ANGLE DX11: Prevent assert when view is minimized or size goes to 0x0

This allows the Direct3D 11 version of ANGLE to gracefully allow
surfaces with dimensions of 0. This is important because Qt may resize
the surface to 0x0 because of window minimization or other user
action (window resize). As EGL specifies that empty (0x0) surfaces are
valid, this makes sure an assert doesn't occur in the case that a valid
surface is resized to an empty one.

Change-Id: Ia60c4c694090d03c1da7f43c56e90b925c8eab6d
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>

src/3rdparty/angle/src/libEGL/Surface.cpp

@@ -172,9 +172,16 @@ bool Surface::resetSwapChain()
 
 bool Surface::resizeSwapChain(int backbufferWidth, int backbufferHeight)
 {
-    ASSERT(backbufferWidth >= 0 && backbufferHeight >= 0);
     ASSERT(mSwapChain);
 
+    // Prevent bad swap chain resize by calling reset if size is invalid
+    if (backbufferWidth < 1 || backbufferHeight < 1)
+    {
+        mWidth = backbufferWidth;
+        mHeight = backbufferHeight;
+        return mSwapChain->reset(0, 0, mSwapInterval) == EGL_SUCCESS;
+    }
+
     EGLint status = mSwapChain->resize(backbufferWidth, backbufferHeight);
 
     if (status == EGL_CONTEXT_LOST)

src/3rdparty/angle/src/libGLESv2/renderer/SwapChain11.cpp

@@ -368,6 +368,9 @@ EGLint SwapChain11::resize(EGLint backbufferWidth, EGLint backbufferHeight)
         return EGL_BAD_ACCESS;
     }
 
+    if (!mSwapChain)
+        reset(backbufferWidth, backbufferHeight, mSwapInterval);
+
     // Can only call resize if we have already created our swap buffer and resources
     ASSERT(mSwapChain && mBackBufferTexture && mBackBufferRTView);
 

src/angle/patches/0008-ANGLE-DX11-Prevent-assert-when-view-is-minimized-or-.patch

@@ -0,0 +1,58 @@
+From 654677720bd856b59387cfd034f441eba8c0e97f Mon Sep 17 00:00:00 2001
+From: Andrew Knight <andrew.knight@digia.com>
+Date: Thu, 4 Apr 2013 14:21:58 +0300
+Subject: [PATCH] ANGLE DX11: Prevent assert when view is minimized or size
+ goes to 0x0
+
+This allows the Direct3D 11 version of ANGLE to gracefully allow
+surfaces with dimensions of 0. This is important because Qt may resize
+the surface to 0x0 because of window minimization or other user
+action (window resize). As EGL specifies that empty (0x0) surfaces are
+valid, this makes sure an assert doesn't occur in the case that a valid
+surface is resized to an empty one.
+
+Change-Id: Ia60c4c694090d03c1da7f43c56e90b925c8eab6d
+---
+ src/3rdparty/angle/src/libEGL/Surface.cpp                 | 9 ++++++++-
+ src/3rdparty/angle/src/libGLESv2/renderer/SwapChain11.cpp | 3 +++
+ 2 files changed, 11 insertions(+), 1 deletion(-)
+
+diff --git a/src/3rdparty/angle/src/libEGL/Surface.cpp b/src/3rdparty/angle/src/libEGL/Surface.cpp
+index 5ece724..8387443 100644
+--- a/src/3rdparty/angle/src/libEGL/Surface.cpp
++++ b/src/3rdparty/angle/src/libEGL/Surface.cpp
+@@ -172,9 +172,16 @@ bool Surface::resetSwapChain()
+ 
+ bool Surface::resizeSwapChain(int backbufferWidth, int backbufferHeight)
+ {
+-    ASSERT(backbufferWidth >= 0 && backbufferHeight >= 0);
+     ASSERT(mSwapChain);
+ 
++    // Prevent bad swap chain resize by calling reset if size is invalid
++    if (backbufferWidth < 1 || backbufferHeight < 1)
++    {
++        mWidth = backbufferWidth;
++        mHeight = backbufferHeight;
++        return mSwapChain->reset(0, 0, mSwapInterval) == EGL_SUCCESS;
++    }
++
+     EGLint status = mSwapChain->resize(backbufferWidth, backbufferHeight);
+ 
+     if (status == EGL_CONTEXT_LOST)
+diff --git a/src/3rdparty/angle/src/libGLESv2/renderer/SwapChain11.cpp b/src/3rdparty/angle/src/libGLESv2/renderer/SwapChain11.cpp
+index 87422be..98f8875 100644
+--- a/src/3rdparty/angle/src/libGLESv2/renderer/SwapChain11.cpp
++++ b/src/3rdparty/angle/src/libGLESv2/renderer/SwapChain11.cpp
+@@ -368,6 +368,9 @@ EGLint SwapChain11::resize(EGLint backbufferWidth, EGLint backbufferHeight)
+         return EGL_BAD_ACCESS;
+     }
+ 
++    if (!mSwapChain)
++        reset(backbufferWidth, backbufferHeight, mSwapInterval);
++
+     // Can only call resize if we have already created our swap buffer and resources
+     ASSERT(mSwapChain && mBackBufferTexture && mBackBufferRTView);
+ 
+-- 
+1.8.1.msysgit.1
+