//
// "$Id: fl_overlay_visual.cpp 6 2002-09-03 11:16:32Z laza2000 $"
//
// X overlay support for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-1999 by Bill Spitzak and others.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA.
//
// Please report all bugs and problems to "fltk-bugs@easysw.com".
//

// Return an overlay visual, if any.  Also allocate a colormap and
// record the depth for fl_color() to use.
// Another disgusting X interface, based on code extracted and
// purified with great difficulty from XLayerUtil.C:

#include <config.h>
#if !defined(_WIN32) && (USE_OVERLAY || USE_GL_OVERLAY)
#include <efltk/Fl.h>
#include <efltk/x.h>

// SERVER_OVERLAY_VISUALS property element:
struct OverlayInfo
{
    long overlay_visual;
    long transparent_type;
    long value;
    long layer;
};

extern Colormap fl_overlay_colormap;
extern XVisualInfo* fl_overlay_visual;
extern ulong fl_transparent_pixel;

XVisualInfo *fl_find_overlay_visual()
{
    static bool beenhere;
    if (beenhere) return fl_overlay_visual;
    beenhere = true;

    fl_open_display();
    Atom overlayVisualsAtom =
        XInternAtom(fl_display,"SERVER_OVERLAY_VISUALS",1);
    if (!overlayVisualsAtom) return 0;
    OverlayInfo *overlayInfo;
    ulong sizeData, bytesLeft;
    Atom actualType;
    int actualFormat;
    if (XGetWindowProperty(fl_display, RootWindow(fl_display, fl_screen),
        overlayVisualsAtom, 0L, 10000L, False,
        overlayVisualsAtom, &actualType, &actualFormat,
        &sizeData, &bytesLeft,
        (unsigned char **) &overlayInfo)) return 0;

    if (actualType == overlayVisualsAtom && actualFormat == 32)
    {
        int n = int(sizeData/4);
        XVisualInfo* v = 0;
        // find the greatest depth that has a transparent pixel:
        for (int i = 0; i < n; i++)
        {
            if (overlayInfo[i].transparent_type != 1) continue;
            if (overlayInfo[i].layer <= 0) continue;
            XVisualInfo templt;
            templt.visualid = overlayInfo[i].overlay_visual;
            int num;
            XVisualInfo *v1=XGetVisualInfo(fl_display, VisualIDMask, &templt, &num);
            if (v1->screen == fl_screen && v1->c_class == PseudoColor
                && (!v || v1->depth > v->depth && v1->depth <= 8))
            {
                if (v) XFree((char*)v);
                v = v1;
                fl_transparent_pixel = overlayInfo[i].value;
            }
            else
            {
                XFree((char*)v1);
            }
        }
        if (v)
        {
            fl_overlay_visual = v;
            fl_overlay_colormap =
                XCreateColormap(fl_display, RootWindow(fl_display, fl_screen),
                v->visual, AllocNone);
        }
    }
    XFree((char*)overlayInfo);
    //printf("overlay visual %d selected\n", fl_overlay_visual->visualid);
    return fl_overlay_visual;
}
#endif

//
// End of "$Id: fl_overlay_visual.cpp 6 2002-09-03 11:16:32Z laza2000 $".
//
