iOS: Update GL render buffers when the accociated window is resized

We keep track of the with and height of the FBO's buffers, and update
their storage if the window size has changed since last time.

Change-Id: I97788b69e7067a5b5b9f28e8498cf1bc5d2cf6ea
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>

1 files changed, 47 insertions, 35 deletions

diff --git a/src/plugins/platforms/ios/qioswindow.mm b/src/plugins/platforms/ios/qioswindow.mm
index b209bbc159..90734e58e8 100644
--- a/src/plugins/platforms/ios/qioswindow.mm
+++ b/src/plugins/platforms/ios/qioswindow.mm
@@ -116,6 +116,10 @@ static QRect fromCGRect(const CGRect &rect)
     QRect geometry = fromCGRect(self.frame);
     m_qioswindow->QPlatformWindow::setGeometry(geometry);
     QWindowSystemInterface::handleGeometryChange(m_qioswindow->window(), geometry);
+
+    // If we have a new size here we need to resize the FBO's corresponding buffers,
+    // but we defer that to when the application calls makeCurrent.
+
     [super layoutSubviews];
 }
 
@@ -200,6 +204,7 @@ QIOSWindow::QIOSWindow(QWindow *window)
     : QPlatformWindow(window)
     , m_view([[EAGLView alloc] initWithQIOSWindow:this])
     , m_requestedGeometry(QPlatformWindow::geometry())
+    , m_glData()
 {
     if ([[UIApplication sharedApplication].delegate isKindOfClass:[QIOSApplicationDelegate class]])
         [[UIApplication sharedApplication].delegate.window.rootViewController.view addSubview:m_view];
@@ -209,6 +214,13 @@ QIOSWindow::QIOSWindow(QWindow *window)
 
 QIOSWindow::~QIOSWindow()
 {
+    if (m_glData.framebufferObject)
+        glDeleteFramebuffers(1, &m_glData.framebufferObject);
+    if (m_glData.colorRenderbuffer)
+        glDeleteRenderbuffers(1, &m_glData.colorRenderbuffer);
+    if (m_glData.depthRenderbuffer)
+        glDeleteRenderbuffers(1, &m_glData.depthRenderbuffer);
+
     [m_view release];
 }
 
@@ -259,56 +271,56 @@ void QIOSWindow::handleContentOrientationChange(Qt::ScreenOrientation orientatio
 
 GLuint QIOSWindow::framebufferObject(const QIOSContext &context) const
 {
-    static GLuint framebuffer = 0;
+    if (!m_glData.framebufferObject) {
+        [EAGLContext setCurrentContext:context.nativeContext()];
 
-    // FIXME: Cache context and recreate framebuffer if window
-    // is used with a different context then last time.
+        glGenFramebuffers(1, &m_glData.framebufferObject);
+        glBindFramebuffer(GL_FRAMEBUFFER, m_glData.framebufferObject);
 
-    if (!framebuffer) {
-        EAGLContext* eaglContext = context.nativeContext();
+        glGenRenderbuffers(1, &m_glData.colorRenderbuffer);
+        glBindRenderbuffer(GL_RENDERBUFFER, m_glData.colorRenderbuffer);
+        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, m_glData.colorRenderbuffer);
 
-        [EAGLContext setCurrentContext:eaglContext];
+        QSurfaceFormat requestedFormat = context.format();
+        if (requestedFormat.depthBufferSize() > 0 || requestedFormat.stencilBufferSize() > 0) {
+            glGenRenderbuffers(1, &m_glData.depthRenderbuffer);
+            glBindRenderbuffer(GL_RENDERBUFFER, m_glData.depthRenderbuffer);
+            glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, m_glData.depthRenderbuffer);
 
-        // Create the framebuffer and bind it
-        glGenFramebuffers(1, &framebuffer);
-        glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
+            if (requestedFormat.stencilBufferSize() > 0)
+                glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, m_glData.depthRenderbuffer);
+        }
+    }
 
-        GLint width;
-        GLint height;
+    return m_glData.framebufferObject;
+}
 
-        // Create a color renderbuffer, allocate storage for it,
-        // and attach it to the framebuffer’s color attachment point.
-        GLuint colorRenderbuffer;
-        glGenRenderbuffers(1, &colorRenderbuffer);
-        glBindRenderbuffer(GL_RENDERBUFFER, colorRenderbuffer);
-        [eaglContext renderbufferStorage:GL_RENDERBUFFER fromDrawable:static_cast<CAEAGLLayer *>(m_view.layer)];
-        glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &width);
-        glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &height);
-        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorRenderbuffer);
+GLuint QIOSWindow::colorRenderbuffer(const QIOSContext &context) const
+{
+    if (!m_glData.colorRenderbuffer ||
+        m_glData.renderbufferWidth != geometry().width() || m_glData.renderbufferHeight != geometry().height()) {
 
-        QSurfaceFormat requestedFormat = context.format();
-        if (requestedFormat.depthBufferSize() > 0 || requestedFormat.stencilBufferSize() > 0) {
-            // Create a depth or depth/stencil renderbuffer, allocate storage for it,
-            // and attach it to the framebuffer’s depth attachment point.
-            GLuint depthRenderbuffer;
-            glGenRenderbuffers(1, &depthRenderbuffer);
-            glBindRenderbuffer(GL_RENDERBUFFER, depthRenderbuffer);
+        glBindRenderbuffer(GL_RENDERBUFFER, m_glData.colorRenderbuffer);
+        [context.nativeContext() renderbufferStorage:GL_RENDERBUFFER fromDrawable:static_cast<CAEAGLLayer *>(m_view.layer)];
+
+        glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &m_glData.renderbufferWidth);
+        glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &m_glData.renderbufferHeight);
+
+        if (m_glData.depthRenderbuffer) {
+            glBindRenderbuffer(GL_RENDERBUFFER, m_glData.depthRenderbuffer);
 
             // FIXME: Support more fine grained control over depth/stencil buffer sizes
-            if (requestedFormat.stencilBufferSize() > 0) {
-                glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, width, height);
-                glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);
-            } else {
-                glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, width, height);
-            }
-            glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);
+            if (context.format().stencilBufferSize() > 0)
+                glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, m_glData.renderbufferWidth, m_glData.renderbufferHeight);
+            else
+                glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, m_glData.renderbufferWidth, m_glData.renderbufferHeight);
         }
 
         if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
             NSLog(@"Failed to make complete framebuffer object %x", glCheckFramebufferStatus(GL_FRAMEBUFFER));
     }
 
-    return framebuffer;
+    return m_glData.colorRenderbuffer;
 }
 
 QT_END_NAMESPACE