Environment variable enabling the workaround FBO readback bug

On some ARM devices the font glyph generation is broken
Add an environment variable to enable workaround_brokenFBOReadBack
in QOpenGLContext, to fix font rendering on such devices as
Mali and Adreno

Change-Id: I9cc99ecb8b71a35bc369ec9dd11b877016b1179e
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

3 files changed, 34 insertions, 32 deletions

diff --git a/src/gui/kernel/qopenglcontext.cpp b/src/gui/kernel/qopenglcontext.cpp
index 8aea593bf0..3dc06ae60e 100644
--- a/src/gui/kernel/qopenglcontext.cpp
+++ b/src/gui/kernel/qopenglcontext.cpp
@@ -982,6 +982,40 @@ bool QOpenGLContext::makeCurrent(QSurface *surface)
     QOpenGLContext *previous = QOpenGLContextPrivate::setCurrentContext(this);
 
     if (d->platformGLContext->makeCurrent(surface->surfaceHandle())) {
+        static bool needsWorkaroundSet = false;
+        static bool needsWorkaround = false;
+
+        if (!needsWorkaroundSet) {
+            QByteArray env;
+#ifdef Q_OS_ANDROID
+            env = qgetenv(QByteArrayLiteral("QT_ANDROID_DISABLE_GLYPH_CACHE_WORKAROUND"));
+            needsWorkaround = env.isEmpty() || env == QByteArrayLiteral("0") || env == QByteArrayLiteral("false");
+#endif
+            env = qgetenv(QByteArrayLiteral("QT_ENABLE_GLYPH_CACHE_WORKAROUND"));
+            if (env == QByteArrayLiteral("1") || env == QByteArrayLiteral("true"))
+                needsWorkaround = true;
+
+            if (!needsWorkaround) {
+                const char *rendererString = reinterpret_cast<const char *>(functions()->glGetString(GL_RENDERER));
+                if (rendererString)
+                    needsWorkaround =
+                            qstrncmp(rendererString, "Mali-4xx", 6) == 0 // Mali-400, Mali-450
+                            || qstrncmp(rendererString, "Adreno (TM) 2xx", 13) == 0 // Adreno 200, 203, 205
+                            || qstrncmp(rendererString, "Adreno 2xx", 8) == 0 // Same as above but without the '(TM)'
+                            || qstrncmp(rendererString, "Adreno (TM) 30x", 14) == 0 // Adreno 302, 305
+                            || qstrncmp(rendererString, "Adreno 30x", 9) == 0 // Same as above but without the '(TM)'
+                            || qstrncmp(rendererString, "Adreno (TM) 4xx", 13) == 0 // Adreno 405, 418, 420, 430
+                            || qstrncmp(rendererString, "Adreno 4xx", 8) == 0 // Same as above but without the '(TM)'
+                            || qstrcmp(rendererString, "GC800 core") == 0
+                            || qstrcmp(rendererString, "GC1000 core") == 0
+                            || qstrcmp(rendererString, "Immersion.16") == 0;
+            }
+            needsWorkaroundSet = true;
+        }
+
+        if (needsWorkaround)
+            d->workaround_brokenFBOReadBack = true;
+
         d->surface = surface;
 
         d->shareGroup->d_func()->deletePendingResources(this);
diff --git a/src/plugins/platforms/android/qandroidplatformopenglcontext.cpp b/src/plugins/platforms/android/qandroidplatformopenglcontext.cpp
index 4d52085a83..6f979f614c 100644
--- a/src/plugins/platforms/android/qandroidplatformopenglcontext.cpp
+++ b/src/plugins/platforms/android/qandroidplatformopenglcontext.cpp
@@ -65,42 +65,11 @@ void QAndroidPlatformOpenGLContext::swapBuffers(QPlatformSurface *surface)
     QEGLPlatformContext::swapBuffers(surface);
 }
 
-bool QAndroidPlatformOpenGLContext::needsFBOReadBackWorkaround()
-{
-    static bool set = false;
-    static bool needsWorkaround = false;
-
-    if (!set) {
-        QByteArray env = qgetenv("QT_ANDROID_DISABLE_GLYPH_CACHE_WORKAROUND");
-        needsWorkaround = env.isEmpty() || env == "0" || env == "false";
-
-        if (!needsWorkaround) {
-            const char *rendererString = reinterpret_cast<const char *>(glGetString(GL_RENDERER));
-            needsWorkaround =
-                    qstrncmp(rendererString, "Mali-4xx", 6) == 0 // Mali-400, Mali-450
-                    || qstrncmp(rendererString, "Adreno (TM) 2xx", 13) == 0 // Adreno 200, 203, 205
-                    || qstrncmp(rendererString, "Adreno 2xx", 8) == 0 // Same as above but without the '(TM)'
-                    || qstrncmp(rendererString, "Adreno (TM) 30x", 14) == 0 // Adreno 302, 305
-                    || qstrncmp(rendererString, "Adreno 30x", 9) == 0 // Same as above but without the '(TM)'
-                    || qstrcmp(rendererString, "GC800 core") == 0
-                    || qstrcmp(rendererString, "GC1000 core") == 0
-                    || qstrcmp(rendererString, "Immersion.16") == 0;
-        }
-
-        set = true;
-    }
-
-    return needsWorkaround;
-}
-
 bool QAndroidPlatformOpenGLContext::makeCurrent(QPlatformSurface *surface)
 {
     bool ret = QEGLPlatformContext::makeCurrent(surface);
     QOpenGLContextPrivate *ctx_d = QOpenGLContextPrivate::get(context());
 
-    if (!ctx_d->workaround_brokenFBOReadBack && needsFBOReadBackWorkaround())
-        ctx_d->workaround_brokenFBOReadBack = true;
-
     return ret;
 }
 
diff --git a/src/plugins/platforms/android/qandroidplatformopenglcontext.h b/src/plugins/platforms/android/qandroidplatformopenglcontext.h
index 3897b3166b..8e65b4cc36 100644
--- a/src/plugins/platforms/android/qandroidplatformopenglcontext.h
+++ b/src/plugins/platforms/android/qandroidplatformopenglcontext.h
@@ -55,7 +55,6 @@ public:
 private:
     EGLSurface eglSurfaceForPlatformSurface(QPlatformSurface *surface) override;
 
-    static bool needsFBOReadBackWorkaround();
 };
 
 QT_END_NAMESPACE