SVG linear gradients objectBoundingBox vs userSpaceOnUse

Question

I am making two gradients: one in objectBoundingBox units and another in userSpaceOnUse. The idea is to make them look the same. But somehow they are different. Here is the svg file.

<svg width="500" height="500" viewBox="0 0 500 500" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
    <defs>
        <linearGradient id="user-grad" gradientUnits="userSpaceOnUse" x1="0" y1="0" x2="200" y2="100">
          <stop stop-color="orange" offset="0"/>
          <stop stop-color="blue" offset="1"/>
        </linearGradient>
        <linearGradient id="box-grad" x1="0" y1="0" x2="1" y2="1">
          <stop stop-color="orange" offset="0"/>
          <stop stop-color="blue" offset="1"/>
        </linearGradient>
    </defs>
    <rect x="0" y="0" width="200" height="100" fill="url(#user-grad)"/>
    <rect x="250" y="0" width="200" height="100" fill="url(#box-grad)"/>    
</svg>

Here is what it looks like

Shouldn't they look the same?

score 14 · Accepted Answer · answered May 31 '18 at 12:46

Shouldn't they look the same?

No. When using object bounding box coordinates, you are basically transforming a 1x1 square onto your rectangle. So the 0 to 1 coordinates are stretched to fit the rectangle. Thus causing the gradient to stretch also.

If you want them to look the same, you would need to apply a gradientTransform, to your userSpaceOnUse one, that applies the equivalent stretch.

<svg width="500" height="500" viewBox="0 0 500 500" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
    <defs>
        <linearGradient id="user-grad" gradientUnits="userSpaceOnUse" x1="0" y1="0" x2="100" y2="100" gradientTransform="scale(2, 1)">
          <stop stop-color="orange" offset="0"/>
          <stop stop-color="blue" offset="1"/>
        </linearGradient>
        <linearGradient id="box-grad" x1="0" y1="0" x2="1" y2="1">
          <stop stop-color="orange" offset="0"/>
          <stop stop-color="blue" offset="1"/>
        </linearGradient>
    </defs>
    <rect x="0" y="0" width="200" height="100" fill="url(#user-grad)"/>
    <rect x="250" y="0" width="200" height="100" fill="url(#box-grad)"/>    
</svg>

SVG linear gradients objectBoundingBox vs userSpaceOnUse

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