/*

File: Stage4.c

Abstract: The forth stage of the sample code.

Version: <1.0>

© Copyright 2005 Apple Computer, Inc. All rights reserved.

IMPORTANT: This Apple software is supplied to

you by Apple Computer, Inc. ("Apple") in

consideration of your agreement to the following

terms, and your use, installation, modification

or redistribution of this Apple software

constitutes acceptance of these terms. If you do

not agree with these terms, please do not use,

install, modify or redistribute this Apple

software.

In consideration of your agreement to abide by

the following terms, and subject to these terms,

Apple grants you a personal, non-exclusive

license, under Apple's copyrights in this

original Apple software (the "Apple Software"),

to use, reproduce, modify and redistribute the

Apple Software, with or without modifications, in

source and/or binary forms; provided that if you

redistribute the Apple Software in its entirety

and without modifications, you must retain this

notice and the following text and disclaimers in

all such redistributions of the Apple Software.

Neither the name, trademarks, service marks or

logos of Apple Computer, Inc. may be used to

endorse or promote products derived from the

Apple Software without specific prior written

permission from Apple. Except as expressly

stated in this notice, no other rights or

licenses, express or implied, are granted by

Apple herein, including but not limited to any

patent rights that may be infringed by your

derivative works or by other works in which the

Apple Software may be incorporated.

The Apple Software is provided by Apple on an "AS

IS" basis. APPLE MAKES NO WARRANTIES, EXPRESS OR

IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED

WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY

AND FITNESS FOR A PARTICULAR PURPOSE, REGARDING

THE APPLE SOFTWARE OR ITS USE AND OPERATION ALONE

OR IN COMBINATION WITH YOUR PRODUCTS.

IN NO EVENT SHALL APPLE BE LIABLE FOR ANY

SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL

DAMAGES (INCLUDING, BUT NOT LIMITED TO,

PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS

OF USE, DATA, OR PROFITS; OR BUSINESS

INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE,

REPRODUCTION, MODIFICATION AND/OR DISTRIBUTION OF

THE APPLE SOFTWARE, HOWEVER CAUSED AND WHETHER

UNDER THEORY OF CONTRACT, TORT (INCLUDING

NEGLIGENCE), STRICT LIABILITY OR OTHERWISE, EVEN

IF APPLE HAS BEEN ADVISED OF THE POSSIBILITY OF

SUCH DAMAGE.

*/

#include "Stages.h"

//

// Stage 4 - Draw a 2K by 2K source image to an offscreen 512 x 512 CG Layer,

// effectively caching the original image. The test measures how fast drawing

// the cached layer takes. The cache alleviates the time taken to color match the

// image and also time required to downsample the image.

// This cache technique is useful when the image has to be repeatedly draw at the

// same scale. The difference between this test the previous is that the previous

// performed the caching using a bitmap context. This one caches using a CGLayerRef.

// Notice that we don't need to know the colorspace or destination context's device

// specific information when creating a CG Layer.

// The source image is created programattically as a gradient between colors.

// Returns: the number of operations per second for this stage

//

float drawStage4(CGContextRef context, CGRect rect)

{

size_t numOperations;

CGImageRef image;

double delta;

int i;

unsigned char *data;

CGLayerRef lyr;

CGContextRef lyrContext;

data = createGradientARGBBuffer(W, H);

if (data == NULL) return 0;

// Create the source image from the data provider

image = createImage(W, H, data);

// Create a layer from the destination context. The layer is the best representation

// for the layer. We have to specify the size of the layer we want to create

// in default userspace units.

lyr = CGLayerCreateWithContext(context,CGSizeMake(ScaledToWidth,ScaledToHeight),NULL);

// Now we want to draw in to layer, so get the CGContext for the layer to draw to

lyrContext = CGLayerGetContext(lyr);

// Draw the 3K x 3K source image once to the layer context

CGContextDrawImage(lyrContext, CGRectMake(0,0,ScaledToWidth,ScaledToHeight), image);

CFRelease(image); // Done with the image - now cached in the layer ref

free(data); // free the source data

// Perform the drawing operation once to get an rough idea of how long it will take

delta = currentTime();

// Draw the contents of the layer to the destination

CGContextDrawLayerAtPoint(context,CGPointMake(0,0),lyr);

delta = currentTime() - delta;

// Calculate the approximage number of operations needed in one second

numOperations = SecsPerTest / delta;

// Now run the test again repeatedly

delta = currentTime();

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

// Draw the contents of the layer to the destination

CGContextDrawLayerAtPoint(context,CGPointMake(0,0),lyr);

}

delta = currentTime() - delta;

CFRelease(lyr); // done with the layer ref

return (numOperations / delta);

}