ANGLE: Fix winrt backing store to support feature level 9_3 devices.

Partially revert c7abf81786f4a0c. Instead of using the ES3 entry point,
use ES2 for framebuffer blitting. This means that a small change is
required to ANGLE for the blit behave the same as ES3 (applied only for
Windows Store apps).

Task-Id: QTBUG-48266
Change-Id: Idc51f00a659c91f740876be071eb71bff69e0e38
Reviewed-by: Andrew Knight <andrew.knight@intopalo.com>

3 files changed, 47 insertions, 6 deletions

diff --git a/src/3rdparty/angle/src/libGLESv2/entry_points_gles_2_0_ext.cpp b/src/3rdparty/angle/src/libGLESv2/entry_points_gles_2_0_ext.cpp
index 8be6ae7d2f..d41c5a4da5 100644
--- a/src/3rdparty/angle/src/libGLESv2/entry_points_gles_2_0_ext.cpp
+++ b/src/3rdparty/angle/src/libGLESv2/entry_points_gles_2_0_ext.cpp
@@ -659,7 +659,11 @@ void GL_APIENTRY BlitFramebufferANGLE(GLint srcX0, GLint srcY0, GLint srcX1, GLi
     {
         if (!ValidateBlitFramebufferParameters(context, srcX0, srcY0, srcX1, srcY1,
                                                dstX0, dstY0, dstX1, dstY1, mask, filter,
+#ifndef ANGLE_ENABLE_WINDOWS_STORE
                                                true))
+#else
+                                               false))
+#endif
         {
             return;
         }
diff --git a/src/angle/patches/0009-ANGLE-Fix-winrt-backing-store-to-support-feature-lev.patch b/src/angle/patches/0009-ANGLE-Fix-winrt-backing-store-to-support-feature-lev.patch
new file mode 100644
index 0000000000..8f66b0c1d8
--- /dev/null
+++ b/src/angle/patches/0009-ANGLE-Fix-winrt-backing-store-to-support-feature-lev.patch
@@ -0,0 +1,38 @@
+From 54461670e035ffcb41268a02e9b0c441cc008ddb Mon Sep 17 00:00:00 2001
+From: Samuel Nevala <samuel.nevala@intopalo.com>
+Date: Thu, 22 Oct 2015 14:02:28 +0300
+Subject: [PATCH] ANGLE: Fix winrt backing store to support feature level 9_3
+ devices.
+
+Partially revert c7abf81786f4a0c. Instead of using ES3 entry point
+use ES2 for blitting. Small change is also required to ANGLE that
+makes ES2 entry to behave same as ES3.
+
+Task-Id: QTBUG-48266
+Change-Id: Idc51f00a659c91f740876be071eb71bff69e0e38
+---
+ .../src/libGLESv2/entry_points_gles_2_0_ext.cpp    |  4 +++
+ ...inrt-backing-store-to-support-feature-lev.patch | 33 ++++++++++++++++++++++
+ src/plugins/platforms/winrt/qwinrtbackingstore.cpp | 11 ++++----
+ 3 files changed, 42 insertions(+), 6 deletions(-)
+ create mode 100644 src/angle/patches/0009-ANGLE-Fix-winrt-backing-store-to-support-feature-lev.patch
+
+diff --git a/src/3rdparty/angle/src/libGLESv2/entry_points_gles_2_0_ext.cpp b/src/3rdparty/angle/src/libGLESv2/entry_points_gles_2_0_ext.cpp
+index 8be6ae7..d41c5a4 100644
+--- a/src/3rdparty/angle/src/libGLESv2/entry_points_gles_2_0_ext.cpp
++++ b/src/3rdparty/angle/src/libGLESv2/entry_points_gles_2_0_ext.cpp
+@@ -659,7 +659,11 @@ void GL_APIENTRY BlitFramebufferANGLE(GLint srcX0, GLint srcY0, GLint srcX1, GLi
+     {
+         if (!ValidateBlitFramebufferParameters(context, srcX0, srcY0, srcX1, srcY1,
+                                                dstX0, dstY0, dstX1, dstY1, mask, filter,
++#ifndef ANGLE_ENABLE_WINDOWS_STORE
+                                                true))
++#else
++                                               false))
++#endif
+         {
+             return;
+         }
+-- 
+1.9.5.msysgit.1
+
diff --git a/src/plugins/platforms/winrt/qwinrtbackingstore.cpp b/src/plugins/platforms/winrt/qwinrtbackingstore.cpp
index dcf8239538..ee54bf795c 100644
--- a/src/plugins/platforms/winrt/qwinrtbackingstore.cpp
+++ b/src/plugins/platforms/winrt/qwinrtbackingstore.cpp
@@ -42,8 +42,8 @@
 #include <QtGui/QOpenGLContext>
 #include <QtGui/QOpenGLFramebufferObject>
 
-#include <GLES3/gl3.h>
-#include <GLES3/gl3ext.h>
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -78,7 +78,6 @@ bool QWinRTBackingStore::initialize()
 
     d->context.reset(new QOpenGLContext);
     QSurfaceFormat format = window()->requestedFormat();
-    format.setVersion(3, 0); // Required for ES3 framebuffer blit
     d->context->setFormat(format);
     d->context->setScreen(window()->screen());
     if (!d->context->create())
@@ -121,13 +120,13 @@ void QWinRTBackingStore::flush(QWindow *window, const QRegion &region, const QPo
                     GL_RGBA, GL_UNSIGNED_BYTE, d->paintDevice.constScanLine(bounds.y()));
     glBindTexture(GL_TEXTURE_2D, 0);
 
-    glBindFramebuffer(GL_READ_FRAMEBUFFER, d->fbo->handle());
-    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
+    glBindFramebuffer(GL_READ_FRAMEBUFFER_ANGLE, d->fbo->handle());
+    glBindFramebuffer(GL_DRAW_FRAMEBUFFER_ANGLE, 0);
     const int y1 = bounds.y();
     const int y2 = y1 + bounds.height();
     const int x1 = bounds.x();
     const int x2 = x1 + bounds.width();
-    glBlitFramebuffer(x1, y1, x2, y2,
+    glBlitFramebufferANGLE(x1, y1, x2, y2,
                       x1, d->size.height() - y1, x2, d->size.height() - y2,
                       GL_COLOR_BUFFER_BIT, GL_NEAREST);