1 /*
2  * Copyright (C) 2013 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 #ifndef JPEG_WRITER_H_
17 #define JPEG_WRITER_H_
18 
19 #include "jerr_hook.h"
20 #include "jni_defines.h"
21 #include "jpeg_config.h"
22 
23 #include <stdint.h>
24 
25 /**
26  * JpegWriter wraps libjpeg's compression functionality and a
27  * java OutputStream object.  Write calls result in input data
28  * being compressed and written to the OuputStream.
29  */
30 class JpegWriter {
31 public:
32     JpegWriter();
33     ~JpegWriter();
34 
35     /**
36      * Call setup with a valid OutputStream reference, bitmap height and
37      * width, pixel format, and compression quality in range (0, 100].
38      *
39      * Returns J_SUCCESS on success or a negative error code.
40      */
41     int32_t setup(JNIEnv *env, jobject out, int32_t width, int32_t height,
42             Jpeg_Config::Format format, int32_t quality);
43 
44     /**
45      * Compresses bytes from the input buffer.
46      *
47      * ***This method will result in bytes being written to the OutputStream***
48      *
49      * Returns J_SUCCESS on success or a negative error code.
50      */
51     int32_t write(int8_t* bytes, int32_t length);
52 
53     /**
54      * Updates the environment pointer.  Call this before write or reset
55      * in any jni function call.
56      */
57     void updateEnv(JNIEnv *env);
58 
59     /**
60      * Frees any java global references held by the JpegWriter, destroys
61      * the compress structure, and frees allocations in libjpeg's pools.
62      */
63     int32_t reset();
64 
65     static const int32_t DEFAULT_X_DENSITY;
66     static const int32_t DEFAULT_Y_DENSITY;
67     static const int32_t DEFAULT_DENSITY_UNIT;
68 private:
69     void formatPixels(uint8_t* buf, int32_t len);
70     struct jpeg_compress_struct mInfo;
71     ErrManager mErrorManager;
72 
73     JSAMPLE* mScanlineBuf;
74     JSAMPLE* mScanlineIter;
75     int32_t mScanlineBuflen;
76     int32_t mScanlineBytesRemaining;
77 
78     Jpeg_Config::Format mFormat;
79     bool mFinished;
80     bool mSetup;
81 };
82 
83 #endif // JPEG_WRITER_H_
84