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