src/motif/colour.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/motif/colour.cpp
   3 // Purpose:     wxColour class
   4 // Author:      Julian Smart
   5 // Modified by:
   6 // Created:     17/09/98
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) Julian Smart
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 //// TODO: make wxColour a ref-counted object,
  13 //// so pixel values get shared.
  14
  15 // For compilers that support precompilation, includes "wx.h".
  16 #include "wx/wxprec.h"
  17
  18 #include "wx/colour.h"
  19
  20 #ifndef WX_PRECOMP
  21     #include "wx/app.h"
  22 #endif
  23
  24 #include "wx/gdicmn.h"
  25
  26 #ifdef __VMS__
  27 #pragma message disable nosimpint
  28 #endif
  29 #include <Xm/Xm.h>
  30 #ifdef __VMS__
  31 #pragma message enable nosimpint
  32 #endif
  33
  34 #include "wx/motif/private.h"
  35
  36 IMPLEMENT_DYNAMIC_CLASS(wxColour, wxObject)
  37
  38 // Colour
  39
  40 void wxColour::Init()
  41 {
  42     m_isInit = false;
  43     m_red =
  44     m_blue =
  45     m_green = 0;
  46     m_pixel = -1;
  47 }
  48
  49 wxColour::wxColour(const wxColour& col)
  50 {
  51     *this = col;
  52 }
  53
  54 wxColour& wxColour::operator =(const wxColour& col)
  55 {
  56     m_red = col.m_red;
  57     m_green = col.m_green;
  58     m_blue = col.m_blue;
  59     m_isInit = col.m_isInit;
  60     m_pixel = col.m_pixel;
  61     return *this;
  62 }
  63
  64 wxColour::~wxColour()
  65 {
  66 }
  67
  68 void wxColour::InitWith(unsigned char r, unsigned char g, unsigned char b)
  69 {
  70     m_red = r;
  71     m_green = g;
  72     m_blue = b;
  73     m_isInit = true;
  74     m_pixel = -1;
  75 }
  76
  77 // Allocate a colour, or nearest colour, using the given display.
  78 // If realloc is true, ignore the existing pixel, otherwise just return
  79 // the existing one.
  80 // Returns the old or allocated pixel.
  81
  82 // TODO: can this handle mono displays? If not, we should have an extra
  83 // flag to specify whether this should be black or white by default.
  84
  85 int wxColour::AllocColour(WXDisplay* display, bool realloc)
  86 {
  87     if ((m_pixel != -1) && !realloc)
  88         return m_pixel;
  89
  90     XColor color;
  91     color.red = (unsigned short) Red ();
  92     color.red |= (unsigned short)(color.red << 8);
  93     color.green = (unsigned short) Green ();
  94     color.green |= (unsigned short)(color.green << 8);
  95     color.blue = (unsigned short) Blue ();
  96     color.blue |= (unsigned short)(color.blue << 8);
  97
  98     color.flags = DoRed | DoGreen | DoBlue;
  99
 100     WXColormap cmap = wxTheApp->GetMainColormap(display);
 101
 102     if (!XAllocColor ((Display*) display, (Colormap) cmap, &color))
 103     {
 104         m_pixel = wxGetBestMatchingPixel((Display*) display, &color,(Colormap) cmap);
 105         return m_pixel;
 106     }
 107     else
 108     {
 109         m_pixel = (int) color.pixel;
 110         return m_pixel;
 111     }
 112 }
 113
 114 /*-------------------------------------------
 115 Markus Emmenegger <mege@iqe.ethz.ch>
 116 Find the pixel value with an assigned color closest to the desired color
 117 Used if color cell allocation fails
 118 As the returned pixel value may be in use by another application,
 119 the color might change anytime.
 120 But in many cases, that is still better than always using black.
 121 --
 122 Chris Breeze <chris@hel.co.uk>
 123 Improvements:
 124 1) More efficient calculation of RGB distance of colour cell from
 125 the desired colour. There is no need to take the sqrt of 'dist', and
 126 since we are only interested in the top 8-bits of R, G and B we
 127 can perform integer arithmetic.
 128 2) Attempt to allocate a read-only colour when a close match is found.
 129 A read-only colour will not change.
 130 3) Fall back to the closest match if no read-only colours are available.
 131
 132   Possible further improvements:
 133   1) Scan the lookup table and sort the colour cells in order of
 134   increasing
 135   distance from the desired colour. Then attempt to allocate a
 136   read-only
 137   colour starting from the nearest match.
 138   2) Linear RGB distance is not a particularly good method of colour
 139   matching
 140   (though it is quick). Converting the colour to HLS and then comparing
 141   may give better matching.
 142 -------------------------------------------*/
 143
 144 int wxGetBestMatchingPixel(Display *display, XColor *desiredColor, Colormap cmap)
 145 {
 146     if (cmap == (Colormap) NULL)
 147         cmap = (Colormap) wxTheApp->GetMainColormap(display);
 148
 149     int numPixVals = XDisplayCells(display, DefaultScreen (display));
 150     int mindist = 256 * 256 * 3;
 151     int bestpixel = (int) BlackPixel (display, DefaultScreen (display));
 152     int red = desiredColor->red >> 8;
 153     int green = desiredColor->green >> 8;
 154     int blue = desiredColor->blue >> 8;
 155     const int threshold = 2 * 2 * 3;    // allow an error of up to 2 in R,G & B
 156
 157     for (int pixelcount = 0; pixelcount < numPixVals; pixelcount++)
 158     {
 159         XColor matching_color;
 160         matching_color.pixel = pixelcount;
 161         XQueryColor(display,cmap,&matching_color);
 162
 163         int delta_red = red - (matching_color.red >> 8);
 164         int delta_green = green - (matching_color.green >> 8);
 165         int delta_blue = blue - (matching_color.blue >> 8);
 166
 167         int dist = delta_red * delta_red +
 168             delta_green * delta_green +
 169             delta_blue * delta_blue;
 170
 171         if (dist <= threshold)
 172         {
 173             // try to allocate a read-only colour...
 174             if (XAllocColor (display, cmap, &matching_color))
 175             {
 176                 return matching_color.pixel;
 177             }
 178         }
 179         if (dist < mindist)
 180         {
 181             bestpixel = pixelcount;
 182             mindist = dist;
 183         }
 184     }
 185     return bestpixel;
 186 }