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 /* static */
  67 wxColour wxColour::CreateByName(const wxString& name)
  68 {
  69     wxColour col;
  70
  71     Display *dpy = wxGlobalDisplay();
  72     WXColormap colormap = wxTheApp->GetMainColormap( dpy );
  73     XColor xcol;
  74     if ( XParseColor( dpy, (Colormap)colormap, name.mb_str(), &xcol ) )
  75     {
  76         col.m_red = xcol.red & 0xff;
  77         col.m_green = xcol.green & 0xff;
  78         col.m_blue = xcol.blue & 0xff;
  79         col.m_isInit = TRUE;
  80         col.m_pixel = -1;
  81     }
  82
  83     return col;
  84 }
  85
  86 wxColour::~wxColour ()
  87 {
  88 }
  89
  90 void wxColour::Set (unsigned char r, unsigned char g, unsigned char b)
  91 {
  92     m_red = r;
  93     m_green = g;
  94     m_blue = b;
  95     m_isInit = TRUE;
  96     m_pixel = -1;
  97 }
  98
  99 // Allocate a colour, or nearest colour, using the given display.
 100 // If realloc is TRUE, ignore the existing pixel, otherwise just return
 101 // the existing one.
 102 // Returns the old or allocated pixel.
 103
 104 // TODO: can this handle mono displays? If not, we should have an extra
 105 // flag to specify whether this should be black or white by default.
 106
 107 int wxColour::AllocColour(WXDisplay* display, bool realloc)
 108 {
 109     if ((m_pixel != -1) && !realloc)
 110         return m_pixel;
 111
 112     XColor color;
 113     color.red = (unsigned short) Red ();
 114     color.red |= color.red << 8;
 115     color.green = (unsigned short) Green ();
 116     color.green |= color.green << 8;
 117     color.blue = (unsigned short) Blue ();
 118     color.blue |= color.blue << 8;
 119
 120     color.flags = DoRed | DoGreen | DoBlue;
 121
 122     WXColormap cmap = wxTheApp->GetMainColormap(display);
 123
 124     if (!XAllocColor ((Display*) display, (Colormap) cmap, &color))
 125     {
 126         m_pixel = wxGetBestMatchingPixel((Display*) display, &color,(Colormap) cmap);
 127         return m_pixel;
 128     }
 129     else
 130     {
 131         m_pixel = (int) color.pixel;
 132         return m_pixel;
 133     }
 134 }
 135
 136 /*-------------------------------------------
 137 Markus Emmenegger <mege@iqe.ethz.ch>
 138 Find the pixel value with an assigned color closest to the desired color
 139 Used if color cell allocation fails
 140 As the returned pixel value may be in use by another application,
 141 the color might change anytime.
 142 But in many cases, that is still better than always using black.
 143 --
 144 Chris Breeze <chris@hel.co.uk>
 145 Improvements:
 146 1) More efficient calculation of RGB distance of colour cell from
 147 the desired colour. There is no need to take the sqrt of 'dist', and
 148 since we are only interested in the top 8-bits of R, G and B we
 149 can perform integer arithmetic.
 150 2) Attempt to allocate a read-only colour when a close match is found.
 151 A read-only colour will not change.
 152 3) Fall back to the closest match if no read-only colours are available.
 153
 154   Possible further improvements:
 155   1) Scan the lookup table and sort the colour cells in order of
 156   increasing
 157   distance from the desired colour. Then attempt to allocate a
 158   read-only
 159   colour starting from the nearest match.
 160   2) Linear RGB distance is not a particularly good method of colour
 161   matching
 162   (though it is quick). Converting the colour to HLS and then comparing
 163   may give better matching.
 164 -------------------------------------------*/
 165
 166 int wxGetBestMatchingPixel(Display *display, XColor *desiredColor, Colormap cmap)
 167 {
 168     if (cmap == (Colormap) NULL)
 169         cmap = (Colormap) wxTheApp->GetMainColormap(display);
 170
 171     int numPixVals = XDisplayCells(display, DefaultScreen (display));
 172     int mindist = 256 * 256 * 3;
 173     int bestpixel = (int) BlackPixel (display, DefaultScreen (display));
 174     int red = desiredColor->red >> 8;
 175     int green = desiredColor->green >> 8;
 176     int blue = desiredColor->blue >> 8;
 177     const int threshold = 2 * 2 * 3;    // allow an error of up to 2 in R,G & B
 178
 179     for (int pixelcount = 0; pixelcount < numPixVals; pixelcount++)
 180     {
 181         XColor matching_color;
 182         matching_color.pixel = pixelcount;
 183         XQueryColor(display,cmap,&matching_color);
 184
 185         int delta_red = red - (matching_color.red >> 8);
 186         int delta_green = green - (matching_color.green >> 8);
 187         int delta_blue = blue - (matching_color.blue >> 8);
 188
 189         int dist = delta_red * delta_red +
 190             delta_green * delta_green +
 191             delta_blue * delta_blue;
 192
 193         if (dist <= threshold)
 194         {
 195             // try to allocate a read-only colour...
 196             if (XAllocColor (display, cmap, &matching_color))
 197             {
 198                 return matching_color.pixel;
 199             }
 200         }
 201         if (dist < mindist)
 202         {
 203             bestpixel = pixelcount;
 204             mindist = dist;
 205         }
 206     }
 207     return bestpixel;
 208 }