123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195 |
- // 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.
- #ifndef UI_GFX_BREAK_LIST_H_
- #define UI_GFX_BREAK_LIST_H_
- #include <stddef.h>
- #include <utility>
- #include <vector>
- #include "base/check_op.h"
- #include "ui/gfx/range/range.h"
- namespace gfx {
- // BreakLists manage ordered, non-overlapping, and non-repeating ranged values.
- // These may be used to apply ranged colors and styles to text, for an example.
- //
- // Each break stores the start position and value of its associated range.
- // A solitary break at position 0 applies to the entire space [0, max_).
- // |max_| is initially 0 and should be set to match the available ranged space.
- // The first break always has position 0, to ensure all positions have a value.
- // The value of the terminal break applies to the range [break.first, max_).
- // The value of other breaks apply to the range [break.first, (break+1).first).
- template <typename T>
- class BreakList {
- public:
- // The break type and const iterator, typedef'ed for convenience.
- using Break = std::pair<size_t, T>;
- using const_iterator = typename std::vector<Break>::const_iterator;
- // Initialize a break at position 0 with the default or supplied |value|.
- BreakList();
- explicit BreakList(T value);
- const std::vector<Break>& breaks() const { return breaks_; }
- // Clear the breaks and set a break at position 0 with the supplied |value|.
- // Returns whether or not the breaks changed while applying the |value|.
- bool SetValue(T value);
- // Adjust the breaks to apply |value| over the supplied |range|.
- // Range |range| must be between [0, max_).
- // Returns true if the breaks changed while applying the |value|.
- bool ApplyValue(T value, const Range& range);
- // Set the max position and trim any breaks at or beyond that position.
- void SetMax(size_t max);
- size_t max() const { return max_; }
- // Get the break applicable to |position| (at or preceding |position|).
- // |position| must be between [0, max_).
- // Returns a valid iterator. Can't return |break_.end()|.
- const_iterator GetBreak(size_t position) const;
- // Get the range of the supplied break; returns the break's start position and
- // the next break's start position (or |max_| for the terminal break).
- // Iterator |i| must be valid and must not be |break_.end()|.
- Range GetRange(const const_iterator& i) const;
- // Comparison functions for testing purposes.
- bool EqualsValueForTesting(T value) const;
- bool EqualsForTesting(const std::vector<Break>& breaks) const;
- private:
- #ifndef NDEBUG
- // Check for ordered breaks [0, |max_|) with no adjacent equivalent values.
- void CheckBreaks();
- #endif
- std::vector<Break> breaks_;
- size_t max_ = 0;
- };
- template <class T>
- BreakList<T>::BreakList() : breaks_(1, Break(0, T())) {}
- template <class T>
- BreakList<T>::BreakList(T value) : breaks_(1, Break(0, value)) {}
- template <class T>
- bool BreakList<T>::SetValue(T value) {
- // Return false if setting |value| does not change the breaks.
- if (breaks_.size() == 1 && breaks_[0].second == value)
- return false;
- breaks_.clear();
- breaks_.push_back(Break(0, value));
- return true;
- }
- template <class T>
- bool BreakList<T>::ApplyValue(T value, const Range& range) {
- if (!range.IsValid() || range.is_empty())
- return false;
- DCHECK(!breaks_.empty());
- DCHECK(!range.is_reversed());
- DCHECK(Range(0, static_cast<uint32_t>(max_)).Contains(range));
- // Return false if setting |value| does not change the breaks.
- const_iterator start = GetBreak(range.start());
- if (start->second == value && GetRange(start).Contains(range))
- return false;
- // Erase any breaks in |range|, then add start and end breaks as needed.
- start += start->first < range.start() ? 1 : 0;
- const_iterator end =
- range.end() == max_ ? breaks_.cend() - 1 : GetBreak(range.end());
- T trailing_value = end->second;
- const_iterator i =
- start == breaks_.cend() ? start : breaks_.erase(start, end + 1);
- if (range.start() == 0 || (i - 1)->second != value)
- i = breaks_.insert(i, Break(range.start(), value)) + 1;
- if (trailing_value != value && range.end() != max_)
- breaks_.insert(i, Break(range.end(), trailing_value));
- #ifndef NDEBUG
- CheckBreaks();
- #endif
- return true;
- }
- template<class T>
- void BreakList<T>::SetMax(size_t max) {
- if (max < max_) {
- const_iterator i = GetBreak(max);
- if (i == breaks_.begin() || i->first < max)
- i++;
- breaks_.erase(i, breaks_.end());
- }
- max_ = max;
- #ifndef NDEBUG
- CheckBreaks();
- #endif
- }
- template <class T>
- typename BreakList<T>::const_iterator BreakList<T>::GetBreak(
- size_t position) const {
- DCHECK(!breaks_.empty());
- DCHECK_LT(position, max_);
- // Find the iterator with a 'strictly greater' position and return the
- // previous one.
- return std::upper_bound(breaks_.cbegin(), breaks_.cend(), position,
- [](size_t offset, const Break& value) {
- return offset < value.first;
- }) -
- 1;
- }
- template<class T>
- Range BreakList<T>::GetRange(
- const typename BreakList<T>::const_iterator& i) const {
- // BreakLists are never empty. Iterator should always be valid.
- DCHECK(i != breaks_.end());
- const const_iterator next = i + 1;
- return Range(i->first, next == breaks_.end() ? max_ : next->first);
- }
- template<class T>
- bool BreakList<T>::EqualsValueForTesting(T value) const {
- return breaks_.size() == 1 && breaks_[0] == Break(0, value);
- }
- template<class T>
- bool BreakList<T>::EqualsForTesting(const std::vector<Break>& breaks) const {
- if (breaks_.size() != breaks.size())
- return false;
- for (size_t i = 0; i < breaks.size(); ++i)
- if (breaks_[i] != breaks[i])
- return false;
- return true;
- }
- #ifndef NDEBUG
- template <class T>
- void BreakList<T>::CheckBreaks() {
- DCHECK(!breaks_.empty()) << "BreakList cannot be empty";
- DCHECK_EQ(breaks_[0].first, 0U) << "The first break must be at position 0.";
- for (size_t i = 0; i < breaks_.size() - 1; ++i) {
- DCHECK_LT(breaks_[i].first, breaks_[i + 1].first) << "Break out of order.";
- DCHECK_NE(breaks_[i].second, breaks_[i + 1].second) << "Redundant break.";
- }
- if (max_ > 0)
- DCHECK_LT(breaks_.back().first, max_) << "Break beyond max position.";
- }
- #endif
- } // namespace gfx
- #endif // UI_GFX_BREAK_LIST_H_
|