[Remoting] OpenGL Rendering Layer

remoting/client/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/gl_render_layer.h"
+
+#include "base/logging.h"
+#include "remoting/client/gl_canvas.h"
+#include "remoting/client/gl_helpers.h"
+#include "third_party/webrtc/modules/desktop_capture/desktop_frame.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};
+
+const int kDefaultUpdateBufferCapacity =
+    2048 * 2048 * webrtc::DesktopFrame::kBytesPerPixel;
+
+}
+
+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 uint8_t* texture, int width, int height) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  CHECK(width > 0 && height > 0);
+  texture_set_ = true;
+  glActiveTexture(GL_TEXTURE0 + texture_id_);
+  glBindTexture(GL_TEXTURE_2D, texture_handle_);
+
+  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);
+
+  glBindTexture(GL_TEXTURE_2D, 0);
+}
+
+void PackDirtyRegion(uint8_t* dest,
+                     const uint8_t* source,
+                     int width,
+                     int height,
+                     int stride) {
+  for (int i = 0; i < height; i++) {
+    memcpy(dest, source, width * webrtc::DesktopFrame::kBytesPerPixel);
+    source += stride;
+    dest += webrtc::DesktopFrame::kBytesPerPixel * width;
+  }
+}
+
+void GlRenderLayer::UpdateTexture(const uint8_t* subtexture,
+                                  int offset_x,
+                                  int offset_y,
+                                  int width,
+                                  int height,
+                                  int stride) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(texture_set_);
+  DCHECK(width > 0 && height > 0);
+  glActiveTexture(GL_TEXTURE0 + texture_id_);
+  glBindTexture(GL_TEXTURE_2D, texture_handle_);
+
+  bool stride_multiple_of_bytes_per_pixel =
+      stride % webrtc::DesktopFrame::kBytesPerPixel == 0;
+  bool loosely_packed =
+      !stride_multiple_of_bytes_per_pixel ||
+      (stride > 0 && stride != webrtc::DesktopFrame::kBytesPerPixel * width);
+
+  const void* buffer_to_update = subtexture;
+
+  if (loosely_packed) {
+    if (stride_multiple_of_bytes_per_pixel && canvas_->GetGlVersion() >= 3) {
+      glPixelStorei(GL_UNPACK_ROW_LENGTH,
+                    stride / webrtc::DesktopFrame::kBytesPerPixel);
+    } else {
+      // Doesn't support GL_UNPACK_ROW_LENGTH or stride not multiple of
+      // kBytesPerPixel. Manually pack the data.
+      int required_size = width * height * webrtc::DesktopFrame::kBytesPerPixel;
+      if (update_buffer_size_ < required_size) {
+        if (required_size < kDefaultUpdateBufferCapacity) {
+          update_buffer_size_ = kDefaultUpdateBufferCapacity;
+        } else {
+          update_buffer_size_ = required_size;
+        }
+        update_buffer_.reset(new uint8_t[update_buffer_size_]);
+      }
+      PackDirtyRegion(update_buffer_.get(), subtexture, width, height, stride);
+      buffer_to_update = update_buffer_.get();
+    }
+  }
+
+  glTexSubImage2D(GL_TEXTURE_2D, 0, offset_x, offset_y, width, height, GL_RGBA,
+                  GL_UNSIGNED_BYTE, buffer_to_update);
+
+  if (loosely_packed && stride_multiple_of_bytes_per_pixel &&
+      canvas_->GetGlVersion() >= 3) {
+    glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
+  }
+  glBindTexture(GL_TEXTURE_2D, 0);
+}
+
+void GlRenderLayer::SetVertexPositions(const std::array<float, 8>& positions) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  glBindBuffer(GL_ARRAY_BUFFER, buffer_handle_);
+  glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(kVertices) / 2, positions.data());
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+}
+
+void GlRenderLayer::SetTextureVisibleArea(
+    const std::array<float, 8>& positions) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  glBindBuffer(GL_ARRAY_BUFFER, buffer_handle_);
+  glBufferSubData(GL_ARRAY_BUFFER, sizeof(kVertices) / 2, sizeof(kVertices) / 2,
+                  positions.data());
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+}
+
+void GlRenderLayer::Draw() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(texture_set_);
+  canvas_->DrawTexture(texture_id_, texture_handle_, buffer_handle_);
+}
+
+}  // namespace remoting