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 #include "Thumbnail.h"
18
19 #define LOG_NDEBUG 0
20 #define LOG_TAG "EmulatedCamera_Thumbnail"
21 #include <log/log.h>
22 #include <libexif/exif-data.h>
23 #include <libyuv.h>
24
25 #include "JpegCompressor.h"
26
27 #include <vector>
28
29 /*
30 * The NV21 format is a YUV format with an 8-bit Y-component and the U and V
31 * components are stored as 8 bits each but they are shared between a block of
32 * 2x2 pixels. So when calculating bits per pixel the 16 bits of U and V are
33 * shared between 4 pixels leading to 4 bits of U and V per pixel. Together
34 * with the 8 bits of Y this gives us 12 bits per pixel..
35 *
36 * The components are not grouped by pixels but separated into one Y-plane and
37 * one interleaved U and V-plane. The first half of the byte sequence is all of
38 * the Y data laid out in a linear fashion. After that the interleaved U and V-
39 * plane starts with one byte of V followed by one byte of U followed by one
40 * byte of V and so on. Each byte of U or V is associated with a 2x2 pixel block
41 * in a linear fashion.
42 *
43 * For an 8 by 4 pixel image the layout would be:
44 *
45 * +-----+-----+-----+-----+-----+-----+-----+-----+
46 * | Y0 | Y1 | Y2 | Y3 | Y4 | Y5 | Y6 | Y7 |
47 * +-----+-----+-----+-----+-----+-----+-----+-----+
48 * | Y8 | Y9 | Y10 | Y11 | Y12 | Y13 | Y14 | Y15 |
49 * +-----+-----+-----+-----+-----+-----+-----+-----+
50 * | Y16 | Y17 | Y18 | Y19 | Y20 | Y21 | Y22 | Y23 |
51 * +-----+-----+-----+-----+-----+-----+-----+-----+
52 * | Y24 | Y25 | Y26 | Y27 | Y28 | Y29 | Y30 | Y31 |
53 * +-----+-----+-----+-----+-----+-----+-----+-----+
54 * | V0 | U0 | V1 | U1 | V2 | U2 | V3 | U3 |
55 * +-----+-----+-----+-----+-----+-----+-----+-----+
56 * | V4 | U4 | V5 | U5 | V6 | U6 | V7 | U7 |
57 * +-----+-----+-----+-----+-----+-----+-----+-----+
58 *
59 * In this image V0 and U0 are the V and U components for the 2x2 block of
60 * pixels whose Y components are Y0, Y1, Y8 and Y9. V1 and U1 are matched with
61 * the Y components Y2, Y3, Y10, Y11, and so on for that row. For the next row
62 * of V and U the V4 and U4 components would be paired with Y16, Y17, Y24 and
63 * Y25.
64 */
65
66 namespace android {
67
createRawThumbnail(const unsigned char * sourceImage,int sourceWidth,int sourceHeight,int thumbnailWidth,int thumbnailHeight,std::vector<unsigned char> * thumbnail)68 static bool createRawThumbnail(const unsigned char* sourceImage,
69 int sourceWidth, int sourceHeight,
70 int thumbnailWidth, int thumbnailHeight,
71 std::vector<unsigned char>* thumbnail) {
72 // Deinterleave the U and V planes into separate planes, this is because
73 // libyuv requires the planes to be separate when scaling
74 const size_t sourceUVPlaneSize = (sourceWidth * sourceHeight) / 4;
75 // Put both U and V planes in one buffer, one after the other, to reduce
76 // memory fragmentation and number of allocations
77 std::vector<unsigned char> sourcePlanes(sourceUVPlaneSize * 2);
78 const unsigned char* ySourcePlane = sourceImage;
79 unsigned char* uSourcePlane = &sourcePlanes[0];
80 unsigned char* vSourcePlane = &sourcePlanes[sourceUVPlaneSize];
81
82 for (size_t i = 0; i < sourceUVPlaneSize; ++i) {
83 vSourcePlane[i] = sourceImage[sourceWidth * sourceHeight + i * 2 + 0];
84 uSourcePlane[i] = sourceImage[sourceWidth * sourceHeight + i * 2 + 1];
85 }
86
87 // Create enough space in the output vector for the result
88 thumbnail->resize((thumbnailWidth * thumbnailHeight * 12) / 8);
89
90 // The downscaled U and V planes will also be linear instead of interleaved,
91 // allocate space for them here
92 const size_t destUVPlaneSize = (thumbnailWidth * thumbnailHeight) / 4;
93 std::vector<unsigned char> destPlanes(destUVPlaneSize * 2);
94 unsigned char* yDestPlane = &(*thumbnail)[0];
95 unsigned char* uDestPlane = &destPlanes[0];
96 unsigned char* vDestPlane = &destPlanes[destUVPlaneSize];
97
98 // The strides for the U and V planes are half the width because the U and V
99 // components are common to 2x2 pixel blocks
100 int result = libyuv::I420Scale(ySourcePlane, sourceWidth,
101 uSourcePlane, sourceWidth / 2,
102 vSourcePlane, sourceWidth / 2,
103 sourceWidth, sourceHeight,
104 yDestPlane, thumbnailWidth,
105 uDestPlane, thumbnailWidth / 2,
106 vDestPlane, thumbnailWidth / 2,
107 thumbnailWidth, thumbnailHeight,
108 libyuv::kFilterBilinear);
109 if (result != 0) {
110 ALOGE("Unable to create thumbnail, downscaling failed with error: %d",
111 result);
112 return false;
113 }
114
115 // Now we need to interleave the downscaled U and V planes into the
116 // output buffer to make it NV21 encoded
117 const size_t uvPlanesOffset = thumbnailWidth * thumbnailHeight;
118 for (size_t i = 0; i < destUVPlaneSize; ++i) {
119 (*thumbnail)[uvPlanesOffset + i * 2 + 0] = vDestPlane[i];
120 (*thumbnail)[uvPlanesOffset + i * 2 + 1] = uDestPlane[i];
121 }
122
123 return true;
124 }
125
createThumbnail(const unsigned char * sourceImage,int sourceWidth,int sourceHeight,int thumbWidth,int thumbHeight,int quality,ExifData * exifData)126 bool createThumbnail(const unsigned char* sourceImage,
127 int sourceWidth, int sourceHeight,
128 int thumbWidth, int thumbHeight, int quality,
129 ExifData* exifData) {
130 if (thumbWidth <= 0 || thumbHeight <= 0) {
131 ALOGE("%s: Invalid thumbnail width=%d or height=%d, must be > 0",
132 __FUNCTION__, thumbWidth, thumbHeight);
133 return false;
134 }
135
136 // First downscale the source image into a thumbnail-sized raw image
137 std::vector<unsigned char> rawThumbnail;
138 if (!createRawThumbnail(sourceImage, sourceWidth, sourceHeight,
139 thumbWidth, thumbHeight, &rawThumbnail)) {
140 // The thumbnail function will log an appropriate error if needed
141 return false;
142 }
143
144 // And then compress it into JPEG format without any EXIF data
145 NV21JpegCompressor compressor;
146 status_t result = compressor.compressRawImage(&rawThumbnail[0],
147 nullptr /* EXIF */,
148 quality, thumbWidth, thumbHeight);
149 if (result != NO_ERROR) {
150 ALOGE("%s: Unable to compress thumbnail", __FUNCTION__);
151 return false;
152 }
153
154 // And finally put it in the EXIF data. This transfers ownership of the
155 // malloc'd memory to the EXIF data structure. As long as the EXIF data
156 // structure is free'd using the EXIF library this memory will be free'd.
157 exifData->size = compressor.getCompressedSize();
158 exifData->data = reinterpret_cast<unsigned char*>(malloc(exifData->size));
159 if (exifData->data == nullptr) {
160 ALOGE("%s: Unable to allocate %u bytes of memory for thumbnail",
161 __FUNCTION__, exifData->size);
162 exifData->size = 0;
163 return false;
164 }
165 compressor.getCompressedImage(exifData->data);
166 return true;
167 }
168
169 } // namespace android
170
171