Defer clearing textures and renderbuffers

gpu/command_buffer/service/texture_manager.h

Index: gpu/command_buffer/service/texture_manager.h
diff --git a/gpu/command_buffer/service/texture_manager.h b/gpu/command_buffer/service/texture_manager.h
index dbb22186c87251f49cb736ddb726c3bb69450b89..0fccbf6cf1f96a9d996bcfcf44810de7904e8b7e 100644
--- a/gpu/command_buffer/service/texture_manager.h
+++ b/gpu/command_buffer/service/texture_manager.h
@@ -16,6 +16,7 @@ namespace gpu {
 namespace gles2 {
 
 class FeatureInfo;
+class GLES2Decoder;
 
 // This class keeps track of the textures and their sizes so we can do NPOT and
 // texture complete checking.
@@ -32,6 +33,8 @@ class TextureManager {
     explicit TextureInfo(GLuint service_id)
         : service_id_(service_id),
           deleted_(false),
+          cleared_(true),
+          num_uncleared_mips_(0),
           target_(0),
           min_filter_(GL_NEAREST_MIPMAP_LINEAR),
           mag_filter_(GL_LINEAR),
@@ -63,6 +66,10 @@ class TextureManager {
       return wrap_t_;
     }
 
+    int num_uncleared_mips() const {
+      return num_uncleared_mips_;
+    }
+
     // True if this texture meets all the GLES2 criteria for rendering.
     // See section 3.8.2 of the GLES2 spec.
     bool CanRender(const FeatureInfo* feature_info) const;
@@ -101,6 +108,10 @@ class TextureManager {
       return npot_;
     }
 
+    bool SafeToRenderFrom() const {
+      return cleared_;
+    }
+
     // Returns true if mipmaps can be generated by GL.
     bool CanGenerateMipmaps(const FeatureInfo* feature_info) const;
 
@@ -146,7 +157,7 @@ class TextureManager {
     }
 
     void DetachFromFramebuffer() {
-      DCHECK(framebuffer_attachment_count_ > 0);
+      DCHECK_GT(framebuffer_attachment_count_, 0);
       --framebuffer_attachment_count_;
     }
 
@@ -158,6 +169,9 @@ class TextureManager {
       return stream_texture_;
     }
 
+    // Whether a particular level/face is cleared.
+    bool IsLevelCleared(GLenum target, GLint level);
+
    private:
     friend class TextureManager;
     friend class base::RefCounted<TextureInfo>;
@@ -166,7 +180,9 @@ class TextureManager {
 
     struct LevelInfo {
       LevelInfo()
-         : valid(false),
+         : cleared(true),
+           target(0),
+           level(-1),
            internal_format(0),
            width(0),
            height(0),
@@ -176,7 +192,9 @@ class TextureManager {
            type(0) {
       }
 
-      bool valid;
+      bool cleared;
+      GLenum target;
+      GLint level;
       GLenum internal_format;
       GLsizei width;
       GLsizei height;
@@ -197,7 +215,22 @@ class TextureManager {
         GLsizei depth,
         GLint border,
         GLenum format,
-        GLenum type);
+        GLenum type,
+        bool cleared);
+
+    // Marks a particular level as cleared or uncleared.
+    void SetLevelCleared(GLenum target, GLint level);
+
+    // Updates the cleared flag for this texture by inspecting all the mips.
+    void UpdateCleared();
+
+    // Clears any renderable uncleared levels.
+    // Returns false if a GL error was generated.
+    bool ClearRenderableLevels(GLES2Decoder* decoder);
+
+    // Clears the level.
+    // Returns false if a GL error was generated.
+    bool ClearLevel(GLES2Decoder* decoder, GLenum target, GLint level);
 
     // Sets a texture parameter.
     // TODO(gman): Expand to SetParameteri,f,iv,fv
@@ -236,6 +269,11 @@ class TextureManager {
     // Whether this texture has been deleted.
     bool deleted_;
 
+    // Whether all renderable mips of this texture have been cleared.
+    bool cleared_;
+
+    int num_uncleared_mips_;
+
     // The target. 0 if unset, otherwise GL_TEXTURE_2D or GL_TEXTURE_CUBE_MAP.
     GLenum target_;
 
@@ -333,7 +371,11 @@ class TextureManager {
       GLsizei depth,
       GLint border,
       GLenum format,
-      GLenum type);
+      GLenum type,
+      bool cleared);
+
+  // Sets a mip as cleared.
+  void SetLevelCleared(TextureInfo* info, GLenum target, GLint level);
 
   // Sets a texture parameter of a TextureInfo
   // TODO(gman): Expand to SetParameteri,f,iv,fv
@@ -343,9 +385,14 @@ class TextureManager {
 
   // Makes each of the mip levels as though they were generated.
   // Returns false if that's not allowed for the given texture.
-  bool MarkMipmapsGenerated(
-      const FeatureInfo* feature_info,
-      TextureManager::TextureInfo* info);
+  bool MarkMipmapsGenerated(const FeatureInfo* feature_info, TextureInfo* info);
+
+  // Clears any uncleared renderable levels.
+  bool ClearRenderableLevels(GLES2Decoder* decoder, TextureInfo* info);
+
+  // Clear a specific level.
+  bool ClearTextureLevel(
+      GLES2Decoder* decoder,TextureInfo* info, GLenum target, GLint level);
 
   // Creates a new texture info.
   TextureInfo* CreateTextureInfo(
@@ -378,6 +425,14 @@ class TextureManager {
     return num_unrenderable_textures_ > 0;
   }
 
+  bool HaveUnsafeTextures() const {
+    return num_unsafe_textures_ > 0;
+  }
+
+  bool HaveUnclearedMips() const {
+    return num_uncleared_mips_ > 0;
+  }
+
   GLuint black_texture_id(GLenum target) const {
     switch (target) {
       case GL_SAMPLER_2D:
@@ -403,6 +458,8 @@ class TextureManager {
   GLint max_cube_map_levels_;
 
   int num_unrenderable_textures_;
+  int num_unsafe_textures_;
+  int num_uncleared_mips_;
 
   // Black (0,0,0,1) textures for when non-renderable textures are used.
   // NOTE: There is no corresponding TextureInfo for these textures.