VR: Avoiding regeneration of RenderText objects for texture rendering

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

Index: chrome/browser/android/vr_shell/textures/ui_texture.cc
diff --git a/chrome/browser/android/vr_shell/textures/ui_texture.cc b/chrome/browser/android/vr_shell/textures/ui_texture.cc
index 6d14ae5cb676b73045bd062227a2fd91cf4c5bdd..ceac570aaddd37841fa00b7c8f7b0cca9aedc243 100644
--- a/chrome/browser/android/vr_shell/textures/ui_texture.cc
+++ b/chrome/browser/android/vr_shell/textures/ui_texture.cc
@@ -12,12 +12,15 @@
 #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 {
@@ -26,6 +29,33 @@ 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)

[cjgrant, 2017/05/11 21:15:40]

It looks like RenderText defaults to either RIGHT or LEFT based on its own RTL. 
You could take advantage of that here to only override if RIGHT or CENTER, but
maybe you're choosing to be very explicit here?

[acondor_, 2017/05/11 22:26:49]

Good catch. I'm removing the flag setup in PrepareDrawStringRect, but if the
flag is explicitly set, we should enforce RenderText alignment too.

+    render_text->SetHorizontalAlignment(gfx::ALIGN_LEFT);
+  else if (flags & UiTexture::TEXT_ALIGN_RIGHT)
+    render_text->SetHorizontalAlignment(gfx::ALIGN_RIGHT);
+  else
+    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()) {
@@ -41,10 +71,78 @@ 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 & (TEXT_ALIGN_LEFT | TEXT_ALIGN_CENTER | TEXT_ALIGN_RIGHT))) {
+    flags |= IsRTL() ? TEXT_ALIGN_RIGHT : TEXT_ALIGN_LEFT;
+  }
+
+  if (flags & MULTI_LINE) {
+    std::vector<base::string16> strings;
+    gfx::ElideRectangleText(text, font_list, bounds->width(),
+                            bounds->height() ? bounds->height() : INT_MAX,
+                            gfx::ELIDE_LONG_WORDS, &strings);

[mthiesse, 2017/05/12 01:14:38]

Probably want WRAP_LONG_WORDS here, to align with the non-eliding UX.

[acondor_, 2017/05/12 14:54:23]

Done.

+
+    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::FADE_TAIL);

[mthiesse, 2017/05/12 01:14:38]

Pretty sure we want gfx::TRUNCATE per UX specs.

[acondor_, 2017/05/12 14:54:23]

Done.

+    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);
+    }
+
+    lines.push_back(std::move(render_text));
+  }
+  return lines;
+}
+
 bool UiTexture::IsRTL() {
   return base::i18n::IsRTL();
 }