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