Add GL_ANGLE_pack_reverse_row_order to command buffer

Bug=82559
Review URL: http://codereview.chromium.org/8513017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@112245 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 116 insertions, 6 deletions

diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index 99eac94..84fc9a7 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -540,9 +540,11 @@ GLES2Implementation::GLES2Implementation(
           helper,
           static_cast<char*>(transfer_buffer) + kStartingOffset),
       transfer_buffer_id_(transfer_buffer_id),
+      angle_pack_reverse_row_order_status(kUnknownExtensionStatus),
       pack_alignment_(4),
       unpack_alignment_(4),
       unpack_flip_y_(false),
+      pack_reverse_row_order_(false),
       active_texture_unit_(0),
       bound_framebuffer_(0),
       bound_renderbuffer_(0),
@@ -648,6 +650,41 @@ void GLES2Implementation::WaitForCmd() {
   helper_->CommandBufferHelper::Finish();
 }
 
+namespace {
+bool IsExtensionAvailable(GLES2Implementation* gles2, const char ext[]) {
+  const char* extensions = reinterpret_cast<const char*>(
+      gles2->GetString(GL_EXTENSIONS));
+  int length = strlen(ext);
+  while (true) {
+    int n = strcspn(extensions, " ");
+    if (n == length && 0 == strncmp(ext, extensions, length)) {
+      return true;
+    }
+    if ('\0' == extensions[n]) {
+      return false;
+    }
+    extensions += n+1;
+  }
+}
+}
+
+bool GLES2Implementation::IsAnglePackReverseRowOrderAvailable() {
+  switch (angle_pack_reverse_row_order_status) {
+    case kAvailableExtensionStatus:
+      return true;
+    case kUnavailableExtensionStatus:
+      return false;
+    default:
+      if (IsExtensionAvailable(this, "GL_ANGLE_pack_reverse_row_order")) {
+          angle_pack_reverse_row_order_status = kAvailableExtensionStatus;
+          return true;
+      } else {
+          angle_pack_reverse_row_order_status = kUnavailableExtensionStatus;
+          return false;
+      }
+  }
+}
+
 GLenum GLES2Implementation::GetError() {
   GPU_CLIENT_LOG("[" << this << "] glGetError()");
   GLenum err = GetGLError();
@@ -1221,6 +1258,10 @@ void GLES2Implementation::PixelStorei(GLenum pname, GLint param) {
     case GL_UNPACK_FLIP_Y_CHROMIUM:
         unpack_flip_y_ = (param != 0);
         return;
+    case GL_PACK_REVERSE_ROW_ORDER_ANGLE:
+        pack_reverse_row_order_ =
+            IsAnglePackReverseRowOrderAvailable() ? (param != 0) : false;
+        break;
     default:
         break;
   }
@@ -1975,13 +2016,25 @@ void GLES2Implementation::ReadPixels(
           result_shm_id(), result_shm_offset());
       WaitForCmd();
       if (*result != 0) {
+        // when doing a y-flip we have to iterate through top-to-bottom chunks
+        // of the dst. The service side handles reversing the rows within a
+        // chunk.
+        int8* rows_dst;
+        if (pack_reverse_row_order_) {
+            rows_dst = dest + (height - num_rows) * padded_row_size;
+        } else {
+            rows_dst = dest;
+        }
         // We have to copy 1 row at a time to avoid writing pad bytes.
         const int8* src = static_cast<const int8*>(buffer);
         for (GLint yy = 0; yy < num_rows; ++yy) {
-          memcpy(dest, src, unpadded_row_size);
-          dest += padded_row_size;
+          memcpy(rows_dst, src, unpadded_row_size);
+          rows_dst += padded_row_size;
           src += padded_row_size;
         }
+        if (!pack_reverse_row_order_) {
+          dest = rows_dst;
+        }
       }
       transfer_buffer_.FreePendingToken(buffer, helper_->InsertToken());
       // If it was not marked as successful exit.
@@ -1998,6 +2051,10 @@ void GLES2Implementation::ReadPixels(
     GLsizeiptr element_size = temp_size;
     max_size -= max_size % element_size;
     GLint max_sub_row_pixels = max_size / element_size;
+    if (pack_reverse_row_order_) {
+      // start at the last row when flipping y.
+      dest = dest + (height - 1) * padded_row_size;
+    }
     for (; height; --height) {
       GLint temp_width = width;
       GLint temp_xoffset = xoffset;
@@ -2025,7 +2082,7 @@ void GLES2Implementation::ReadPixels(
         temp_width -= num_pixels;
       }
       ++yoffset;
-      dest += padded_row_size;
+      dest += pack_reverse_row_order_ ? -padded_row_size : padded_row_size;
     }
   }
 }
@@ -2520,6 +2577,10 @@ void GLES2Implementation::RequestExtensionCHROMIUM(const char* extension) {
   SetBucketAsCString(kResultBucketId, extension);
   helper_->RequestExtensionCHROMIUM(kResultBucketId);
   helper_->SetBucketSize(kResultBucketId, 0);
+  if (kUnavailableExtensionStatus == angle_pack_reverse_row_order_status &&
+      !strcmp(extension, "GL_ANGLE_pack_reverse_row_order")) {
+    angle_pack_reverse_row_order_status = kUnknownExtensionStatus;
+  }
 }
 
 void GLES2Implementation::RateLimitOffscreenContextCHROMIUM() {
diff --git a/gpu/command_buffer/client/gles2_implementation.h b/gpu/command_buffer/client/gles2_implementation.h
index 407bd51..e085efc 100644
--- a/gpu/command_buffer/client/gles2_implementation.h
+++ b/gpu/command_buffer/client/gles2_implementation.h
@@ -202,6 +202,13 @@ class GLES2Implementation {
   void FreeUnusedSharedMemory();
 
  private:
+  // Used to track whether an extension is available
+  enum ExtensionStatus {
+      kAvailableExtensionStatus,
+      kUnavailableExtensionStatus,
+      kUnknownExtensionStatus
+  };
+
   // Wraps RingBufferWrapper to provide aligned allocations.
   class AlignedRingBuffer : public RingBufferWrapper {
    public:
@@ -338,6 +345,9 @@ class GLES2Implementation {
     return static_cast<T>(result_buffer_);
   }
 
+  // Lazily determines if GL_ANGLE_pack_reverse_row_order is available
+  bool IsAnglePackReverseRowOrderAvailable();
+
   // Gets the GLError through our wrapper.
   GLenum GetGLError();
 
@@ -432,6 +442,8 @@ class GLES2Implementation {
   std::queue<int32> swap_buffers_tokens_;
   std::queue<int32> rate_limit_tokens_;
 
+  ExtensionStatus angle_pack_reverse_row_order_status;
+
   GLState gl_state_;
 
   // pack alignment as last set by glPixelStorei
@@ -443,6 +455,9 @@ class GLES2Implementation {
   // unpack yflip as last set by glPixelstorei
   bool unpack_flip_y_;
 
+  // pack reverse row order as last set by glPixelstorei
+  bool pack_reverse_row_order_;
+
   scoped_array<TextureUnit> texture_units_;
 
   // 0 to gl_state_.max_combined_texture_image_units.
diff --git a/gpu/command_buffer/common/gles2_cmd_utils.cc b/gpu/command_buffer/common/gles2_cmd_utils.cc
index 22763b6..b2be64b 100644
--- a/gpu/command_buffer/common/gles2_cmd_utils.cc
+++ b/gpu/command_buffer/common/gles2_cmd_utils.cc
@@ -127,6 +127,8 @@ int GLES2Util::GLGetNumValuesReturned(int id) const {
       return 1;
     case GL_PACK_ALIGNMENT:
       return 1;
+    case GL_PACK_REVERSE_ROW_ORDER_ANGLE:
+      return 1;
     case GL_POLYGON_OFFSET_FACTOR:
       return 1;
     case GL_POLYGON_OFFSET_FILL:
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index ea74412..c3cb1ee9 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -397,6 +397,14 @@ void FeatureInfo::AddFeatures(const char* desired_features) {
   if (ext.HaveAndDesire("GL_CHROMIUM_front_buffer_cached")) {
     AddExtensionString("GL_CHROMIUM_front_buffer_cached");
   }
+
+  if (ext.Desire("GL_ANGLE_pack_reverse_row_order") &&
+      ext.Have("GL_ANGLE_pack_reverse_row_order")) {
+    AddExtensionString("GL_ANGLE_pack_reverse_row_order");
+    feature_flags_.angle_pack_reverse_row_order = true;
+    validators_.pixel_store.AddValue(GL_PACK_REVERSE_ROW_ORDER_ANGLE);
+    validators_.g_l_state.AddValue(GL_PACK_REVERSE_ROW_ORDER_ANGLE);
+  }
 }
 
 void FeatureInfo::AddExtensionString(const std::string& str) {
diff --git a/gpu/command_buffer/service/feature_info.h b/gpu/command_buffer/service/feature_info.h
index fb4177b..c71ab9b 100644
--- a/gpu/command_buffer/service/feature_info.h
+++ b/gpu/command_buffer/service/feature_info.h
@@ -26,6 +26,7 @@ class FeatureInfo {
           chromium_webglsl(false),
           chromium_stream_texture(false),
           angle_translated_shader_source(false),
+          angle_pack_reverse_row_order(false),
           arb_texture_rectangle(false) {
     }
 
@@ -38,6 +39,7 @@ class FeatureInfo {
     bool chromium_webglsl;
     bool chromium_stream_texture;
     bool angle_translated_shader_source;
+    bool angle_pack_reverse_row_order;
     bool arb_texture_rectangle;
   };
 
diff --git a/gpu/command_buffer/service/gl_utils.h b/gpu/command_buffer/service/gl_utils.h
index 0aae91d..8371b5f 100644
--- a/gpu/command_buffer/service/gl_utils.h
+++ b/gpu/command_buffer/service/gl_utils.h
@@ -42,6 +42,9 @@
 // GL_ANGLE_translated_shader_source
 #define GL_TRANSLATED_SHADER_SOURCE_LENGTH_ANGLE 0x93A0
 
+// GL_ANGLE_pack_reverse_row_order
+#define GL_PACK_REVERSE_ROW_ORDER_ANGLE    0x93A4
+
 #define GL_GLEXT_PROTOTYPES 1
 
 // Define this for extra GL error debugging (slower).
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 6ba84f9..e2d60da 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -5801,15 +5801,24 @@ error::Error GLES2DecoderImpl::HandlePixelStorei(
     SetGLError(GL_INVALID_ENUM, "glPixelStorei: pname GL_INVALID_ENUM");
     return error::kNoError;
   }
-  if (!validators_->pixel_store_alignment.IsValid(param)) {
-    SetGLError(GL_INVALID_VALUE, "glPixelSTore: param GL_INVALID_VALUE");
-    return error::kNoError;
+  switch (pname) {
+    case GL_PACK_ALIGNMENT:
+    case GL_UNPACK_ALIGNMENT:
+        if (!validators_->pixel_store_alignment.IsValid(param)) {
+            SetGLError(GL_INVALID_VALUE,
+                       "glPixelSTore: param GL_INVALID_VALUE");
+            return error::kNoError;
+        }
+    default:
+        break;
   }
   glPixelStorei(pname, param);
   switch (pname) {
   case GL_PACK_ALIGNMENT:
       pack_alignment_ = param;
       break;
+  case GL_PACK_REVERSE_ROW_ORDER_ANGLE:
+      break;
   case GL_UNPACK_ALIGNMENT:
       unpack_alignment_ = param;
       break;
diff --git a/third_party/khronos/GLES2/gl2ext.h b/third_party/khronos/GLES2/gl2ext.h
index f1a49dc..fb105eb 100644
--- a/third_party/khronos/GLES2/gl2ext.h
+++ b/third_party/khronos/GLES2/gl2ext.h
@@ -207,6 +207,11 @@ typedef void* GLeglImageOES;
 #define GL_MAX_SAMPLES_ANGLE                                    0x8D57
 #endif
 
+/* GL_ANGLE_pack_reverse_row_order */
+#ifndef GL_ANGLE_pack_reverse_row_order
+#define GL_PACK_REVERSE_ROW_ORDER_ANGLE                         0x93A4
+#endif
+
 /*------------------------------------------------------------------------*
  * APPLE extension tokens
  *------------------------------------------------------------------------*/
@@ -790,6 +795,11 @@ GL_APICALL void GL_APIENTRY glRenderbufferStorageMultisampleANGLE (GLenum target
 typedef void (GL_APIENTRYP PFNGLRENDERBUFFERSTORAGEMULTISAMPLEANGLEPROC) (GLenum target, GLsizei samples, GLenum internalformat, GLsizei width, GLsizei height);
 #endif
 
+/* GL_ANGLE_pack_reverse_row_order */
+#ifndef GL_ANGLE_pack_reverse_row_order
+#define GL_ANGLE_pack_reverse_row_order 1
+#endif
+
 /*------------------------------------------------------------------------*
  * APPLE extension functions
  *------------------------------------------------------------------------*/