ui/gfx/canvas_skia.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ui/gfx/canvas.h"
   6
   7 #include "base/i18n/rtl.h"
   8 #include "base/logging.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "ui/gfx/font_list.h"
  11 #include "ui/gfx/insets.h"
  12 #include "ui/gfx/range/range.h"
  13 #include "ui/gfx/rect.h"
  14 #include "ui/gfx/render_text.h"
  15 #include "ui/gfx/shadow_value.h"
  16 #include "ui/gfx/text_elider.h"
  17 #include "ui/gfx/text_utils.h"
  18
  19 namespace gfx {
  20
  21 namespace {
  22
  23 #if defined(OS_WIN)
  24 // If necessary, wraps |text| with RTL/LTR directionality characters based on
  25 // |flags| and |text| content.
  26 // Returns true if the text will be rendered right-to-left.
  27 // TODO(msw): Nix this, now that RenderTextWin supports directionality directly.
  28 bool AdjustStringDirection(int flags, base::string16* text) {
  29   // TODO(msw): FORCE_LTR_DIRECTIONALITY does not work for RTL text now.
  30
  31   // If the string is empty or LTR was forced, simply return false since the
  32   // default RenderText directionality is already LTR.
  33   if (text->empty() || (flags & Canvas::FORCE_LTR_DIRECTIONALITY))
  34     return false;
  35
  36   // If RTL is forced, apply it to the string.
  37   if (flags & Canvas::FORCE_RTL_DIRECTIONALITY) {
  38     base::i18n::WrapStringWithRTLFormatting(text);
  39     return true;
  40   }
  41
  42   // If a direction wasn't forced but the UI language is RTL and there were
  43   // strong RTL characters, ensure RTL is applied.
  44   if (base::i18n::IsRTL() && base::i18n::StringContainsStrongRTLChars(*text)) {
  45     base::i18n::WrapStringWithRTLFormatting(text);
  46     return true;
  47   }
  48
  49   // In the default case, the string should be rendered as LTR. RenderText's
  50   // default directionality is LTR, so the text doesn't need to be wrapped.
  51   // Note that individual runs within the string may still be rendered RTL
  52   // (which will be the case for RTL text under non-RTL locales, since under RTL
  53   // locales it will be handled by the if statement above).
  54   return false;
  55 }
  56 #endif  // defined(OS_WIN)
  57
  58 // Checks each pixel immediately adjacent to the given pixel in the bitmap. If
  59 // any of them are not the halo color, returns true. This defines the halo of
  60 // pixels that will appear around the text. Note that we have to check each
  61 // pixel against both the halo color and transparent since
  62 // |DrawStringRectWithHalo| will modify the bitmap as it goes, and cleared
  63 // pixels shouldn't count as changed.
  64 bool PixelShouldGetHalo(const SkBitmap& bitmap,
  65                         int x, int y,
  66                         SkColor halo_color) {
  67   if (x > 0 &&
  68       *bitmap.getAddr32(x - 1, y) != halo_color &&
  69       *bitmap.getAddr32(x - 1, y) != 0)
  70     return true;  // Touched pixel to the left.
  71   if (x < bitmap.width() - 1 &&
  72       *bitmap.getAddr32(x + 1, y) != halo_color &&
  73       *bitmap.getAddr32(x + 1, y) != 0)
  74     return true;  // Touched pixel to the right.
  75   if (y > 0 &&
  76       *bitmap.getAddr32(x, y - 1) != halo_color &&
  77       *bitmap.getAddr32(x, y - 1) != 0)
  78     return true;  // Touched pixel above.
  79   if (y < bitmap.height() - 1 &&
  80       *bitmap.getAddr32(x, y + 1) != halo_color &&
  81       *bitmap.getAddr32(x, y + 1) != 0)
  82     return true;  // Touched pixel below.
  83   return false;
  84 }
  85
  86 // Strips accelerator character prefixes in |text| if needed, based on |flags|.
  87 // Returns a range in |text| to underline or Range::InvalidRange() if
  88 // underlining is not needed.
  89 Range StripAcceleratorChars(int flags, base::string16* text) {
  90   if (flags & (Canvas::SHOW_PREFIX | Canvas::HIDE_PREFIX)) {
  91     int char_pos = -1;
  92     int char_span = 0;
  93     *text = RemoveAcceleratorChar(*text, '&', &char_pos, &char_span);
  94     if ((flags & Canvas::SHOW_PREFIX) && char_pos != -1)
  95       return Range(char_pos, char_pos + char_span);
  96   }
  97   return Range::InvalidRange();
  98 }
  99
 100 // Elides |text| and adjusts |range| appropriately. If eliding causes |range|
 101 // to no longer point to the same character in |text|, |range| is made invalid.
 102 void ElideTextAndAdjustRange(const FontList& font_list,
 103                              int width,
 104                              base::string16* text,
 105                              Range* range) {
 106   const base::char16 start_char =
 107       (range->IsValid() ? text->at(range->start()) : 0);
 108   *text = ElideText(*text, font_list, width, ELIDE_TAIL);
 109   if (!range->IsValid())
 110     return;
 111   if (range->start() >= text->length() ||
 112       text->at(range->start()) != start_char) {
 113     *range = Range::InvalidRange();
 114   }
 115 }
 116
 117 // Updates |render_text| from the specified parameters.
 118 void UpdateRenderText(const Rect& rect,
 119                       const base::string16& text,
 120                       const FontList& font_list,
 121                       int flags,
 122                       SkColor color,
 123                       RenderText* render_text) {
 124   render_text->SetFontList(font_list);
 125   render_text->SetText(text);
 126   render_text->SetCursorEnabled(false);
 127
 128   Rect display_rect = rect;
 129   display_rect.set_height(font_list.GetHeight());
 130   render_text->SetDisplayRect(display_rect);
 131
 132   // Set the text alignment explicitly based on the directionality of the UI,
 133   // if not specified.
 134   if (!(flags & (Canvas::TEXT_ALIGN_CENTER |
 135                  Canvas::TEXT_ALIGN_RIGHT |
 136                  Canvas::TEXT_ALIGN_LEFT))) {
 137     flags |= Canvas::DefaultCanvasTextAlignment();
 138   }
 139
 140   if (flags & Canvas::TEXT_ALIGN_RIGHT)
 141     render_text->SetHorizontalAlignment(ALIGN_RIGHT);
 142   else if (flags & Canvas::TEXT_ALIGN_CENTER)
 143     render_text->SetHorizontalAlignment(ALIGN_CENTER);
 144   else
 145     render_text->SetHorizontalAlignment(ALIGN_LEFT);
 146
 147   if (flags & Canvas::NO_SUBPIXEL_RENDERING)
 148     render_text->set_background_is_transparent(true);
 149
 150   render_text->SetColor(color);
 151   const int font_style = font_list.GetFontStyle();
 152   render_text->SetStyle(BOLD, (font_style & Font::BOLD) != 0);
 153   render_text->SetStyle(ITALIC, (font_style & Font::ITALIC) != 0);
 154   render_text->SetStyle(UNDERLINE, (font_style & Font::UNDERLINE) != 0);
 155 }
 156
 157 }  // namespace
 158
 159 // static
 160 void Canvas::SizeStringFloat(const base::string16& text,
 161                              const FontList& font_list,
 162                              float* width, float* height,
 163                              int line_height,
 164                              int flags) {
 165   DCHECK_GE(*width, 0);
 166   DCHECK_GE(*height, 0);
 167
 168   base::string16 adjusted_text = text;
 169 #if defined(OS_WIN)
 170   AdjustStringDirection(flags, &adjusted_text);
 171 #endif
 172
 173   if ((flags & MULTI_LINE) && *width != 0) {
 174     WordWrapBehavior wrap_behavior = TRUNCATE_LONG_WORDS;
 175     if (flags & CHARACTER_BREAK)
 176       wrap_behavior = WRAP_LONG_WORDS;
 177     else if (!(flags & NO_ELLIPSIS))
 178       wrap_behavior = ELIDE_LONG_WORDS;
 179
 180     Rect rect(*width, INT_MAX);
 181     std::vector<base::string16> strings;
 182     ElideRectangleText(adjusted_text, font_list, rect.width(), rect.height(),
 183                        wrap_behavior, &strings);
 184     scoped_ptr<RenderText> render_text(RenderText::CreateInstance());
 185     UpdateRenderText(rect, base::string16(), font_list, flags, 0,
 186                      render_text.get());
 187
 188     float h = 0;
 189     float w = 0;
 190     for (size_t i = 0; i < strings.size(); ++i) {
 191       StripAcceleratorChars(flags, &strings[i]);
 192       render_text->SetText(strings[i]);
 193       const SizeF& string_size = render_text->GetStringSizeF();
 194       w = std::max(w, string_size.width());
 195       h += (i > 0 && line_height > 0) ? line_height : string_size.height();
 196     }
 197     *width = w;
 198     *height = h;
 199   } else {
 200     // If the string is too long, the call by |RenderTextWin| to |ScriptShape()|
 201     // will inexplicably fail with result E_INVALIDARG. Guard against this.
 202     const size_t kMaxRenderTextLength = 5000;
 203     if (adjusted_text.length() >= kMaxRenderTextLength) {
 204       *width = font_list.GetExpectedTextWidth(adjusted_text.length());
 205       *height = font_list.GetHeight();
 206     } else {
 207       scoped_ptr<RenderText> render_text(RenderText::CreateInstance());
 208       Rect rect(*width, *height);
 209       StripAcceleratorChars(flags, &adjusted_text);
 210       UpdateRenderText(rect, adjusted_text, font_list, flags, 0,
 211                        render_text.get());
 212       const SizeF& string_size = render_text->GetStringSizeF();
 213       *width = string_size.width();
 214       *height = string_size.height();
 215     }
 216   }
 217 }
 218
 219 void Canvas::DrawStringRectWithShadows(const base::string16& text,
 220                                        const FontList& font_list,
 221                                        SkColor color,
 222                                        const Rect& text_bounds,
 223                                        int line_height,
 224                                        int flags,
 225                                        const ShadowValues& shadows) {
 226   if (!IntersectsClipRect(text_bounds))
 227     return;
 228
 229   Rect clip_rect(text_bounds);
 230   clip_rect.Inset(ShadowValue::GetMargin(shadows));
 231
 232   canvas_->save();
 233   ClipRect(clip_rect);
 234
 235   Rect rect(text_bounds);
 236   base::string16 adjusted_text = text;
 237
 238 #if defined(OS_WIN)
 239   AdjustStringDirection(flags, &adjusted_text);
 240 #endif
 241
 242   scoped_ptr<RenderText> render_text(RenderText::CreateInstance());
 243   render_text->set_shadows(shadows);
 244
 245   if (flags & MULTI_LINE) {
 246     WordWrapBehavior wrap_behavior = IGNORE_LONG_WORDS;
 247     if (flags & CHARACTER_BREAK)
 248       wrap_behavior = WRAP_LONG_WORDS;
 249     else if (!(flags & NO_ELLIPSIS))
 250       wrap_behavior = ELIDE_LONG_WORDS;
 251
 252     std::vector<base::string16> strings;
 253     ElideRectangleText(adjusted_text, font_list, text_bounds.width(),
 254                        text_bounds.height(), wrap_behavior, &strings);
 255
 256     for (size_t i = 0; i < strings.size(); i++) {
 257       Range range = StripAcceleratorChars(flags, &strings[i]);
 258       UpdateRenderText(rect, strings[i], font_list, flags, color,
 259                        render_text.get());
 260       int line_padding = 0;
 261       if (line_height > 0)
 262         line_padding = line_height - render_text->GetStringSize().height();
 263       else
 264         line_height = render_text->GetStringSize().height();
 265
 266       // TODO(msw|asvitkine): Center Windows multi-line text: crbug.com/107357
 267 #if !defined(OS_WIN)
 268       if (i == 0) {
 269         // TODO(msw|asvitkine): Support multi-line text with varied heights.
 270         const int text_height = strings.size() * line_height - line_padding;
 271         rect += Vector2d(0, (text_bounds.height() - text_height) / 2);
 272       }
 273 #endif
 274
 275       rect.set_height(line_height - line_padding);
 276
 277       if (range.IsValid())
 278         render_text->ApplyStyle(UNDERLINE, true, range);
 279       render_text->SetDisplayRect(rect);
 280       render_text->Draw(this);
 281       rect += Vector2d(0, line_height);
 282     }
 283   } else {
 284     Range range = StripAcceleratorChars(flags, &adjusted_text);
 285     bool elide_text = ((flags & NO_ELLIPSIS) == 0);
 286
 287 #if defined(OS_LINUX)
 288     // On Linux, eliding really means fading the end of the string. But only
 289     // for LTR text. RTL text is still elided (on the left) with "...".
 290     if (elide_text) {
 291       render_text->SetText(adjusted_text);
 292       if (render_text->GetTextDirection() == base::i18n::LEFT_TO_RIGHT) {
 293         render_text->SetElideBehavior(FADE_TAIL);
 294         elide_text = false;
 295       }
 296     }
 297 #endif
 298
 299     if (elide_text) {
 300       ElideTextAndAdjustRange(font_list, text_bounds.width(), &adjusted_text,
 301                               &range);
 302     }
 303
 304     UpdateRenderText(rect, adjusted_text, font_list, flags, color,
 305                      render_text.get());
 306
 307     const int text_height = render_text->GetStringSize().height();
 308     rect += Vector2d(0, (text_bounds.height() - text_height) / 2);
 309     rect.set_height(text_height);
 310     render_text->SetDisplayRect(rect);
 311     if (range.IsValid())
 312       render_text->ApplyStyle(UNDERLINE, true, range);
 313     render_text->Draw(this);
 314   }
 315
 316   canvas_->restore();
 317 }
 318
 319 void Canvas::DrawStringRectWithHalo(const base::string16& text,
 320                                     const FontList& font_list,
 321                                     SkColor text_color,
 322                                     SkColor halo_color_in,
 323                                     const Rect& display_rect,
 324                                     int flags) {
 325   // Some callers will have semitransparent halo colors, which we don't handle
 326   // (since the resulting image can have 1-bit transparency only).
 327   SkColor halo_color = SkColorSetA(halo_color_in, 0xFF);
 328
 329   // Create a temporary buffer filled with the halo color. It must leave room
 330   // for the 1-pixel border around the text.
 331   Size size(display_rect.width() + 2, display_rect.height() + 2);
 332   Canvas text_canvas(size, image_scale(), false);
 333   SkPaint bkgnd_paint;
 334   bkgnd_paint.setColor(halo_color);
 335   text_canvas.DrawRect(Rect(size), bkgnd_paint);
 336
 337   // Draw the text into the temporary buffer. This will have correct
 338   // ClearType since the background color is the same as the halo color.
 339   text_canvas.DrawStringRectWithFlags(
 340       text, font_list, text_color,
 341       Rect(1, 1, display_rect.width(), display_rect.height()), flags);
 342
 343   uint32_t halo_premul = SkPreMultiplyColor(halo_color);
 344   SkBitmap& text_bitmap = const_cast<SkBitmap&>(
 345       skia::GetTopDevice(*text_canvas.sk_canvas())->accessBitmap(true));
 346
 347   for (int cur_y = 0; cur_y < text_bitmap.height(); cur_y++) {
 348     uint32_t* text_row = text_bitmap.getAddr32(0, cur_y);
 349     for (int cur_x = 0; cur_x < text_bitmap.width(); cur_x++) {
 350       if (text_row[cur_x] == halo_premul) {
 351         // This pixel was not touched by the text routines. See if it borders
 352         // a touched pixel in any of the 4 directions (not diagonally).
 353         if (!PixelShouldGetHalo(text_bitmap, cur_x, cur_y, halo_premul))
 354           text_row[cur_x] = 0;  // Make transparent.
 355       } else {
 356         text_row[cur_x] |= 0xff << SK_A32_SHIFT;  // Make opaque.
 357       }
 358     }
 359   }
 360
 361   // Draw the halo bitmap with blur.
 362   ImageSkia text_image = ImageSkia(ImageSkiaRep(text_bitmap,
 363       text_canvas.image_scale()));
 364   DrawImageInt(text_image, display_rect.x() - 1, display_rect.y() - 1);
 365 }
 366
 367 void Canvas::DrawFadedString(const base::string16& text,
 368                              const FontList& font_list,
 369                              SkColor color,
 370                              const Rect& display_rect,
 371                              int flags) {
 372   // If the whole string fits in the destination then just draw it directly.
 373   if (GetStringWidth(text, font_list) <= display_rect.width()) {
 374     DrawStringRectWithFlags(text, font_list, color, display_rect, flags);
 375     return;
 376   }
 377
 378   // Align with forced content directionality, overriding alignment flags.
 379   if (flags & FORCE_RTL_DIRECTIONALITY) {
 380     flags &= ~(TEXT_ALIGN_CENTER | TEXT_ALIGN_LEFT);
 381     flags |= TEXT_ALIGN_RIGHT;
 382   } else if (flags & FORCE_LTR_DIRECTIONALITY) {
 383     flags &= ~(TEXT_ALIGN_CENTER | TEXT_ALIGN_RIGHT);
 384     flags |= TEXT_ALIGN_LEFT;
 385   } else if (!(flags & TEXT_ALIGN_LEFT) && !(flags & TEXT_ALIGN_RIGHT)) {
 386     // Also align with content directionality instead of fading both ends.
 387     flags &= ~TEXT_ALIGN_CENTER;
 388     const bool is_rtl = base::i18n::GetFirstStrongCharacterDirection(text) ==
 389                         base::i18n::RIGHT_TO_LEFT;
 390     flags |= is_rtl ? TEXT_ALIGN_RIGHT : TEXT_ALIGN_LEFT;
 391   }
 392   flags |= NO_ELLIPSIS;
 393
 394   scoped_ptr<RenderText> render_text(RenderText::CreateInstance());
 395   Rect rect = display_rect;
 396   UpdateRenderText(rect, text, font_list, flags, color, render_text.get());
 397   render_text->SetElideBehavior(FADE_TAIL);
 398
 399   const int line_height = render_text->GetStringSize().height();
 400   rect += Vector2d(0, (display_rect.height() - line_height) / 2);
 401   rect.set_height(line_height);
 402   render_text->SetDisplayRect(rect);
 403
 404   canvas_->save();
 405   ClipRect(display_rect);
 406   render_text->Draw(this);
 407   canvas_->restore();
 408 }
 409
 410 }  // namespace gfx