[Remoting] OpenGL Rendering Layer

remoting/client/opengl/gl_render_layer.cc

+// Copyright 2016 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 "remoting/client/opengl/gl_render_layer.h"
+
+#include "base/logging.h"
+#include "remoting/client/opengl/gl_canvas.h"
+#include "remoting/client/opengl/gl_helpers.h"
+
+namespace {
+
+// Assign texture coordinates to buffers for use in shader program.
+const float kVertices[] = {
+    // Points order: upper-left, bottom-left, upper-right, bottom-right.
+
+    // Positions to draw the texture on the normalized canvas coordinate.
+    0, 0, 0, 1, 1, 0, 1, 1,
+
+    // Region of the texture to be used (normally the whole texture).
+    0, 0, 0, 1, 1, 0, 1, 1};
+}
+
+namespace remoting {
+
+GlRenderLayer::GlRenderLayer(int texture_id, GlCanvas* canvas)
+    : texture_id_(texture_id), canvas_(canvas) {
+  texture_handle_ = CreateTexture();
+  buffer_handle_ = CreateBuffer(kVertices, sizeof(kVertices));
+}
+
+GlRenderLayer::~GlRenderLayer() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  glDeleteBuffers(1, &buffer_handle_);
+  glDeleteTextures(1, &texture_handle_);
+}
+
+void GlRenderLayer::SetTexture(const void* texture, int width, int height) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  CHECK(width > 0 && height > 0);
+  glActiveTexture(GL_TEXTURE0 + texture_id_);
+  glBindTexture(GL_TEXTURE_2D, texture_handle_);
+
+  if (width != texture_width_ || height != texture_height_) {
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA,
+                 GL_UNSIGNED_BYTE, texture);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    texture_width_ = width;
+    texture_height_ = height;
+  } else {
+    // Size not changed. Just update the texture.
+    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RGBA,
+                    GL_UNSIGNED_BYTE, texture);
+  }
+  glBindTexture(GL_TEXTURE_2D, 0);
+}
+
+void GlRenderLayer::SetVertexPositions(const float positions[8]) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  glBindBuffer(GL_ARRAY_BUFFER, buffer_handle_);
+  glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(kVertices) / 2, positions);
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+}
+
+void GlRenderLayer::SetTextureVisibleArea(const float positions[8]) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  glBindBuffer(GL_ARRAY_BUFFER, buffer_handle_);
+  glBufferSubData(GL_ARRAY_BUFFER, sizeof(kVertices) / 2, sizeof(kVertices) / 2,
+                  positions);
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+}
+
+void GlRenderLayer::Draw() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (texture_width_ == 0 || texture_height_ == 0) {
+    return;
+  }
+  canvas_->DrawTexture(texture_id_, texture_handle_, buffer_handle_);
+}
+
+}  // namespace remoting