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      1 /*
      2  * Copyright (C) 2006 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 _ANDROID_GRAPHICS_UTILS_H_
     18 #define _ANDROID_GRAPHICS_UTILS_H_
     19 
     20 #include "SkStream.h"
     21 
     22 #include "android_util_Binder.h"
     23 
     24 #include <jni.h>
     25 #include <androidfw/Asset.h>
     26 
     27 namespace android {
     28 
     29 class AssetStreamAdaptor : public SkStreamRewindable {
     30 public:
     31     explicit AssetStreamAdaptor(Asset*);
     32 
     33     virtual bool rewind();
     34     virtual size_t read(void* buffer, size_t size);
     35     virtual bool hasLength() const { return true; }
     36     virtual size_t getLength() const;
     37     virtual bool hasPosition() const;
     38     virtual size_t getPosition() const;
     39     virtual bool seek(size_t position);
     40     virtual bool move(long offset);
     41     virtual bool isAtEnd() const;
     42 
     43 protected:
     44     SkStreamRewindable* onDuplicate() const override;
     45 
     46 private:
     47     Asset* fAsset;
     48 };
     49 
     50 /**
     51  *  Make a deep copy of the asset, and return it as a stream, or NULL if there
     52  *  was an error.
     53  *  FIXME: If we could "ref/reopen" the asset, we may not need to copy it here.
     54  */
     55 
     56 SkMemoryStream* CopyAssetToStream(Asset*);
     57 
     58 /** Restore the file descriptor's offset in our destructor
     59  */
     60 class AutoFDSeek {
     61 public:
     62     explicit AutoFDSeek(int fd) : fFD(fd) {
     63         fCurr = ::lseek(fd, 0, SEEK_CUR);
     64     }
     65     ~AutoFDSeek() {
     66         if (fCurr >= 0) {
     67             ::lseek(fFD, fCurr, SEEK_SET);
     68         }
     69     }
     70 private:
     71     int     fFD;
     72     off64_t   fCurr;
     73 };
     74 
     75 jobject nullObjectReturn(const char msg[]);
     76 
     77 /** Check if the file descriptor is seekable.
     78  */
     79 bool isSeekable(int descriptor);
     80 
     81 JNIEnv* get_env_or_die(JavaVM* jvm);
     82 
     83 }; // namespace android
     84 
     85 #endif  // _ANDROID_GRAPHICS_UTILS_H_
     86