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 // For compilers that support precompilation, includes "wx.h".
  20 #include "wx/wxprec.h"
  21
  22 #include "wx/gdicmn.h"
  23 #include "wx/colour.h"
  24 #include "wx/app.h"
  25
  26 #ifdef __VMS__
  27 #pragma message disable nosimpint
  28 #endif
  29 #include <Xm/Xm.h>
  30 #ifdef __VMS__
  31 #pragma message enable nosimpint
  32 #endif
  33
  34 #include "wx/motif/private.h"
  35
  36 IMPLEMENT_DYNAMIC_CLASS(wxColour, wxObject)
  37
  38 // Colour
  39
  40 void wxColour::Init()
  41 {
  42     m_isInit = false;
  43     m_red =
  44     m_blue =
  45     m_green = 0;
  46     m_pixel = -1;
  47 }
  48
  49 wxColour::wxColour()
  50 {
  51     Init();
  52 }
  53
  54 wxColour::wxColour(const wxColour& col)
  55 {
  56     *this = col;
  57 }
  58
  59 wxColour& wxColour::operator =(const wxColour& col)
  60 {
  61     m_red = col.m_red;
  62     m_green = col.m_green;
  63     m_blue = col.m_blue;
  64     m_isInit = col.m_isInit;
  65     m_pixel = col.m_pixel;
  66     return *this;
  67 }
  68
  69 void wxColour::InitFromName(const wxString& name)
  70 {
  71     if ( wxTheColourDatabase )
  72     {
  73         wxColour col = wxTheColourDatabase->Find(name);
  74         if ( col.Ok() )
  75         {
  76             *this = col;
  77             return;
  78         }
  79     }
  80
  81     // leave invalid
  82     Init();
  83 }
  84
  85 /* static */
  86 wxColour wxColour::CreateByName(const wxString& name)
  87 {
  88     wxColour col;
  89
  90     Display *dpy = wxGlobalDisplay();
  91     WXColormap colormap = wxTheApp->GetMainColormap( dpy );
  92     XColor xcol;
  93     if ( XParseColor( dpy, (Colormap)colormap, name.mb_str(), &xcol ) )
  94     {
  95         col.m_red = xcol.red & 0xff;
  96         col.m_green = xcol.green & 0xff;
  97         col.m_blue = xcol.blue & 0xff;
  98         col.m_isInit = true;
  99         col.m_pixel = -1;
 100     }
 101
 102     return col;
 103 }
 104
 105 wxColour::~wxColour()
 106 {
 107 }
 108
 109 void wxColour::Set(unsigned char r, unsigned char g, unsigned char b)
 110 {
 111     m_red = r;
 112     m_green = g;
 113     m_blue = b;
 114     m_isInit = true;
 115     m_pixel = -1;
 116 }
 117
 118 // Allocate a colour, or nearest colour, using the given display.
 119 // If realloc is true, ignore the existing pixel, otherwise just return
 120 // the existing one.
 121 // Returns the old or allocated pixel.
 122
 123 // TODO: can this handle mono displays? If not, we should have an extra
 124 // flag to specify whether this should be black or white by default.
 125
 126 int wxColour::AllocColour(WXDisplay* display, bool realloc)
 127 {
 128     if ((m_pixel != -1) && !realloc)
 129         return m_pixel;
 130
 131     XColor color;
 132     color.red = (unsigned short) Red ();
 133     color.red |= color.red << 8;
 134     color.green = (unsigned short) Green ();
 135     color.green |= color.green << 8;
 136     color.blue = (unsigned short) Blue ();
 137     color.blue |= color.blue << 8;
 138
 139     color.flags = DoRed | DoGreen | DoBlue;
 140
 141     WXColormap cmap = wxTheApp->GetMainColormap(display);
 142
 143     if (!XAllocColor ((Display*) display, (Colormap) cmap, &color))
 144     {
 145         m_pixel = wxGetBestMatchingPixel((Display*) display, &color,(Colormap) cmap);
 146         return m_pixel;
 147     }
 148     else
 149     {
 150         m_pixel = (int) color.pixel;
 151         return m_pixel;
 152     }
 153 }
 154
 155 /*-------------------------------------------
 156 Markus Emmenegger <mege@iqe.ethz.ch>
 157 Find the pixel value with an assigned color closest to the desired color
 158 Used if color cell allocation fails
 159 As the returned pixel value may be in use by another application,
 160 the color might change anytime.
 161 But in many cases, that is still better than always using black.
 162 --
 163 Chris Breeze <chris@hel.co.uk>
 164 Improvements:
 165 1) More efficient calculation of RGB distance of colour cell from
 166 the desired colour. There is no need to take the sqrt of 'dist', and
 167 since we are only interested in the top 8-bits of R, G and B we
 168 can perform integer arithmetic.
 169 2) Attempt to allocate a read-only colour when a close match is found.
 170 A read-only colour will not change.
 171 3) Fall back to the closest match if no read-only colours are available.
 172
 173   Possible further improvements:
 174   1) Scan the lookup table and sort the colour cells in order of
 175   increasing
 176   distance from the desired colour. Then attempt to allocate a
 177   read-only
 178   colour starting from the nearest match.
 179   2) Linear RGB distance is not a particularly good method of colour
 180   matching
 181   (though it is quick). Converting the colour to HLS and then comparing
 182   may give better matching.
 183 -------------------------------------------*/
 184
 185 int wxGetBestMatchingPixel(Display *display, XColor *desiredColor, Colormap cmap)
 186 {
 187     if (cmap == (Colormap) NULL)
 188         cmap = (Colormap) wxTheApp->GetMainColormap(display);
 189
 190     int numPixVals = XDisplayCells(display, DefaultScreen (display));
 191     int mindist = 256 * 256 * 3;
 192     int bestpixel = (int) BlackPixel (display, DefaultScreen (display));
 193     int red = desiredColor->red >> 8;
 194     int green = desiredColor->green >> 8;
 195     int blue = desiredColor->blue >> 8;
 196     const int threshold = 2 * 2 * 3;    // allow an error of up to 2 in R,G & B
 197
 198     for (int pixelcount = 0; pixelcount < numPixVals; pixelcount++)
 199     {
 200         XColor matching_color;
 201         matching_color.pixel = pixelcount;
 202         XQueryColor(display,cmap,&matching_color);
 203
 204         int delta_red = red - (matching_color.red >> 8);
 205         int delta_green = green - (matching_color.green >> 8);
 206         int delta_blue = blue - (matching_color.blue >> 8);
 207
 208         int dist = delta_red * delta_red +
 209             delta_green * delta_green +
 210             delta_blue * delta_blue;
 211
 212         if (dist <= threshold)
 213         {
 214             // try to allocate a read-only colour...
 215             if (XAllocColor (display, cmap, &matching_color))
 216             {
 217                 return matching_color.pixel;
 218             }
 219         }
 220         if (dist < mindist)
 221         {
 222             bestpixel = pixelcount;
 223             mindist = dist;
 224         }
 225     }
 226     return bestpixel;
 227 }