Fix gfx::Canvas::DrawStringRectWithHalo

ui/gfx/canvas_skia.cc

 // Copyright (c) 2012 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 "ui/gfx/canvas.h"
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 10 matching lines @@
 #include "ui/gfx/range/range.h"
 #include "ui/gfx/render_text.h"
 #include "ui/gfx/shadow_value.h"
 #include "ui/gfx/text_elider.h"
 #include "ui/gfx/text_utils.h"
 
 namespace gfx {
 
 namespace {
 
-// Checks each pixel immediately adjacent to the given pixel in the bitmap. If
-// any of them are not the halo color, returns true. This defines the halo of
-// pixels that will appear around the text. Note that we have to check each
-// pixel against both the halo color and transparent since
-// |DrawStringRectWithHalo| will modify the bitmap as it goes, and cleared
-// pixels shouldn't count as changed.
-bool PixelShouldGetHalo(const SkPixmap& pixmap,
-                        int x, int y,
-                        SkColor halo_color) {
-  if (x > 0 &&
-      *pixmap.addr32(x - 1, y) != halo_color &&
-      *pixmap.addr32(x - 1, y) != 0)
-    return true;  // Touched pixel to the left.
-  if (x < pixmap.width() - 1 &&
-      *pixmap.addr32(x + 1, y) != halo_color &&
-      *pixmap.addr32(x + 1, y) != 0)
-    return true;  // Touched pixel to the right.
-  if (y > 0 &&
-      *pixmap.addr32(x, y - 1) != halo_color &&
-      *pixmap.addr32(x, y - 1) != 0)
-    return true;  // Touched pixel above.
-  if (y < pixmap.height() - 1 &&
-      *pixmap.addr32(x, y + 1) != halo_color &&
-      *pixmap.addr32(x, y + 1) != 0)
-    return true;  // Touched pixel below.
-  return false;
-}
-
 // Strips accelerator character prefixes in |text| if needed, based on |flags|.
 // Returns a range in |text| to underline or Range::InvalidRange() if
 // underlining is not needed.
 Range StripAcceleratorChars(int flags, base::string16* text) {
   if (flags & (Canvas::SHOW_PREFIX | Canvas::HIDE_PREFIX)) {
     int char_pos = -1;
     int char_span = 0;
     *text = RemoveAcceleratorChar(*text, '&', &char_pos, &char_span);
     if ((flags & Canvas::SHOW_PREFIX) && char_pos != -1)
       return Range(char_pos, char_pos + char_span);
@@ skipping 124 matching lines @@
   Rect clip_rect(text_bounds);
   clip_rect.Inset(ShadowValue::GetMargin(shadows));
 
   canvas_->save();
   ClipRect(clip_rect);
 
   Rect rect(text_bounds);
 
   scoped_ptr<RenderText> render_text(RenderText::CreateInstance());
   render_text->set_shadows(shadows);
+  render_text->set_halo_effect(!!(flags & HALO_EFFECT));
 
   if (flags & MULTI_LINE) {
     WordWrapBehavior wrap_behavior = IGNORE_LONG_WORDS;
     if (flags & CHARACTER_BREAK)
       wrap_behavior = WRAP_LONG_WORDS;
     else if (!(flags & NO_ELLIPSIS))
       wrap_behavior = ELIDE_LONG_WORDS;
 
     std::vector<base::string16> strings;
     ElideRectangleText(text, font_list,
@@ skipping 63 matching lines @@
 void Canvas::DrawStringRectWithHalo(const base::string16& text,
                                     const FontList& font_list,
                                     SkColor text_color,
                                     SkColor halo_color_in,
                                     const Rect& display_rect,
                                     int flags) {
   // Some callers will have semitransparent halo colors, which we don't handle
   // (since the resulting image can have 1-bit transparency only).
   SkColor halo_color = SkColorSetA(halo_color_in, 0xFF);
 
-  // Create a temporary buffer filled with the halo color. It must leave room
-  // for the 1-pixel border around the text.
-  Size size(display_rect.width() + 2, display_rect.height() + 2);
-  Canvas text_canvas(size, image_scale(), false);
-  SkPaint bkgnd_paint;
-  bkgnd_paint.setColor(halo_color);
-  text_canvas.DrawRect(Rect(size), bkgnd_paint);
-
-  // Draw the text into the temporary buffer. This will have correct
-  // ClearType since the background color is the same as the halo color.
-  text_canvas.DrawStringRectWithFlags(
-      text, font_list, text_color,
-      Rect(1, 1, display_rect.width(), display_rect.height()), flags);
-
-  uint32_t halo_premul = SkPreMultiplyColor(halo_color);
-  SkPixmap pixmap;
-  skia::GetWritablePixels(text_canvas.sk_canvas(), &pixmap);
-
-  for (int cur_y = 0; cur_y < pixmap.height(); cur_y++) {
-    uint32_t* text_row = pixmap.writable_addr32(0, cur_y);
-    for (int cur_x = 0; cur_x < pixmap.width(); cur_x++) {
-      if (text_row[cur_x] == halo_premul) {
-        // This pixel was not touched by the text routines. See if it borders
-        // a touched pixel in any of the 4 directions (not diagonally).
-        if (!PixelShouldGetHalo(pixmap, cur_x, cur_y, halo_premul))
-          text_row[cur_x] = 0;  // Make transparent.
-      } else {
-        text_row[cur_x] |= 0xff << SK_A32_SHIFT;  // Make opaque.
-      }
-    }
-  }
-
-  // Draw the halo bitmap with blur.
-  SkBitmap bitmap;
-  bitmap.installPixels(pixmap.info(), pixmap.writable_addr(),
-                       pixmap.rowBytes());
-  ImageSkia text_image = ImageSkia(ImageSkiaRep(bitmap,
-      text_canvas.image_scale()));
-  DrawImageInt(text_image, display_rect.x() - 1, display_rect.y() - 1);
+  // Draw the halo.
+  DrawStringRectWithFlags(text, font_list, halo_color, display_rect,
+                          flags | HALO_EFFECT | NO_SUBPIXEL_RENDERING);
+  // Draw the text.
+  DrawStringRectWithFlags(text, font_list, text_color, display_rect,
+                          flags | NO_SUBPIXEL_RENDERING);
 }
 
 void Canvas::DrawFadedString(const base::string16& text,
                              const FontList& font_list,
                              SkColor color,
                              const Rect& display_rect,
                              int flags) {
   // If the whole string fits in the destination then just draw it directly.
   if (GetStringWidth(text, font_list) <= display_rect.width()) {
     DrawStringRectWithFlags(text, font_list, color, display_rect, flags);
@@ skipping 10 matching lines @@
   UpdateRenderText(rect, text, font_list, flags, color, render_text.get());
   render_text->SetElideBehavior(FADE_TAIL);
 
   canvas_->save();
   ClipRect(display_rect);
   render_text->Draw(this);
   canvas_->restore();
 }
 
 }  // namespace gfx