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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     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 isAtEnd() const;
     38 
     39     virtual SkStreamRewindable* duplicate() const;
     40 private:
     41     Asset* fAsset;
     42 };
     43 
     44 /**
     45  *  Make a deep copy of the asset, and return it as a stream, or NULL if there
     46  *  was an error.
     47  *  FIXME: If we could "ref/reopen" the asset, we may not need to copy it here.
     48  */
     49 
     50 SkMemoryStream* CopyAssetToStream(Asset*);
     51 
     52 /** Restore the file descriptor's offset in our destructor
     53  */
     54 class AutoFDSeek {
     55 public:
     56     AutoFDSeek(int fd) : fFD(fd) {
     57         fCurr = ::lseek(fd, 0, SEEK_CUR);
     58     }
     59     ~AutoFDSeek() {
     60         if (fCurr >= 0) {
     61             ::lseek(fFD, fCurr, SEEK_SET);
     62         }
     63     }
     64 private:
     65     int     fFD;
     66     off64_t   fCurr;
     67 };
     68 
     69 jobject nullObjectReturn(const char msg[]);
     70 
     71 /** Check if the file descriptor is seekable.
     72  */
     73 bool isSeekable(int descriptor);
     74 
     75 }; // namespace android
     76 
     77 #endif  // _ANDROID_GRAPHICS_UTILS_H_
     78