Wrong gradient with dpi other than 72

[bczhc]

As the title says. 1.pdf is produced with dpi 72, and 2.pdf with 96, 3.pdf with 48. The gradient is shifted.

demo svg

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!-- Created with Inkscape (http://www.inkscape.org/) -->

<svg
   width="100mm"
   height="50mm"
   viewBox="0 0 377.95323 188.97662"
   version="1.1"
   id="svg1"
   xmlns:xlink="http://www.w3.org/1999/xlink"
   xmlns="http://www.w3.org/2000/svg"
   xmlns:svg="http://www.w3.org/2000/svg">
  <defs
     id="defs1">
    <linearGradient
       id="linearGradient8">
      <stop
         style="stop-color:#00ff09;stop-opacity:1;"
         offset="0"
         id="stop7" />
      <stop
         style="stop-color:#000cff;stop-opacity:1;"
         offset="1"
         id="stop8" />
    </linearGradient>
    <linearGradient
       id="linearGradient4">
      <stop
         style="stop-color:#00f7ff;stop-opacity:1;"
         offset="0"
         id="stop5" />
      <stop
         style="stop-color:#000cff;stop-opacity:1;"
         offset="1"
         id="stop6" />
    </linearGradient>
    <radialGradient
       xlink:href="#linearGradient4"
       id="radialGradient6"
       cx="188.97662"
       cy="94.488312"
       fx="188.97662"
       fy="94.488312"
       r="122.51537"
       gradientTransform="matrix(1,0,0,0.36743513,0,59.769984)"
       gradientUnits="userSpaceOnUse" />
    <linearGradient
       xlink:href="#linearGradient8"
       id="linearGradient7"
       x1="66.46125"
       y1="162.01299"
       x2="311.49197"
       y2="162.01299"
       gradientUnits="userSpaceOnUse" />
  </defs>
  <g
     id="layer1">
    <g
       id="g8"
       transform="translate(0,-22.508224)">
      <rect
         style="fill:url(#radialGradient6);fill-opacity:1;fill-rule:evenodd;stroke-width:0.264567;stroke-linecap:square;stroke-miterlimit:0;stroke-dasharray:0.264567, 0.264567;paint-order:stroke fill markers"
         id="rect1"
         width="245.03073"
         height="90.032898"
         x="66.46125"
         y="49.471859" />
      <rect
         style="fill:url(#linearGradient7);fill-opacity:1;fill-rule:evenodd;stroke-width:0.187077;stroke-linecap:square;stroke-miterlimit:0;stroke-dasharray:0.187077, 0.187077;paint-order:stroke fill markers"
         id="rect6"
         width="245.03073"
         height="45.016441"
         x="66.46125"
         y="139.50476" />
    </g>
  </g>
</svg>

[LaurenzV]

Thanks, I probably have a good idea why that is happening. Unfortunately, svg2pdf is currently pretty much unmaintained and has been replaced by krilla and krilla-svg (https://github.com/LaurenzV/krilla/). I plan on porting svg2pdf-cli to use krilla at some point, but I haven't gotten to it yet unfortunately.

[bczhc]

Thanks, I probably have a good idea why that is happening. Unfortunately, svg2pdf is currently pretty much unmaintained and has been replaced by krilla and krilla-svg (https://github.com/LaurenzV/krilla/). I plan on porting svg2pdf-cli to use krilla at some point, but I haven't gotten to it yet unfortunately.

That's cool! Tried it, and krilla was able to generate the correct gradient in other DPIs (specifically for my Inkscape svgs).

I just did these few changes on the svg.rs example code:

     let svg_size = Size::from_wh(svg_tree.size().width(), svg_tree.size().height()).unwrap();
+    const PDF_DPI: f32 = 72.0;
+    const INKSCAPE_SVG_DPI: f32 = 96.0;
+    let ratio = PDF_DPI / INKSCAPE_SVG_DPI;
+
+    let pdf_dots = (svg_size.width() * ratio, svg_size.height() * ratio);
+
     // Start a new page, with the same dimensions as the SVG.
-    let mut page = document.start_page_with(PageSettings::new(svg_size.width(), svg_size.height()));
+    let mut page = document.start_page_with(PageSettings::new(pdf_dots.0,pdf_dots.1));
     let mut surface = page.surface();
     // Draw the SVG.
-    surface.draw_svg(&svg_tree, svg_size, SvgSettings::default());
+    surface.draw_svg(&svg_tree, Size::from_wh(pdf_dots.0, pdf_dots.1).unwrap(), SvgSettings::default());
     surface.finish();
     page.finish();