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<h1>Source code for PIL.GimpGradientFile</h1><div class="highlight"><pre>
<span class="c">#</span>
<span class="c"># Python Imaging Library</span>
<span class="c"># $Id$</span>
<span class="c">#</span>
<span class="c"># stuff to read (and render) GIMP gradient files</span>
<span class="c">#</span>
<span class="c"># History:</span>
<span class="c"># 97-08-23 fl Created</span>
<span class="c">#</span>
<span class="c"># Copyright (c) Secret Labs AB 1997.</span>
<span class="c"># Copyright (c) Fredrik Lundh 1997.</span>
<span class="c">#</span>
<span class="c"># See the README file for information on usage and redistribution.</span>
<span class="c">#</span>
<span class="kn">from</span> <span class="nn">math</span> <span class="kn">import</span> <span class="n">pi</span><span class="p">,</span> <span class="n">log</span><span class="p">,</span> <span class="n">sin</span><span class="p">,</span> <span class="n">sqrt</span>
<span class="kn">from</span> <span class="nn">PIL._binary</span> <span class="kn">import</span> <span class="n">o8</span>
<span class="c"># --------------------------------------------------------------------</span>
<span class="c"># Stuff to translate curve segments to palette values (derived from</span>
<span class="c"># the corresponding code in GIMP, written by Federico Mena Quintero.</span>
<span class="c"># See the GIMP distribution for more information.)</span>
<span class="c">#</span>
<span class="n">EPSILON</span> <span class="o">=</span> <span class="mf">1e-10</span>
<div class="viewcode-block" id="linear"><a class="viewcode-back" href="../../PIL.html#PIL.GimpGradientFile.linear">[docs]</a><span class="k">def</span> <span class="nf">linear</span><span class="p">(</span><span class="n">middle</span><span class="p">,</span> <span class="n">pos</span><span class="p">):</span>
<span class="k">if</span> <span class="n">pos</span> <span class="o"><=</span> <span class="n">middle</span><span class="p">:</span>
<span class="k">if</span> <span class="n">middle</span> <span class="o"><</span> <span class="n">EPSILON</span><span class="p">:</span>
<span class="k">return</span> <span class="mf">0.0</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">return</span> <span class="mf">0.5</span> <span class="o">*</span> <span class="n">pos</span> <span class="o">/</span> <span class="n">middle</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">pos</span> <span class="o">=</span> <span class="n">pos</span> <span class="o">-</span> <span class="n">middle</span>
<span class="n">middle</span> <span class="o">=</span> <span class="mf">1.0</span> <span class="o">-</span> <span class="n">middle</span>
<span class="k">if</span> <span class="n">middle</span> <span class="o"><</span> <span class="n">EPSILON</span><span class="p">:</span>
<span class="k">return</span> <span class="mf">1.0</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">return</span> <span class="mf">0.5</span> <span class="o">+</span> <span class="mf">0.5</span> <span class="o">*</span> <span class="n">pos</span> <span class="o">/</span> <span class="n">middle</span>
</div>
<div class="viewcode-block" id="curved"><a class="viewcode-back" href="../../PIL.html#PIL.GimpGradientFile.curved">[docs]</a><span class="k">def</span> <span class="nf">curved</span><span class="p">(</span><span class="n">middle</span><span class="p">,</span> <span class="n">pos</span><span class="p">):</span>
<span class="k">return</span> <span class="n">pos</span> <span class="o">**</span> <span class="p">(</span><span class="n">log</span><span class="p">(</span><span class="mf">0.5</span><span class="p">)</span> <span class="o">/</span> <span class="n">log</span><span class="p">(</span><span class="nb">max</span><span class="p">(</span><span class="n">middle</span><span class="p">,</span> <span class="n">EPSILON</span><span class="p">)))</span>
</div>
<div class="viewcode-block" id="sine"><a class="viewcode-back" href="../../PIL.html#PIL.GimpGradientFile.sine">[docs]</a><span class="k">def</span> <span class="nf">sine</span><span class="p">(</span><span class="n">middle</span><span class="p">,</span> <span class="n">pos</span><span class="p">):</span>
<span class="k">return</span> <span class="p">(</span><span class="n">sin</span><span class="p">((</span><span class="o">-</span><span class="n">pi</span> <span class="o">/</span> <span class="mf">2.0</span><span class="p">)</span> <span class="o">+</span> <span class="n">pi</span> <span class="o">*</span> <span class="n">linear</span><span class="p">(</span><span class="n">middle</span><span class="p">,</span> <span class="n">pos</span><span class="p">))</span> <span class="o">+</span> <span class="mf">1.0</span><span class="p">)</span> <span class="o">/</span> <span class="mf">2.0</span>
</div>
<div class="viewcode-block" id="sphere_increasing"><a class="viewcode-back" href="../../PIL.html#PIL.GimpGradientFile.sphere_increasing">[docs]</a><span class="k">def</span> <span class="nf">sphere_increasing</span><span class="p">(</span><span class="n">middle</span><span class="p">,</span> <span class="n">pos</span><span class="p">):</span>
<span class="k">return</span> <span class="n">sqrt</span><span class="p">(</span><span class="mf">1.0</span> <span class="o">-</span> <span class="p">(</span><span class="n">linear</span><span class="p">(</span><span class="n">middle</span><span class="p">,</span> <span class="n">pos</span><span class="p">)</span> <span class="o">-</span> <span class="mf">1.0</span><span class="p">)</span> <span class="o">**</span> <span class="mi">2</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="sphere_decreasing"><a class="viewcode-back" href="../../PIL.html#PIL.GimpGradientFile.sphere_decreasing">[docs]</a><span class="k">def</span> <span class="nf">sphere_decreasing</span><span class="p">(</span><span class="n">middle</span><span class="p">,</span> <span class="n">pos</span><span class="p">):</span>
<span class="k">return</span> <span class="mf">1.0</span> <span class="o">-</span> <span class="n">sqrt</span><span class="p">(</span><span class="mf">1.0</span> <span class="o">-</span> <span class="n">linear</span><span class="p">(</span><span class="n">middle</span><span class="p">,</span> <span class="n">pos</span><span class="p">)</span> <span class="o">**</span> <span class="mi">2</span><span class="p">)</span>
</div>
<span class="n">SEGMENTS</span> <span class="o">=</span> <span class="p">[</span> <span class="n">linear</span><span class="p">,</span> <span class="n">curved</span><span class="p">,</span> <span class="n">sine</span><span class="p">,</span> <span class="n">sphere_increasing</span><span class="p">,</span> <span class="n">sphere_decreasing</span> <span class="p">]</span>
<div class="viewcode-block" id="GradientFile"><a class="viewcode-back" href="../../PIL.html#PIL.GimpGradientFile.GradientFile">[docs]</a><span class="k">class</span> <span class="nc">GradientFile</span><span class="p">:</span>
<span class="n">gradient</span> <span class="o">=</span> <span class="bp">None</span>
<div class="viewcode-block" id="GradientFile.getpalette"><a class="viewcode-back" href="../../PIL.html#PIL.GimpGradientFile.GradientFile.getpalette">[docs]</a> <span class="k">def</span> <span class="nf">getpalette</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">entries</span> <span class="o">=</span> <span class="mi">256</span><span class="p">):</span>
<span class="n">palette</span> <span class="o">=</span> <span class="p">[]</span>
<span class="n">ix</span> <span class="o">=</span> <span class="mi">0</span>
<span class="n">x0</span><span class="p">,</span> <span class="n">x1</span><span class="p">,</span> <span class="n">xm</span><span class="p">,</span> <span class="n">rgb0</span><span class="p">,</span> <span class="n">rgb1</span><span class="p">,</span> <span class="n">segment</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">gradient</span><span class="p">[</span><span class="n">ix</span><span class="p">]</span>
<span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="n">entries</span><span class="p">):</span>
<span class="n">x</span> <span class="o">=</span> <span class="n">i</span> <span class="o">/</span> <span class="nb">float</span><span class="p">(</span><span class="n">entries</span><span class="o">-</span><span class="mi">1</span><span class="p">)</span>
<span class="k">while</span> <span class="n">x1</span> <span class="o"><</span> <span class="n">x</span><span class="p">:</span>
<span class="n">ix</span> <span class="o">=</span> <span class="n">ix</span> <span class="o">+</span> <span class="mi">1</span>
<span class="n">x0</span><span class="p">,</span> <span class="n">x1</span><span class="p">,</span> <span class="n">xm</span><span class="p">,</span> <span class="n">rgb0</span><span class="p">,</span> <span class="n">rgb1</span><span class="p">,</span> <span class="n">segment</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">gradient</span><span class="p">[</span><span class="n">ix</span><span class="p">]</span>
<span class="n">w</span> <span class="o">=</span> <span class="n">x1</span> <span class="o">-</span> <span class="n">x0</span>
<span class="k">if</span> <span class="n">w</span> <span class="o"><</span> <span class="n">EPSILON</span><span class="p">:</span>
<span class="n">scale</span> <span class="o">=</span> <span class="n">segment</span><span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">scale</span> <span class="o">=</span> <span class="n">segment</span><span class="p">((</span><span class="n">xm</span> <span class="o">-</span> <span class="n">x0</span><span class="p">)</span> <span class="o">/</span> <span class="n">w</span><span class="p">,</span> <span class="p">(</span><span class="n">x</span> <span class="o">-</span> <span class="n">x0</span><span class="p">)</span> <span class="o">/</span> <span class="n">w</span><span class="p">)</span>
<span class="c"># expand to RGBA</span>
<span class="n">r</span> <span class="o">=</span> <span class="n">o8</span><span class="p">(</span><span class="nb">int</span><span class="p">(</span><span class="mi">255</span> <span class="o">*</span> <span class="p">((</span><span class="n">rgb1</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="o">-</span> <span class="n">rgb0</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span> <span class="o">*</span> <span class="n">scale</span> <span class="o">+</span> <span class="n">rgb0</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span> <span class="o">+</span> <span class="mf">0.5</span><span class="p">))</span>
<span class="n">g</span> <span class="o">=</span> <span class="n">o8</span><span class="p">(</span><span class="nb">int</span><span class="p">(</span><span class="mi">255</span> <span class="o">*</span> <span class="p">((</span><span class="n">rgb1</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span> <span class="o">-</span> <span class="n">rgb0</span><span class="p">[</span><span class="mi">1</span><span class="p">])</span> <span class="o">*</span> <span class="n">scale</span> <span class="o">+</span> <span class="n">rgb0</span><span class="p">[</span><span class="mi">1</span><span class="p">])</span> <span class="o">+</span> <span class="mf">0.5</span><span class="p">))</span>
<span class="n">b</span> <span class="o">=</span> <span class="n">o8</span><span class="p">(</span><span class="nb">int</span><span class="p">(</span><span class="mi">255</span> <span class="o">*</span> <span class="p">((</span><span class="n">rgb1</span><span class="p">[</span><span class="mi">2</span><span class="p">]</span> <span class="o">-</span> <span class="n">rgb0</span><span class="p">[</span><span class="mi">2</span><span class="p">])</span> <span class="o">*</span> <span class="n">scale</span> <span class="o">+</span> <span class="n">rgb0</span><span class="p">[</span><span class="mi">2</span><span class="p">])</span> <span class="o">+</span> <span class="mf">0.5</span><span class="p">))</span>
<span class="n">a</span> <span class="o">=</span> <span class="n">o8</span><span class="p">(</span><span class="nb">int</span><span class="p">(</span><span class="mi">255</span> <span class="o">*</span> <span class="p">((</span><span class="n">rgb1</span><span class="p">[</span><span class="mi">3</span><span class="p">]</span> <span class="o">-</span> <span class="n">rgb0</span><span class="p">[</span><span class="mi">3</span><span class="p">])</span> <span class="o">*</span> <span class="n">scale</span> <span class="o">+</span> <span class="n">rgb0</span><span class="p">[</span><span class="mi">3</span><span class="p">])</span> <span class="o">+</span> <span class="mf">0.5</span><span class="p">))</span>
<span class="c"># add to palette</span>
<span class="n">palette</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">r</span> <span class="o">+</span> <span class="n">g</span> <span class="o">+</span> <span class="n">b</span> <span class="o">+</span> <span class="n">a</span><span class="p">)</span>
<span class="k">return</span> <span class="n">b</span><span class="s">""</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">palette</span><span class="p">),</span> <span class="s">"RGBA"</span>
<span class="c">##</span>
<span class="c"># File handler for GIMP's gradient format.</span>
</div></div>
<div class="viewcode-block" id="GimpGradientFile"><a class="viewcode-back" href="../../PIL.html#PIL.GimpGradientFile.GimpGradientFile">[docs]</a><span class="k">class</span> <span class="nc">GimpGradientFile</span><span class="p">(</span><span class="n">GradientFile</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">fp</span><span class="p">):</span>
<span class="k">if</span> <span class="n">fp</span><span class="o">.</span><span class="n">readline</span><span class="p">()[:</span><span class="mi">13</span><span class="p">]</span> <span class="o">!=</span> <span class="n">b</span><span class="s">"GIMP Gradient"</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">SyntaxError</span><span class="p">(</span><span class="s">"not a GIMP gradient file"</span><span class="p">)</span>
<span class="n">count</span> <span class="o">=</span> <span class="nb">int</span><span class="p">(</span><span class="n">fp</span><span class="o">.</span><span class="n">readline</span><span class="p">())</span>
<span class="n">gradient</span> <span class="o">=</span> <span class="p">[]</span>
<span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="n">count</span><span class="p">):</span>
<span class="n">s</span> <span class="o">=</span> <span class="n">fp</span><span class="o">.</span><span class="n">readline</span><span class="p">()</span><span class="o">.</span><span class="n">split</span><span class="p">()</span>
<span class="n">w</span> <span class="o">=</span> <span class="p">[</span><span class="nb">float</span><span class="p">(</span><span class="n">x</span><span class="p">)</span> <span class="k">for</span> <span class="n">x</span> <span class="ow">in</span> <span class="n">s</span><span class="p">[:</span><span class="mi">11</span><span class="p">]]</span>
<span class="n">x0</span><span class="p">,</span> <span class="n">x1</span> <span class="o">=</span> <span class="n">w</span><span class="p">[</span><span class="mi">0</span><span class="p">],</span> <span class="n">w</span><span class="p">[</span><span class="mi">2</span><span class="p">]</span>
<span class="n">xm</span> <span class="o">=</span> <span class="n">w</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span>
<span class="n">rgb0</span> <span class="o">=</span> <span class="n">w</span><span class="p">[</span><span class="mi">3</span><span class="p">:</span><span class="mi">7</span><span class="p">]</span>
<span class="n">rgb1</span> <span class="o">=</span> <span class="n">w</span><span class="p">[</span><span class="mi">7</span><span class="p">:</span><span class="mi">11</span><span class="p">]</span>
<span class="n">segment</span> <span class="o">=</span> <span class="n">SEGMENTS</span><span class="p">[</span><span class="nb">int</span><span class="p">(</span><span class="n">s</span><span class="p">[</span><span class="mi">11</span><span class="p">])]</span>
<span class="n">cspace</span> <span class="o">=</span> <span class="nb">int</span><span class="p">(</span><span class="n">s</span><span class="p">[</span><span class="mi">12</span><span class="p">])</span>
<span class="k">if</span> <span class="n">cspace</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">IOError</span><span class="p">(</span><span class="s">"cannot handle HSV colour space"</span><span class="p">)</span>
<span class="n">gradient</span><span class="o">.</span><span class="n">append</span><span class="p">((</span><span class="n">x0</span><span class="p">,</span> <span class="n">x1</span><span class="p">,</span> <span class="n">xm</span><span class="p">,</span> <span class="n">rgb0</span><span class="p">,</span> <span class="n">rgb1</span><span class="p">,</span> <span class="n">segment</span><span class="p">))</span>
<span class="bp">self</span><span class="o">.</span><span class="n">gradient</span> <span class="o">=</span> <span class="n">gradient</span></div>
</pre></div>
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