commit 739bd8baafb4ba9720c18fde70dcfeaef7ab0f1f
author Frank Henigman <fjhenigman@chromium.org> Mon Jun 19 21:02:27 2017 -0400
committer Commit Bot <commit-bot@chromium.org> Tue Jul 04 19:57:20 2017 +0000
tree eb99f55e69a5ef998cbbd5dda16b73b2a2fd4e0b
parent e145def0fc48ed4b1c3ae1dd3ea2e6969e56bd45

Clip FramebufferD3D::readPixels to framebuffer.

In GL, ReadPixels() is allowed to modify memory that corresponds to
pixels outside the framebuffer.
In WebGL it must not do that, so clip the read area to the framebuffer.

Enable corresponding test.

BUG=angleproject:1815

Change-Id: Ie99401a2102c352ffb1193a57aa66a5b96c184aa
Reviewed-on: https://chromium-review.googlesource.com/540556
Commit-Queue: Frank Henigman <fjhenigman@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>

src/libANGLE/renderer/d3d/FramebufferD3D.cpp

diff --git a/src/libANGLE/renderer/d3d/FramebufferD3D.cpp b/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
index 4d3b064..e1f9bc5 100644
--- a/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
+++ b/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
@@ -236,22 +236,34 @@
 }
 
 gl::Error FramebufferD3D::readPixels(const gl::Context *context,
-                                     const gl::Rectangle &area,
+                                     const gl::Rectangle &origArea,
                                      GLenum format,
                                      GLenum type,
                                      void *pixels) const
 {
+    // Clip read area to framebuffer.
+    const gl::Extents fbSize = getState().getReadAttachment()->getSize();
+    const gl::Rectangle fbRect(0, 0, fbSize.width, fbSize.height);
+    gl::Rectangle area;
+    if (!ClipRectangle(origArea, fbRect, &area))
+    {
+        // nothing to read
+        return gl::NoError();
+    }
+
     const gl::PixelPackState &packState = context->getGLState().getPackState();
 
     const gl::InternalFormat &sizedFormatInfo = gl::GetInternalFormatInfo(format, type);
 
     GLuint outputPitch = 0;
-    ANGLE_TRY_RESULT(
-        sizedFormatInfo.computeRowPitch(type, area.width, packState.alignment, packState.rowLength),
-        outputPitch);
+    ANGLE_TRY_RESULT(sizedFormatInfo.computeRowPitch(type, origArea.width, packState.alignment,
+                                                     packState.rowLength),
+                     outputPitch);
     GLuint outputSkipBytes = 0;
     ANGLE_TRY_RESULT(sizedFormatInfo.computeSkipBytes(outputPitch, 0, packState, false),
                      outputSkipBytes);
+    outputSkipBytes +=
+        (area.x - origArea.x) * sizedFormatInfo.pixelBytes + (area.y - origArea.y) * outputPitch;
 
     return readPixelsImpl(context, area, format, type, outputPitch, packState,
                           reinterpret_cast<uint8_t *>(pixels) + outputSkipBytes);