From 8ec98fc2dc40237730f99af099dffe2920ef5bcc Mon Sep 17 00:00:00 2001
From: Allan Sandfeld Jensen <allan.jensen@qt.io>
Date: Fri, 13 Apr 2018 11:44:41 +0200
Subject: [PATCH] Fix launching with depth 30 XOrg

Our fallback logic for inexact matches was not very good at accepting
better suggestions.

Change-Id: I40fb78bf583171105725156148e4a2245fb81354
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>
---
 .../eglconvenience/qxlibeglintegration.cpp    | 14 ++++----
 .../glxconvenience/qglxconvenience.cpp        | 33 +++++++++++++++++++
 2 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/src/platformsupport/eglconvenience/qxlibeglintegration.cpp b/src/platformsupport/eglconvenience/qxlibeglintegration.cpp
index 565dbfb11b..ac743e1e38 100644
--- a/src/platformsupport/eglconvenience/qxlibeglintegration.cpp
+++ b/src/platformsupport/eglconvenience/qxlibeglintegration.cpp
@@ -91,21 +91,21 @@ VisualID QXlibEglIntegration::getCompatibleVisualId(Display *display, EGLDisplay
             int visualRedSize = qPopulationCount(chosenVisualInfo->red_mask);
             int visualGreenSize = qPopulationCount(chosenVisualInfo->green_mask);
             int visualBlueSize = qPopulationCount(chosenVisualInfo->blue_mask);
-            int visualAlphaSize = chosenVisualInfo->depth == 32 ? 8 : 0;
+            int visualAlphaSize = chosenVisualInfo->depth - visualRedSize - visualBlueSize - visualGreenSize;
 
-            const bool visualMatchesConfig = visualRedSize == configRedSize
-                && visualGreenSize == configGreenSize
-                && visualBlueSize == configBlueSize
-                && visualAlphaSize == configAlphaSize;
+            const bool visualMatchesConfig = visualRedSize >= configRedSize
+                && visualGreenSize >= configGreenSize
+                && visualBlueSize >= configBlueSize
+                && visualAlphaSize >= configAlphaSize;
 
             // In some cases EGL tends to suggest a 24-bit visual for 8888
             // configs. In such a case we have to fall back to XGetVisualInfo.
             if (!visualMatchesConfig) {
                 visualId = 0;
                 qCDebug(lcXlibEglDebug,
-                        "EGL suggested using X Visual ID %d (%d %d %d depth %d) for EGL config %d"
+                        "EGL suggested using X Visual ID %d (%d %d %d %d depth %d) for EGL config %d"
                         "(%d %d %d %d), but this is incompatible",
-                        (int)visualId, visualRedSize, visualGreenSize, visualBlueSize, chosenVisualInfo->depth,
+                        (int)visualId, visualRedSize, visualGreenSize, visualBlueSize, visualAlphaSize, chosenVisualInfo->depth,
                         configId, configRedSize, configGreenSize, configBlueSize, configAlphaSize);
             }
         } else {
diff --git a/src/platformsupport/glxconvenience/qglxconvenience.cpp b/src/platformsupport/glxconvenience/qglxconvenience.cpp
index 8d2e58b57b..d7cc36627a 100644
--- a/src/platformsupport/glxconvenience/qglxconvenience.cpp
+++ b/src/platformsupport/glxconvenience/qglxconvenience.cpp
@@ -42,13 +42,18 @@
 #include <QtCore/QByteArray>
 #include <QtCore/QScopedPointer>
 
+#include <QtCore/qmetatype.h>
+#include <QtCore/qtextstream.h>
 #include "qglxconvenience_p.h"
 
+#include <QtCore/QLoggingCategory>
 #include <QtCore/QVector>
 #include <QtCore/QVarLengthArray>
 
 #include <GL/glxext.h>
 
+Q_LOGGING_CATEGORY(lcGlx, "qt.glx")
+
 enum {
     XFocusOut = FocusOut,
     XFocusIn = FocusIn,
@@ -207,6 +212,7 @@ GLXFBConfig qglx_findConfig(Display *display, int screen , QSurfaceFormat format
         const int requestedBlue = qMax(0, format.blueBufferSize());
         const int requestedAlpha = qMax(0, format.alphaBufferSize());
 
+        GLXFBConfig compatibleCandidate = nullptr;
         for (int i = 0; i < confcount; i++) {
             GLXFBConfig candidate = configs[i];
 
@@ -226,6 +232,16 @@ GLXFBConfig qglx_findConfig(Display *display, int screen , QSurfaceFormat format
             const int actualBlue = qPopulationCount(visual->blue_mask);
             const int actualAlpha = visual->depth - actualRed - actualGreen - actualBlue;
 
+            if (requestedRed && actualRed < requestedRed)
+                continue;
+            if (requestedGreen && actualGreen < requestedGreen)
+                continue;
+            if (requestedBlue && actualBlue < requestedBlue)
+                continue;
+            if (requestedAlpha && actualAlpha < requestedAlpha)
+                continue;
+            compatibleCandidate = candidate;
+
             if (requestedRed && actualRed != requestedRed)
                 continue;
             if (requestedGreen && actualGreen != requestedGreen)
@@ -237,6 +253,11 @@ GLXFBConfig qglx_findConfig(Display *display, int screen , QSurfaceFormat format
 
             return candidate;
         }
+        if (compatibleCandidate) {
+            qCDebug(lcGlx) << "qglx_findConfig: Found non-matching but compatible FBConfig";
+            return compatibleCandidate;
+        }
+        qCWarning(lcGlx, "qglx_findConfig: Failed to finding matching FBConfig (%d %d %d %d)", requestedRed, requestedGreen, requestedBlue, requestedAlpha);
     } while (qglx_reduceFormat(&format));
 
     return config;
@@ -352,6 +373,18 @@ void qglx_surfaceFormatFromVisualInfo(QSurfaceFormat *format, Display *display,
 bool qglx_reduceFormat(QSurfaceFormat *format)
 {
     Q_ASSERT(format);
+    if (std::max(std::max(format->redBufferSize(), format->greenBufferSize()), format->blueBufferSize()) > 8) {
+        if (format->alphaBufferSize() > 2) {
+            // First try to match 10 10 10 2
+            format->setAlphaBufferSize(2);
+            return true;
+        }
+
+        format->setRedBufferSize(std::min(format->redBufferSize(), 8));
+        format->setGreenBufferSize(std::min(format->greenBufferSize(), 8));
+        format->setBlueBufferSize(std::min(format->blueBufferSize(), 8));
+        return true;
+    }
 
     if (format->redBufferSize() > 1) {
         format->setRedBufferSize(1);