1 /*
2 * Copyright (C) 2016 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 V4L2_CAMERA_HAL_METADATA_MAP_CONVERTER_H_
18 #define V4L2_CAMERA_HAL_METADATA_MAP_CONVERTER_H_
19
20 #include <cerrno>
21 #include <map>
22 #include <memory>
23
24 #include <android-base/macros.h>
25 #include "common.h"
26 #include "converter_interface.h"
27
28 namespace v4l2_camera_hal {
29
30 // A MapConverter fits values converted by a wrapped converter
31 // to a map entry corresponding to the key with the nearest value.
32 template <typename TMetadata, typename TV4L2, typename TMapKey>
33 class MapConverter : public ConverterInterface<TMetadata, TV4L2> {
34 public:
35 MapConverter(
36 std::shared_ptr<ConverterInterface<TMetadata, TMapKey>> wrapped_converter,
37 std::map<TMapKey, TV4L2> conversion_map);
38
39 virtual int MetadataToV4L2(TMetadata value, TV4L2* conversion) override;
40 virtual int V4L2ToMetadata(TV4L2 value, TMetadata* conversion) override;
41
42 private:
43 std::shared_ptr<ConverterInterface<TMetadata, TMapKey>> wrapped_converter_;
44 std::map<TMapKey, TV4L2> conversion_map_;
45
46 DISALLOW_COPY_AND_ASSIGN(MapConverter);
47 };
48
49 // -----------------------------------------------------------------------------
50
51 template <typename TMetadata, typename TV4L2, typename TMapKey>
MapConverter(std::shared_ptr<ConverterInterface<TMetadata,TMapKey>> wrapped_converter,std::map<TMapKey,TV4L2> conversion_map)52 MapConverter<TMetadata, TV4L2, TMapKey>::MapConverter(
53 std::shared_ptr<ConverterInterface<TMetadata, TMapKey>> wrapped_converter,
54 std::map<TMapKey, TV4L2> conversion_map)
55 : wrapped_converter_(std::move(wrapped_converter)),
56 conversion_map_(conversion_map) {
57 HAL_LOG_ENTER();
58 }
59
60 template <typename TMetadata, typename TV4L2, typename TMapKey>
MetadataToV4L2(TMetadata value,TV4L2 * conversion)61 int MapConverter<TMetadata, TV4L2, TMapKey>::MetadataToV4L2(TMetadata value,
62 TV4L2* conversion) {
63 HAL_LOG_ENTER();
64
65 if (conversion_map_.empty()) {
66 HAL_LOGE("Empty conversion map.");
67 return -EINVAL;
68 }
69
70 TMapKey raw_conversion = 0;
71 int res = wrapped_converter_->MetadataToV4L2(value, &raw_conversion);
72 if (res) {
73 HAL_LOGE("Failed to perform underlying conversion.");
74 return res;
75 }
76
77 // Find nearest key.
78 auto kv = conversion_map_.lower_bound(raw_conversion);
79 // lower_bound finds the first >= element.
80 if (kv == conversion_map_.begin()) {
81 // Searching for less than the smallest key, so that will be the nearest.
82 *conversion = kv->second;
83 } else if (kv == conversion_map_.end()) {
84 // Searching for greater than the largest key, so that will be the nearest.
85 --kv;
86 *conversion = kv->second;
87 } else {
88 // Since kv points to the first >= element, either that or the previous
89 // element will be nearest.
90 *conversion = kv->second;
91 TMapKey diff = kv->first - raw_conversion;
92
93 // Now compare to the previous. This element will be < raw conversion,
94 // so reverse the order of the subtraction.
95 --kv;
96 if (raw_conversion - kv->first < diff) {
97 *conversion = kv->second;
98 }
99 }
100
101 return 0;
102 }
103
104 template <typename TMetadata, typename TV4L2, typename TMapKey>
V4L2ToMetadata(TV4L2 value,TMetadata * conversion)105 int MapConverter<TMetadata, TV4L2, TMapKey>::V4L2ToMetadata(
106 TV4L2 value, TMetadata* conversion) {
107 HAL_LOG_ENTER();
108
109 // Unfortunately no bi-directional map lookup in C++.
110 // Breaking on second, not first found so that a warning
111 // can be given if there are multiple values.
112 size_t count = 0;
113 int res;
114 for (auto kv : conversion_map_) {
115 if (kv.second == value) {
116 ++count;
117 if (count == 1) {
118 // First match.
119 res = wrapped_converter_->V4L2ToMetadata(kv.first, conversion);
120 } else {
121 // second match.
122 break;
123 }
124 }
125 }
126
127 if (count == 0) {
128 HAL_LOGE("Couldn't find map conversion of V4L2 value %d.", value);
129 return -EINVAL;
130 } else if (count > 1) {
131 HAL_LOGW("Multiple map conversions found for V4L2 value %d, using first.",
132 value);
133 }
134 return res;
135 }
136
137 } // namespace v4l2_camera_hal
138
139 #endif // V4L2_CAMERA_HAL_METADATA_MAP_CONVERTER_H_
140