Percentages in patterns should be relative to the viewport of the <svg> they are defined in. Right now they are interpreted as relative to the viewport of the referencing shape element.
This could either mean somehow saving the viewport of each <svg> element (but when parsing the <pattern> the <svg> element it is defined in might not have been parsed yet), parsing all patterns in an initial pass (to an intermediate format) and then reference them in a second pass parsing all shape elements.
To test this, use the following svg:
<svg width="100" height="100">
<defs>
<pattern id="a" x="0" y="0" width="50%" height="50%" patternUnits="userSpaceOnUse">
<circle cx="25%" cy="25%" r="25%" stroke="none" fill="blue"/>
</pattern>
</defs>
<rect x="0" y="0" width="50" height="50" stroke="none" fill="url(#a)"/>
<svg x="50" y="50" width="50" height="50">
<rect x="0" y="0" width="50" height="50" stroke="none" fill="url(#a)"/>
</svg>
</svg>It should show two circles of the same size, and not one big one and a cluster of four small ones.
Percentages in patterns should be relative to the viewport of the
<svg>they are defined in. Right now they are interpreted as relative to the viewport of the referencing shape element.This could either mean somehow saving the viewport of each
<svg>element (but when parsing the<pattern>the<svg>element it is defined in might not have been parsed yet), parsing all patterns in an initial pass (to an intermediate format) and then reference them in a second pass parsing all shape elements.To test this, use the following svg:
It should show two circles of the same size, and not one big one and a cluster of four small ones.