Canvas refactoring part 2....

gfx/canvas_win.cc

Index: gfx/canvas_win.cc
===================================================================
--- gfx/canvas_win.cc	(revision 50557)
+++ gfx/canvas_win.cc	(working copy)
@@ -1,293 +0,0 @@
-// Copyright (c) 2010 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 "gfx/canvas.h"
-
-#include <limits>
-
-#include "base/i18n/rtl.h"
-#include "gfx/font.h"
-#include "gfx/rect.h"
-#include "third_party/skia/include/core/SkShader.h"
-
-namespace {
-
-// We make sure that LTR text we draw in an RTL context is modified
-// appropriately to make sure it maintains it LTR orientation.
-void DoDrawText(HDC hdc, const std::wstring& text,
-                RECT* text_bounds, int flags) {
-  std::wstring localized_text;
-  const wchar_t* string_ptr = text.c_str();
-  int string_size = static_cast<int>(text.length());
-  // Only adjust string directionality if both of the following are true:
-  // 1. The current locale is RTL.
-  // 2. The string itself has RTL directionality.
-  if (flags & DT_RTLREADING) {
-    if (base::i18n::AdjustStringForLocaleDirection(text, &localized_text)) {
-      string_ptr = localized_text.c_str();
-      string_size = static_cast<int>(localized_text.length());
-    }
-  }
-
-  DrawText(hdc, string_ptr, string_size, text_bounds, flags);
-}
-
-// Compute the windows flags necessary to implement the provided text Canvas
-// flags.
-int ComputeFormatFlags(int flags, const std::wstring& text) {
-  // Setting the text alignment explicitly in case it hasn't already been set.
-  // This will make sure that we don't align text to the left on RTL locales
-  // just because no alignment flag was passed to DrawStringInt().
-  if (!(flags & (gfx::Canvas::TEXT_ALIGN_CENTER |
-                 gfx::Canvas::TEXT_ALIGN_RIGHT |
-                 gfx::Canvas::TEXT_ALIGN_LEFT))) {
-    flags |= gfx::Canvas::DefaultCanvasTextAlignment();
-  }
-
-  // horizontal alignment
-  int f = 0;
-  if (flags & gfx::Canvas::TEXT_ALIGN_CENTER)
-    f |= DT_CENTER;
-  else if (flags & gfx::Canvas::TEXT_ALIGN_RIGHT)
-    f |= DT_RIGHT;
-  else
-    f |= DT_LEFT;
-
-  // vertical alignment
-  if (flags & gfx::Canvas::TEXT_VALIGN_TOP)
-    f |= DT_TOP;
-  else if (flags & gfx::Canvas::TEXT_VALIGN_BOTTOM)
-    f |= DT_BOTTOM;
-  else
-    f |= DT_VCENTER;
-
-  if (flags & gfx::Canvas::MULTI_LINE) {
-    f |= DT_WORDBREAK;
-    if (flags & gfx::Canvas::CHARACTER_BREAK)
-      f |= DT_EDITCONTROL;  // Turns on character breaking (not documented)
-    else if (!(flags & gfx::Canvas::NO_ELLIPSIS))
-      f |= DT_WORD_ELLIPSIS;
-  } else {
-    f |= DT_SINGLELINE;
-  }
-
-  if (flags & gfx::Canvas::HIDE_PREFIX)
-    f |= DT_HIDEPREFIX;
-  else if ((flags & gfx::Canvas::SHOW_PREFIX) == 0)
-    f |= DT_NOPREFIX;
-
-  if (!(flags & gfx::Canvas::NO_ELLIPSIS))
-    f |= DT_END_ELLIPSIS;
-
-  // In order to make sure RTL/BiDi strings are rendered correctly, we must
-  // pass the flag DT_RTLREADING to DrawText (when the locale's language is
-  // a right-to-left language) so that Windows does the right thing.
-  //
-  // In addition to correctly displaying text containing both RTL and LTR
-  // elements (for example, a string containing a telephone number within a
-  // sentence in Hebrew, or a sentence in Hebrew that contains a word in
-  // English) this flag also makes sure that if there is not enough space to
-  // display the entire string, the ellipsis is displayed on the left hand side
-  // of the truncated string and not on the right hand side.
-  //
-  // We make a distinction between Chrome UI strings and text coming from a web
-  // page.
-  //
-  // For text coming from a web page we determine the alignment based on the
-  // first character with strong directionality. If the directionality of the
-  // first character with strong directionality in the text is LTR, the
-  // alignment is set to DT_LEFT, and the directionality should not be set as
-  // DT_RTLREADING.
-  //
-  // This heuristic doesn't work for Chrome UI strings since even in RTL
-  // locales, some of those might start with English text but we know they're
-  // localized so we always want them to be right aligned, and their
-  // directionality should be set as DT_RTLREADING.
-  //
-  // Caveat: If the string is purely LTR, don't set DTL_RTLREADING since when
-  // the flag is set, LRE-PDF don't have the desired effect of rendering
-  // multiline English-only text as LTR.
-  //
-  // Note that if the caller is explicitly requesting displaying the text
-  // using RTL directionality then we respect that and pass DT_RTLREADING to
-  // ::DrawText even if the locale is LTR.
-  if ((flags & gfx::Canvas::FORCE_RTL_DIRECTIONALITY) ||
-      (base::i18n::IsRTL() &&
-       (f & DT_RIGHT) && base::i18n::StringContainsStrongRTLChars(text))) {
-    f |= DT_RTLREADING;
-  }
-
-  return f;
-}
-
-}  // anonymous namespace
-
-namespace gfx {
-
-Canvas::Canvas(int width, int height, bool is_opaque)
-    : skia::PlatformCanvas(width, height, is_opaque) {
-}
-
-Canvas::Canvas() : skia::PlatformCanvas() {
-}
-
-Canvas::~Canvas() {
-}
-
-// static
-void Canvas::SizeStringInt(const std::wstring& text,
-                           const gfx::Font& font,
-                           int* width, int* height, int flags) {
-  // Clamp the max amount of text we'll measure to 2K.  When the string is
-  // actually drawn, it will be clipped to whatever size box is provided, and
-  // the time to do that doesn't depend on the length being clipped off.
-  const int kMaxStringLength = 2048 - 1;  // So the trailing \0 fits in 2K.
-  std::wstring clamped_string(text.substr(0, kMaxStringLength));
-
-  if (*width == 0) {
-    // If multi-line + character break are on, the computed width will be one
-    // character wide (useless).  Furthermore, if in this case the provided text
-    // contains very long "words" (substrings without a word-breaking point),
-    // DrawText() can run extremely slowly (e.g. several seconds).  So in this
-    // case, we turn character breaking off to get a more accurate "desired"
-    // width and avoid the slowdown.
-    if (flags & (gfx::Canvas::MULTI_LINE | gfx::Canvas::CHARACTER_BREAK))
-      flags &= ~gfx::Canvas::CHARACTER_BREAK;
-
-    // Weird undocumented behavior: if the width is 0, DoDrawText() won't
-    // calculate a size at all.  So set it to 1, which it will then change.
-    if (!text.empty())
-      *width = 1;
-  }
-  RECT r = { 0, 0, *width, *height };
-
-  HDC dc = GetDC(NULL);
-  HFONT old_font = static_cast<HFONT>(SelectObject(dc, font.hfont()));
-  DoDrawText(dc, clamped_string, &r,
-             ComputeFormatFlags(flags, clamped_string) | DT_CALCRECT);
-  SelectObject(dc, old_font);
-  ReleaseDC(NULL, dc);
-
-  *width = r.right;
-  *height = r.bottom;
-}
-
-void Canvas::DrawStringInt(const std::wstring& text, HFONT font,
-                           const SkColor& color, int x, int y, int w, int h,
-                           int flags) {
-  if (!IntersectsClipRectInt(x, y, w, h))
-    return;
-
-  // Clamp the max amount of text we'll draw to 32K.  There seem to be bugs in
-  // DrawText() if you e.g. ask it to character-break a no-whitespace string of
-  // length > 43680 (for which it draws nothing), and since we clamped to 2K in
-  // SizeStringInt() we're unlikely to be able to display this much anyway.
-  const int kMaxStringLength = 32768 - 1;  // So the trailing \0 fits in 32K.
-  std::wstring clamped_string(text.substr(0, kMaxStringLength));
-
-  RECT text_bounds = { x, y, x + w, y + h };
-  HDC dc = beginPlatformPaint();
-  SetBkMode(dc, TRANSPARENT);
-  HFONT old_font = (HFONT)SelectObject(dc, font);
-  COLORREF brush_color = RGB(SkColorGetR(color), SkColorGetG(color),
-                             SkColorGetB(color));
-  SetTextColor(dc, brush_color);
-
-  int f = ComputeFormatFlags(flags, clamped_string);
-  DoDrawText(dc, clamped_string, &text_bounds, f);
-  endPlatformPaint();
-
-  // Restore the old font. This way we don't have to worry if the caller
-  // deletes the font and the DC lives longer.
-  SelectObject(dc, old_font);
-
-  // Windows will have cleared the alpha channel of the text we drew. Assume
-  // we're drawing to an opaque surface, or at least the text rect area is
-  // opaque.
-  getTopPlatformDevice().makeOpaque(x, y, w, h);
-}
-
-void Canvas::DrawStringInt(const std::wstring& text,
-                           const gfx::Font& font,
-                           const SkColor& color,
-                           int x, int y, int w, int h, int flags) {
-  DrawStringInt(text, font.hfont(), color, x, y, w, h, flags);
-}
-
-// 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 DrawStringWithHalo
-// will modify the bitmap as it goes, and clears pixels shouldn't count as
-// changed.
-static bool pixelShouldGetHalo(const SkBitmap& bitmap, int x, int y,
-                               SkColor halo_color) {
-  if (x > 0 &&
-      *bitmap.getAddr32(x - 1, y) != halo_color &&
-      *bitmap.getAddr32(x - 1, y) != 0)
-    return true;  // Touched pixel to the left.
-  if (x < bitmap.width() - 1 &&
-      *bitmap.getAddr32(x + 1, y) != halo_color &&
-      *bitmap.getAddr32(x + 1, y) != 0)
-    return true;  // Touched pixel to the right.
-  if (y > 0 &&
-      *bitmap.getAddr32(x, y - 1) != halo_color &&
-      *bitmap.getAddr32(x, y - 1) != 0)
-    return true;  // Touched pixel above.
-  if (y < bitmap.height() - 1 &&
-      *bitmap.getAddr32(x, y + 1) != halo_color &&
-      *bitmap.getAddr32(x, y + 1) != 0)
-    return true;  // Touched pixel below.
-  return false;
-}
-
-void Canvas::DrawStringWithHalo(const std::wstring& text,
-                                const gfx::Font& font,
-                                const SkColor& text_color,
-                                const SkColor& halo_color_in,
-                                int x, int y, int w, int h,
-                                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 = halo_color_in | 0xFF000000;
-
-  // Create a temporary buffer filled with the halo color. It must leave room
-  // for the 1-pixel border around the text.
-  Canvas text_canvas(w + 2, h + 2, true);
-  SkPaint bkgnd_paint;
-  bkgnd_paint.setColor(halo_color);
-  text_canvas.FillRectInt(0, 0, w + 2, h + 2, 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.DrawStringInt(text, font, text_color, 1, 1, w, h, flags);
-
-  // Windows will have cleared the alpha channel for the pixels it drew. Make it
-  // opaque. We have to do this first since pixelShouldGetHalo will check for
-  // 0 to see if a pixel has been modified to transparent, and black text that
-  // Windows draw will look transparent to it!
-  text_canvas.getTopPlatformDevice().makeOpaque(0, 0, w + 2, h + 2);
-
-  uint32_t halo_premul = SkPreMultiplyColor(halo_color);
-  SkBitmap& text_bitmap = const_cast<SkBitmap&>(
-      text_canvas.getTopPlatformDevice().accessBitmap(true));
-  for (int cur_y = 0; cur_y < h + 2; cur_y++) {
-    uint32_t* text_row = text_bitmap.getAddr32(0, cur_y);
-    for (int cur_x = 0; cur_x < w + 2; 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(text_bitmap, 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.
-  drawBitmap(text_bitmap, SkIntToScalar(x - 1), SkIntToScalar(y - 1));
-}
-
-}  // namespace gfx