path: root/ui/gfx/text_elider.h

// 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.
//
// This file defines utility functions for eliding and formatting UI text.

#ifndef UI_GFX_TEXT_ELIDER_H_
#define UI_GFX_TEXT_ELIDER_H_

#include <string>
#include <vector>

#include "base/basictypes.h"
#include "base/strings/string16.h"
#include "third_party/icu/source/common/unicode/uchar.h"
#include "third_party/icu/source/i18n/unicode/coll.h"
#include "ui/gfx/gfx_export.h"

class GURL;

namespace base {
class FilePath;
}

namespace gfx {
class Font;
class FontList;

GFX_EXPORT extern const char kEllipsis[];
GFX_EXPORT extern const char16 kEllipsisUTF16[];

// Elides a well-formed email address (e.g. username@domain.com) to fit into
// |available_pixel_width| using the specified |font_list|.
// This function guarantees that the string returned will contain at least one
// character, other than the ellipses, on either side of the '@'. If it is
// impossible to achieve these requirements: only an ellipsis will be returned.
// If possible: this elides only the username portion of the |email|. Otherwise,
// the domain is elided in the middle so that it splits the available width
// equally with the elided username (should the username be short enough that it
// doesn't need half the available width: the elided domain will occupy that
// extra width).
GFX_EXPORT string16 ElideEmail(const string16& email,
                               const gfx::FontList& font_list,
                               int available_pixel_width);
// Obsolete version.  Use the above version which takes gfx::FontList.
GFX_EXPORT string16 ElideEmail(const string16& email,
                               const gfx::Font& font,
                               int available_pixel_width);

// This function takes a GURL object and elides it. It returns a string
// which composed of parts from subdomain, domain, path, filename and query.
// A "..." is added automatically at the end if the elided string is bigger
// than the |available_pixel_width|. For |available_pixel_width| == 0, a
// formatted, but un-elided, string is returned. |languages| is a comma
// separated list of ISO 639 language codes and is used to determine what
// characters are understood by a user. It should come from
// |prefs::kAcceptLanguages|.
//
// Note: in RTL locales, if the URL returned by this function is going to be
// displayed in the UI, then it is likely that the string needs to be marked
// as an LTR string (using base::i18n::WrapStringWithLTRFormatting()) so that it
// is displayed properly in an RTL context. Please refer to
// http://crbug.com/6487 for more information.
GFX_EXPORT string16 ElideUrl(const GURL& url,
                             const gfx::FontList& font_list,
                             int available_pixel_width,
                             const std::string& languages);
// Obsolete version.  Use the above version which takes gfx::FontList.
GFX_EXPORT string16 ElideUrl(const GURL& url,
                             const gfx::Font& font,
                             int available_pixel_width,
                             const std::string& languages);

enum ElideBehavior {
  // Add ellipsis at the end of the string.
  ELIDE_AT_END,
  // Add ellipsis in the middle of the string.
  ELIDE_IN_MIDDLE,
  // Truncate the end of the string.
  TRUNCATE_AT_END
};

// Elides |text| to fit in |available_pixel_width| according to the specified
// |elide_behavior|.
GFX_EXPORT string16 ElideText(const string16& text,
                              const gfx::FontList& font_list,
                              int available_pixel_width,
                              ElideBehavior elide_behavior);
// Obsolete version.  Use the above version which takes gfx::FontList.
GFX_EXPORT string16 ElideText(const string16& text,
                              const gfx::Font& font,
                              int available_pixel_width,
                              ElideBehavior elide_behavior);

// Elide a filename to fit a given pixel width, with an emphasis on not hiding
// the extension unless we have to. If filename contains a path, the path will
// be removed if filename doesn't fit into available_pixel_width. The elided
// filename is forced to have LTR directionality, which means that in RTL UI
// the elided filename is wrapped with LRE (Left-To-Right Embedding) mark and
// PDF (Pop Directional Formatting) mark.
GFX_EXPORT string16 ElideFilename(const base::FilePath& filename,
                                  const gfx::FontList& font_list,
                                  int available_pixel_width);
// Obsolete version.  Use the above version which takes gfx::FontList.
GFX_EXPORT string16 ElideFilename(const base::FilePath& filename,
                                  const gfx::Font& font,
                                  int available_pixel_width);

// SortedDisplayURL maintains a string from a URL suitable for display to the
// use. SortedDisplayURL also provides a function used for comparing two
// SortedDisplayURLs for use in visually ordering the SortedDisplayURLs.
//
// SortedDisplayURL is relatively cheap and supports value semantics.
class GFX_EXPORT SortedDisplayURL {
 public:
  SortedDisplayURL(const GURL& url, const std::string& languages);
  SortedDisplayURL();
  ~SortedDisplayURL();

  // Compares this SortedDisplayURL to |url| using |collator|. Returns a value
  // < 0, = 1 or > 0 as to whether this url is less then, equal to or greater
  // than the supplied url.
  int Compare(const SortedDisplayURL& other, icu::Collator* collator) const;

  // Returns the display string for the URL.
  const string16& display_url() const { return display_url_; }

 private:
  // Returns everything after the host. This is used by Compare if the hosts
  // match.
  string16 AfterHost() const;

  // Host name minus 'www.'. Used by Compare.
  string16 sort_host_;

  // End of the prefix (spec and separator) in display_url_.
  size_t prefix_end_;

  string16 display_url_;

  DISALLOW_COPY_AND_ASSIGN(SortedDisplayURL);
};

// Functions to elide strings when the font information is unknown.  As
// opposed to the above functions, the ElideString() and
// ElideRectangleString() functions operate in terms of character units,
// not pixels.

// If the size of |input| is more than |max_len|, this function returns
// true and |input| is shortened into |output| by removing chars in the
// middle (they are replaced with up to 3 dots, as size permits).
// Ex: ElideString(ASCIIToUTF16("Hello"), 10, &str) puts Hello in str and
// returns false.  ElideString(ASCIIToUTF16("Hello my name is Tom"), 10, &str)
// puts "Hell...Tom" in str and returns true.
// TODO(tsepez): Doesn't handle UTF-16 surrogate pairs properly.
// TODO(tsepez): Doesn't handle bidi properly.
GFX_EXPORT bool ElideString(const string16& input, int max_len,
                            string16* output);

// Reformat |input| into |output| so that it fits into a |max_rows| by
// |max_cols| rectangle of characters.  Input newlines are respected, but
// lines that are too long are broken into pieces.  If |strict| is true,
// we break first at naturally occuring whitespace boundaries, otherwise
// we assume some other mechanism will do this in approximately the same
// spot after the fact.  If the word itself is too long, we always break
// intra-word (respecting UTF-16 surrogate pairs) as necssary. Truncation
// (indicated by an added 3 dots) occurs if the result is still too long.
//  Returns true if the input had to be truncated (and not just reformatted).
GFX_EXPORT bool ElideRectangleString(const string16& input, size_t max_rows,
                                     size_t max_cols, bool strict,
                                     string16* output);

// Specifies the word wrapping behavior of |ElideRectangleText()| when a word
// would exceed the available width.
enum WordWrapBehavior {
  // Words that are too wide will be put on a new line, but will not be
  // truncated or elided.
  IGNORE_LONG_WORDS,

  // Words that are too wide will be put on a new line and will be truncated to
  // the available width.
  TRUNCATE_LONG_WORDS,

  // Words that are too wide will be put on a new line and will be elided to the
  // available width.
  ELIDE_LONG_WORDS,

  // Words that are too wide will be put on a new line and will be wrapped over
  // multiple lines.
  WRAP_LONG_WORDS,
};

// Indicates whether the |available_pixel_width| by |available_pixel_height|
// rectangle passed to |ElideRectangleText()| had insufficient space to
// accommodate the given |text|, leading to elision or truncation.
enum ReformattingResultFlags {
  INSUFFICIENT_SPACE_HORIZONTAL = 1 << 0,
  INSUFFICIENT_SPACE_VERTICAL = 1 << 1,
};

// Reformats |text| into output vector |lines| so that the resulting text fits
// into an |available_pixel_width| by |available_pixel_height| rectangle with
// the specified |font_list|. Input newlines are respected, but lines that are
// too long are broken into pieces. For words that are too wide to fit on a
// single line, the wrapping behavior can be specified with the |wrap_behavior|
// param. Returns a combination of |ReformattingResultFlags| that indicate
// whether the given rectangle had insufficient space to accommodate |texŧ|,
// leading to elision or truncation (and not just reformatting).
GFX_EXPORT int ElideRectangleText(const string16& text,
                                  const gfx::FontList& font_list,
                                  int available_pixel_width,
                                  int available_pixel_height,
                                  WordWrapBehavior wrap_behavior,
                                  std::vector<string16>* lines);
// Obsolete version.  Use the above version which takes gfx::FontList.
GFX_EXPORT int ElideRectangleText(const string16& text,
                                  const gfx::Font& font,
                                  int available_pixel_width,
                                  int available_pixel_height,
                                  WordWrapBehavior wrap_behavior,
                                  std::vector<string16>* lines);

// Truncates the string to length characters. This breaks the string at
// the first word break before length, adding the horizontal ellipsis
// character (unicode character 0x2026) to render ...
// The supplied string is returned if the string has length characters or
// less.
GFX_EXPORT string16 TruncateString(const string16& string, size_t length);

}  // namespace gfx

#endif  // UI_GFX_TEXT_ELIDER_H_