Initial checkin of the compositor_model_bench tool, which simulates the GPU demands of Chromium's...

gpu/tools/compositor_model_bench/render_model_utils.cc

Index: gpu/tools/compositor_model_bench/render_model_utils.cc
===================================================================
--- gpu/tools/compositor_model_bench/render_model_utils.cc	(revision 0)
+++ gpu/tools/compositor_model_bench/render_model_utils.cc	(revision 0)
@@ -0,0 +1,176 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Whole-tree processing that's likely to be helpful in multiple render models.
+
+#include "gpu/tools/compositor_model_bench/render_model_utils.h"
+
+#include <cstdlib>
+#include <map>
+#include <set>
+#include <vector>
+
+#include "base/logging.h"
+
+TextureGenerator::TextureGenerator(RenderNode* root)
+    : stage_(DiscoveryStage),
+      tex_ids_(NULL),
+      image_data_(NULL),
+      images_generated_(0) {
+  DiscoverInputIDs(root);
+  GenerateGLTexIDs();
+  AssignIDMapping();
+  WriteOutNewIDs(root);
+  AllocateImageArray();
+  BuildTextureImages(root);
+}
+
+TextureGenerator::~TextureGenerator() OVERRIDE {
+  if (tex_ids_.get()) {
+    glDeleteTextures(discovered_ids_.size(), tex_ids_.get());
+  }
+}
+
+void TextureGenerator::BeginVisitRenderNode(RenderNode* node) OVERRIDE {
+  for (size_t n = 0; n < node->num_tiles(); ++n) {
+    Tile* i = node->tile(n);
+    HandleTexture(&i->texID,
+                  node->tile_width(),
+                  node->tile_height(),
+                  GL_RGBA);
+  }
+}
+
+void TextureGenerator::BeginVisitCCNode(CCNode* node) OVERRIDE {
+  for (size_t n = 0; n < node->num_textures(); ++n) {
+    Texture* i = node->texture(n);
+    HandleTexture(&i->texID, i->width, i->height, i->format);
+  }
+  BeginVisitRenderNode(node);
+}
+
+void TextureGenerator::DiscoverInputIDs(RenderNode* root) {
+  // Pass 1: see which texture ID's have been used.
+  stage_ = DiscoveryStage;
+  root->Accept(this);
+}
+
+void TextureGenerator::GenerateGLTexIDs() {
+  int numTextures = discovered_ids_.size();
+  tex_ids_.reset(new GLuint[numTextures]);
+  glGenTextures(numTextures, tex_ids_.get());
+}
+
+void TextureGenerator::AssignIDMapping() {
+  // In the original version of this code the assigned ID's were not
+  // GL tex ID's, but newly generated consecutive ID's that indexed
+  // into an array of GL tex ID's. There's no need for this and now
+  // I'm instead generating the GL tex ID's upfront and assigning
+  // *those* in the remapping -- this more accurately reflects the
+  // behavior in Chromium, and it also takes out some design
+  // complexity that came from the extra layer of indirection.
+  // HOWEVER -- when I was assigning my own ID's before, I did some
+  // clever tricks to make sure the assignation was idempotent.
+  // Instead of going to even more clever lengths to preserve that
+  // property, I now just assume that the visitor will encounter each
+  // node (and consequently each texture) exactly once during a
+  // traversal of the tree -- this shouldn't be a hard guarantee
+  // to make.
+  int j = 0;
+  typedef std::set<int>::iterator id_itr;
+  for (id_itr i = discovered_ids_.begin();
+       i != discovered_ids_.end();
+       ++i, ++j) {
+    remapped_ids_[*i] = tex_ids_[j];
+  }
+}
+
+void TextureGenerator::WriteOutNewIDs(RenderNode* root) {
+  // Pass 2: write the new texture ID's back into the texture objects.
+  stage_ = RemappingStage;
+  root->Accept(this);
+}
+
+void TextureGenerator::AllocateImageArray() {
+  image_data_.reset(new ImagePtr[discovered_ids_.size()]);
+  images_generated_ = 0;
+}
+
+void TextureGenerator::BuildTextureImages(RenderNode* root) {
+  // Pass 3: use the texture metadata to generate images for the
+  // textures, and set up the textures for use by OpenGL. This
+  // doesn't *have* to be a separate pass (it could be rolled
+  // into pass 2) but I think this is more clear and performance
+  // shouldn't be bad.
+  stage_ = ImageGenerationStage;
+  root->Accept(this);
+}
+
+void TextureGenerator::HandleTexture(int* texID,
+                                     int width,
+                                     int height,
+                                     GLenum format) {
+  if (*texID == -1)
+    return;    // -1 means it's not a real texture.
+  switch (stage_) {
+    case DiscoveryStage:
+      discovered_ids_.insert(*texID);
+      break;
+    case RemappingStage:
+      *texID = remapped_ids_[*texID];
+      break;
+    case ImageGenerationStage:
+      // Only handle this one if we haven't already built a
+      // texture for its ID.
+      if (ids_for_completed_textures_.count(*texID))
+        return;
+      GenerateImageForTexture(*texID, width, height, format);
+      ids_for_completed_textures_.insert(*texID);
+      break;
+  }
+}
+
+void TextureGenerator::GenerateImageForTexture(int texID,
+                                               int width,
+                                               int height,
+                                               GLenum format) {
+  int bytes_per_pixel = FormatBytesPerPixel(format);
+  DCHECK_LE(bytes_per_pixel, 4);
+  int imgID = images_generated_++;
+  image_data_[imgID].reset(new uint8[width*height*bytes_per_pixel]);
+  // Pick random colors to use for this texture.
+  uint8 random_color[4];
+  for (int c = 0; c < 4; ++c) {
+    random_color[c] = std::rand() % 255;
+  }
+  // Create the image from those colors.
+  for (int x = 0; x < width; ++x) {
+    for (int y = 0; y < height; ++y) {
+      int pix_addr = (y * width + x) * bytes_per_pixel;
+      for (int c = 0; c < bytes_per_pixel; ++c) {
+        bool on = ((x/8) + (y/8)) % 2;
+        uint8 v = on ? random_color[c] : ~random_color[c];
+        (image_data_[imgID])[pix_addr + c] = v;
+      }
+      if (bytes_per_pixel == 4) {    // Randomize alpha.
+        image_data_[imgID][pix_addr + 3] = std::rand() % 255;
+      }
+    }
+  }
+  // Set up GL texture.
+  glBindTexture(GL_TEXTURE_2D, texID);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+  glPixelStorei(GL_PACK_ALIGNMENT, 1);
+  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+  glTexImage2D(GL_TEXTURE_2D,
+               0,
+               format,
+               width, height,
+               0,
+               format,
+               GL_UNSIGNED_BYTE,
+               image_data_[imgID].get());
+}
+