/*
* Copyright 2006 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkStream_DEFINED
#define SkStream_DEFINED
#include "SkRefCnt.h"
#include "SkScalar.h"
class SkData;
class SkStream;
class SkStreamRewindable;
class SkStreamSeekable;
class SkStreamAsset;
class SkStreamMemory;
/**
* SkStream -- abstraction for a source of bytes. Subclasses can be backed by
* memory, or a file, or something else.
*
* NOTE:
*
* Classic "streams" APIs are sort of async, in that on a request for N
* bytes, they may return fewer than N bytes on a given call, in which case
* the caller can "try again" to get more bytes, eventually (modulo an error)
* receiving their total N bytes.
*
* Skia streams behave differently. They are effectively synchronous, and will
* always return all N bytes of the request if possible. If they return fewer
* (the read() call returns the number of bytes read) then that means there is
* no more data (at EOF or hit an error). The caller should *not* call again
* in hopes of fulfilling more of the request.
*/
class SK_API SkStream : public SkNoncopyable {
public:
virtual ~SkStream() {}
/**
* Attempts to open the specified file, and return a stream to it (using
* mmap if available). On success, the caller is responsible for deleting.
* On failure, returns NULL.
*/
static SkStreamAsset* NewFromFile(const char path[]);
/** Reads or skips size number of bytes.
* If buffer == NULL, skip size bytes, return how many were skipped.
* If buffer != NULL, copy size bytes into buffer, return how many were copied.
* @param buffer when NULL skip size bytes, otherwise copy size bytes into buffer
* @param size the number of bytes to skip or copy
* @return the number of bytes actually read.
*/
virtual size_t read(void* buffer, size_t size) = 0;
/** Skip size number of bytes.
* @return the actual number bytes that could be skipped.
*/
size_t skip(size_t size) {
return this->read(NULL, size);
}
/**
* Attempt to peek at size bytes.
* If this stream supports peeking, copy min(size, peekable bytes) into
* buffer, and return the number of bytes copied.
* If the stream does not support peeking, or cannot peek any bytes,
* return 0 and leave buffer unchanged.
* The stream is guaranteed to be in the same visible state after this
* call, regardless of success or failure.
* @param buffer Must not be NULL, and must be at least size bytes. Destination
* to copy bytes.
* @param size Number of bytes to copy.
* @return The number of bytes peeked/copied.
*/
virtual size_t peek(void* /*buffer*/, size_t /*size*/) const { return 0; }
/** Returns true when all the bytes in the stream have been read.
* This may return true early (when there are no more bytes to be read)
* or late (after the first unsuccessful read).
*/
virtual bool isAtEnd() const = 0;
int8_t readS8();
int16_t readS16();
int32_t readS32();
uint8_t readU8() { return (uint8_t)this->readS8(); }
uint16_t readU16() { return (uint16_t)this->readS16(); }
uint32_t readU32() { return (uint32_t)this->readS32(); }
bool readBool() { return this->readU8() != 0; }
SkScalar readScalar();
size_t readPackedUInt();
//SkStreamRewindable
/** Rewinds to the beginning of the stream. Returns true if the stream is known
* to be at the beginning after this call returns.
*/
virtual bool rewind() { return false; }
/** Duplicates this stream. If this cannot be done, returns NULL.
* The returned stream will be positioned at the beginning of its data.
*/
virtual SkStreamRewindable* duplicate() const { return NULL; }
//SkStreamSeekable
/** Returns true if this stream can report it's current position. */
virtual bool hasPosition() const { return false; }
/** Returns the current position in the stream. If this cannot be done, returns 0. */
virtual size_t getPosition() const { return 0; }
/** Seeks to an absolute position in the stream. If this cannot be done, returns false.
* If an attempt is made to seek past the end of the stream, the position will be set
* to the end of the stream.
*/
virtual bool seek(size_t /*position*/) { return false; }
/** Seeks to an relative offset in the stream. If this cannot be done, returns false.
* If an attempt is made to move to a position outside the stream, the position will be set
* to the closest point within the stream (beginning or end).
*/
virtual bool move(long /*offset*/) { return false; }
/** Duplicates this stream. If this cannot be done, returns NULL.
* The returned stream will be positioned the same as this stream.
*/
virtual SkStreamSeekable* fork() const { return NULL; }
//SkStreamAsset
/** Returns true if this stream can report it's total length. */
virtual bool hasLength() const { return false; }
/** Returns the total length of the stream. If this cannot be done, returns 0. */
virtual size_t getLength() const { return 0; }
//SkStreamMemory
/** Returns the starting address for the data. If this cannot be done, returns NULL. */
//TODO: replace with virtual const SkData* getData()
virtual const void* getMemoryBase() { return NULL; }
};
/** SkStreamRewindable is a SkStream for which rewind and duplicate are required. */
class SK_API SkStreamRewindable : public SkStream {
public:
bool rewind() override = 0;
SkStreamRewindable* duplicate() const override = 0;
};
/** SkStreamSeekable is a SkStreamRewindable for which position, seek, move, and fork are required. */
class SK_API SkStreamSeekable : public SkStreamRewindable {
public:
SkStreamSeekable* duplicate() const override = 0;
bool hasPosition() const override { return true; }
size_t getPosition() const override = 0;
bool seek(size_t position) override = 0;
bool move(long offset) override = 0;
SkStreamSeekable* fork() const override = 0;
};
/** SkStreamAsset is a SkStreamSeekable for which getLength is required. */
class SK_API SkStreamAsset : public SkStreamSeekable {
public:
SkStreamAsset* duplicate() const override = 0;
SkStreamAsset* fork() const override = 0;
bool hasLength() const override { return true; }
size_t getLength() const override = 0;
};
/** SkStreamMemory is a SkStreamAsset for which getMemoryBase is required. */
class SK_API SkStreamMemory : public SkStreamAsset {
public:
SkStreamMemory* duplicate() const override = 0;
SkStreamMemory* fork() const override = 0;
const void* getMemoryBase() override = 0;
};
class SK_API SkWStream : SkNoncopyable {
public:
virtual ~SkWStream();
/** Called to write bytes to a SkWStream. Returns true on success
@param buffer the address of at least size bytes to be written to the stream
@param size The number of bytes in buffer to write to the stream
@return true on success
*/
virtual bool write(const void* buffer, size_t size) = 0;
virtual void newline();
virtual void flush();
virtual size_t bytesWritten() const = 0;
// helpers
bool write8(U8CPU);
bool write16(U16CPU);
bool write32(uint32_t);
bool writeText(const char text[]);
bool writeDecAsText(int32_t);
bool writeBigDecAsText(int64_t, int minDigits = 0);
bool writeHexAsText(uint32_t, int minDigits = 0);
bool writeScalarAsText(SkScalar);
bool writeBool(bool v) { return this->write8(v); }
bool writeScalar(SkScalar);
bool writePackedUInt(size_t);
bool writeStream(SkStream* input, size_t length);
/**
* This returns the number of bytes in the stream required to store
* 'value'.
*/
static int SizeOfPackedUInt(size_t value);
};
////////////////////////////////////////////////////////////////////////////////////////
#include "SkString.h"
#include <stdio.h>
/** A stream that wraps a C FILE* file stream. */
class SK_API SkFILEStream : public SkStreamAsset {
public:
/** Initialize the stream by calling sk_fopen on the specified path.
* This internal stream will be closed in the destructor.
*/
explicit SkFILEStream(const char path[] = NULL);
enum Ownership {
kCallerPasses_Ownership,
kCallerRetains_Ownership
};
/** Initialize the stream with an existing C file stream.
* While this stream exists, it assumes exclusive access to the C file stream.
* The C file stream will be closed in the destructor unless the caller specifies
* kCallerRetains_Ownership.
*/
explicit SkFILEStream(FILE* file, Ownership ownership = kCallerPasses_Ownership);
virtual ~SkFILEStream();
/** Returns true if the current path could be opened. */
bool isValid() const { return fFILE != NULL; }
/** Close the current file, and open a new file with the specified path.
* If path is NULL, just close the current file.
*/
void setPath(const char path[]);
size_t read(void* buffer, size_t size) override;
bool isAtEnd() const override;
bool rewind() override;
SkStreamAsset* duplicate() const override;
size_t getPosition() const override;
bool seek(size_t position) override;
bool move(long offset) override;
SkStreamAsset* fork() const override;
size_t getLength() const override;
const void* getMemoryBase() override;
private:
FILE* fFILE;
SkString fName;
Ownership fOwnership;
// fData is lazilly initialized when needed.
mutable SkAutoTUnref<SkData> fData;
typedef SkStreamAsset INHERITED;
};
class SK_API SkMemoryStream : public SkStreamMemory {
public:
SkMemoryStream();
/** We allocate (and free) the memory. Write to it via getMemoryBase() */
SkMemoryStream(size_t length);
/** If copyData is true, the stream makes a private copy of the data. */
SkMemoryStream(const void* data, size_t length, bool copyData = false);
/** Use the specified data as the memory for this stream.
* The stream will call ref() on the data (assuming it is not NULL).
*/
SkMemoryStream(SkData*);
virtual ~SkMemoryStream();
/** Resets the stream to the specified data and length,
just like the constructor.
if copyData is true, the stream makes a private copy of the data
*/
virtual void setMemory(const void* data, size_t length,
bool copyData = false);
/** Replace any memory buffer with the specified buffer. The caller
must have allocated data with sk_malloc or sk_realloc, since it
will be freed with sk_free.
*/
void setMemoryOwned(const void* data, size_t length);
/** Return the stream's data in a SkData.
* The caller must call unref() when it is finished using the data.
*/
SkData* copyToData() const;
/**
* Use the specified data as the memory for this stream.
* The stream will call ref() on the data (assuming it is not NULL).
* The function returns the data parameter as a convenience.
*/
SkData* setData(SkData*);
void skipToAlign4();
const void* getAtPos();
size_t read(void* buffer, size_t size) override;
bool isAtEnd() const override;
size_t peek(void* buffer, size_t size) const override;
bool rewind() override;
SkMemoryStream* duplicate() const override;
size_t getPosition() const override;
bool seek(size_t position) override;
bool move(long offset) override;
SkMemoryStream* fork() const override;
size_t getLength() const override;
const void* getMemoryBase() override;
private:
SkData* fData;
size_t fOffset;
typedef SkStreamMemory INHERITED;
};
/////////////////////////////////////////////////////////////////////////////////////////////
class SK_API SkFILEWStream : public SkWStream {
public:
SkFILEWStream(const char path[]);
virtual ~SkFILEWStream();
/** Returns true if the current path could be opened.
*/
bool isValid() const { return fFILE != NULL; }
bool write(const void* buffer, size_t size) override;
void flush() override;
void fsync();
size_t bytesWritten() const override;
private:
FILE* fFILE;
typedef SkWStream INHERITED;
};
class SkMemoryWStream : public SkWStream {
public:
SkMemoryWStream(void* buffer, size_t size);
bool write(const void* buffer, size_t size) override;
size_t bytesWritten() const override { return fBytesWritten; }
private:
char* fBuffer;
size_t fMaxLength;
size_t fBytesWritten;
typedef SkWStream INHERITED;
};
class SK_API SkDynamicMemoryWStream : public SkWStream {
public:
SkDynamicMemoryWStream();
virtual ~SkDynamicMemoryWStream();
bool write(const void* buffer, size_t size) override;
size_t bytesWritten() const override { return fBytesWritten; }
// random access write
// modifies stream and returns true if offset + size is less than or equal to getOffset()
bool write(const void* buffer, size_t offset, size_t size);
bool read(void* buffer, size_t offset, size_t size);
size_t getOffset() const { return fBytesWritten; }
// copy what has been written to the stream into dst
void copyTo(void* dst) const;
void writeToStream(SkWStream* dst) const;
/**
* Return a copy of the data written so far. This call is responsible for
* calling unref() when they are finished with the data.
*/
SkData* copyToData() const;
/** Reset, returning a reader stream with the current content. */
SkStreamAsset* detachAsStream();
/** Reset the stream to its original, empty, state. */
void reset();
void padToAlign4();
private:
struct Block;
Block* fHead;
Block* fTail;
size_t fBytesWritten;
mutable SkData* fCopy; // is invalidated if we write after it is created
void invalidateCopy();
// For access to the Block type.
friend class SkBlockMemoryStream;
friend class SkBlockMemoryRefCnt;
typedef SkWStream INHERITED;
};
class SK_API SkDebugWStream : public SkWStream {
public:
SkDebugWStream() : fBytesWritten(0) {}
// overrides
bool write(const void* buffer, size_t size) override;
void newline() override;
size_t bytesWritten() const override { return fBytesWritten; }
private:
size_t fBytesWritten;
typedef SkWStream INHERITED;
};
// for now
typedef SkFILEStream SkURLStream;
#endif