text: /* cairo - a vector graphics library with display and print output
   *
   * Copyright © 2009 Eric Anholt
   * Copyright © 2009 Chris Wilson
   * Copyright © 2005 Red Hat, Inc
   *
   * This library is free software; you can redistribute it and/or
   * modify it either under the terms of the GNU Lesser General Public
   * License version 2.1 as published by the Free Software Foundation
   * (the "LGPL") or, at your option, under the terms of the Mozilla
   * Public License Version 1.1 (the "MPL"). If you do not alter this
   * notice, a recipient may use your version of this file under either
   * the MPL or the LGPL.
   *
   * You should have received a copy of the LGPL along with this library
   * in the file COPYING-LGPL-2.1; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
   * You should have received a copy of the MPL along with this library
   * in the file COPYING-MPL-1.1
   *
   * The contents of this file are subject to the Mozilla Public License
   * Version 1.1 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   * http://www.mozilla.org/MPL/
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
   * OF ANY KIND, either express or implied. See the LGPL or the MPL for
   * the specific language governing rights and limitations.
   *
   * The Original Code is the cairo graphics library.
   *
   * The Initial Developer of the Original Code is Red Hat, Inc.
   *
   * Contributor(s):
   *	Carl Worth <cworth@cworth.org>
   *	Chris Wilson <chris@chris-wilson.co.uk>
   */
  
  #include "cairoint.h"
  
  #include "cairo-gl-private.h"
  
  #include "cairo-error-private.h"
  
  #include <X11/Xutil.h>
  
  /* XXX needs hooking into XCloseDisplay() */
  
  typedef struct _cairo_glx_context {
      cairo_gl_context_t base;
  
      Display *display;
      Window dummy_window;
      GLXContext context;
  
      GLXDrawable previous_drawable;
      GLXContext previous_context;
  
      cairo_bool_t has_multithread_makecurrent;
  } cairo_glx_context_t;
  
  typedef struct _cairo_glx_surface {
      cairo_gl_surface_t base;
  
      Window win;
  } cairo_glx_surface_t;
  
  static cairo_bool_t
  _context_acquisition_changed_glx_state (cairo_glx_context_t *ctx,
  					GLXDrawable current_drawable)
  {
      return ctx->previous_drawable != current_drawable ||
  	   ctx->previous_context != ctx->context;
  }
  
  static GLXDrawable
  _glx_get_current_drawable (cairo_glx_context_t *ctx)
  {
      if (ctx->base.current_target == NULL ||
  	_cairo_gl_surface_is_texture (ctx->base.current_target)) {
  	return ctx->dummy_window;
      }
  
      return ((cairo_glx_surface_t *) ctx->base.current_target)->win;
  }
  
  static void
  _glx_query_current_state (cairo_glx_context_t * ctx)
  {
      ctx->previous_drawable = glXGetCurrentDrawable ();
      ctx->previous_context = glXGetCurrentContext ();
  
      /* If any of the values were none, assume they are all none. Not all
         drivers seem well behaved when it comes to using these values across
         multiple threads. */
      if (ctx->previous_drawable == None ||
  	ctx->previous_context == None) {
  	ctx->previous_drawable = None;
  	ctx->previous_context = None;
      }
  }
  
  static void
  _glx_acquire (void *abstract_ctx)
  {
      cairo_glx_context_t *ctx = abstract_ctx;
      GLXDrawable current_drawable = _glx_get_current_drawable (ctx);
  
      _glx_query_current_state (ctx);
      if (!_context_acquisition_changed_glx_state (ctx, current_drawable))
  	return;
  
      glXMakeCurrent (ctx->display, current_drawable, ctx->context);
  }
  
  static void
  _glx_make_current (void *abstract_ctx, cairo_gl_surface_t *abstract_surface)
  {
      cairo_glx_context_t *ctx = abstract_ctx;
      cairo_glx_surface_t *surface = (cairo_glx_surface_t *) abstract_surface;
  
      /* Set the window as the target of our context. */
      glXMakeCurrent (ctx->display, surface->win, ctx->context);
  }
  
  static void
  _glx_release (void *abstract_ctx)
  {
      cairo_glx_context_t *ctx = abstract_ctx;
  
      if (ctx->has_multithread_makecurrent || !ctx->base.thread_aware ||
  	!_context_acquisition_changed_glx_state (ctx,
  						_glx_get_current_drawable (ctx))) {
  	return;
      }
  
      glXMakeCurrent (ctx->display, None, None);
  }
  
  static void
  _glx_swap_buffers (void *abstract_ctx,
  		   cairo_gl_surface_t *abstract_surface)
  {
      cairo_glx_context_t *ctx = abstract_ctx;
      cairo_glx_surface_t *surface = (cairo_glx_surface_t *) abstract_surface;
  
      glXSwapBuffers (ctx->display, surface->win);
  }
  
  static void
  _glx_destroy (void *abstract_ctx)
  {
      cairo_glx_context_t *ctx = abstract_ctx;
  
      if (ctx->dummy_window != None)
  	XDestroyWindow (ctx->display, ctx->dummy_window);
  
      glXMakeCurrent (ctx->display, None, None);
  }
  
  static cairo_status_t
  _glx_dummy_window (Display *dpy, GLXContext gl_ctx, Window *dummy)
  {
      int attr[3] = { GLX_FBCONFIG_ID, 0, None };
      GLXFBConfig *config;
      XVisualInfo *vi;
      Colormap cmap;
      XSetWindowAttributes swa;
      Window win = None;
      int cnt;
  
      /* Create a dummy window created for the target GLX context that we can
       * use to query the available GL/GLX extensions.
       */
      glXQueryContext (dpy, gl_ctx, GLX_FBCONFIG_ID, &attr[1]);
  
      cnt = 0;
      config = glXChooseFBConfig (dpy, DefaultScreen (dpy), attr, &cnt);
      if (unlikely (cnt == 0))
  	return _cairo_error (CAIRO_STATUS_INVALID_FORMAT);
  
      vi = glXGetVisualFromFBConfig (dpy, config[0]);
      XFree (config);
  
      if (unlikely (vi == NULL))
  	return _cairo_error (CAIRO_STATUS_INVALID_FORMAT);
  
      cmap = XCreateColormap (dpy,
  			    RootWindow (dpy, vi->screen),
  			    vi->visual,
  			    AllocNone);
      swa.colormap = cmap;
      swa.border_pixel = 0;
      win = XCreateWindow (dpy, RootWindow (dpy, vi->screen),
  			 -1, -1, 1, 1, 0,
  			 vi->depth,
  			 InputOutput,
  			 vi->visual,
  			 CWBorderPixel | CWColormap, &swa);
      XFreeColormap (dpy, cmap);
      XFree (vi);
  
      XFlush (dpy);
      if (unlikely (! glXMakeCurrent (dpy, win, gl_ctx))) {
  	XDestroyWindow (dpy, win);
  	return _cairo_error (CAIRO_STATUS_NO_MEMORY);
      }
  
      *dummy = win;
      return CAIRO_STATUS_SUCCESS;
  }
  
  cairo_device_t *
  cairo_glx_device_create (Display *dpy, GLXContext gl_ctx)
  {
      cairo_glx_context_t *ctx;
      cairo_status_t status;
      Window dummy = None;
      const char *glx_extensions;
  
      ctx = calloc (1, sizeof (cairo_glx_context_t));
      if (unlikely (ctx == NULL))
  	return _cairo_gl_context_create_in_error (CAIRO_STATUS_NO_MEMORY);
  
      /* glx_dummy_window will call glXMakeCurrent, so we need to
       *  query the current state of the context now. */
      _glx_query_current_state (ctx);
  
      status = _glx_dummy_window (dpy, gl_ctx, &dummy);
      if (unlikely (status)) {
  	free (ctx);
  	return _cairo_gl_context_create_in_error (status);
      }
  
      ctx->display = dpy;
      ctx->dummy_window = dummy;
      ctx->context = gl_ctx;
  
      ctx->base.acquire = _glx_acquire;
      ctx->base.release = _glx_release;
      ctx->base.make_current = _glx_make_current;
      ctx->base.swap_buffers = _glx_swap_buffers;
      ctx->base.destroy = _glx_destroy;
  
      status = _cairo_gl_dispatch_init (&ctx->base.dispatch,
  				      (cairo_gl_get_proc_addr_func_t) glXGetProcAddress);
      if (unlikely (status)) {
  	free (ctx);
  	return _cairo_gl_context_create_in_error (status);
      }
  
      status = _cairo_gl_context_init (&ctx->base);
      if (unlikely (status)) {
  	free (ctx);
  	return _cairo_gl_context_create_in_error (status);
      }
  
      glx_extensions = glXQueryExtensionsString (dpy, DefaultScreen (dpy));
      if (strstr(glx_extensions, "GLX_MESA_multithread_makecurrent")) {
  	ctx->has_multithread_makecurrent = TRUE;
      }
  
      ctx->base.release (ctx);
  
      return &ctx->base.base;
  }
  
  Display *
  cairo_glx_device_get_display (cairo_device_t *device)
  {
      cairo_glx_context_t *ctx;
  
      if (device->backend->type != CAIRO_DEVICE_TYPE_GL) {
  	_cairo_error_throw (CAIRO_STATUS_DEVICE_TYPE_MISMATCH);
  	return NULL;
      }
  
      ctx = (cairo_glx_context_t *) device;
  
      return ctx->display;
  }
  
  GLXContext
  cairo_glx_device_get_context (cairo_device_t *device)
  {
      cairo_glx_context_t *ctx;
  
      if (device->backend->type != CAIRO_DEVICE_TYPE_GL) {
  	_cairo_error_throw (CAIRO_STATUS_DEVICE_TYPE_MISMATCH);
  	return NULL;
      }
  
      ctx = (cairo_glx_context_t *) device;
  
      return ctx->context;
  }
  
  cairo_surface_t *
  cairo_gl_surface_create_for_window (cairo_device_t	*device,
  				    Window		 win,
  				    int			 width,
  				    int			 height)
  {
      cairo_glx_surface_t *surface;
  
      if (unlikely (device->status))
  	return _cairo_surface_create_in_error (device->status);
  
      if (device->backend->type != CAIRO_DEVICE_TYPE_GL)
  	return _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH));
  
      if (width <= 0 || height <= 0)
  	return _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_INVALID_SIZE));
  
      surface = calloc (1, sizeof (cairo_glx_surface_t));
      if (unlikely (surface == NULL))
  	return _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
  
      _cairo_gl_surface_init (device, &surface->base,
  			    CAIRO_CONTENT_COLOR_ALPHA, width, height);
      surface->win = win;
  
      return &surface->base.base;
  }
  