Refactor GL surface format handling

ui/gl/gl_surface_format.cc

+// Copyright (c) 2017 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 "base/logging.h"
+#include "ui/gl/gl_surface_format.h"
+
+namespace gl {
+
+GLSurfaceFormat::GLSurfaceFormat() {
+}
+
+GLSurfaceFormat::GLSurfaceFormat(SurfaceFormat format) {
+  is_default = false;
+  switch (format) {
+    case SURFACE_ARGB8888:
+      red_bits = green_bits = blue_bits = alpha_bits = 8;
+      // For backwards compatibility, treat this as equivalent to the
+      // default format.
+      is_default = true;
+      break;
+    case SURFACE_RGB565:
+      red_bits = blue_bits = 5;
+      green_bits = 6;
+      alpha_bits = 0;
+      break;
+    case SURFACE_OSMESA_BGRA:
+      pixel_layout = SURFACE_PIXEL_LAYOUT_BGRA;
+      break;
+    case SURFACE_OSMESA_RGBA:
+      pixel_layout = SURFACE_PIXEL_LAYOUT_RGBA;
+      break;
+    case SURFACE_SURFACELESS:
+      is_surfaceless = true;
+      break;
+    default:
+      NOTREACHED();
+  }
+}
+
+bool GLSurfaceFormat::IsSurfaceless() {
+  return is_surfaceless;
+}
+
+GLSurfaceFormat::SurfacePixelLayout GLSurfaceFormat::GetPixelLayout() {
+  return pixel_layout;
+}
+
+static int GetValue(int num, int default_value) {
+  return num == -1 ? default_value : num;
+}
+
+static int GetBitSize(int num) {
+  return GetValue(num, 8);
+}
+
+
+bool GLSurfaceFormat::IsDefault() {
+  return is_default;
+}
+
+bool GLSurfaceFormat::IsCompatible(GLSurfaceFormat other) {
+  if (this->IsDefault() && other.IsDefault()) return true;
+
+  if (GetBitSize(this->red_bits) == GetBitSize(other.red_bits) &&
+      GetBitSize(this->green_bits) == GetBitSize(other.green_bits) &&
+      GetBitSize(this->blue_bits) == GetBitSize(other.blue_bits) &&
+      GetBitSize(this->alpha_bits) == GetBitSize(other.alpha_bits) &&
+      GetValue(this->stencil_bits, 8) == GetValue(other.stencil_bits, 8) &&
+      GetValue(this->depth_bits, 24) == GetValue(other.depth_bits, 24) &&
+      GetValue(this->samples, 0) == GetValue(other.samples, 0) &&
+      this->is_surfaceless == other.is_surfaceless &&
+      this->pixel_layout == other.pixel_layout) {
+    return true;
+  }
+  return false;
+}
+
+void GLSurfaceFormat::SetDepthBits(int bits) {
+  depth_bits = bits;
+}
+
+void GLSurfaceFormat::SetStencilBits(int bits) {
+  stencil_bits = bits;
+}
+
+void GLSurfaceFormat::SetSamples(int num) {
+  samples = num;
+}
+
+int GLSurfaceFormat::GetBufferSize() {
+  int bits = GetBitSize(red_bits) + GetBitSize(green_bits) +
+      GetBitSize(blue_bits) + GetBitSize(alpha_bits);
+  if (bits <= 16) {
+    return 16;
+  } else if (bits <= 32) {
+    return 32;
+  }
+  NOTREACHED();
+  return 64;
+}
+
+}  // namespace gl