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      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_READER_H_
     17 #define JPEG_READER_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  * JpegReader wraps libjpeg's decompression functionality and a
     27  * java InputStream object.  Read calls return data from the
     28  * InputStream that has been decompressed.
     29  */
     30 class JpegReader {
     31 public:
     32     JpegReader();
     33     ~JpegReader();
     34 
     35     /**
     36      * Call setup with a valid InputStream reference and pixel format.
     37      * If this method is successful, the contents of width and height will
     38      * be set to the dimensions of the bitmap to be read.
     39      *
     40      * ***This method will result in the jpeg file header being read
     41      * from the InputStream***
     42      *
     43      * Returns J_SUCCESS on success or a negative error code.
     44      */
     45     int32_t setup(JNIEnv *env, jobject in, int32_t* width, int32_t* height,
     46             Jpeg_Config::Format format);
     47 
     48     /**
     49      * Decompresses bytes from the InputStream and writes at most count
     50      * bytes into the buffer, bytes, starting at some offset.  Passing a
     51      * NULL as the bytes pointer effectively skips those bytes.
     52      *
     53      * ***This method will result in bytes being read from the InputStream***
     54      *
     55      * Returns the number of bytes written into the input buffer or a
     56      * negative error code.
     57      */
     58     int32_t read(int8_t * bytes, int32_t offset, int32_t count);
     59 
     60     /**
     61      * Updates the environment pointer.  Call this before read or reset
     62      * in any jni function call.
     63      */
     64     void updateEnv(JNIEnv *env);
     65 
     66     /**
     67      * Frees any java global references held by the JpegReader, destroys
     68      * the decompress structure, and frees allocations in libjpeg's pools.
     69      */
     70     int32_t reset();
     71 
     72 private:
     73     void formatPixels(uint8_t* buf, int32_t len);
     74     struct jpeg_decompress_struct mInfo;
     75     ErrManager mErrorManager;
     76 
     77     JSAMPLE* mScanlineBuf;
     78     JSAMPLE* mScanlineIter;
     79     int32_t mScanlineBuflen;
     80     int32_t mScanlineUnformattedBuflen;
     81     int32_t mScanlineBytesRemaining;
     82 
     83     Jpeg_Config::Format mFormat;
     84     bool mFinished;
     85     bool mSetup;
     86 };
     87 
     88 #endif // JPEG_READER_H_
     89