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// -*- mode:objc -*-
** DVREncoder.h
** Copyright 20101
** Author: George Nachman
** Project: iTerm2
** Description: Encodes screen images into a DVRBuffer. Implements
** a basic key-frame + differential encoding scheme.
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** GNU General Public License for more details.
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#import <Cocoa/Cocoa.h>
#import <DVRBuffer.h>
@interface DVREncoder : NSObject
// Underlying buffer to write to. Not owned by us.
DVRBuffer* buffer_;
// The last encoded frame.
NSMutableData* lastFrame_;
// Info from the last frame.
DVRFrameInfo lastInfo_;
// Number of frames. Used to ensure key frames are encoded every so often.
int count_;
// Used to ensure that reserve is called before appendFrame.
BOOL haveReservation_;
// Used to ensure a key frame is encoded before the circular buffer wraps.
long long bytesSinceLastKeyFrame_;
// Number of bytes reserved.
int reservation_;
- (id)initWithBuffer:(DVRBuffer*)buffer;
- (void)dealloc;
// Encoded a frame into the DVRBuffer. Call -[reserve:] first.
// buffer: points to an array of screen_char_t described by info.
// length: number of bytes (not elements) in buffer.
// info: screen state.
- (void)appendFrame:(char*)buffer length:(int)length info:(DVRFrameInfo*)info;
// Allocate some number of bytes for an upcoming appendFrame call.
// Returns true if some frames were freed to make room. The caller should
// invalidate nonexistent leading frames in all decoders.
- (BOOL)reserve:(int)length;
@interface DVREncoder (Private)
// Save a key frame into DVRBuffer.
- (void)_appendKeyFrame:(char*)buffer length:(int)length info:(DVRFrameInfo*)info;
// Save a diff frame into DVRBuffer.
- (void)_appendDiffFrame:(char*)buffer length:(int)length info:(DVRFrameInfo*)info;
// Save a frame into DVRBuffer.
- (void)_appendFrameImpl:(char*)buffer length:(int)length type:(DVRFrameType)type info:(DVRFrameInfo*)info;
// Calculate the diff between buffer,length and the previous frame. Saves results into
// scratch. Won't use more than maxSize bytes in scratch. Returns number of bytes used or
// -1 if the diff was larger than maxSize.
- (int)_computeDiff:(char*)buffer length:(int)length dest:(char*)scratch maxSize:(int)maxSize;