[Remoting Android] Cursor & Cursor Feedback for OpenGL Renderer

remoting/client/gl_cursor_feedback_texture.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_cursor_feedback_texture.h"
+
+#include "remoting/client/gl_render_layer.h"
+
+namespace remoting {
+
+namespace {
+
+const int kColorRingsCount = 4;
+const int kFeedbackTexturePixelDiameter = 512;
+const int kFeedbackTexturePixelRadius = kFeedbackTexturePixelDiameter / 2;
+
+// RGBA8888 colors. From inside to outside.
+const uint8_t kFeedbackRingColors[kColorRingsCount]
+                                 [GlRenderLayer::kBytesPerPixel] = {
+                                     {0, 0, 0, 0},  // transparent black
+                                     {0xff, 0xff, 0xff, 0xff},  // white
+                                     {0, 0, 0, 0xff},           // black
+                                     {0, 0, 0, 0}  // transparent black
+};
+
+const float kFeedbackRadiusStops[kColorRingsCount] = {0.0f, 0.8f, 0.9f, 1.0f};
+
+uint32_t GetColorByRadius(float radius) {
+  int ring_index = kColorRingsCount - 1;
+  // Find first radius stop that is not smaller than current radius.
+  while (radius < kFeedbackRadiusStops[ring_index] && ring_index >= 0) {
+    ring_index--;
+  }
+
+  if (ring_index < 0) {
+    NOTREACHED();
+    return -1;
+  }
+
+  if (ring_index == kColorRingsCount - 1) {
+    // Area outside the circle. Just use the outermost color.
+    return *reinterpret_cast<const uint32_t*>(kFeedbackRingColors[ring_index]);
+  }
+
+  const uint8_t* first_color = kFeedbackRingColors[ring_index];
+  const uint8_t* second_color = kFeedbackRingColors[ring_index + 1];
+  float first_radius = kFeedbackRadiusStops[ring_index];
+  float second_radius = kFeedbackRadiusStops[ring_index + 1];
+
+  uint8_t progress =
+      (radius - first_radius) * 256 / (second_radius - first_radius);
+  uint32_t color;
+  uint8_t* color_ptr = reinterpret_cast<uint8_t*>(&color);
+  for (int i = 0; i < GlRenderLayer::kBytesPerPixel; i++) {
+    color_ptr[i] =
+        (first_color[i] * (256 - progress) + second_color[i] * progress) / 256;
+  }
+  return color;
+}
+
+void FillFeedbackTexture(uint32_t* texture) {
+  for (int x = 0; x < kFeedbackTexturePixelRadius; x++) {
+    for (int y = 0; y <= x; y++) {
+      float radius = sqrt(x * x + y * y) / kFeedbackTexturePixelRadius;
+      uint32_t color = GetColorByRadius(radius);
+
+      int x1 = kFeedbackTexturePixelRadius + x;
+      int x2 = kFeedbackTexturePixelRadius - 1 - x;
+
+      int y1 = kFeedbackTexturePixelRadius + y;
+      int y2 = kFeedbackTexturePixelRadius - 1 - y;
+
+      texture[x1 + y1 * kFeedbackTexturePixelDiameter] = color;
+      texture[x1 + y2 * kFeedbackTexturePixelDiameter] = color;
+      texture[x2 + y1 * kFeedbackTexturePixelDiameter] = color;
+      texture[x2 + y2 * kFeedbackTexturePixelDiameter] = color;
+      texture[y1 + x1 * kFeedbackTexturePixelDiameter] = color;
+      texture[y1 + x2 * kFeedbackTexturePixelDiameter] = color;
+      texture[y2 + x1 * kFeedbackTexturePixelDiameter] = color;
+      texture[y2 + x2 * kFeedbackTexturePixelDiameter] = color;
+    }
+  }
+}
+
+}  // namespace
+
+// static
+const int GlCursorFeedbackTexture::kTextureWidth =
+    kFeedbackTexturePixelDiameter;
+
+GlCursorFeedbackTexture* GlCursorFeedbackTexture::GetInstance() {
+  return base::Singleton<GlCursorFeedbackTexture>::get();
+}
+
+const std::vector<uint8_t>& GlCursorFeedbackTexture::GetTexture() const {
+  return texture_;
+}
+
+GlCursorFeedbackTexture::GlCursorFeedbackTexture() {
+  texture_.resize(kTextureWidth * kTextureWidth *
+                  GlRenderLayer::kBytesPerPixel);
+  FillFeedbackTexture(reinterpret_cast<uint32_t*>(texture_.data()));
+}
+
+GlCursorFeedbackTexture::~GlCursorFeedbackTexture() {}
+
+}  // namespace remoting