight:
integer): TBGRABitmap;var svg: TBGRASVG;  FWHFactor, cw, ch:
single;begin  Result := NIL;  svg := TBGRASVG.Create( aSVGFileName ); 
try    cw := svg.WidthAsPixel;    ch := svg.HeightAsPixel;   
FWHFactor := cw/ch;     if (aWidth > -1) and (aHeight > -1) then
begin      // return a streched image that fit in the given rectangle
(don't keep aspect ratio).      Result := TBGRABitmap.Create(aWidth,
aHeight, BGRAPixelTransparent);      svg.StretchDraw(Result.Canvas2D,
0, 0, aWidth, aHeight, False);      exit;    end;     if (aWidth = -1)
and (aHeight = -1) then begin      // return an image with original
size as described in svg.      aWidth := Round(cw);      aHeight :=
Round(ch);    end    else    if aWidth = -1      then aWidth :=
round(aHeight*FWHFactor) // compute width to keep aspect ratio   
else    if aHeight = -1      then aHeight := round(aWidth/FWHFactor);
// compute height to keep aspect ratio     Result :=
TBGRABitmap.Create(aWidth, aHeight, BGRAPixelTransparent);   
svg.StretchDraw(Result.Canvas2D, 0, 0, aWidth, aHeight, False); 
finally    svg.Free;  end;end;

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Thaddy · 2025-04-16 08:07

@Lulu
That is very helpful, thanks a lot!
@zamtmn
I am a retired cs (erratic but knowledgable), I can do that.