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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 2019 Olzhas Zhumabek &lt;anonymous.from.applecity@gmail.com&gt;</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">// Use, modification and distribution are subject to the Boost Software License,</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno"> 5</span><span class="comment">// Version 1.0. (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_IMAGE_PROCESSING_SCALING_HPP</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno"> 9</span><span class="preprocessor">#define BOOST_GIL_IMAGE_PROCESSING_SCALING_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/image_view.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/rgb.hpp&gt;</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno"> 13</span><span class="preprocessor">#include &lt;boost/gil/pixel.hpp&gt;</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno"> 14</span><span class="preprocessor">#include &lt;boost/gil/image_processing/numeric.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="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="l00017" name="l00017"></a><span class="lineno"> 17</span> </div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno"> 36</span><span class="keyword">template</span> &lt;<span class="keyword">typename</span> ImageView&gt;</div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno"> 37</span><span class="keywordtype">void</span> lanczos_at(</div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno"> 38</span> ImageView input_view,</div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno"> 39</span> ImageView output_view,</div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno"> 40</span> <span class="keyword">typename</span> ImageView::x_coord_t source_x,</div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno"> 41</span> <span class="keyword">typename</span> ImageView::y_coord_t source_y,</div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno"> 42</span> <span class="keyword">typename</span> ImageView::x_coord_t target_x,</div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno"> 43</span> <span class="keyword">typename</span> ImageView::y_coord_t target_y,</div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno"> 44</span> std::ptrdiff_t a)</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> <span class="keyword">using </span>x_coord_t = <span class="keyword">typename</span> ImageView::x_coord_t;</div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno"> 47</span> <span class="keyword">using </span>y_coord_t = <span class="keyword">typename</span> ImageView::y_coord_t;</div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno"> 48</span> <span class="keyword">using </span>pixel_t = <span class="keyword">typename</span> std::remove_reference&lt;decltype(std::declval&lt;ImageView&gt;()(0, 0))&gt;::type;</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">// C++11 doesn&#39;t allow auto in lambdas</span></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno"> 51</span> <span class="keyword">using </span>channel_t = <span class="keyword">typename</span> std::remove_reference</div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno"> 52</span> &lt;</div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno"> 53</span> <span class="keyword">decltype</span>(std::declval&lt;pixel_t&gt;().at(std::integral_constant&lt;int, 0&gt;{}))</div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno"> 54</span> &gt;::type;</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> pixel_t result_pixel;</div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno"> 57</span> static_transform(result_pixel, result_pixel, [](channel_t) {</div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno"> 58</span> <span class="keywordflow">return</span> <span class="keyword">static_cast&lt;</span>channel_t<span class="keyword">&gt;</span>(0);</div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno"> 59</span> });</div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno"> 60</span> <span class="keyword">auto</span> x_zero = <span class="keyword">static_cast&lt;</span>x_coord_t<span class="keyword">&gt;</span>(0);</div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno"> 61</span> <span class="keyword">auto</span> x_one = <span class="keyword">static_cast&lt;</span>x_coord_t<span class="keyword">&gt;</span>(1);</div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno"> 62</span> <span class="keyword">auto</span> y_zero = <span class="keyword">static_cast&lt;</span>y_coord_t<span class="keyword">&gt;</span>(0);</div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno"> 63</span> <span class="keyword">auto</span> y_one = <span class="keyword">static_cast&lt;</span>y_coord_t<span class="keyword">&gt;</span>(1);</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="keywordflow">for</span> (y_coord_t y_i = (std::max)(source_y - <span class="keyword">static_cast&lt;</span>y_coord_t<span class="keyword">&gt;</span>(a) + y_one, y_zero);</div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno"> 66</span> y_i &lt;= (std::min)(source_y + static_cast&lt;y_coord_t&gt;(a), input_view.height() - y_one);</div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno"> 67</span> ++y_i)</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> <span class="keywordflow">for</span> (x_coord_t x_i = (std::max)(source_x - <span class="keyword">static_cast&lt;</span>x_coord_t<span class="keyword">&gt;</span>(a) + x_one, x_zero);</div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno"> 70</span> x_i &lt;= (std::min)(source_x + static_cast&lt;x_coord_t&gt;(a), input_view.width() - x_one);</div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno"> 71</span> ++x_i)</div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno"> 72</span> {</div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno"> 73</span> <span class="keywordtype">double</span> lanczos_response = <a class="code hl_function" href="group___image_processing_math.html#gae9f1ef23591e1b4a5d974090b3aef0c7">lanczos</a>(source_x - x_i, a) * <a class="code hl_function" href="group___image_processing_math.html#gae9f1ef23591e1b4a5d974090b3aef0c7">lanczos</a>(source_y - y_i, a);</div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno"> 74</span> <span class="keyword">auto</span> op = [lanczos_response](channel_t prev, channel_t next)</div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno"> 75</span> {</div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno"> 76</span> <span class="keywordflow">return</span> <span class="keyword">static_cast&lt;</span>channel_t<span class="keyword">&gt;</span>(prev + next * lanczos_response);</div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno"> 77</span> };</div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno"> 78</span> static_transform(result_pixel, input_view(source_x, source_y), result_pixel, op);</div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno"> 79</span> }</div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno"> 80</span> }</div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno"> 81</span> </div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno"> 82</span> output_view(target_x, target_y) = result_pixel;</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> </div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno"> 94</span><span class="keyword">template</span> &lt;<span class="keyword">typename</span> ImageView&gt;</div>
<div class="foldopen" id="foldopen00095" data-start="{" data-end="}">
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno"><a class="line" href="group___down_scaling_algorithms.html#ga3c46f2bebfe5add39863df37237d5dc9"> 95</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="group___down_scaling_algorithms.html#ga3c46f2bebfe5add39863df37237d5dc9">scale_lanczos</a>(ImageView input_view, ImageView output_view, std::ptrdiff_t a)</div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno"> 96</span>{</div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno"> 97</span> <span class="keywordtype">double</span> scale_x = (<span class="keyword">static_cast&lt;</span><span class="keywordtype">double</span><span class="keyword">&gt;</span>(output_view.width()))</div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno"> 98</span> / <span class="keyword">static_cast&lt;</span><span class="keywordtype">double</span><span class="keyword">&gt;</span>(input_view.width());</div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno"> 99</span> <span class="keywordtype">double</span> scale_y = (<span class="keyword">static_cast&lt;</span><span class="keywordtype">double</span><span class="keyword">&gt;</span>(output_view.height()))</div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno"> 100</span> / <span class="keyword">static_cast&lt;</span><span class="keywordtype">double</span><span class="keyword">&gt;</span>(input_view.height());</div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno"> 101</span> </div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno"> 102</span> <span class="keyword">using </span>x_coord_t = <span class="keyword">typename</span> ImageView::x_coord_t;</div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno"> 103</span> <span class="keyword">using </span>y_coord_t = <span class="keyword">typename</span> ImageView::y_coord_t;</div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno"> 104</span> <span class="keywordflow">for</span> (y_coord_t y = 0; y &lt; output_view.height(); ++y)</div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno"> 105</span> {</div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno"> 106</span> <span class="keywordflow">for</span> (x_coord_t x = 0; x &lt; output_view.width(); ++x)</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> lanczos_at(input_view, output_view, x / scale_x, y / scale_y, x, y, a);</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>}</div>
</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="comment">// namespace boost::gil</span></div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno"> 114</span> </div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno"> 115</span><span class="preprocessor">#endif</span></div>
<div class="ttc" id="agroup___down_scaling_algorithms_html_ga3c46f2bebfe5add39863df37237d5dc9"><div class="ttname"><a href="group___down_scaling_algorithms.html#ga3c46f2bebfe5add39863df37237d5dc9">boost::gil::scale_lanczos</a></div><div class="ttdeci">void scale_lanczos(ImageView input_view, ImageView output_view, std::ptrdiff_t a)</div><div class="ttdoc">Complete Lanczos algorithm.</div><div class="ttdef"><b>Definition</b> scaling.hpp:95</div></div>
<div class="ttc" id="agroup___image_processing_math_html_gae9f1ef23591e1b4a5d974090b3aef0c7"><div class="ttname"><a href="group___image_processing_math.html#gae9f1ef23591e1b4a5d974090b3aef0c7">boost::gil::lanczos</a></div><div class="ttdeci">double lanczos(double x, std::ptrdiff_t a)</div><div class="ttdoc">Lanczos response at point x.</div><div class="ttdef"><b>Definition</b> numeric.hpp:46</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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