Skia
2DGraphicsLibrary
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SkStream – abstraction for a source of bytes. More...
#include <SkStream.h>
Public Member Functions | |
virtual size_t | read (void *buffer, size_t size)=0 |
Reads or skips size number of bytes. More... | |
size_t | skip (size_t size) |
Skip size number of bytes. More... | |
virtual size_t | peek (void *, size_t) const |
Attempt to peek at size bytes. More... | |
virtual bool | isAtEnd () const =0 |
Returns true when all the bytes in the stream have been read. More... | |
int8_t | readS8 () |
int16_t | readS16 () |
int32_t | readS32 () |
uint8_t | readU8 () |
uint16_t | readU16 () |
uint32_t | readU32 () |
bool | readBool () |
SkScalar | readScalar () |
size_t | readPackedUInt () |
virtual bool | rewind () |
Rewinds to the beginning of the stream. More... | |
virtual SkStreamRewindable * | duplicate () const |
Duplicates this stream. More... | |
virtual bool | hasPosition () const |
Returns true if this stream can report it's current position. More... | |
virtual size_t | getPosition () const |
Returns the current position in the stream. More... | |
virtual bool | seek (size_t) |
Seeks to an absolute position in the stream. More... | |
virtual bool | move (long) |
Seeks to an relative offset in the stream. More... | |
virtual SkStreamSeekable * | fork () const |
Duplicates this stream. More... | |
virtual bool | hasLength () const |
Returns true if this stream can report it's total length. More... | |
virtual size_t | getLength () const |
Returns the total length of the stream. More... | |
virtual const void * | getMemoryBase () |
Returns the starting address for the data. More... | |
Static Public Member Functions | |
static std::unique_ptr < SkStreamAsset > | MakeFromFile (const char path[]) |
Attempts to open the specified file as a stream, returns nullptr on failure. | |
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.
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inlinevirtual |
Duplicates this stream.
If this cannot be done, returns NULL. The returned stream will be positioned at the beginning of its data.
Reimplemented in SkMemoryStream, SkFILEStream, SkStreamMemory, SkStreamAsset, SkStreamSeekable, and SkStreamRewindable.
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inlinevirtual |
Duplicates this stream.
If this cannot be done, returns NULL. The returned stream will be positioned the same as this stream.
Reimplemented in SkMemoryStream, SkFILEStream, SkStreamMemory, SkStreamAsset, and SkStreamSeekable.
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inlinevirtual |
Returns the total length of the stream.
If this cannot be done, returns 0.
Reimplemented in SkMemoryStream, SkFILEStream, and SkStreamAsset.
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inlinevirtual |
Returns the starting address for the data.
If this cannot be done, returns NULL.
Reimplemented in SkMemoryStream, and SkStreamMemory.
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inlinevirtual |
Returns the current position in the stream.
If this cannot be done, returns 0.
Reimplemented in SkMemoryStream, SkFILEStream, and SkStreamSeekable.
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inlinevirtual |
Returns true if this stream can report it's total length.
Reimplemented in SkStreamAsset.
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inlinevirtual |
Returns true if this stream can report it's current position.
Reimplemented in SkStreamSeekable.
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pure virtual |
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).
Implemented in SkMemoryStream, and SkFILEStream.
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inlinevirtual |
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).
Reimplemented in SkMemoryStream, SkFILEStream, and SkStreamSeekable.
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inlinevirtual |
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.
buffer | Must not be NULL, and must be at least size bytes. Destination to copy bytes. |
size | Number of bytes to copy. |
Reimplemented in SkMemoryStream.
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pure virtual |
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.
buffer | when NULL skip size bytes, otherwise copy size bytes into buffer |
size | the number of bytes to skip or copy |
Implemented in SkMemoryStream, and SkFILEStream.
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inlinevirtual |
Rewinds to the beginning of the stream.
Returns true if the stream is known to be at the beginning after this call returns.
Reimplemented in SkMemoryStream, SkFILEStream, and SkStreamRewindable.
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inlinevirtual |
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.
Reimplemented in SkMemoryStream, SkFILEStream, and SkStreamSeekable.
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inline |
Skip size number of bytes.