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 // For compilers that support precompilation, includes "wx.h".
  16 #include "wx/wxprec.h"
  17
  18 #include "wx/gdicmn.h"
  19 #include "wx/colour.h"
  20 #include "wx/app.h"
  21
  22 #ifdef __VMS__
  23 #pragma message disable nosimpint
  24 #endif
  25 #include <Xm/Xm.h>
  26 #ifdef __VMS__
  27 #pragma message enable nosimpint
  28 #endif
  29
  30 #include "wx/motif/private.h"
  31
  32 IMPLEMENT_DYNAMIC_CLASS(wxColour, wxObject)
  33
  34 // Colour
  35
  36 void wxColour::Init()
  37 {
  38     m_isInit = false;
  39     m_red =
  40     m_blue =
  41     m_green = 0;
  42     m_pixel = -1;
  43 }
  44
  45 wxColour::wxColour()
  46 {
  47     Init();
  48 }
  49
  50 wxColour::wxColour(const wxColour& col)
  51 {
  52     *this = col;
  53 }
  54
  55 wxColour& wxColour::operator =(const wxColour& col)
  56 {
  57     m_red = col.m_red;
  58     m_green = col.m_green;
  59     m_blue = col.m_blue;
  60     m_isInit = col.m_isInit;
  61     m_pixel = col.m_pixel;
  62     return *this;
  63 }
  64
  65 void wxColour::InitFromName(const wxString& name)
  66 {
  67     if ( wxTheColourDatabase )
  68     {
  69         wxColour col = wxTheColourDatabase->Find(name);
  70         if ( col.Ok() )
  71         {
  72             *this = col;
  73             return;
  74         }
  75     }
  76
  77     // leave invalid
  78     Init();
  79 }
  80
  81 /* static */
  82 wxColour wxColour::CreateByName(const wxString& name)
  83 {
  84     wxColour col;
  85
  86     Display *dpy = wxGlobalDisplay();
  87     WXColormap colormap = wxTheApp->GetMainColormap( dpy );
  88     XColor xcol;
  89     if ( XParseColor( dpy, (Colormap)colormap, name.mb_str(), &xcol ) )
  90     {
  91         col.m_red = xcol.red & 0xff;
  92         col.m_green = xcol.green & 0xff;
  93         col.m_blue = xcol.blue & 0xff;
  94         col.m_isInit = true;
  95         col.m_pixel = -1;
  96     }
  97
  98     return col;
  99 }
 100
 101 wxColour::~wxColour()
 102 {
 103 }
 104
 105 void wxColour::Set(unsigned char r, unsigned char g, unsigned char b)
 106 {
 107     m_red = r;
 108     m_green = g;
 109     m_blue = b;
 110     m_isInit = true;
 111     m_pixel = -1;
 112 }
 113
 114 // Allocate a colour, or nearest colour, using the given display.
 115 // If realloc is true, ignore the existing pixel, otherwise just return
 116 // the existing one.
 117 // Returns the old or allocated pixel.
 118
 119 // TODO: can this handle mono displays? If not, we should have an extra
 120 // flag to specify whether this should be black or white by default.
 121
 122 int wxColour::AllocColour(WXDisplay* display, bool realloc)
 123 {
 124     if ((m_pixel != -1) && !realloc)
 125         return m_pixel;
 126
 127     XColor color;
 128     color.red = (unsigned short) Red ();
 129     color.red |= color.red << 8;
 130     color.green = (unsigned short) Green ();
 131     color.green |= color.green << 8;
 132     color.blue = (unsigned short) Blue ();
 133     color.blue |= color.blue << 8;
 134
 135     color.flags = DoRed | DoGreen | DoBlue;
 136
 137     WXColormap cmap = wxTheApp->GetMainColormap(display);
 138
 139     if (!XAllocColor ((Display*) display, (Colormap) cmap, &color))
 140     {
 141         m_pixel = wxGetBestMatchingPixel((Display*) display, &color,(Colormap) cmap);
 142         return m_pixel;
 143     }
 144     else
 145     {
 146         m_pixel = (int) color.pixel;
 147         return m_pixel;
 148     }
 149 }
 150
 151 /*-------------------------------------------
 152 Markus Emmenegger <mege@iqe.ethz.ch>
 153 Find the pixel value with an assigned color closest to the desired color
 154 Used if color cell allocation fails
 155 As the returned pixel value may be in use by another application,
 156 the color might change anytime.
 157 But in many cases, that is still better than always using black.
 158 --
 159 Chris Breeze <chris@hel.co.uk>
 160 Improvements:
 161 1) More efficient calculation of RGB distance of colour cell from
 162 the desired colour. There is no need to take the sqrt of 'dist', and
 163 since we are only interested in the top 8-bits of R, G and B we
 164 can perform integer arithmetic.
 165 2) Attempt to allocate a read-only colour when a close match is found.
 166 A read-only colour will not change.
 167 3) Fall back to the closest match if no read-only colours are available.
 168
 169   Possible further improvements:
 170   1) Scan the lookup table and sort the colour cells in order of
 171   increasing
 172   distance from the desired colour. Then attempt to allocate a
 173   read-only
 174   colour starting from the nearest match.
 175   2) Linear RGB distance is not a particularly good method of colour
 176   matching
 177   (though it is quick). Converting the colour to HLS and then comparing
 178   may give better matching.
 179 -------------------------------------------*/
 180
 181 int wxGetBestMatchingPixel(Display *display, XColor *desiredColor, Colormap cmap)
 182 {
 183     if (cmap == (Colormap) NULL)
 184         cmap = (Colormap) wxTheApp->GetMainColormap(display);
 185
 186     int numPixVals = XDisplayCells(display, DefaultScreen (display));
 187     int mindist = 256 * 256 * 3;
 188     int bestpixel = (int) BlackPixel (display, DefaultScreen (display));
 189     int red = desiredColor->red >> 8;
 190     int green = desiredColor->green >> 8;
 191     int blue = desiredColor->blue >> 8;
 192     const int threshold = 2 * 2 * 3;    // allow an error of up to 2 in R,G & B
 193
 194     for (int pixelcount = 0; pixelcount < numPixVals; pixelcount++)
 195     {
 196         XColor matching_color;
 197         matching_color.pixel = pixelcount;
 198         XQueryColor(display,cmap,&matching_color);
 199
 200         int delta_red = red - (matching_color.red >> 8);
 201         int delta_green = green - (matching_color.green >> 8);
 202         int delta_blue = blue - (matching_color.blue >> 8);
 203
 204         int dist = delta_red * delta_red +
 205             delta_green * delta_green +
 206             delta_blue * delta_blue;
 207
 208         if (dist <= threshold)
 209         {
 210             // try to allocate a read-only colour...
 211             if (XAllocColor (display, cmap, &matching_color))
 212             {
 213                 return matching_color.pixel;
 214             }
 215         }
 216         if (dist < mindist)
 217         {
 218             bestpixel = pixelcount;
 219             mindist = dist;
 220         }
 221     }
 222     return bestpixel;
 223 }