rhi: gl: Pick up context loss

...and change the return value of makeThreadLocalNativeContextCurrent() to
a bool since we expect this to mirror QOpenGLContext::makeCurrent().

Change-Id: I339507152e461fe28fcf7fe777165e6d0072f055
Reviewed-by: Christian Strømme <christian.stromme@qt.io>

src/gui/rhi/qrhi.cpp

@@ -468,7 +468,7 @@ Q_LOGGING_CATEGORY(QRHI_LOG_INFO, "qt.rhi.general")
     \value FrameOpDeviceLost The graphics device was lost. This can be
     recoverable by attempting to repeat the operation (such as, beginFrame())
     after releasing and reinitializing all objects backed by native graphics
-    resources.
+    resources. See isDeviceLost().
  */
 
 /*!
@@ -5022,10 +5022,17 @@ const QRhiNativeHandles *QRhi::nativeHandles()
     has to ensure external OpenGL code provided by the application can still
     run like it did before with direct usage of OpenGL, as long as the QRhi is
     using the OpenGL backend.
+
+    \return false when failed, similarly to QOpenGLContext::makeCurrent(). When
+    the operation failed, isDeviceLost() can be called to determine if there
+    was a loss of context situation. Such a check is equivalent to checking via
+    QOpenGLContext::isValid().
+
+    \sa QOpenGLContext::makeCurrent(), QOpenGLContext::isValid()
  */
-void QRhi::makeThreadLocalNativeContextCurrent()
+bool QRhi::makeThreadLocalNativeContextCurrent()
 {
-    d->makeThreadLocalNativeContextCurrent();
+    return d->makeThreadLocalNativeContextCurrent();
 }
 
 /*!
@@ -5092,6 +5099,12 @@ void QRhi::releaseCachedResources()
     reinitialized then. However, applications and libraries working directly
     with QRhi are expected to be prepared to check and handle device loss
     situations themselves.
+
+    \note With OpenGL, applications may need to opt-in to context reset
+    notifications by setting QSurfaceFormat::ResetNotification on the
+    QOpenGLContext. This is typically done by enabling the flag in
+    QRhiGles2InitParams::format. Keep in mind however that some systems may
+    generate context resets situations even when this flag is not set.
  */
 bool QRhi::isDeviceLost() const
 {
@@ -5259,7 +5272,17 @@ QRhiSwapChain *QRhi::newSwapChain()
 
     \endlist
 
-    \sa endFrame(), beginOffscreenFrame()
+    \return QRhi::FrameOpSuccess on success, or another QRhi::FrameOpResult
+    value on failure. Some of these should be treated as soft, "try again
+    later" type of errors: When QRhi::FrameOpSwapChainOutOfDate is returned,
+    the swapchain is to be resized or updated by calling
+    QRhiSwapChain::buildOrResize(). The application should then attempt to
+    generate a new frame. QRhi::FrameOpDeviceLost means the graphics device is
+    lost but this may also be recoverable by releasing all resources, including
+    the QRhi itself, and then recreating all resources. See isDeviceLost() for
+    further discussion.
+
+    \sa endFrame(), beginOffscreenFrame(), isDeviceLost()
  */
 QRhi::FrameOpResult QRhi::beginFrame(QRhiSwapChain *swapChain, BeginFrameFlags flags)
 {
@@ -5284,7 +5307,17 @@ QRhi::FrameOpResult QRhi::beginFrame(QRhiSwapChain *swapChain, BeginFrameFlags f
     Passing QRhi::SkipPresent skips queuing the Present command or calling
     swapBuffers.
 
-    \sa beginFrame()
+    \return QRhi::FrameOpSuccess on success, or another QRhi::FrameOpResult
+    value on failure. Some of these should be treated as soft, "try again
+    later" type of errors: When QRhi::FrameOpSwapChainOutOfDate is returned,
+    the swapchain is to be resized or updated by calling
+    QRhiSwapChain::buildOrResize(). The application should then attempt to
+    generate a new frame. QRhi::FrameOpDeviceLost means the graphics device is
+    lost but this may also be recoverable by releasing all resources, including
+    the QRhi itself, and then recreating all resources. See isDeviceLost() for
+    further discussion.
+
+    \sa beginFrame(), isDeviceLost()
  */
 QRhi::FrameOpResult QRhi::endFrame(QRhiSwapChain *swapChain, EndFrameFlags flags)
 {

src/gui/rhi/qrhi_p.h

@@ -1414,7 +1414,7 @@ public:
     int resourceLimit(ResourceLimit limit) const;
 
     const QRhiNativeHandles *nativeHandles();
-    void makeThreadLocalNativeContextCurrent();
+    bool makeThreadLocalNativeContextCurrent();
 
     QRhiProfiler *profiler();
 

src/gui/rhi/qrhi_p_p.h

@@ -156,7 +156,7 @@ public:
     virtual int resourceLimit(QRhi::ResourceLimit limit) const = 0;
     virtual const QRhiNativeHandles *nativeHandles() = 0;
     virtual void sendVMemStatsToProfiler() = 0;
-    virtual void makeThreadLocalNativeContextCurrent() = 0;
+    virtual bool makeThreadLocalNativeContextCurrent() = 0;
     virtual void releaseCachedResources() = 0;
     virtual bool isDeviceLost() const = 0;
 

src/gui/rhi/qrhid3d11.cpp

@@ -502,9 +502,10 @@ void QRhiD3D11::sendVMemStatsToProfiler()
     // nothing to do here
 }
 
-void QRhiD3D11::makeThreadLocalNativeContextCurrent()
+bool QRhiD3D11::makeThreadLocalNativeContextCurrent()
 {
-    // nothing to do here
+    // not applicable
+    return false;
 }
 
 void QRhiD3D11::releaseCachedResources()

src/gui/rhi/qrhid3d11_p_p.h

@@ -631,7 +631,7 @@ public:
     int resourceLimit(QRhi::ResourceLimit limit) const override;
     const QRhiNativeHandles *nativeHandles() override;
     void sendVMemStatsToProfiler() override;
-    void makeThreadLocalNativeContextCurrent() override;
+    bool makeThreadLocalNativeContextCurrent() override;
     void releaseCachedResources() override;
     bool isDeviceLost() const override;
 

src/gui/rhi/qrhigles2.cpp

@@ -371,7 +371,12 @@ bool QRhiGles2::ensureContext(QSurface *surface) const
         return true;
 
     if (!ctx->makeCurrent(surface)) {
-        qWarning("QRhiGles2: Failed to make context current. Expect bad things to happen.");
+        if (ctx->isValid()) {
+            qWarning("QRhiGles2: Failed to make context current. Expect bad things to happen.");
+        } else {
+            qWarning("QRhiGles2: Context is lost.");
+            contextLost = true;
+        }
         return false;
     }
 
@@ -491,6 +496,8 @@ bool QRhiGles2::create(QRhi::Flags flags)
 
     nativeHandlesStruct.context = ctx;
 
+    contextLost = false;
+
     return true;
 }
 
@@ -753,12 +760,12 @@ void QRhiGles2::sendVMemStatsToProfiler()
     // nothing to do here
 }
 
-void QRhiGles2::makeThreadLocalNativeContextCurrent()
+bool QRhiGles2::makeThreadLocalNativeContextCurrent()
 {
     if (inFrame && !ofr.active)
-        ensureContext(currentSwapChain->surface);
+        return ensureContext(currentSwapChain->surface);
     else
-        ensureContext();
+        return ensureContext();
 }
 
 void QRhiGles2::releaseCachedResources()
@@ -774,7 +781,7 @@ void QRhiGles2::releaseCachedResources()
 
 bool QRhiGles2::isDeviceLost() const
 {
-    return false;
+    return contextLost;
 }
 
 QRhiRenderBuffer *QRhiGles2::createRenderBuffer(QRhiRenderBuffer::Type type, const QSize &pixelSize,
@@ -1161,7 +1168,7 @@ QRhi::FrameOpResult QRhiGles2::beginFrame(QRhiSwapChain *swapChain, QRhi::BeginF
 
     QGles2SwapChain *swapChainD = QRHI_RES(QGles2SwapChain, swapChain);
     if (!ensureContext(swapChainD->surface))
-        return QRhi::FrameOpError;
+        return contextLost ? QRhi::FrameOpDeviceLost : QRhi::FrameOpError;
 
     currentSwapChain = swapChainD;
 
@@ -1184,7 +1191,7 @@ QRhi::FrameOpResult QRhiGles2::endFrame(QRhiSwapChain *swapChain, QRhi::EndFrame
     addBoundaryCommand(&swapChainD->cb, QGles2CommandBuffer::Command::EndFrame);
 
     if (!ensureContext(swapChainD->surface))
-        return QRhi::FrameOpError;
+        return contextLost ? QRhi::FrameOpDeviceLost : QRhi::FrameOpError;
 
     executeCommandBuffer(&swapChainD->cb);
 
@@ -1208,7 +1215,7 @@ QRhi::FrameOpResult QRhiGles2::beginOffscreenFrame(QRhiCommandBuffer **cb, QRhi:
 {
     Q_UNUSED(flags);
     if (!ensureContext())
-        return QRhi::FrameOpError;
+        return contextLost ? QRhi::FrameOpDeviceLost : QRhi::FrameOpError;
 
     ofr.active = true;
 
@@ -1230,7 +1237,7 @@ QRhi::FrameOpResult QRhiGles2::endOffscreenFrame(QRhi::EndFrameFlags flags)
     addBoundaryCommand(&ofr.cbWrapper, QGles2CommandBuffer::Command::EndFrame);
 
     if (!ensureContext())
-        return QRhi::FrameOpError;
+        return contextLost ? QRhi::FrameOpDeviceLost : QRhi::FrameOpError;
 
     executeCommandBuffer(&ofr.cbWrapper);
 
@@ -1244,14 +1251,14 @@ QRhi::FrameOpResult QRhiGles2::finish()
             Q_ASSERT(!currentSwapChain);
             Q_ASSERT(ofr.cbWrapper.recordingPass == QGles2CommandBuffer::NoPass);
             if (!ensureContext())
-                return QRhi::FrameOpError;
+                return contextLost ? QRhi::FrameOpDeviceLost : QRhi::FrameOpError;
             executeCommandBuffer(&ofr.cbWrapper);
             ofr.cbWrapper.resetCommands();
         } else {
             Q_ASSERT(currentSwapChain);
             Q_ASSERT(currentSwapChain->cb.recordingPass == QGles2CommandBuffer::NoPass);
             if (!ensureContext(currentSwapChain->surface))
-                return QRhi::FrameOpError;
+                return contextLost ? QRhi::FrameOpDeviceLost : QRhi::FrameOpError;
             executeCommandBuffer(&currentSwapChain->cb);
             currentSwapChain->cb.resetCommands();
         }

src/gui/rhi/qrhigles2_p_p.h

@@ -664,7 +664,7 @@ public:
     int resourceLimit(QRhi::ResourceLimit limit) const override;
     const QRhiNativeHandles *nativeHandles() override;
     void sendVMemStatsToProfiler() override;
-    void makeThreadLocalNativeContextCurrent() override;
+    bool makeThreadLocalNativeContextCurrent() override;
     void releaseCachedResources() override;
     bool isDeviceLost() const override;
 
@@ -770,6 +770,7 @@ public:
     QVector<GLint> supportedCompressedFormats;
     mutable QVector<int> supportedSampleCountList;
     QRhiGles2NativeHandles nativeHandlesStruct;
+    mutable bool contextLost = false;
 
     struct DeferredReleaseEntry {
         enum Type {

src/gui/rhi/qrhimetal.mm

@@ -583,9 +583,10 @@ void QRhiMetal::sendVMemStatsToProfiler()
     // nothing to do here
 }
 
-void QRhiMetal::makeThreadLocalNativeContextCurrent()
+bool QRhiMetal::makeThreadLocalNativeContextCurrent()
 {
-    // nothing to do here
+    // not applicable
+    return false;
 }
 
 void QRhiMetal::releaseCachedResources()

src/gui/rhi/qrhimetal_p_p.h

@@ -416,7 +416,7 @@ public:
     int resourceLimit(QRhi::ResourceLimit limit) const override;
     const QRhiNativeHandles *nativeHandles() override;
     void sendVMemStatsToProfiler() override;
-    void makeThreadLocalNativeContextCurrent() override;
+    bool makeThreadLocalNativeContextCurrent() override;
     void releaseCachedResources() override;
     bool isDeviceLost() const override;
 

src/gui/rhi/qrhinull.cpp

@@ -169,9 +169,10 @@ void QRhiNull::sendVMemStatsToProfiler()
     // nothing to do here
 }
 
-void QRhiNull::makeThreadLocalNativeContextCurrent()
+bool QRhiNull::makeThreadLocalNativeContextCurrent()
 {
-    // nothing to do here
+    // not applicable
+    return false;
 }
 
 void QRhiNull::releaseCachedResources()

src/gui/rhi/qrhinull_p_p.h

@@ -282,7 +282,7 @@ public:
     int resourceLimit(QRhi::ResourceLimit limit) const override;
     const QRhiNativeHandles *nativeHandles() override;
     void sendVMemStatsToProfiler() override;
-    void makeThreadLocalNativeContextCurrent() override;
+    bool makeThreadLocalNativeContextCurrent() override;
     void releaseCachedResources() override;
     bool isDeviceLost() const override;
 

src/gui/rhi/qrhivulkan.cpp

@@ -3767,9 +3767,10 @@ void QRhiVulkan::sendVMemStatsToProfiler()
                          quint32(stats.total.usedBytes), quint32(stats.total.unusedBytes)));
 }
 
-void QRhiVulkan::makeThreadLocalNativeContextCurrent()
+bool QRhiVulkan::makeThreadLocalNativeContextCurrent()
 {
-    // nothing to do here
+    // not applicable
+    return false;
 }
 
 void QRhiVulkan::releaseCachedResources()

src/gui/rhi/qrhivulkan_p_p.h

@@ -711,7 +711,7 @@ public:
     int resourceLimit(QRhi::ResourceLimit limit) const override;
     const QRhiNativeHandles *nativeHandles() override;
     void sendVMemStatsToProfiler() override;
-    void makeThreadLocalNativeContextCurrent() override;
+    bool makeThreadLocalNativeContextCurrent() override;
     void releaseCachedResources() override;
     bool isDeviceLost() const override;