chromium/src/third_party/blink/renderer/platform/fonts/string_truncator.cc - manifest_repos/chromium_src - Git at Google

 /*
  * Copyright (C) 2005, 2006, 2007 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  *     its contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "third_party/blink/renderer/platform/fonts/string_truncator.h"

 #include "third_party/blink/renderer/platform/fonts/font.h"
 #include "third_party/blink/renderer/platform/text/text_break_iterator.h"
 #include "third_party/blink/renderer/platform/text/text_run.h"
 #include "third_party/blink/renderer/platform/wtf/assertions.h"
 #include "third_party/blink/renderer/platform/wtf/text/character_names.h"

 namespace blink {

 #define STRING_BUFFER_SIZE 2048

 typedef unsigned TruncationFunction(const String&,
                                     unsigned length,
                                     unsigned keep_count,
                                     UChar* buffer);

 static inline int TextBreakAtOrPreceding(
     const NonSharedCharacterBreakIterator& it,
     int offset) {
   if (it.IsBreak(offset))
     return offset;

   int result = it.Preceding(offset);
   return result == kTextBreakDone ? 0 : result;
 }

 static inline int BoundedTextBreakFollowing(
     const NonSharedCharacterBreakIterator& it,
     int offset,
     int length) {
   int result = it.Following(offset);
   return result == kTextBreakDone ? length : result;
 }

 static unsigned CenterTruncateToBuffer(const String& string,
                                        unsigned length,
                                        unsigned keep_count,
                                        UChar* buffer) {
   DCHECK_LT(keep_count, length);
   DCHECK(keep_count < STRING_BUFFER_SIZE);

   unsigned omit_start = (keep_count + 1) / 2;
   NonSharedCharacterBreakIterator it(string);
   unsigned omit_end = BoundedTextBreakFollowing(
       it, omit_start + (length - keep_count) - 1, length);
   omit_start = TextBreakAtOrPreceding(it, omit_start);

   unsigned truncated_length = omit_start + 1 + (length - omit_end);
   DCHECK_LE(truncated_length, length);

   string.CopyTo(buffer, 0, omit_start);
   buffer[omit_start] = kHorizontalEllipsisCharacter;
   string.CopyTo(&buffer[omit_start + 1], omit_end, length - omit_end);

   return truncated_length;
 }

 static unsigned RightTruncateToBuffer(const String& string,
                                       unsigned length,
                                       unsigned keep_count,
                                       UChar* buffer) {
   DCHECK_LT(keep_count, length);
   DCHECK(keep_count < STRING_BUFFER_SIZE);

   NonSharedCharacterBreakIterator it(string);
   unsigned keep_length = TextBreakAtOrPreceding(it, keep_count);
   unsigned truncated_length = keep_length + 1;

   string.CopyTo(buffer, 0, keep_length);
   buffer[keep_length] = kHorizontalEllipsisCharacter;

   return truncated_length;
 }

 static float StringWidth(const Font& renderer,
                          const UChar* characters,
                          unsigned length) {
   TextRun run(characters, length);
   return renderer.Width(run);
 }

 static String TruncateString(const String& string,
                              float max_width,
                              const Font& font,
                              TruncationFunction truncate_to_buffer) {
   if (string.IsEmpty())
     return string;

   DCHECK_GE(max_width, 0);

   float current_ellipsis_width =
       StringWidth(font, &kHorizontalEllipsisCharacter, 1);

   UChar string_buffer[STRING_BUFFER_SIZE];
   unsigned truncated_length;
   unsigned keep_count;
   unsigned length = string.length();

   if (length > STRING_BUFFER_SIZE) {
     keep_count = STRING_BUFFER_SIZE - 1;  // need 1 character for the ellipsis
     truncated_length =
         CenterTruncateToBuffer(string, length, keep_count, string_buffer);
   } else {
     keep_count = length;
     string.CopyTo(string_buffer, 0, length);
     truncated_length = length;
   }

   float width = StringWidth(font, string_buffer, truncated_length);
   if (width <= max_width)
     return string;

   unsigned keep_count_for_largest_known_to_fit = 0;
   float width_for_largest_known_to_fit = current_ellipsis_width;

   unsigned keep_count_for_smallest_known_to_not_fit = keep_count;
   float width_for_smallest_known_to_not_fit = width;

   if (current_ellipsis_width >= max_width) {
     keep_count_for_largest_known_to_fit = 1;
     keep_count_for_smallest_known_to_not_fit = 2;
   }

   while (keep_count_for_largest_known_to_fit + 1 <
          keep_count_for_smallest_known_to_not_fit) {
     DCHECK_LE(width_for_largest_known_to_fit, max_width);
     DCHECK_GT(width_for_smallest_known_to_not_fit, max_width);

     float ratio =
         (keep_count_for_smallest_known_to_not_fit -
          keep_count_for_largest_known_to_fit) /
         (width_for_smallest_known_to_not_fit - width_for_largest_known_to_fit);
     keep_count = static_cast<unsigned>(max_width * ratio);

     if (keep_count <= keep_count_for_largest_known_to_fit) {
       keep_count = keep_count_for_largest_known_to_fit + 1;
     } else if (keep_count >= keep_count_for_smallest_known_to_not_fit) {
       keep_count = keep_count_for_smallest_known_to_not_fit - 1;
     }

     DCHECK_LT(keep_count, length);
     DCHECK_GT(keep_count, 0u);
     DCHECK_LT(keep_count, keep_count_for_smallest_known_to_not_fit);
     DCHECK_GT(keep_count, keep_count_for_largest_known_to_fit);

     truncated_length =
         truncate_to_buffer(string, length, keep_count, string_buffer);

     width = StringWidth(font, string_buffer, truncated_length);
     if (width <= max_width) {
       keep_count_for_largest_known_to_fit = keep_count;
       width_for_largest_known_to_fit = width;
     } else {
       keep_count_for_smallest_known_to_not_fit = keep_count;
       width_for_smallest_known_to_not_fit = width;
     }
   }

   if (!keep_count_for_largest_known_to_fit)
     keep_count_for_largest_known_to_fit = 1;

   if (keep_count != keep_count_for_largest_known_to_fit) {
     keep_count = keep_count_for_largest_known_to_fit;
     truncated_length =
         truncate_to_buffer(string, length, keep_count, string_buffer);
   }

   return String(string_buffer, truncated_length);
 }

 String StringTruncator::CenterTruncate(const String& string,
                                        float max_width,
                                        const Font& font) {
   return TruncateString(string, max_width, font, CenterTruncateToBuffer);
 }

 String StringTruncator::RightTruncate(const String& string,
                                       float max_width,
                                       const Font& font) {
   return TruncateString(string, max_width, font, RightTruncateToBuffer);
 }

 }  // namespace blink
	/*
	* Copyright (C) 2005, 2006, 2007 Apple Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
	* its contributors may be used to endorse or promote products derived
	* from this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
	* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
	* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
	* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "third_party/blink/renderer/platform/fonts/string_truncator.h"

	#include "third_party/blink/renderer/platform/fonts/font.h"
	#include "third_party/blink/renderer/platform/text/text_break_iterator.h"
	#include "third_party/blink/renderer/platform/text/text_run.h"
	#include "third_party/blink/renderer/platform/wtf/assertions.h"
	#include "third_party/blink/renderer/platform/wtf/text/character_names.h"

	namespace blink {

	#define STRING_BUFFER_SIZE 2048

	typedef unsigned TruncationFunction(const String&,
	unsigned length,
	unsigned keep_count,
	UChar* buffer);

	static inline int TextBreakAtOrPreceding(
	const NonSharedCharacterBreakIterator& it,
	int offset) {
	if (it.IsBreak(offset))
	return offset;

	int result = it.Preceding(offset);
	return result == kTextBreakDone ? 0 : result;
	}

	static inline int BoundedTextBreakFollowing(
	const NonSharedCharacterBreakIterator& it,
	int offset,
	int length) {
	int result = it.Following(offset);
	return result == kTextBreakDone ? length : result;
	}

	static unsigned CenterTruncateToBuffer(const String& string,
	unsigned length,
	unsigned keep_count,
	UChar* buffer) {
	DCHECK_LT(keep_count, length);
	DCHECK(keep_count < STRING_BUFFER_SIZE);

	unsigned omit_start = (keep_count + 1) / 2;
	NonSharedCharacterBreakIterator it(string);
	unsigned omit_end = BoundedTextBreakFollowing(
	it, omit_start + (length - keep_count) - 1, length);
	omit_start = TextBreakAtOrPreceding(it, omit_start);

	unsigned truncated_length = omit_start + 1 + (length - omit_end);
	DCHECK_LE(truncated_length, length);

	string.CopyTo(buffer, 0, omit_start);
	buffer[omit_start] = kHorizontalEllipsisCharacter;
	string.CopyTo(&buffer[omit_start + 1], omit_end, length - omit_end);

	return truncated_length;
	}

	static unsigned RightTruncateToBuffer(const String& string,
	unsigned length,
	unsigned keep_count,
	UChar* buffer) {
	DCHECK_LT(keep_count, length);
	DCHECK(keep_count < STRING_BUFFER_SIZE);

	NonSharedCharacterBreakIterator it(string);
	unsigned keep_length = TextBreakAtOrPreceding(it, keep_count);
	unsigned truncated_length = keep_length + 1;

	string.CopyTo(buffer, 0, keep_length);
	buffer[keep_length] = kHorizontalEllipsisCharacter;

	return truncated_length;
	}

	static float StringWidth(const Font& renderer,
	const UChar* characters,
	unsigned length) {
	TextRun run(characters, length);
	return renderer.Width(run);
	}

	static String TruncateString(const String& string,
	float max_width,
	const Font& font,
	TruncationFunction truncate_to_buffer) {
	if (string.IsEmpty())
	return string;

	DCHECK_GE(max_width, 0);

	float current_ellipsis_width =
	StringWidth(font, &kHorizontalEllipsisCharacter, 1);

	UChar string_buffer[STRING_BUFFER_SIZE];
	unsigned truncated_length;
	unsigned keep_count;
	unsigned length = string.length();

	if (length > STRING_BUFFER_SIZE) {
	keep_count = STRING_BUFFER_SIZE - 1; // need 1 character for the ellipsis
	truncated_length =
	CenterTruncateToBuffer(string, length, keep_count, string_buffer);
	} else {
	keep_count = length;
	string.CopyTo(string_buffer, 0, length);
	truncated_length = length;
	}

	float width = StringWidth(font, string_buffer, truncated_length);
	if (width <= max_width)
	return string;

	unsigned keep_count_for_largest_known_to_fit = 0;
	float width_for_largest_known_to_fit = current_ellipsis_width;

	unsigned keep_count_for_smallest_known_to_not_fit = keep_count;
	float width_for_smallest_known_to_not_fit = width;

	if (current_ellipsis_width >= max_width) {
	keep_count_for_largest_known_to_fit = 1;
	keep_count_for_smallest_known_to_not_fit = 2;
	}

	while (keep_count_for_largest_known_to_fit + 1 <
	keep_count_for_smallest_known_to_not_fit) {
	DCHECK_LE(width_for_largest_known_to_fit, max_width);
	DCHECK_GT(width_for_smallest_known_to_not_fit, max_width);

	float ratio =
	(keep_count_for_smallest_known_to_not_fit -
	keep_count_for_largest_known_to_fit) /
	(width_for_smallest_known_to_not_fit - width_for_largest_known_to_fit);
	keep_count = static_cast<unsigned>(max_width * ratio);

	if (keep_count <= keep_count_for_largest_known_to_fit) {
	keep_count = keep_count_for_largest_known_to_fit + 1;
	} else if (keep_count >= keep_count_for_smallest_known_to_not_fit) {
	keep_count = keep_count_for_smallest_known_to_not_fit - 1;
	}

	DCHECK_LT(keep_count, length);
	DCHECK_GT(keep_count, 0u);
	DCHECK_LT(keep_count, keep_count_for_smallest_known_to_not_fit);
	DCHECK_GT(keep_count, keep_count_for_largest_known_to_fit);

	truncated_length =
	truncate_to_buffer(string, length, keep_count, string_buffer);

	width = StringWidth(font, string_buffer, truncated_length);
	if (width <= max_width) {
	keep_count_for_largest_known_to_fit = keep_count;
	width_for_largest_known_to_fit = width;
	} else {
	keep_count_for_smallest_known_to_not_fit = keep_count;
	width_for_smallest_known_to_not_fit = width;
	}
	}

	if (!keep_count_for_largest_known_to_fit)
	keep_count_for_largest_known_to_fit = 1;

	if (keep_count != keep_count_for_largest_known_to_fit) {
	keep_count = keep_count_for_largest_known_to_fit;
	truncated_length =
	truncate_to_buffer(string, length, keep_count, string_buffer);
	}

	return String(string_buffer, truncated_length);
	}

	String StringTruncator::CenterTruncate(const String& string,
	float max_width,
	const Font& font) {
	return TruncateString(string, max_width, font, CenterTruncateToBuffer);
	}

	String StringTruncator::RightTruncate(const String& string,
	float max_width,
	const Font& font) {
	return TruncateString(string, max_width, font, RightTruncateToBuffer);
	}

	} // namespace blink