glx: Duplicate relevant fbconfigs for compositing visuals

Previously, before GLX_OML_swap_method was fixed, both the X server and
client ignored the swapMethod fbconfig value, which meant that, if the dri
driver thought it exposed more than one swapMethod, it actually just
exported a duplicated set of fbconfigs. When fixing GLX_OML_swap_method
and restricting the choice for built-in visuals to a single swap method
that meant we didn't have that many fbconfigs to choose from when pairing
the compositing visual with an fbconfig, resulting in the fbconfig paired
with the compositing visual becoming too restrictive for some applications,
(at least for kwin). This problem would also happen if the dri driver
only exposed a single swap method to begin with.

So, to make sure the compositing visual gets a good enough fbconfig,
duplicate fbconfigs that are suitable for compositing visuals and make
sure these duplicated fbconfigs can be used only by compositing visuals.
For duplicated fbconfigs not paired with a compositing visual, construct
new compositing visuals, making compositing clients able to choose visuals
/ fbconfig more adapted to their needs.

This is in some sense equivalent to adding a new "TRUECOLOR_COMPOSITING"
GLX visualtype.

Fixes: 4486d199bd ("glx: Fix visual fbconfig matching with respect to
                      swap method")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102806
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Tested-By: Nick Sarnie <commendsarnex@gmail.com>
Tested-by: Fredrik Höglund <fredrik@kde.org>
Reviewed-by: Adam Jackson <ajax@redhat.com>
(cherry picked from commit f84e59a4f4)

glx/glxdricommon.c

@@ -139,13 +139,15 @@ render_type_is_pbuffer_only(unsigned renderType)
 static __GLXconfig *
 createModeFromConfig(const __DRIcoreExtension * core,
                      const __DRIconfig * driConfig,
-                     unsigned int visualType)
+                     unsigned int visualType,
+                     GLboolean duplicateForComp)
 {
     __GLXDRIconfig *config;
     GLint renderType = 0;
     unsigned int attrib, value, drawableType = GLX_PBUFFER_BIT;
     int i;
 
+
     config = calloc(1, sizeof *config);
 
     config->driConfig = driConfig;
@@ -203,6 +205,28 @@ createModeFromConfig(const __DRIcoreExtension * core,
     config->config.drawableType = drawableType;
     config->config.yInverted = GL_TRUE;
 
+#ifdef COMPOSITE
+    /*
+     * Here we decide what fbconfigs will be duplicated for compositing.
+     * fgbconfigs marked with duplicatedForConf will be reserved for
+     * compositing visuals.
+     * It might look strange to do this decision this late when translation
+     * from a __DRIConfig is already done, but using the __DRIConfig
+     * accessor function becomes worse both with respect to code complexity
+     * and CPU usage.
+     */
+    if (duplicateForComp &&
+        (render_type_is_pbuffer_only(renderType) ||
+         config->config.rgbBits != 32 ||
+         config->config.visualRating != GLX_NONE ||
+         config->config.sampleBuffers != 0)) {
+        free(config);
+        return NULL;
+    }
+
+    config->config.duplicatedForComp = duplicateForComp;
+#endif
+
     return &config->config;
 }
 
@@ -217,21 +241,34 @@ glxConvertConfigs(const __DRIcoreExtension * core,
     head.next = NULL;
 
     for (i = 0; configs[i]; i++) {
-        tail->next = createModeFromConfig(core, configs[i], GLX_TRUE_COLOR);
+        tail->next = createModeFromConfig(core, configs[i], GLX_TRUE_COLOR,
+                                          GL_FALSE);
         if (tail->next == NULL)
             break;
-
         tail = tail->next;
     }
 
     for (i = 0; configs[i]; i++) {
-        tail->next = createModeFromConfig(core, configs[i], GLX_DIRECT_COLOR);
+        tail->next = createModeFromConfig(core, configs[i], GLX_DIRECT_COLOR,
+                                          GL_FALSE);
         if (tail->next == NULL)
             break;
 
         tail = tail->next;
     }
 
+#ifdef COMPOSITE
+    /* Duplicate fbconfigs for use with compositing visuals */
+    for (i = 0; configs[i]; i++) {
+        tail->next = createModeFromConfig(core, configs[i], GLX_TRUE_COLOR,
+                                          GL_TRUE);
+        if (tail->next == NULL)
+            continue;
+
+	tail = tail->next;
+    }
+#endif
+
     return head.next;
 }
 

glx/glxscreens.c

@@ -278,7 +278,12 @@ pickFBConfig(__GLXscreen * pGlxScreen, VisualPtr visual)
         /* Can't use the same FBconfig for multiple X visuals.  I think. */
         if (config->visualID != 0)
             continue;
-
+#ifdef COMPOSITE
+	/* Use only duplicated configs for compIsAlternateVisuals */
+        if (!!compIsAlternateVisual(pGlxScreen->pScreen, visual->vid) !=
+	    !!config->duplicatedForComp)
+            continue;
+#endif
         /*
          * If possible, use the same swapmethod for all built-in visual
          * fbconfigs, to avoid getting the 32-bit composite visual when
@@ -369,7 +374,12 @@ __glXScreenInit(__GLXscreen * pGlxScreen, ScreenPtr pScreen)
          * set up above is for.
          */
         depth = config->redBits + config->greenBits + config->blueBits;
-
+#ifdef COMPOSITE
+	if (config->duplicatedForComp) {
+		depth += config->alphaBits;
+		config->visualSelectGroup++;
+	}
+#endif
         /* Make sure that our FBconfig's depth can actually be displayed
          * (corresponds to an existing visual).
          */
@@ -392,6 +402,10 @@ __glXScreenInit(__GLXscreen * pGlxScreen, ScreenPtr pScreen)
         if (visual == NULL)
             continue;
 
+#ifdef COMPOSITE
+        if (config->duplicatedForComp)
+	    (void) CompositeRegisterAlternateVisuals(pScreen, &visual->vid, 1);
+#endif
         pGlxScreen->visuals[pGlxScreen->numVisuals++] = config;
         initGlxVisual(visual, config);
     }

glx/glxscreens.h

@@ -39,7 +39,11 @@
 
 typedef struct __GLXconfig __GLXconfig;
 struct __GLXconfig {
+    /* Management */
     __GLXconfig *next;
+#ifdef COMPOSITE
+    GLboolean duplicatedForComp;
+#endif
     GLuint doubleBufferMode;
     GLuint stereoMode;