Generating a Gradient Checkerboard

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Generating a Multi-Gradient Checkerboard

Consider the multi-gradient checkerboard pattern rendered in Figure 4.5.

Figure 4.5: A multi-gradient checkerboard pattern.

The SVG document in Listing 4.6 demonstrates how to use the SVG pattern element in order to generate a multi-gradient checkerboard pattern.

Listing 4.6 checkerBoardMultiGradient1.svg

<?xml version="1.0" encoding="iso-8859-1"?> <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20001102//EN"  "http://www.w3.org/TR/2000/CR-SVG-20001102/DTD/svg-20001102.dtd"> <svg width="800" height="400">   <defs>   <linearGradient       x1="0" y1="0" x2="40" y2="40"      gradientUnits="userSpaceOnUse">      <stop offset="0%"   style="stop-color:#FF0000"/>      <stop offset="100%" style="stop-color:#000000"/>   </linearGradient>   <linearGradient       x1="0" y1="0" x2="40" y2="40"      gradientUnits="userSpaceOnUse">      <stop offset="0%"   style="stop-color:#FFFF00"/>      <stop offset="100%" style="stop-color:#000000"/>   </linearGradient>   <pattern             width="80" height="80"            stroke-width="1"            patternUnits="userSpaceOnUse">      <rect fill="url(#gradientDefinition1)"            stroke="white" stroke-dasharray="1 1 1 1"            stroke-width="2"            x="0" y="0" width="40" height="40"/>      <rect fill="url(#gradientDefinition2)"            stroke="green" stroke-dasharray="4 4 4 4"            x="40" y="0" width="40" height="40"/>      <rect fill="url(#gradientDefinition2)"            stroke-width="2"            stroke="white" stroke-dasharray="8 8 8 8"            x="0" y="40" width="40" height="40"/>      <rect fill="url(#gradientDefinition1)"            stroke="#880088" stroke-dasharray="4 2 4 2"            stroke-width="4"            x="40" y="40" width="40" height="40"/>   </pattern>   </defs>   <rect      fill="url(#checkerPattern)"      style="stroke:red"      x="0" y="0" width="800" height="400"/> </svg>

Remarks

The SVG defs element in Listing 4.6 contains an SVG pattern element that has an id attribute with the value checkerPattern. This pattern consists of a 2x2 grid of squares with a color pattern that references two linear gradients with id values of gradientDefinition1 and gradientDefinition2, both of which define diagonal linear color gradients in order to create a quasi checkerboard pattern. The key point to observe is that both of these linear color gradients contain the following line:

x1="0" y1="0" x2="40" y2="40" 

Because of the preceding line, both linear gradients start from the point (0,0) and end at the point (40,40), thereby creating the diagonal linear gradient effect.

The SVG g element defines a rectangle with a width of 800 and a height of 400. This rectangle has a fill attribute that refers to the pattern checkerPattern defined in the SVG defs element by using the following syntax:

fill="url(#checkerPattern)"

If you double-click on this file, you will see a quasi-checkerboard pattern that is the result of using two linear gradients.

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