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//
// UKFadedDrawing.m
// UKFadedDrawing
//
// Created by Uli Kusterer on 08.05.08.
// Copyright 2008 Uli Kusterer.
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would be
// appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
// distribution.
//

#import "UKFadedDrawing.h"



void UKSetUpOpposingFades( NSRect box, float startFadeDistance, float endFadeDistance, BOOL horzNotVert )
{
float distanceToGo = horzNotVert ? box.size.width : box.size.height;
NSMutableData* maskData = [NSMutableData dataWithLength: distanceToGo * sizeof(float)];
float* currPixel = (float*) [maskData mutableBytes];
if( distanceToGo < (startFadeDistance + endFadeDistance) )
startFadeDistance = endFadeDistance = distanceToGo / 2;

int x = 0;
for( ; x < startFadeDistance; x++ )
currPixel[x] = ((float)x) / startFadeDistance;

int startOfEndFade = distanceToGo -endFadeDistance;
for( ; (x < startOfEndFade) && (x < distanceToGo); x++ )
currPixel[x] = 1.0;

for( ; x < distanceToGo; x++ )
currPixel[x] = ((float) endFadeDistance -(x -startOfEndFade)) / endFadeDistance;

CGContextRef ctx = [[NSGraphicsContext currentContext] graphicsPort];
CGContextSaveGState( ctx );
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
CGDataProviderRef dataProvider = CGDataProviderCreateWithCFData( (CFDataRef) maskData );

float width = horzNotVert ? distanceToGo : 1,
height = horzNotVert ? 1 : distanceToGo;

CGImageRef maskImage = CGImageCreate( width, height, sizeof(float) * 8, sizeof(float) * 8,
width * sizeof(float), colorSpace,
kCGBitmapFloatComponents | kCGBitmapByteOrder32Host, dataProvider, NULL, true,
kCGRenderingIntentDefault );
CGContextClipToMask( ctx, *((CGRect*)&box), maskImage );

CGDataProviderRelease( dataProvider );
CGColorSpaceRelease( colorSpace );
CGImageRelease( maskImage );
}


void UKTearDownFades()
{
CGContextRef ctx = [[NSGraphicsContext currentContext] graphicsPort];
CGContextRestoreGState( ctx );
}

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