1 /*
2  * Copyright (C) 2018 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef MINIKIN_BIDI_UTILS_H
18 #define MINIKIN_BIDI_UTILS_H
19 
20 #define LOG_TAG "Minikin"
21 
22 #include "minikin/Layout.h"
23 
24 #include <memory>
25 
26 #include <unicode/ubidi.h>
27 
28 #include "minikin/Macros.h"
29 #include "minikin/U16StringPiece.h"
30 
31 namespace minikin {
32 
33 struct UBiDiDeleter {
operatorUBiDiDeleter34     void operator()(UBiDi* v) { ubidi_close(v); }
35 };
36 
37 using UBiDiUniquePtr = std::unique_ptr<UBiDi, UBiDiDeleter>;
38 
39 // A helper class for iterating the bidi run transitions.
40 class BidiText {
41 public:
42     struct RunInfo {
43         Range range;
44         bool isRtl;
45     };
46 
47     BidiText(const U16StringPiece& textBuf, const Range& range, Bidi bidiFlags);
48 
49     RunInfo getRunInfoAt(uint32_t runOffset) const;
50 
51     class iterator {
52     public:
53         inline bool operator==(const iterator& o) const {
54             return mRunOffset == o.mRunOffset && mParent == o.mParent;
55         }
56 
57         inline bool operator!=(const iterator& o) const { return !(*this == o); }
58 
59         inline RunInfo operator*() const { return mParent->getRunInfoAt(mRunOffset); }
60 
61         inline iterator& operator++() {
62             mRunOffset++;
63             return *this;
64         }
65 
66     private:
67         friend class BidiText;
68 
iterator(const BidiText * parent,uint32_t runOffset)69         iterator(const BidiText* parent, uint32_t runOffset)
70                 : mParent(parent), mRunOffset(runOffset) {}
71 
72         const BidiText* mParent;
73         uint32_t mRunOffset;
74     };
75 
begin()76     inline iterator begin() const { return iterator(this, 0); }
end()77     inline iterator end() const { return iterator(this, mRunCount); }
78 
79 private:
80     UBiDiUniquePtr mBidi;  // Maybe null for single run.
81     const Range mRange;    // The range in the original buffer. Used for range check.
82     bool mIsRtl;           // The paragraph direction.
83     uint32_t mRunCount;    // The number of the bidi run in this text.
84 
85     MINIKIN_PREVENT_COPY_AND_ASSIGN(BidiText);
86 };
87 
88 }  // namespace minikin
89 
90 #endif  // MINIKIN_BIDI_UTILS_H
91