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