/*

File: FrameReader.m

Abstract: Implements the FrameReader class.

Version: 1.0

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Inc. may be used to endorse or promote products derived from the Apple

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as expressly stated in this notice, no other rights or licenses, express

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MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS

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Copyright © 2005 Apple Computer, Inc., All Rights Reserved

*/

#import <OpenGL/CGLMacro.h>

#import "FrameReader.h"

@implementation FrameReader

- (id) init

{

    //Make sure client goes through designated initializer

    [self doesNotRecognizeSelector:_cmd];

    return nil;

}

- (id) initWithOpenGLContext:(NSOpenGLContext*)context pixelsWide:(unsigned)width pixelsHigh:(unsigned)height asynchronousFetching:(BOOL)asynchronous

{

    //IMPORTANT: We use the macros provided by <OpenGL/CGLMacro.h> which provide better performances and allows us not to bother with making sure the current context is valid

    CGLContextObj                   cgl_ctx = [context CGLContextObj];

    GLint                           save1,

                                    save2,

                                    save3,

                                    save4;

    CVReturn                        theError;

    NSMutableDictionary*            attributes;

    //Check parameters

    if((context == nil) || ((width == 0) || (height == 0))) {

        [self release];

        return nil;

    }

    if(self = [super init]) {

        //Keep essential parameters around

        _glContext = [context retain];

        _width = width;

        _height = height;

        //Create memory buffers - Make sure the buffers are paged-aligned and rowbytes is a multiple of 64 for performance reasons

        _bufferRowBytes = (_width * 4 + 63) & ~63;

        if(asynchronous) {

            _frameBuffers[0] = valloc(_height * _bufferRowBytes);

            _frameBuffers[1] = valloc(_height * _bufferRowBytes);

        }

        else

        _frameBuffer = valloc(_height * _bufferRowBytes);

        if((asynchronous && (!_frameBuffers[0] || !_frameBuffers[1])) || (!asynchronous && !_frameBuffer)) {

            NSLog(@"Memory allocation failed");

            [self release];

            return nil;

        }

        //Create OpenGL textures - For extra safety, save & restore OpenGL states that are changed

        if(asynchronous) {

            //Create and configure first texture

            glGenTextures(1, &_textureNames[0]);

            glGetIntegerv(GL_TEXTURE_BINDING_RECTANGLE_EXT, &save1);

            glBindTexture(GL_TEXTURE_RECTANGLE_EXT, _textureNames[0]);

            glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_STORAGE_HINT_APPLE, GL_STORAGE_SHARED_APPLE);

            glGetIntegerv(GL_UNPACK_ALIGNMENT, &save2);

            glPixelStorei(GL_UNPACK_ALIGNMENT, 4);

            glGetIntegerv(GL_UNPACK_ROW_LENGTH, &save3);

            glPixelStorei(GL_UNPACK_ROW_LENGTH, _bufferRowBytes / 4);

            glGetIntegerv(GL_UNPACK_CLIENT_STORAGE_APPLE, &save4);

            glPixelStorei(GL_UNPACK_CLIENT_STORAGE_APPLE, GL_TRUE);

            glTexImage2D(GL_TEXTURE_RECTANGLE_EXT, 0, GL_RGBA, _width, _height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, _frameBuffers[0]);

            glPixelStorei(GL_UNPACK_CLIENT_STORAGE_APPLE, save4);

            glPixelStorei(GL_UNPACK_ROW_LENGTH, save3);

            glPixelStorei(GL_UNPACK_ALIGNMENT, save2);

            glBindTexture(GL_TEXTURE_RECTANGLE_EXT, save1);

            //Create and configure second texture

            glGenTextures(1, &_textureNames[1]);

            glGetIntegerv(GL_TEXTURE_BINDING_RECTANGLE_EXT, &save1);

            glBindTexture(GL_TEXTURE_RECTANGLE_EXT, _textureNames[1]);

            glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_STORAGE_HINT_APPLE, GL_STORAGE_SHARED_APPLE);

            glGetIntegerv(GL_UNPACK_ALIGNMENT, &save2);

            glPixelStorei(GL_UNPACK_ALIGNMENT, 4);

            glGetIntegerv(GL_UNPACK_ROW_LENGTH, &save3);

            glPixelStorei(GL_UNPACK_ROW_LENGTH, _bufferRowBytes / 4);

            glGetIntegerv(GL_UNPACK_CLIENT_STORAGE_APPLE, &save4);

            glPixelStorei(GL_UNPACK_CLIENT_STORAGE_APPLE, GL_TRUE);

            glTexImage2D(GL_TEXTURE_RECTANGLE_EXT, 0, GL_RGBA, _width, _height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, _frameBuffers[1]);

            glPixelStorei(GL_UNPACK_CLIENT_STORAGE_APPLE, save4);

            glPixelStorei(GL_UNPACK_ROW_LENGTH, save3);

            glPixelStorei(GL_UNPACK_ALIGNMENT, save2);

            glBindTexture(GL_TEXTURE_RECTANGLE_EXT, save1);

            //Check for OpenGL errors

            theError = glGetError();

            if(theError) {

                NSLog(@"OpenGL texture creation failed (error 0x%04X)", theError);

                [self release];

                return nil;

            }

        }

        //Create buffer pool

        attributes = [NSMutableDictionary dictionary];

        [attributes setObject:[NSNumber numberWithUnsignedInt:k32ARGBPixelFormat] forKey:(NSString*)kCVPixelBufferPixelFormatTypeKey];

        [attributes setObject:[NSNumber numberWithUnsignedInt:width] forKey:(NSString*)kCVPixelBufferWidthKey];

        [attributes setObject:[NSNumber numberWithUnsignedInt:height] forKey:(NSString*)kCVPixelBufferHeightKey];

        theError = CVPixelBufferPoolCreate(kCFAllocatorDefault, NULL, (CFDictionaryRef)attributes, &_bufferPool);

        if(theError) {

            NSLog(@"CVPixelBufferPoolCreate() failed with error %i", theError);

            [self release];

            return nil;

        }

        //If we use asynchronous fetching, we need to skip the first buffer which will contain undefined pixels

        _skipFirstBuffer = asynchronous;

    }

    return self;

}

- (void) dealloc

{

    //IMPORTANT: We use the macros provided by <OpenGL/CGLMacro.h> which provide better performances and allows us not to bother with making sure the current context is valid

    CGLContextObj                   cgl_ctx = [_glContext CGLContextObj];

    //Destroy resources

    if(_bufferPool)

    CVPixelBufferPoolRelease(_bufferPool);

    if(_frameBuffer)

    free(_frameBuffer);

    if(_frameBuffers[0])

    free(_frameBuffers[0]);

    if(_textureNames[0])

    glDeleteTextures(1, &_textureNames[0]);

    if(_frameBuffers[1])

    free(_frameBuffers[1]);

    if(_textureNames[1])

    glDeleteTextures(1, &_textureNames[1]);

    //Release context

    [_glContext release];

    [super dealloc];

}

- (CVPixelBufferRef) readFrame

{

    //IMPORTANT: We use the macros provided by <OpenGL/CGLMacro.h> which provide better performances and allows us not to bother with making sure the current context is valid

    CGLContextObj                   cgl_ctx = [_glContext CGLContextObj];

    GLint                           save1,

                                    save2,

                                    save3;

    unsigned char*                  src;

    unsigned char*                  dst;

    unsigned                        i;

    CVReturn                        theError;

    CVPixelBufferRef                pixelBuffer;

    unsigned char*                  baseAddress;

    unsigned                        rowbytes;

    //Get image from OpenGL context

    if(_frameBuffer) {

        //Read OpenGL context pixels directly

        glGetIntegerv(GL_PACK_ALIGNMENT, &save1);

        glPixelStorei(GL_PACK_ALIGNMENT, 4);

        glGetIntegerv(GL_PACK_ROW_LENGTH, &save2);

        glPixelStorei(GL_PACK_ROW_LENGTH, _bufferRowBytes / 4);

        glReadPixels(0, 0, _width, _height, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, _frameBuffer);

        glPixelStorei(GL_PACK_ROW_LENGTH, save2);

        glPixelStorei(GL_PACK_ALIGNMENT, save1);

    }

    else {

        //Copy OpenGL context pixels to non-current texture

        glGetIntegerv(GL_TEXTURE_BINDING_RECTANGLE_EXT, &save1);

        glBindTexture(GL_TEXTURE_RECTANGLE_EXT, _textureNames[1 - _currentTextureIndex]);

        glCopyTexSubImage2D(GL_TEXTURE_RECTANGLE_EXT, 0, 0, 0, 0, 0, _width, _height);

        //Read pixels from current texture

        glBindTexture(GL_TEXTURE_RECTANGLE_EXT, _textureNames[_currentTextureIndex]);

        glGetIntegerv(GL_PACK_ALIGNMENT, &save2);

        glPixelStorei(GL_PACK_ALIGNMENT, 4);

        glGetIntegerv(GL_PACK_ROW_LENGTH, &save3);

        glPixelStorei(GL_PACK_ROW_LENGTH, _bufferRowBytes / 4);

        glGetTexImage(GL_TEXTURE_RECTANGLE_EXT, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, _frameBuffers[_currentTextureIndex]);

        glPixelStorei(GL_PACK_ROW_LENGTH, save3);

        glPixelStorei(GL_PACK_ALIGNMENT, save2);

        glBindTexture(GL_TEXTURE_RECTANGLE_EXT, save1);

    }

    //Check for OpenGL errors

    theError = glGetError();

    if(theError) {

        NSLog(@"OpenGL pixels read failed (error 0x%04X)", theError);

        return NULL;

    }

    //Check if this image is valid

    if(_skipFirstBuffer) {

        _skipFirstBuffer = NO;

        return NULL;

    }

    //Get pixel buffer from pool

    theError = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, _bufferPool, &pixelBuffer);

    if(theError) {

        NSLog(@"CVPixelBufferPoolCreatePixelBuffer() failed with error %i", theError);

        return NULL;

    }

    //Lock pixel buffer bits

    theError = CVPixelBufferLockBaseAddress(pixelBuffer, 0);

    if(theError) {

        NSLog(@"CVPixelBufferLockBaseAddress() failed with error %i", theError);

        return NULL;

    }

    baseAddress = CVPixelBufferGetBaseAddress(pixelBuffer);

    rowbytes = CVPixelBufferGetBytesPerRow(pixelBuffer);

    //Copy image to pixel buffer vertically flipped - OpenGL copies pixels upside-down

    if(_frameBuffer) {

        for(i = 0; i < _height; ++i) {

            src = _frameBuffer + _bufferRowBytes * i;

            dst = baseAddress + rowbytes * (_height - 1 - i);

            bcopy(src, dst, _width * 4);

        }

    }

    else {

        for(i = 0; i < _height; ++i) {

            src = _frameBuffers[_currentTextureIndex] + _bufferRowBytes * i;

            dst = baseAddress + rowbytes * (_height - 1 - i);

            bcopy(src, dst, _width * 4);

        }

    }

    //Unlock pixel buffer

    CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);

    //Toggle current texture index if necesary

    if(!_frameBuffer)

    _currentTextureIndex = 1 - _currentTextureIndex;

    return (CVPixelBufferRef)[(id)pixelBuffer autorelease];

}

@end