command_buffer: Implement path rendering functions for CHROMIUM_path_rendering

gpu/command_buffer/service/path_manager.cc

+// Copyright (c) 2014 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.
+
+#include "gpu/command_buffer/service/path_manager.h"
+#include "base/logging.h"
+#include "gpu/command_buffer/common/gles2_cmd_utils.h"
+#include "ui/gl/gl_bindings.h"
+
+namespace {
+void callDeletePaths(GLuint first_id, GLuint range) {
+  while (range > 0) {
+    GLsizei irange;
+    if (range > std::numeric_limits<GLsizei>::max()) {
+      irange = std::numeric_limits<GLsizei>::max();
+    } else {
+      irange = static_cast<GLsizei>(range);
+    }
+    glDeletePathsNV(first_id, irange);
+    range -= irange;
+    first_id += irange + 1;
+  }
+}
+}  // anonymous namespace
+
+namespace gpu {
+namespace gles2 {
+
+PathManager::PathManager() {
+}
+
+PathManager::~PathManager() {
+  DCHECK(path_map_.empty());
+}
+
+void PathManager::Destroy(bool have_context) {
+  if (have_context) {
+    for (PathRangeMap::const_iterator it = path_map_.begin();
+         it != path_map_.end();
+         ++it) {
+      callDeletePaths(FirstServiceId(it), RangeSize(it));
+    }
+  }
+  path_map_.clear();
+}
+
+void PathManager::CreatePathRange(GLuint first_client_id,
+                                  GLuint last_client_id,
+                                  GLuint first_service_id) {
+  DCHECK(!HasPathsInRange(first_client_id, last_client_id));
+  DCHECK(first_service_id > 0);
+  bool check_before = false;
+
+  PathRangeMap::iterator it = path_map_.lower_bound(first_client_id);
+  PathRangeMap::iterator next_range = it;
+  if (it != path_map_.begin()) {
+    --it;
+    check_before = true;
+  }
+  if (next_range != path_map_.end()) {
+    GLuint last_service_id =
+        first_service_id + last_client_id - first_client_id;
+    // FirstClientId(next_range) - 1 does not underflow because lower_bound
+    // returns > first_client_id.
+    // It does not return == first_client_id (== 0) because this would
+    // contradict
+    // !HasPathsInRange(first_client_id, last_client_id).
+    // FirstServiceId(next_range) - 1 does not underflow because
+    // first_service_id > 0.
+    if (FirstClientId(next_range) - 1 == last_client_id &&
+        FirstServiceId(next_range) - 1 == last_service_id) {
+      last_client_id = LastClientId(next_range);
+      path_map_.erase(next_range);
+    }
+  }
+
+  if (it != path_map_.end() && check_before) {
+    // The last first client id -1 does not underflow because then  lower_bound
+    // would have found something, which contradicts
+    // !HasPathsInRange(first_client_id, last_client_id).
+    // first_service_id -1 does not underflow because first_service_id > 0.
+    if (LastClientId(it) == first_client_id - 1 &&
+        LastServiceId(it) == first_service_id - 1) {
+      LastClientId(it) = last_client_id;
+      return;
+    }
+  }
+
+  path_map_.insert(std::make_pair(
+      first_client_id, PathRangeDescription(last_client_id, first_service_id)));
+}
+
+bool PathManager::HasPathsInRange(GLuint first_client_id,
+                                  GLuint last_client_id) const {
+  PathRangeMap::const_iterator it = path_map_.lower_bound(first_client_id);
+  if (it != path_map_.end() && (FirstClientId(it) == first_client_id ||
+                                FirstClientId(it) <= last_client_id)) {
+    return true;
+  }
+  if (it == path_map_.begin()) {
+    return false;
+  }
+  --it;
+  return LastClientId(it) >= first_client_id;
+}
+
+bool PathManager::GetPath(GLuint client_id, GLuint* service_id) const {
+  PathRangeMap::const_iterator it = path_map_.lower_bound(client_id);
+  if (it != path_map_.end() && FirstClientId(it) == client_id) {
+    *service_id = FirstServiceId(it);
+    return true;
+  }
+  if (it == path_map_.begin()) {
+    return false;
+  }
+  --it;
+  if (LastClientId(it) < client_id) {
+    return false;
+  }
+
+  *service_id = FirstServiceId(it) + client_id - FirstClientId(it);
+
+  return true;
+}
+
+void PathManager::RemovePaths(GLuint first_client_id, GLuint last_client_id) {
+  PathRangeMap::iterator it = path_map_.lower_bound(first_client_id);
+  if (it == path_map_.end() || FirstClientId(it) != first_client_id) {
+    if (it != path_map_.begin()) {
+      --it;
+      if (LastClientId(it) < first_client_id) {
+        ++it;
+      }
+    }
+  }
+
+  while (it != path_map_.end() && FirstClientId(it) <= last_client_id) {
+    GLuint delete_first_client_id =
+        std::max(first_client_id, FirstClientId(it));
+    GLuint delete_last_client_id = std::min(last_client_id, LastClientId(it));
+    GLuint delete_first_service_id =
+        FirstServiceId(it) + delete_first_client_id - FirstClientId(it);
+    GLuint delete_range = delete_last_client_id - delete_first_client_id + 1;
+
+    callDeletePaths(delete_first_service_id, delete_range);
+
+    PathRangeMap::iterator current = it;
+    ++it;
+
+    GLuint current_last_client_id = LastClientId(current);
+
+    if (FirstClientId(current) < delete_first_client_id) {
+      LastClientId(current) = delete_first_client_id - 1;
+    } else {
+      path_map_.erase(current);
+    }
+
+    if (current_last_client_id > delete_last_client_id) {
+      path_map_.insert(std::make_pair(
+          delete_last_client_id + 1,
+          PathRangeDescription(current_last_client_id,
+                               delete_first_service_id + delete_range)));
+      DCHECK(delete_last_client_id == last_client_id);
+      // This is necessarily the last range to check. Return early due to
+      // consistency. Iterator increment would skip the inserted range. The
+      // algorithm would work ok, but it looks weird.
+      return;
+    }
+  }
+}
+
+}  // namespace gles2
+}  // namespace gpu