winrt: Move EGL surface to window.

Fixes GPU memory leak when window is created/deleted dynamically and
repeatedly. EGL context used to own EGL surface, but the context
outlives the surface if window is created/deleted dynamically. The
EGL surface is now owned by the window and destroyed with it.

Change-Id: Ib949261ef6e77217018e60aad3e36e4a6d2eaba0
Reviewed-by: Andrew Knight <andrew.knight@intopalo.com>

src/plugins/platforms/winrt/qwinrteglcontext.cpp

@@ -56,7 +56,6 @@ public:
     EGLDisplay eglDisplay;
     EGLConfig eglConfig;
     EGLContext eglContext;
-    QHash<QPlatformSurface *, EGLSurface> surfaceForWindow;
 };
 
 QWinRTEGLContext::QWinRTEGLContext(QOpenGLContext *context)
@@ -70,8 +69,6 @@ QWinRTEGLContext::QWinRTEGLContext(QOpenGLContext *context)
 QWinRTEGLContext::~QWinRTEGLContext()
 {
     Q_D(QWinRTEGLContext);
-    foreach (const EGLSurface &surface, d->surfaceForWindow)
-        eglDestroySurface(d->eglDisplay, surface);
     if (d->eglContext != EGL_NO_CONTEXT)
         eglDestroyContext(d->eglDisplay, d->eglContext);
     if (d->eglDisplay != EGL_NO_DISPLAY)
@@ -112,23 +109,13 @@ bool QWinRTEGLContext::makeCurrent(QPlatformSurface *windowSurface)
     Q_D(QWinRTEGLContext);
     Q_ASSERT(windowSurface->surface()->surfaceType() == QSurface::OpenGLSurface);
 
-    EGLSurface surface = d->surfaceForWindow.value(windowSurface);
-    if (surface == EGL_NO_SURFACE) {
-        QWinRTWindow *window = static_cast<QWinRTWindow *>(windowSurface);
-        HRESULT hr = QEventDispatcherWinRT::runOnXamlThread([this, d, window, &surface]() {
-            surface = eglCreateWindowSurface(d->eglDisplay, d->eglConfig,
-                                             reinterpret_cast<EGLNativeWindowType>(window->winId()),
-                                             nullptr);
-            if (surface == EGL_NO_SURFACE) {
-                qCritical("Failed to create EGL window surface: 0x%x", eglGetError());
-                return E_FAIL;
-            }
-            return S_OK;
-        });
-        if (FAILED(hr))
-            return false;
-        d->surfaceForWindow.insert(windowSurface, surface);
-    }
+    QWinRTWindow *window = static_cast<QWinRTWindow *>(windowSurface);
+    if (window->eglSurface() == EGL_NO_SURFACE)
+        window->createEglSurface(d->eglDisplay, d->eglConfig);
+
+    EGLSurface surface = window->eglSurface();
+    if (surface == EGL_NO_SURFACE)
+        return false;
 
     const bool ok = eglMakeCurrent(d->eglDisplay, surface, surface, d->eglContext);
     if (!ok) {
@@ -153,7 +140,8 @@ void QWinRTEGLContext::swapBuffers(QPlatformSurface *windowSurface)
     Q_D(QWinRTEGLContext);
     Q_ASSERT(windowSurface->surface()->surfaceType() == QSurface::OpenGLSurface);
 
-    eglSwapBuffers(d->eglDisplay, d->surfaceForWindow.value(windowSurface));
+    const QWinRTWindow *window = static_cast<QWinRTWindow *>(windowSurface);
+    eglSwapBuffers(d->eglDisplay, window->eglSurface());
 }
 
 QSurfaceFormat QWinRTEGLContext::format() const

src/plugins/platforms/winrt/qwinrtwindow.cpp

@@ -88,6 +88,8 @@ public:
     QSurfaceFormat surfaceFormat;
     QString windowTitle;
     Qt::WindowState state;
+    EGLDisplay display;
+    EGLSurface surface;
 
     ComPtr<ISwapChainPanel> swapChainPanel;
     ComPtr<ICanvasStatics> canvas;
@@ -100,6 +102,8 @@ QWinRTWindow::QWinRTWindow(QWindow *window)
 {
     Q_D(QWinRTWindow);
 
+    d->surface = EGL_NO_SURFACE;
+    d->display = EGL_NO_DISPLAY;
     d->screen = static_cast<QWinRTScreen *>(screen());
     setWindowFlags(window->flags());
     setWindowState(window->windowState());
@@ -170,6 +174,11 @@ QWinRTWindow::~QWinRTWindow()
         return S_OK;
     });
     RETURN_VOID_IF_FAILED("Failed to completely destroy window resources, likely because the application is shutting down");
+
+    EGLBoolean value = eglDestroySurface(d->display, d->surface);
+    d->surface = EGL_NO_SURFACE;
+    if (value == EGL_FALSE)
+        qCritical("Failed to destroy EGL window surface: 0x%x", eglGetError());
 }
 
 QSurfaceFormat QWinRTWindow::format() const
@@ -293,4 +302,26 @@ void QWinRTWindow::setWindowState(Qt::WindowState state)
     d->state = state;
 }
 
+EGLSurface QWinRTWindow::eglSurface() const
+{
+    Q_D(const QWinRTWindow);
+    return d->surface;
+}
+
+void QWinRTWindow::createEglSurface(EGLDisplay display, EGLConfig config)
+{
+    Q_D(QWinRTWindow);
+    if (d->surface == EGL_NO_SURFACE) {
+        d->display = display;
+        QEventDispatcherWinRT::runOnXamlThread([this, d, display, config]() {
+            d->surface = eglCreateWindowSurface(display, config,
+                                                reinterpret_cast<EGLNativeWindowType>(winId()),
+                                                nullptr);
+            if (d->surface == EGL_NO_SURFACE)
+                qCritical("Failed to create EGL window surface: 0x%x", eglGetError());
+            return S_OK;
+        });
+    }
+}
+
 QT_END_NAMESPACE

src/plugins/platforms/winrt/qwinrtwindow.h

@@ -39,6 +39,7 @@
 
 #include <qpa/qplatformwindow.h>
 #include <qpa/qwindowsysteminterface.h>
+#include <EGL/egl.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -63,6 +64,9 @@ public:
     qreal devicePixelRatio() const Q_DECL_OVERRIDE;
     void setWindowState(Qt::WindowState state) Q_DECL_OVERRIDE;
 
+    EGLSurface eglSurface() const;
+    void createEglSurface(EGLDisplay display, EGLConfig config);
+
 private:
     QScopedPointer<QWinRTWindowPrivate> d_ptr;
     Q_DECLARE_PRIVATE(QWinRTWindow)