src/motif/colour.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        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 #if defined(__GNUG__) && !defined(NO_GCC_PRAGMA)
  16 #pragma implementation "colour.h"
  17 #endif
  18
  19 #include "wx/gdicmn.h"
  20 #include "wx/colour.h"
  21 #include "wx/app.h"
  22
  23 #ifdef __VMS__
  24 #pragma message disable nosimpint
  25 #endif
  26 #include <Xm/Xm.h>
  27 #ifdef __VMS__
  28 #pragma message enable nosimpint
  29 #endif
  30
  31 #include "wx/motif/private.h"
  32
  33 IMPLEMENT_DYNAMIC_CLASS(wxColour, wxObject)
  34
  35 // Colour
  36
  37 wxColour::wxColour ()
  38 {
  39     m_isInit = FALSE;
  40     m_red =
  41     m_blue =
  42     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 void wxColour::InitFromName(const wxString& name)
  62 {
  63     *this = wxTheColourDatabase->Find(name);
  64 }
  65
  66 wxColour::~wxColour ()
  67 {
  68 }
  69
  70 void wxColour::Set (unsigned char r, unsigned char g, unsigned char b)
  71 {
  72     m_red = r;
  73     m_green = g;
  74     m_blue = b;
  75     m_isInit = TRUE;
  76     m_pixel = -1;
  77 }
  78
  79 // Allocate a colour, or nearest colour, using the given display.
  80 // If realloc is TRUE, ignore the existing pixel, otherwise just return
  81 // the existing one.
  82 // Returns the old or allocated pixel.
  83
  84 // TODO: can this handle mono displays? If not, we should have an extra
  85 // flag to specify whether this should be black or white by default.
  86
  87 int wxColour::AllocColour(WXDisplay* display, bool realloc)
  88 {
  89     if ((m_pixel != -1) && !realloc)
  90         return m_pixel;
  91
  92     XColor color;
  93     color.red = (unsigned short) Red ();
  94     color.red |= color.red << 8;
  95     color.green = (unsigned short) Green ();
  96     color.green |= color.green << 8;
  97     color.blue = (unsigned short) Blue ();
  98     color.blue |= color.blue << 8;
  99
 100     color.flags = DoRed | DoGreen | DoBlue;
 101
 102     WXColormap cmap = wxTheApp->GetMainColormap(display);
 103
 104     if (!XAllocColor ((Display*) display, (Colormap) cmap, &color))
 105     {
 106         m_pixel = wxGetBestMatchingPixel((Display*) display, &color,(Colormap) cmap);
 107         return m_pixel;
 108     }
 109     else
 110     {
 111         m_pixel = (int) color.pixel;
 112         return m_pixel;
 113     }
 114 }
 115
 116 /*-------------------------------------------
 117 Markus Emmenegger <mege@iqe.ethz.ch>
 118 Find the pixel value with an assigned color closest to the desired color
 119 Used if color cell allocation fails
 120 As the returned pixel value may be in use by another application,
 121 the color might change anytime.
 122 But in many cases, that is still better than always using black.
 123 --
 124 Chris Breeze <chris@hel.co.uk>
 125 Improvements:
 126 1) More efficient calculation of RGB distance of colour cell from
 127 the desired colour. There is no need to take the sqrt of 'dist', and
 128 since we are only interested in the top 8-bits of R, G and B we
 129 can perform integer arithmetic.
 130 2) Attempt to allocate a read-only colour when a close match is found.
 131 A read-only colour will not change.
 132 3) Fall back to the closest match if no read-only colours are available.
 133
 134   Possible further improvements:
 135   1) Scan the lookup table and sort the colour cells in order of
 136   increasing
 137   distance from the desired colour. Then attempt to allocate a
 138   read-only
 139   colour starting from the nearest match.
 140   2) Linear RGB distance is not a particularly good method of colour
 141   matching
 142   (though it is quick). Converting the colour to HLS and then comparing
 143   may give better matching.
 144 -------------------------------------------*/
 145
 146 int wxGetBestMatchingPixel(Display *display, XColor *desiredColor, Colormap cmap)
 147 {
 148     if (cmap == (Colormap) NULL)
 149         cmap = (Colormap) wxTheApp->GetMainColormap(display);
 150
 151     int numPixVals = XDisplayCells(display, DefaultScreen (display));
 152     int mindist = 256 * 256 * 3;
 153     int bestpixel = (int) BlackPixel (display, DefaultScreen (display));
 154     int red = desiredColor->red >> 8;
 155     int green = desiredColor->green >> 8;
 156     int blue = desiredColor->blue >> 8;
 157     const int threshold = 2 * 2 * 3;    // allow an error of up to 2 in R,G & B
 158
 159     for (int pixelcount = 0; pixelcount < numPixVals; pixelcount++)
 160     {
 161         XColor matching_color;
 162         matching_color.pixel = pixelcount;
 163         XQueryColor(display,cmap,&matching_color);
 164
 165         int delta_red = red - (matching_color.red >> 8);
 166         int delta_green = green - (matching_color.green >> 8);
 167         int delta_blue = blue - (matching_color.blue >> 8);
 168
 169         int dist = delta_red * delta_red +
 170             delta_green * delta_green +
 171             delta_blue * delta_blue;
 172
 173         if (dist <= threshold)
 174         {
 175             // try to allocate a read-only colour...
 176             if (XAllocColor (display, cmap, &matching_color))
 177             {
 178                 return matching_color.pixel;
 179             }
 180         }
 181         if (dist < mindist)
 182         {
 183             bestpixel = pixelcount;
 184             mindist = dist;
 185         }
 186     }
 187     return bestpixel;
 188 }