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[gl] Construct a dummy window for the initial context

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In order to make the initial context current we need a Drawable that
matches the context. In general, the RootWindow may not match the desired
context so we need to query the context and construct an appropriate
Drawable.
This commit is contained in:
Chris Wilson 2009-06-09 16:20:32 +01:00
parent 911482e5ae
commit 5deb8fa213
1 changed files with 63 additions and 7 deletions
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70
src/cairo-glx-context.c
View file

@ -40,10 +40,13 @@
#include "cairo-gl-private.h"
#include <X11/Xutil.h>
typedef struct _cairo_glx_context {
cairo_gl_context_t base;
Display *display;
Window dummy_window;
GLXContext context;
} cairo_glx_context_t;
@ -77,6 +80,61 @@ _glx_swap_buffers (void *abstract_ctx,
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);
}
static cairo_status_t
_glx_dummy_ctx (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;
cairo_status_t status = CAIRO_STATUS_SUCCESS;
/* 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 (cnt == 0)
return _cairo_error (CAIRO_STATUS_INVALID_FORMAT);
vi = glXGetVisualFromFBConfig (dpy, config[0]);
XFree (config);
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 (! glXMakeCurrent (dpy, win, gl_ctx)) {
status = _cairo_error (CAIRO_STATUS_NO_MEMORY);
XDestroyWindow (dpy, win);
win = None;
}
*dummy = win;
return status;
}
cairo_gl_context_t *
@ -84,20 +142,18 @@ cairo_glx_context_create (Display *dpy, GLXContext gl_ctx)
{
cairo_glx_context_t *ctx;
cairo_status_t status;
Window dummy = None;
/* Make our GL context active. While we'll be setting the destination
* drawable with each rendering operation, in order to set the context
* we have to choose a drawable. The root window happens to be convenient
* for this.
*/
if (! glXMakeCurrent (dpy, RootWindow (dpy, DefaultScreen (dpy)), gl_ctx))
return _cairo_gl_context_create_in_error (CAIRO_STATUS_NO_MEMORY);
status = _glx_dummy_ctx (dpy, gl_ctx, &dummy);
if (status)
return _cairo_gl_context_create_in_error (status);
ctx = calloc (1, sizeof (cairo_glx_context_t));
if (ctx == NULL)
return _cairo_gl_context_create_in_error (CAIRO_STATUS_NO_MEMORY);
ctx->display = dpy;
ctx->dummy_window = dummy;
ctx->context = gl_ctx;
ctx->base.make_current = _glx_make_current;