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authorRuben Brunk <rubenbrunk@google.com>2013-06-28 20:02:54 -0700
committerRuben Brunk <rubenbrunk@google.com>2013-07-11 13:41:29 -0700
commit0a7720cce4068a08a5b9a06cefa537de846fa099 (patch)
tree30ab88f07cf62a44a95db2804c6d760026fbab50 /jni_jpegstream/src/jpeg_reader.h
parenta053a3179cfee3d2bb666eff5f4f03a96b092e04 (diff)
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Added jpeg streaming classes.
- Provides streaming operations for decompressing/compressing JPEG files. - Allows pixel operations to be performed on large JPEG images without holding the entire bitmap in memory. Change-Id: I597ddf282b59d2ba6d6bca4722208121e3728f94
Diffstat (limited to 'jni_jpegstream/src/jpeg_reader.h')
-rw-r--r--jni_jpegstream/src/jpeg_reader.h88
1 files changed, 88 insertions, 0 deletions
diff --git a/jni_jpegstream/src/jpeg_reader.h b/jni_jpegstream/src/jpeg_reader.h
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+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef JPEG_READER_H_
+#define JPEG_READER_H_
+
+#include "jerr_hook.h"
+#include "jni_defines.h"
+#include "jpeg_config.h"
+
+#include <stdint.h>
+
+/**
+ * JpegReader wraps libjpeg's decompression functionality and a
+ * java InputStream object. Read calls return data from the
+ * InputStream that has been decompressed.
+ */
+class JpegReader {
+public:
+ JpegReader();
+ ~JpegReader();
+
+ /**
+ * Call setup with a valid InputStream reference and pixel format.
+ * If this method is successful, the contents of width and height will
+ * be set to the dimensions of the bitmap to be read.
+ *
+ * ***This method will result in the jpeg file header being read
+ * from the InputStream***
+ *
+ * Returns J_SUCCESS on success or a negative error code.
+ */
+ int32_t setup(JNIEnv *env, jobject in, int32_t* width, int32_t* height,
+ Jpeg_Config::Format format);
+
+ /**
+ * Decompresses bytes from the InputStream and writes at most count
+ * bytes into the buffer, bytes, starting at some offset. Passing a
+ * NULL as the bytes pointer effectively skips those bytes.
+ *
+ * ***This method will result in bytes being read from the InputStream***
+ *
+ * Returns the number of bytes written into the input buffer or a
+ * negative error code.
+ */
+ int32_t read(int8_t * bytes, int32_t offset, int32_t count);
+
+ /**
+ * Updates the environment pointer. Call this before read or reset
+ * in any jni function call.
+ */
+ void updateEnv(JNIEnv *env);
+
+ /**
+ * Frees any java global references held by the JpegReader, destroys
+ * the decompress structure, and frees allocations in libjpeg's pools.
+ */
+ int32_t reset();
+
+private:
+ void formatPixels(uint8_t* buf, int32_t len);
+ struct jpeg_decompress_struct mInfo;
+ ErrManager mErrorManager;
+
+ JSAMPLE* mScanlineBuf;
+ JSAMPLE* mScanlineIter;
+ int32_t mScanlineBuflen;
+ int32_t mScanlineUnformattedBuflen;
+ int32_t mScanlineBytesRemaining;
+
+ Jpeg_Config::Format mFormat;
+ bool mFinished;
+ bool mSetup;
+};
+
+#endif // JPEG_READER_H_