VR: Avoiding regeneration of RenderText objects for texture rendering

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

 // 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.
 
 #include "chrome/browser/android/vr_shell/textures/ui_texture.h"
 
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/i18n/char_iterator.h"
 #include "base/i18n/rtl.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_util.h"
+#include "base/trace_event/trace_event.h"
 #include "chrome/browser/android/vr_shell/font_fallback.h"
 #include "chrome/browser/browser_process.h"
 #include "third_party/icu/source/common/unicode/uscript.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/font_list.h"
+#include "ui/gfx/render_text.h"
+#include "ui/gfx/text_elider.h"
 #include "ui/gl/gl_bindings.h"
 
 namespace vr_shell {
 
 namespace {
 
 static constexpr char kDefaultFontFamily[] = "sans-serif";
 
+std::unique_ptr<gfx::RenderText> CreateRenderText(
+    const base::string16& text,
+    const gfx::FontList& font_list,
+    SkColor color,
+    int flags) {
+  std::unique_ptr<gfx::RenderText> render_text(
+      gfx::RenderText::CreateInstance());
+  render_text->SetText(text);
+  render_text->SetFontList(font_list);
+  render_text->SetColor(color);
+
+  if (flags & UiTexture::TEXT_ALIGN_LEFT)
+    render_text->SetHorizontalAlignment(gfx::ALIGN_LEFT);
+  else if (flags & UiTexture::TEXT_ALIGN_RIGHT)
+    render_text->SetHorizontalAlignment(gfx::ALIGN_RIGHT);
+  else if (flags & UiTexture::TEXT_ALIGN_CENTER)
+    render_text->SetHorizontalAlignment(gfx::ALIGN_CENTER);
+
+  const int font_style = font_list.GetFontStyle();
+  render_text->SetStyle(gfx::ITALIC, (font_style & gfx::Font::ITALIC) != 0);
+  render_text->SetStyle(gfx::UNDERLINE,
+                        (font_style & gfx::Font::UNDERLINE) != 0);
+  render_text->SetWeight(font_list.GetFontWeight());
+
+  return render_text;
+}
+
 std::set<UChar32> CollectDifferentChars(base::string16 text) {
   std::set<UChar32> characters;
   for (base::i18n::UTF16CharIterator it(&text); !it.end(); it.Advance()) {
     characters.insert(it.get());
   }
   return characters;
 }
 
 }  // namespace
 
 UiTexture::UiTexture() = default;
 
 UiTexture::~UiTexture() = default;
 
 void UiTexture::DrawAndLayout(SkCanvas* canvas, const gfx::Size& texture_size) {
+  TRACE_EVENT0("gpu", "UiTexture::DrawAndLayout");
   canvas->drawColor(SK_ColorTRANSPARENT);
   Draw(canvas, texture_size);
 }
 
+std::vector<std::unique_ptr<gfx::RenderText>> UiTexture::PrepareDrawStringRect(
+    const base::string16& text,
+    const gfx::FontList& font_list,
+    SkColor color,
+    gfx::Rect* bounds,
+    int flags) {
+  DCHECK(bounds);
+
+  std::vector<std::unique_ptr<gfx::RenderText>> lines;
+  gfx::Rect rect(*bounds);
+
+  if (flags & MULTI_LINE) {
+    std::vector<base::string16> strings;
+    gfx::ElideRectangleText(text, font_list, bounds->width(),
+                            bounds->height() ? bounds->height() : INT_MAX,
+                            gfx::WRAP_LONG_WORDS, &strings);
+
+    int height = 0;
+    int line_height = 0;
+    for (size_t i = 0; i < strings.size(); i++) {
+      std::unique_ptr<gfx::RenderText> render_text =
+          CreateRenderText(strings[i], font_list, color, flags);
+
+      if (i == 0) {
+        // Measure line and center text vertically.
+        line_height = render_text->GetStringSize().height();
+        rect.set_height(line_height);
+        if (bounds->height()) {
+          const int text_height = strings.size() * line_height;
+          rect += gfx::Vector2d(0, (bounds->height() - text_height) / 2);
+        }
+      }
+
+      render_text->SetDisplayRect(rect);
+      height += line_height;
+      rect += gfx::Vector2d(0, line_height);
+      lines.push_back(std::move(render_text));
+    }
+
+    // Set calculated height.
+    if (bounds->height() == 0)
+      bounds->set_height(height);
+
+  } else {
+    std::unique_ptr<gfx::RenderText> render_text =
+        CreateRenderText(text, font_list, color, flags);
+    if (bounds->width() != 0)
+      render_text->SetElideBehavior(gfx::TRUNCATE);
+    else
+      rect.set_width(INT_MAX);
+
+    render_text->SetDisplayRect(rect);
+
+    if (bounds->width() == 0) {
+      int text_width = render_text->GetStringSize().width();
+      bounds->set_width(text_width);
+
+      // bringing text back to the left.

[mthiesse, 2017/05/12 19:32:59]

The comment doesn't really make sense. I'd just remove it as it seems obvious
enough from the code.

+      rect.set_width(text_width);
+      render_text->SetDisplayRect(rect);
+    }
+
+    lines.push_back(std::move(render_text));
+  }
+  return lines;
+}
+
 bool UiTexture::IsRTL() {
   return base::i18n::IsRTL();
 }
 
 gfx::FontList UiTexture::GetDefaultFontList(int size) {
   return gfx::FontList(gfx::Font(kDefaultFontFamily, size));
 }
 
 gfx::FontList UiTexture::GetFontList(int size, base::string16 text) {
   gfx::Font default_font(kDefaultFontFamily, size);
   std::vector<gfx::Font> fonts{default_font};
 
   std::set<std::string> names;
   // TODO(acondor): Query BrowserProcess to obtain the application locale.
   for (UChar32 c : CollectDifferentChars(text)) {
     std::string name = GetFallbackFontNameForChar(default_font, c, "");
     if (!name.empty())
       names.insert(name);
   }
   for (const auto& name : names)
     fonts.push_back(gfx::Font(name, size));
   return gfx::FontList(fonts);
 }
 
 }  // namespace vr_shell