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      1 /*
      2  Copyright (c) 2008-2011 Apple Inc.
      3 
      4  Permission is hereby granted, free of charge, to any person
      5  obtaining a copy of this software and associated documentation files
      6  (the "Software"), to deal in the Software without restriction,
      7  including without limitation the rights to use, copy, modify, merge,
      8  publish, distribute, sublicense, and/or sell copies of the Software,
      9  and to permit persons to whom the Software is furnished to do so,
     10  subject to the following conditions:
     11 
     12  The above copyright notice and this permission notice shall be
     13  included in all copies or substantial portions of the Software.
     14 
     15  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
     16  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     17  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
     18  NONINFRINGEMENT.  IN NO EVENT SHALL THE ABOVE LISTED COPYRIGHT
     19  HOLDER(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
     20  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     21  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
     22  DEALINGS IN THE SOFTWARE.
     23 
     24  Except as contained in this notice, the name(s) of the above
     25  copyright holders shall not be used in advertising or otherwise to
     26  promote the sale, use or other dealings in this Software without
     27  prior written authorization.
     28 */
     29 
     30 /*
     31  * This file works with the glXMakeContextCurrent readable drawable.
     32  *
     33  * The way it works is by swapping the currentDrawable for the currentReadable
     34  * drawable if they are different.
     35  */
     36 #include <stdbool.h>
     37 #include "glxclient.h"
     38 #include "apple_glx_context.h"
     39 #include "apple_xgl_api.h"
     40 #include "glapitable.h"
     41 
     42 extern struct _glapi_table * __ogl_framework_api;
     43 
     44 struct apple_xgl_saved_state
     45 {
     46    bool swapped;
     47 };
     48 
     49 static void
     50 SetRead(struct apple_xgl_saved_state *saved)
     51 {
     52    struct glx_context *gc = __glXGetCurrentContext();
     53 
     54    /*
     55     * By default indicate that the state was not swapped, so that UnsetRead
     56     * functions correctly.
     57     */
     58    saved->swapped = false;
     59 
     60    /*
     61     * If the readable drawable isn't the same as the drawable then
     62     * the user has requested a readable drawable with glXMakeContextCurrent().
     63     * We emulate this behavior by switching the current drawable.
     64     */
     65    if (None != gc->currentReadable
     66        && gc->currentReadable != gc->currentDrawable) {
     67       Display *dpy = glXGetCurrentDisplay();
     68 
     69       saved->swapped = true;
     70 
     71       if (apple_glx_make_current_context(dpy, gc->driContext, gc->driContext,
     72                                          gc->currentReadable)) {
     73          /* An error occurred, so try to restore the old context state. */
     74          (void) apple_glx_make_current_context(dpy, gc->driContext, gc->driContext,
     75                                                gc->currentDrawable);
     76          saved->swapped = false;
     77       }
     78    }
     79 }
     80 
     81 static void
     82 UnsetRead(struct apple_xgl_saved_state *saved)
     83 {
     84    if (saved->swapped) {
     85       struct glx_context *gc = __glXGetCurrentContext();
     86       Display *dpy = glXGetCurrentDisplay();
     87 
     88       if (apple_glx_make_current_context(dpy, gc->driContext, gc->driContext,
     89                                          gc->currentDrawable)) {
     90          /*
     91           * An error occurred restoring the drawable.
     92           * It's unclear what to do about that.
     93           */
     94       }
     95    }
     96 }
     97 
     98 void
     99 __applegl_glReadPixels(GLint x, GLint y, GLsizei width, GLsizei height,
    100              GLenum format, GLenum type, void *pixels)
    101 {
    102    struct apple_xgl_saved_state saved;
    103 
    104    SetRead(&saved);
    105 
    106    __ogl_framework_api->ReadPixels(x, y, width, height, format, type, pixels);
    107 
    108    UnsetRead(&saved);
    109 }
    110 
    111 void
    112 __applegl_glCopyPixels(GLint x, GLint y, GLsizei width, GLsizei height, GLenum type)
    113 {
    114    struct apple_xgl_saved_state saved;
    115 
    116    SetRead(&saved);
    117 
    118    __ogl_framework_api->CopyPixels(x, y, width, height, type);
    119 
    120    UnsetRead(&saved);
    121 }
    122 
    123 void
    124 __applegl_glCopyColorTable(GLenum target, GLenum internalformat, GLint x, GLint y,
    125                  GLsizei width)
    126 {
    127    struct apple_xgl_saved_state saved;
    128 
    129    SetRead(&saved);
    130 
    131    __ogl_framework_api->CopyColorTable(target, internalformat, x, y, width);
    132 
    133    UnsetRead(&saved);
    134 }
    135