VR: Avoiding regeneration of RenderText objects for texture rendering

chrome/browser/android/vr_shell/textures/ui_texture.h

 // Copyright 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.
 
 #ifndef CHROME_BROWSER_ANDROID_VR_SHELL_TEXTURES_UI_TEXTURE_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_TEXTURES_UI_TEXTURE_H_
 
 #include <memory>
+#include <vector>
 
 #include "base/strings/string16.h"
+#include "third_party/skia/include/core/SkColor.h"
+#include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/geometry/size_f.h"
 
 class SkCanvas;
 
 namespace gfx {
+
 class FontList;
+class RenderText;
+
 }  // namespace gfx
 
 namespace vr_shell {
 
 class UiTexture {
  public:
+  enum {
+    // Flags to configure PrepareDrawStringRect
+    TEXT_ALIGN_LEFT = 1 << 0,
+    TEXT_ALIGN_CENTER = 1 << 1,
+    TEXT_ALIGN_RIGHT = 1 << 2,
+    MULTI_LINE = 1 << 3
+  };
+
   UiTexture();
   virtual ~UiTexture();
 
   void DrawAndLayout(SkCanvas* canvas, const gfx::Size& texture_size);
   virtual gfx::Size GetPreferredTextureSize(int maximum_width) const = 0;
   virtual gfx::SizeF GetDrawnSize() const = 0;
 
  protected:
   virtual void Draw(SkCanvas* canvas, const gfx::Size& texture_size) = 0;
 
+  // Prepares a set of RenderText objects with the given color and fonts.
+  // Attempts to fit the text within the provided size. |flags| specifies how
+  // the text should be rendered. If multiline is requested and provided height
+  // is 0, it will be set to the minimum needed to fit the whole text. If
+  // multiline is not requested and provided width is 0, it will be set to the
+  // minimum needed to fit the whole text.
+  static std::vector<std::unique_ptr<gfx::RenderText>> PrepareDrawStringRect(
+      const base::string16& text,
+      const gfx::FontList& font_list,
+      SkColor color,
+      gfx::Rect* bounds,
+      int flags);
+
   static bool IsRTL();
   static gfx::FontList GetDefaultFontList(int size);
   static gfx::FontList GetFontList(int size, base::string16 text);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_TEXTURES_UI_TEXTURE_H_