1 | /* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
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2 | * Qwt Widget Library
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3 | * Copyright (C) 1997 Josef Wilgen
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4 | * Copyright (C) 2002 Uwe Rathmann
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5 | *
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6 | * This library is free software; you can redistribute it and/or
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7 | * modify it under the terms of the Qwt License, Version 1.0
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8 | *****************************************************************************/
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9 |
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10 | #include "qwt_color_map.h"
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11 | #include "qwt_math.h"
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12 | #include "qwt_interval.h"
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13 | #include <qnumeric.h>
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14 |
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15 | class QwtLinearColorMap::ColorStops
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16 | {
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17 | public:
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18 | ColorStops():
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19 | d_doAlpha( false )
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20 | {
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21 | d_stops.reserve( 256 );
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22 | }
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23 |
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24 | void insert( double pos, const QColor &color );
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25 | QRgb rgb( QwtLinearColorMap::Mode, double pos ) const;
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26 |
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27 | QVector<double> stops() const;
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28 |
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29 | private:
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30 |
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31 | class ColorStop
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32 | {
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33 | public:
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34 | ColorStop():
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35 | pos( 0.0 ),
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36 | rgb( 0 )
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37 | {
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38 | };
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39 |
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40 | ColorStop( double p, const QColor &c ):
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41 | pos( p ),
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42 | rgb( c.rgba() )
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43 | {
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44 | r = qRed( rgb );
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45 | g = qGreen( rgb );
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46 | b = qBlue( rgb );
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47 | a = qAlpha( rgb );
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48 |
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49 | /*
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50 | when mapping a value to rgb we will have to calcualate:
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51 | - const int v = int( ( s1.v0 + ratio * s1.vStep ) + 0.5 );
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52 |
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53 | Thus adding 0.5 ( for rounding ) can be done in advance
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54 | */
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55 | r0 = r + 0.5;
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56 | g0 = g + 0.5;
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57 | b0 = b + 0.5;
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58 | a0 = a + 0.5;
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59 |
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60 | rStep = gStep = bStep = aStep = 0.0;
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61 | posStep = 0.0;
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62 | }
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63 |
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64 | void updateSteps( const ColorStop &nextStop )
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65 | {
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66 | rStep = nextStop.r - r;
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67 | gStep = nextStop.g - g;
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68 | bStep = nextStop.b - b;
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69 | aStep = nextStop.a - a;
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70 | posStep = nextStop.pos - pos;
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71 | }
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72 |
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73 | double pos;
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74 | QRgb rgb;
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75 | int r, g, b, a;
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76 |
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77 | // precalculated values
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78 | double rStep, gStep, bStep, aStep;
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79 | double r0, g0, b0, a0;
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80 | double posStep;
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81 | };
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82 |
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83 | inline int findUpper( double pos ) const;
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84 | QVector<ColorStop> d_stops;
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85 | bool d_doAlpha;
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86 | };
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87 |
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88 | void QwtLinearColorMap::ColorStops::insert( double pos, const QColor &color )
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89 | {
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90 | // Lookups need to be very fast, insertions are not so important.
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91 | // Anyway, a balanced tree is what we need here. TODO ...
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92 |
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93 | if ( pos < 0.0 || pos > 1.0 )
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94 | return;
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95 |
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96 | int index;
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97 | if ( d_stops.size() == 0 )
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98 | {
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99 | index = 0;
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100 | d_stops.resize( 1 );
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101 | }
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102 | else
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103 | {
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104 | index = findUpper( pos );
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105 | if ( index == d_stops.size() ||
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106 | qAbs( d_stops[index].pos - pos ) >= 0.001 )
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107 | {
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108 | d_stops.resize( d_stops.size() + 1 );
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109 | for ( int i = d_stops.size() - 1; i > index; i-- )
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110 | d_stops[i] = d_stops[i-1];
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111 | }
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112 | }
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113 |
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114 | d_stops[index] = ColorStop( pos, color );
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115 | if ( color.alpha() != 255 )
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116 | d_doAlpha = true;
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117 |
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118 | if ( index > 0 )
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119 | d_stops[index-1].updateSteps( d_stops[index] );
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120 |
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121 | if ( index < d_stops.size() - 1 )
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122 | d_stops[index].updateSteps( d_stops[index+1] );
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123 | }
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124 |
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125 | inline QVector<double> QwtLinearColorMap::ColorStops::stops() const
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126 | {
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127 | QVector<double> positions( d_stops.size() );
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128 | for ( int i = 0; i < d_stops.size(); i++ )
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129 | positions[i] = d_stops[i].pos;
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130 | return positions;
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131 | }
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132 |
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133 | inline int QwtLinearColorMap::ColorStops::findUpper( double pos ) const
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134 | {
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135 | int index = 0;
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136 | int n = d_stops.size();
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137 |
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138 | const ColorStop *stops = d_stops.data();
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139 |
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140 | while ( n > 0 )
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141 | {
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142 | const int half = n >> 1;
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143 | const int middle = index + half;
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144 |
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145 | if ( stops[middle].pos <= pos )
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146 | {
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147 | index = middle + 1;
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148 | n -= half + 1;
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149 | }
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150 | else
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151 | n = half;
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152 | }
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153 |
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154 | return index;
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155 | }
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156 |
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157 | inline QRgb QwtLinearColorMap::ColorStops::rgb(
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158 | QwtLinearColorMap::Mode mode, double pos ) const
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159 | {
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160 | if ( pos <= 0.0 )
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161 | return d_stops[0].rgb;
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162 | if ( pos >= 1.0 )
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163 | return d_stops[ d_stops.size() - 1 ].rgb;
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164 |
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165 | const int index = findUpper( pos );
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166 | if ( mode == FixedColors )
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167 | {
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168 | return d_stops[index-1].rgb;
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169 | }
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170 | else
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171 | {
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172 | const ColorStop &s1 = d_stops[index-1];
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173 |
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174 | const double ratio = ( pos - s1.pos ) / ( s1.posStep );
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175 |
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176 | const int r = int( s1.r0 + ratio * s1.rStep );
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177 | const int g = int( s1.g0 + ratio * s1.gStep );
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178 | const int b = int( s1.b0 + ratio * s1.bStep );
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179 |
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180 | if ( d_doAlpha )
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181 | {
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182 | if ( s1.aStep )
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183 | {
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184 | const int a = int( s1.a0 + ratio * s1.aStep );
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185 | return qRgba( r, g, b, a );
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186 | }
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187 | else
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188 | {
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189 | return qRgba( r, g, b, s1.a );
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190 | }
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191 | }
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192 | else
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193 | {
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194 | return qRgb( r, g, b );
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195 | }
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196 | }
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197 | }
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198 |
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199 | //! Constructor
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200 | QwtColorMap::QwtColorMap( Format format ):
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201 | d_format( format )
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202 | {
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203 | }
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204 |
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205 | //! Destructor
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206 | QwtColorMap::~QwtColorMap()
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207 | {
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208 | }
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209 |
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210 | /*!
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211 | Build and return a color map of 256 colors
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212 |
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213 | The color table is needed for rendering indexed images in combination
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214 | with using colorIndex().
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215 |
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216 | \param interval Range for the values
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217 | \return A color table, that can be used for a QImage
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218 | */
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219 | QVector<QRgb> QwtColorMap::colorTable( const QwtInterval &interval ) const
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220 | {
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221 | QVector<QRgb> table( 256 );
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222 |
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223 | if ( interval.isValid() )
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224 | {
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225 | const double step = interval.width() / ( table.size() - 1 );
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226 | for ( int i = 0; i < table.size(); i++ )
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227 | table[i] = rgb( interval, interval.minValue() + step * i );
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228 | }
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229 |
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230 | return table;
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231 | }
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232 |
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233 | class QwtLinearColorMap::PrivateData
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234 | {
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235 | public:
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236 | ColorStops colorStops;
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237 | QwtLinearColorMap::Mode mode;
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238 | };
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239 |
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240 | /*!
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241 | Build a color map with two stops at 0.0 and 1.0. The color
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242 | at 0.0 is Qt::blue, at 1.0 it is Qt::yellow.
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243 |
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244 | \param format Preferred format of the color map
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245 | */
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246 | QwtLinearColorMap::QwtLinearColorMap( QwtColorMap::Format format ):
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247 | QwtColorMap( format )
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248 | {
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249 | d_data = new PrivateData;
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250 | d_data->mode = ScaledColors;
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251 |
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252 | setColorInterval( Qt::blue, Qt::yellow );
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253 | }
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254 |
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255 | /*!
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256 | Build a color map with two stops at 0.0 and 1.0.
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257 |
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258 | \param color1 Color used for the minimum value of the value interval
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259 | \param color2 Color used for the maximum value of the value interval
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260 | \param format Preferred format for the color map
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261 | */
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262 | QwtLinearColorMap::QwtLinearColorMap( const QColor &color1,
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263 | const QColor &color2, QwtColorMap::Format format ):
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264 | QwtColorMap( format )
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265 | {
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266 | d_data = new PrivateData;
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267 | d_data->mode = ScaledColors;
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268 | setColorInterval( color1, color2 );
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269 | }
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270 |
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271 | //! Destructor
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272 | QwtLinearColorMap::~QwtLinearColorMap()
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273 | {
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274 | delete d_data;
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275 | }
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276 |
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277 | /*!
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278 | \brief Set the mode of the color map
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279 |
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280 | FixedColors means the color is calculated from the next lower
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281 | color stop. ScaledColors means the color is calculated
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282 | by interpolating the colors of the adjacent stops.
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283 |
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284 | \sa mode()
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285 | */
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286 | void QwtLinearColorMap::setMode( Mode mode )
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287 | {
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288 | d_data->mode = mode;
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289 | }
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290 |
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291 | /*!
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292 | \return Mode of the color map
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293 | \sa setMode()
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294 | */
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295 | QwtLinearColorMap::Mode QwtLinearColorMap::mode() const
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296 | {
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297 | return d_data->mode;
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298 | }
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299 |
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300 | /*!
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301 | Set the color range
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302 |
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303 | Add stops at 0.0 and 1.0.
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304 |
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305 | \param color1 Color used for the minimum value of the value interval
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306 | \param color2 Color used for the maximum value of the value interval
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307 |
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308 | \sa color1(), color2()
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309 | */
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310 | void QwtLinearColorMap::setColorInterval(
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311 | const QColor &color1, const QColor &color2 )
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312 | {
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313 | d_data->colorStops = ColorStops();
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314 | d_data->colorStops.insert( 0.0, color1 );
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315 | d_data->colorStops.insert( 1.0, color2 );
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316 | }
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317 |
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318 | /*!
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319 | Add a color stop
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320 |
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321 | The value has to be in the range [0.0, 1.0].
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322 | F.e. a stop at position 17.0 for a range [10.0,20.0] must be
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323 | passed as: (17.0 - 10.0) / (20.0 - 10.0)
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324 |
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325 | \param value Value between [0.0, 1.0]
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326 | \param color Color stop
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327 | */
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328 | void QwtLinearColorMap::addColorStop( double value, const QColor& color )
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329 | {
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330 | if ( value >= 0.0 && value <= 1.0 )
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331 | d_data->colorStops.insert( value, color );
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332 | }
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333 |
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334 | /*!
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335 | \return Positions of color stops in increasing order
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336 | */
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337 | QVector<double> QwtLinearColorMap::colorStops() const
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338 | {
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339 | return d_data->colorStops.stops();
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340 | }
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341 |
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342 | /*!
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343 | \return the first color of the color range
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344 | \sa setColorInterval()
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345 | */
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346 | QColor QwtLinearColorMap::color1() const
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347 | {
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348 | return QColor( d_data->colorStops.rgb( d_data->mode, 0.0 ) );
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349 | }
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350 |
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351 | /*!
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352 | \return the second color of the color range
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353 | \sa setColorInterval()
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354 | */
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355 | QColor QwtLinearColorMap::color2() const
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356 | {
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357 | return QColor( d_data->colorStops.rgb( d_data->mode, 1.0 ) );
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358 | }
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359 |
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360 | /*!
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361 | Map a value of a given interval into a RGB value
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362 |
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363 | \param interval Range for all values
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364 | \param value Value to map into a RGB value
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365 |
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366 | \return RGB value for value
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367 | */
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368 | QRgb QwtLinearColorMap::rgb(
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369 | const QwtInterval &interval, double value ) const
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370 | {
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371 | if ( qIsNaN(value) )
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372 | return 0u;
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373 |
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374 | const double width = interval.width();
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375 | if ( width <= 0.0 )
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376 | return 0u;
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377 |
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378 | const double ratio = ( value - interval.minValue() ) / width;
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379 | return d_data->colorStops.rgb( d_data->mode, ratio );
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380 | }
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381 |
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382 | /*!
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383 | \brief Map a value of a given interval into a color index
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384 |
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385 | \param interval Range for all values
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386 | \param value Value to map into a color index
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387 |
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388 | \return Index, between 0 and 255
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389 | */
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390 | unsigned char QwtLinearColorMap::colorIndex(
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391 | const QwtInterval &interval, double value ) const
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392 | {
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393 | const double width = interval.width();
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394 |
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395 | if ( qIsNaN(value) || width <= 0.0 || value <= interval.minValue() )
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396 | return 0;
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397 |
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398 | if ( value >= interval.maxValue() )
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399 | return 255;
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400 |
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401 | const double ratio = ( value - interval.minValue() ) / width;
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402 |
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403 | unsigned char index;
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404 | if ( d_data->mode == FixedColors )
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405 | index = static_cast<unsigned char>( ratio * 255 ); // always floor
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406 | else
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407 | index = static_cast<unsigned char>( ratio * 255 + 0.5 );
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408 |
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409 | return index;
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410 | }
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411 |
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412 | class QwtAlphaColorMap::PrivateData
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413 | {
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414 | public:
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415 | QColor color;
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416 | QRgb rgb;
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417 | QRgb rgbMax;
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418 | };
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419 |
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420 |
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421 | /*!
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422 | Constructor
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423 | \param color Color of the map
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424 | */
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425 | QwtAlphaColorMap::QwtAlphaColorMap( const QColor &color ):
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426 | QwtColorMap( QwtColorMap::RGB )
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427 | {
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428 | d_data = new PrivateData;
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429 | setColor( color );
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430 | }
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431 |
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432 | //! Destructor
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433 | QwtAlphaColorMap::~QwtAlphaColorMap()
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434 | {
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435 | delete d_data;
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436 | }
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437 |
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438 | /*!
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439 | Set the color
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440 |
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441 | \param color Color
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442 | \sa color()
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443 | */
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444 | void QwtAlphaColorMap::setColor( const QColor &color )
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445 | {
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446 | d_data->color = color;
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447 | d_data->rgb = color.rgb() & qRgba( 255, 255, 255, 0 );
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448 | d_data->rgbMax = d_data->rgb | ( 255 << 24 );
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449 | }
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450 |
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451 | /*!
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452 | \return the color
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453 | \sa setColor()
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454 | */
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455 | QColor QwtAlphaColorMap::color() const
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456 | {
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457 | return d_data->color;
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458 | }
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459 |
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460 | /*!
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461 | \brief Map a value of a given interval into a alpha value
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462 |
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463 | alpha := (value - interval.minValue()) / interval.width();
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464 |
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465 | \param interval Range for all values
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466 | \param value Value to map into a RGB value
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467 | \return RGB value, with an alpha value
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468 | */
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469 | QRgb QwtAlphaColorMap::rgb( const QwtInterval &interval, double value ) const
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470 | {
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471 | if ( qIsNaN(value) )
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472 | return 0u;
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473 |
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474 | const double width = interval.width();
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475 | if ( width <= 0.0 )
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476 | return 0u;
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477 |
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478 | if ( value <= interval.minValue() )
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479 | return d_data->rgb;
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480 |
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481 | if ( value >= interval.maxValue() )
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482 | return d_data->rgbMax;
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483 |
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484 | const double ratio = ( value - interval.minValue() ) / width;
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485 | return d_data->rgb | ( qRound( 255 * ratio ) << 24 );
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486 | }
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487 |
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488 | /*!
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489 | Dummy function, needed to be implemented as it is pure virtual
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490 | in QwtColorMap. Color indices make no sense in combination with
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491 | an alpha channel.
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492 |
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493 | \return Always 0
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494 | */
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495 | unsigned char QwtAlphaColorMap::colorIndex(
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496 | const QwtInterval &, double ) const
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497 | {
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498 | return 0;
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499 | }
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