[BATIK-1285] offset should be set to 0 if this attribute is missing in stop tag

[bulenkov]

https://issues.apache.org/jira/browse/BATIK-1285

Many modern design tools like Figma and others do not put offset attribute when generating a svg image if offset equals 0. See https://www.w3.org/TR/SVG/pservers.html#GradientStopAttributes

Batik fails with exception while trying to read such svgs. Other programs successfully open these files.
The pull request sets offset to 0 when the attribute is missing.
Example of an icon:

<svg width="32" height="32" viewBox="0 0 32 32" fill="none" xmlns="http://www.w3.org/2000/svg">
<path d="M5.80005 22.2L1.30005 18.7L3.90005 13.9L7.80005 15.2L5.80005 22.2Z" fill="url(#paint0_linear)"/>
<path d="M31 9L30.5 26.4L18.9 31L12.6 26.9L31 9Z" fill="#087CFA"/>
<path d="M31 9L24.9 15L17.8 5.7L21.6 1.5L31 9Z" fill="url(#paint1_linear)"/>
<path d="M12.6 26.9L3.4 30.3L5.3 23.5L7.8 15.2L1 12.9L5.3 1L15.2 2.2L24.5 14L24.8 15L12.6 26.9Z" fill="url(#paint2_linear)"/>
<path d="M25 7H7V25H25V7Z" fill="url(#paint3_linear)"/>
<path d="M15.7 21.9H9V23H15.7V21.9Z" fill="white"/>
<path d="M12.63 10.49V9.25H9.26001V10.49H10.2V14.76H9.26001V15.99H12.63V14.76H11.68V10.49H12.63Z" fill="white"/>
<path d="M15.87 16.09C15.34 16.09 14.9 15.99 14.55 15.79C14.19 15.59 13.9 15.35 13.67 15.08L14.6 14.04C14.79 14.25 14.99 14.42 15.18 14.54C15.38 14.66 15.59 14.72 15.83 14.72C16.11 14.72 16.33 14.63 16.49 14.45C16.65 14.27 16.73 13.99 16.73 13.6V9.26001H18.25V13.67C18.25 14.07 18.2 14.42 18.09 14.72C17.98 15.02 17.82 15.27 17.62 15.47C17.41 15.68 17.16 15.83 16.86 15.94C16.56 16.04 16.23 16.09 15.87 16.09Z" fill="white"/>
<defs>
<linearGradient id="paint0_linear" x1="3.21765" y1="18.0954" x2="18.1487" y2="17.3385" gradientUnits="userSpaceOnUse">
<stop offset="0.0910927" stop-color="#FC801D"/>
<stop offset="0.2312" stop-color="#B07F61"/>
<stop offset="0.4086" stop-color="#577DB3"/>
<stop offset="0.5334" stop-color="#1E7CE6"/>
<stop offset="0.5934" stop-color="#087CFA"/>
</linearGradient>
<linearGradient id="paint1_linear" x1="27.5676" y1="16.8208" x2="22.4964" y2="1.6674" gradientUnits="userSpaceOnUse">
<stop stop-color="#FE2857"/>
<stop offset="0.0784" stop-color="#CB3979"/>
<stop offset="0.1601" stop-color="#9E4997"/>
<stop offset="0.2474" stop-color="#7557B2"/>
<stop offset="0.3392" stop-color="#5362C8"/>
<stop offset="0.4365" stop-color="#386CDA"/>
<stop offset="0.5414" stop-color="#2373E8"/>
<stop offset="0.6576" stop-color="#1478F2"/>
<stop offset="0.794" stop-color="#0B7BF8"/>
<stop offset="1" stop-color="#087CFA"/>
</linearGradient>
<linearGradient id="paint2_linear" x1="5.3142" y1="8.0695" x2="24.0899" y2="39.1256" gradientUnits="userSpaceOnUse">
<stop stop-color="#FE2857"/>
<stop offset="0.0800816" stop-color="#FE295F"/>
<stop offset="0.2065" stop-color="#FF2D76"/>
<stop offset="0.3034" stop-color="#FF318C"/>
<stop offset="0.3846" stop-color="#EA3896"/>
<stop offset="0.5532" stop-color="#B248AE"/>
<stop offset="0.7923" stop-color="#5A63D6"/>
<stop offset="1" stop-color="#087CFA"/>
</linearGradient>
<linearGradient id="paint3_linear" x1="15.976" y1="2.6251" x2="15.976" y2="18.7675" gradientUnits="userSpaceOnUse">
<stop offset="0.0842986" stop-color="#878585"/>
<stop offset="0.5377"/>
</linearGradient>
</defs>
</svg> 

[simonsteiner1984]

Can you add the jira id here

[bulenkov]

Sure, https://issues.apache.org/jira/browse/BATIK-1285

[framaglia]

This problem is still affecting the library, even more now with an increased usage of Figma.
Could someone please merge this PR or provide feedback to improve the solution?
Thank you!

[nikiJava]

Any updates?

@simonsteiner1984 Could you merge the fix please?

[simonsteiner1984]

Can you add a unit test

[nikiJava]

@simonsteiner1984 Sorry, but what kind of test is needed? We need to check what? Bug was reported three years ago and there is no any messages about unit test. I think if you texted about message early author of issue did it.

@bulenkov Excuse me, is it possible for you to continue to fix the bug?

[simonsteiner1984]

It would be a test run thru junit