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<div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno"> 1</span><span class="comment">//</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno"> 2</span><span class="comment">// Copyright 2014 Bill Gallafent</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno"> 3</span><span class="comment">//</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno"> 4</span><span class="comment">// Distributed under the Boost Software License, Version 1.0</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno"> 5</span><span class="comment">// See accompanying file LICENSE_1_0.txt or copy at</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno"> 6</span><span class="comment">// http://www.boost.org/LICENSE_1_0.txt</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno"> 7</span><span class="comment">//</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno"> 8</span><span class="preprocessor">#ifndef BOOST_GIL_PREMULTIPLY_HPP</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno"> 9</span><span class="preprocessor">#define BOOST_GIL_PREMULTIPLY_HPP</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno"> 10</span> </div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno"> 11</span><span class="preprocessor">#include &lt;boost/gil/rgba.hpp&gt;</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno"> 12</span><span class="preprocessor">#include &lt;boost/gil/detail/mp11.hpp&gt;</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno"> 13</span> </div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno"> 14</span><span class="preprocessor">#include &lt;boost/core/ignore_unused.hpp&gt;</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno"> 15</span> </div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno"> 16</span><span class="preprocessor">#include &lt;type_traits&gt;</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno"> 17</span> </div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno"> 18</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceboost.html">boost</a> { <span class="keyword">namespace </span>gil {</div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno"> 19</span> </div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno"> 20</span><span class="keyword">template</span> &lt;<span class="keyword">typename</span> SrcP, <span class="keyword">typename</span> DstP&gt;</div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno"> 21</span><span class="keyword">struct </span>channel_premultiply</div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno"> 22</span>{</div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno"> 23</span> channel_premultiply(SrcP <span class="keyword">const</span> &amp; src, DstP &amp; dst)</div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno"> 24</span> : src_(src), dst_(dst)</div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno"> 25</span> {}</div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno"> 26</span> </div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno"> 27</span> <span class="keyword">template</span> &lt;<span class="keyword">typename</span> Channel&gt;</div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno"> 28</span> <span class="keywordtype">void</span> operator()(Channel <span class="comment">/* channel */</span>)<span class="keyword"> const</span></div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno"> 29</span><span class="keyword"> </span>{</div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno"> 30</span> <span class="comment">// TODO: Explain why &#39;channel&#39; input parameter is not used, or used as tag only.</span></div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno"> 31</span> </div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno"> 32</span> <span class="comment">// @todo: need to do a &quot;channel_convert&quot; too, in case the channel types aren&#39;t the same?</span></div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno"> 33</span> <a class="code hl_function" href="group___color_base_algorithm_color.html#ga3d51123e3188e07cd11fd322ef9a3a03">get_color</a>(dst_, Channel()) = <a class="code hl_function" href="group___channel_multiply_algorithm.html#ga0ba61722109fe5a1246c04558160449e">channel_multiply</a>(<a class="code hl_function" href="group___color_base_algorithm_color.html#ga3d51123e3188e07cd11fd322ef9a3a03">get_color</a>(src_,Channel()), alpha_or_max(src_));</div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno"> 34</span> }</div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno"> 35</span> SrcP <span class="keyword">const</span> &amp; src_;</div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno"> 36</span> DstP &amp; dst_;</div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno"> 37</span>};</div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno"> 38</span> </div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno"> 39</span><span class="keyword">namespace </span>detail</div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno"> 40</span>{</div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno"> 41</span> <span class="keyword">template</span> &lt;<span class="keyword">typename</span> SrcP, <span class="keyword">typename</span> DstP&gt;</div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno"> 42</span> <span class="keywordtype">void</span> assign_alpha_if(std::true_type, SrcP <span class="keyword">const</span> &amp;src, DstP &amp;dst)</div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno"> 43</span> {</div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno"> 44</span> <a class="code hl_function" href="group___color_base_algorithm_color.html#ga3d51123e3188e07cd11fd322ef9a3a03">get_color</a>(dst,alpha_t()) = alpha_or_max(src);</div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno"> 45</span> }</div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno"> 46</span> </div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno"> 47</span> <span class="keyword">template</span> &lt;<span class="keyword">typename</span> SrcP, <span class="keyword">typename</span> DstP&gt;</div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno"> 48</span> <span class="keywordtype">void</span> assign_alpha_if(std::false_type, SrcP <span class="keyword">const</span>&amp; src, DstP&amp; dst)</div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno"> 49</span> {</div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno"> 50</span> <span class="comment">// nothing to do</span></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno"> 51</span> boost::ignore_unused(src);</div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno"> 52</span> boost::ignore_unused(dst);</div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno"> 53</span> }</div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno"> 54</span>}</div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno"> 55</span> </div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno"> 56</span><span class="keyword">struct </span>premultiply</div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno"> 57</span>{</div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno"> 58</span> <span class="keyword">template</span> &lt;<span class="keyword">typename</span> SrcP, <span class="keyword">typename</span> DstP&gt;</div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno"> 59</span> <span class="keywordtype">void</span> operator()(<span class="keyword">const</span> SrcP&amp; src, DstP&amp; dst)<span class="keyword"> const</span></div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno"> 60</span><span class="keyword"> </span>{</div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno"> 61</span> <span class="keyword">using </span>src_colour_space_t = <span class="keyword">typename</span> color_space_type&lt;SrcP&gt;::type;</div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno"> 62</span> <span class="keyword">using </span>dst_colour_space_t = <span class="keyword">typename</span> color_space_type&lt;DstP&gt;::type;</div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno"> 63</span> <span class="keyword">using </span>src_colour_channels = mp11::mp_remove&lt;src_colour_space_t, alpha_t&gt;;</div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno"> 64</span> </div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno"> 65</span> <span class="keyword">using </span>has_alpha_t = std::integral_constant&lt;bool, mp11::mp_contains&lt;dst_colour_space_t, alpha_t&gt;::value&gt;;</div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno"> 66</span> mp11::mp_for_each&lt;src_colour_channels&gt;(channel_premultiply&lt;SrcP, DstP&gt;(src, dst));</div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno"> 67</span> detail::assign_alpha_if(has_alpha_t(), src, dst);</div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno"> 68</span> }</div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno"> 69</span>};</div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno"> 70</span> </div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno"> 71</span><span class="keyword">template</span> &lt;<span class="keyword">typename</span> SrcConstRefP, <span class="comment">// const reference to the source pixel</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno"> 72</span> <span class="keyword">typename</span> DstP&gt; <span class="comment">// Destination pixel value (models PixelValueConcept)</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno"> 73</span><span class="keyword">class </span>premultiply_deref_fn</div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno"> 74</span>{</div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno"> 75</span><span class="keyword">public</span>:</div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno"> 76</span> <span class="keyword">using </span>const_t = premultiply_deref_fn&lt;SrcConstRefP, DstP&gt;;</div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno"> 77</span> <span class="keyword">using </span>value_type = DstP;</div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno"> 78</span> <span class="keyword">using </span>reference = value_type; <span class="comment">// read-only dereferencing</span></div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno"> 79</span> <span class="keyword">using </span>const_reference = <span class="keyword">const</span> value_type &amp;;</div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno"> 80</span> <span class="keyword">using </span>argument_type = SrcConstRefP;</div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno"> 81</span> <span class="keyword">using </span>result_type = reference;</div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno"> 82</span> <span class="keyword">static</span> <span class="keyword">constexpr</span> <span class="keywordtype">bool</span> is_mutable = <span class="keyword">false</span>;</div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno"> 83</span> </div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno"> 84</span> result_type operator()(argument_type srcP)<span class="keyword"> const</span></div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno"> 85</span><span class="keyword"> </span>{</div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno"> 86</span> result_type dstP;</div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno"> 87</span> premultiply()(srcP,dstP);</div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno"> 88</span> <span class="keywordflow">return</span> dstP;</div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno"> 89</span> }</div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno"> 90</span>};</div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno"> 91</span> </div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno"> 92</span><span class="keyword">template</span> &lt;<span class="keyword">typename</span> SrcView, <span class="keyword">typename</span> DstP&gt;</div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno"> 93</span><span class="keyword">struct </span>premultiplied_view_type</div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno"> 94</span>{</div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno"> 95</span><span class="keyword">private</span>:</div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno"> 96</span> <span class="keyword">using </span>src_pix_ref = <span class="keyword">typename</span> SrcView::const_t::reference; <span class="comment">// const reference to pixel in SrcView</span></div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno"> 97</span> <span class="keyword">using </span>deref_t = premultiply_deref_fn&lt;src_pix_ref, DstP&gt;; <span class="comment">// the dereference adaptor that performs color conversion</span></div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno"> 98</span> <span class="keyword">using </span>add_ref_t = <span class="keyword">typename</span> SrcView::template add_deref&lt;deref_t&gt;;</div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno"> 99</span><span class="keyword">public</span>:</div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno"> 100</span> <span class="keyword">using </span>type = <span class="keyword">typename</span> add_ref_t::type; <span class="comment">// the color converted view type</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno"> 101</span> <span class="keyword">static</span> type make(SrcView <span class="keyword">const</span>&amp; sv) { <span class="keywordflow">return</span> add_ref_t::make(sv, deref_t()); }</div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno"> 102</span>};</div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno"> 103</span> </div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno"> 104</span><span class="keyword">template</span> &lt;<span class="keyword">typename</span> DstP, <span class="keyword">typename</span> View&gt;</div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno"> 105</span><span class="keyword">inline</span> <span class="keyword">auto</span> premultiply_view(View <span class="keyword">const</span>&amp; src)</div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno"> 106</span> -&gt; <span class="keyword">typename</span> premultiplied_view_type&lt;View,DstP&gt;::type</div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno"> 107</span>{</div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno"> 108</span> <span class="keywordflow">return</span> premultiplied_view_type&lt;View,DstP&gt;::make(src);</div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno"> 109</span>}</div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno"> 110</span> </div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno"> 111</span>}} <span class="comment">// namespace boost::gil</span></div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno"> 112</span> </div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno"> 113</span><span class="preprocessor">#endif</span></div>
<div class="ttc" id="agroup___channel_multiply_algorithm_html_ga0ba61722109fe5a1246c04558160449e"><div class="ttname"><a href="group___channel_multiply_algorithm.html#ga0ba61722109fe5a1246c04558160449e">boost::gil::channel_multiply</a></div><div class="ttdeci">auto channel_multiply(Channel a, Channel b) -&gt; typename channel_traits&lt; Channel &gt;::value_type</div><div class="ttdoc">A function multiplying two channels. result = a * b / max_value.</div><div class="ttdef"><b>Definition</b> channel_algorithm.hpp:561</div></div>
<div class="ttc" id="agroup___color_base_algorithm_color_html_ga3d51123e3188e07cd11fd322ef9a3a03"><div class="ttname"><a href="group___color_base_algorithm_color.html#ga3d51123e3188e07cd11fd322ef9a3a03">boost::gil::get_color</a></div><div class="ttdeci">auto get_color(ColorBase &amp;cb, Color=Color()) -&gt; typename color_element_reference_type&lt; ColorBase, Color &gt;::type</div><div class="ttdoc">Mutable accessor to the element associated with a given color name.</div><div class="ttdef"><b>Definition</b> color_base_algorithm.hpp:190</div></div>
<div class="ttc" id="anamespaceboost_html"><div class="ttname"><a href="namespaceboost.html">boost</a></div><div class="ttdoc">defined(BOOST_NO_CXX17_HDR_MEMORY_RESOURCE)</div><div class="ttdef"><b>Definition</b> algorithm.hpp:36</div></div>
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