/*

    File:       ShadeRect.c

    Version:    1.0

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                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

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                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

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                IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR

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    Copyright © 2002 Apple Computer, Inc., All Rights Reserved

*/

#include <Carbon/Carbon.h>

#include "ShadeRect.h"

// -----------------------------------------------------------------------------

//  types

// -----------------------------------------------------------------------------

//

typedef struct

{

    float   start;

    float   range;

} ShadeData;

typedef struct

{

    CGRGB   start;

    CGRGB   range;

} ColorShadeData;

// -----------------------------------------------------------------------------

//  prototypes

// -----------------------------------------------------------------------------

//

void GrayscaleGradientEvaluate(

    void*               info,

    const float*        in,

    float*              out );

void ColorGradientEvaluate(

    void*               info,

    const float*        in,

    float*              out );

// -----------------------------------------------------------------------------

//  GrayscaleGradientEvaluate

// -----------------------------------------------------------------------------

//

void GrayscaleGradientEvaluate(

    void*               inInfo,

    const float*        in,

    float*              out )

{

    ShadeData*          data = (ShadeData*) inInfo;

    out[ 0 ] = out[ 1 ] = out[ 2 ] = data->start + in[ 0 ] * data->range;

    // always 100% alpha  CGShading alpha isn't working in Jaguar right now

    // anyway, so if it does start working, the behavior won't change.

    out[ 3 ] = 1;

}

// -----------------------------------------------------------------------------

//  ShadeRect

// -----------------------------------------------------------------------------

//

OSStatus ShadeRect(

    float               inStartShade,

    float               inEndShade,

    const HIRect*       inRect,

    CGContextRef        inContext )

{

    OSStatus            err = noErr;

    CGColorSpaceRef     colorSpace;

    CGFunctionCallbacks callbacks = { 0, GrayscaleGradientEvaluate, NULL };

    CGFunctionRef       function;

    CGShadingRef        shading;

    ShadeData           data;

    // Warning: this stuff is sitting on the stack.  Be careful if you move

    // the shading code around.

    data.start = inStartShade;

    data.range = inEndShade - inStartShade;

    CGContextSaveGState( inContext );

    CGContextClipToRect( inContext, *inRect );

    colorSpace = CGColorSpaceCreateDeviceRGB();

    require_action( colorSpace != NULL, CantCreateColorSpace, err = memFullErr );

    function = CGFunctionCreate(

            &data,          // info

            1,              // domainDimension

            NULL,           // input domain NULL == no range clipping

            4,              // rangeDimension,

            NULL,           // output domain NULL == no range clipping

            &callbacks );   // CGFunctionCallbacks

    require_action( function != NULL, CantCreateFunction, err = memFullErr );

    shading = CGShadingCreateAxial(

            colorSpace,

            inRect->origin, // start

            CGPointMake( CGRectGetMinX( *inRect ), CGRectGetMaxY( *inRect ) ),  // end

            function,

            false,          // extendStart

            false );        // extendEnd

    require_action( colorSpace != NULL, CantCreateShading, err = memFullErr );

    CGContextDrawShading( inContext, shading);

CantCreateFunction:

    CGShadingRelease( shading );

CantCreateShading:

    CGColorSpaceRelease( colorSpace );

CantCreateColorSpace:

    CGContextRestoreGState( inContext );

    return err;

}

// -----------------------------------------------------------------------------

//  ColorGradientEvaluate

// -----------------------------------------------------------------------------

//

void ColorGradientEvaluate(

    void*               inInfo,

    const float*        in,

    float*              out )

{

    ColorShadeData*     data = (ColorShadeData*) inInfo;

    out[ 0 ] = data->start.red + in[ 0 ] * data->range.red;

    out[ 1 ] = data->start.green + in[ 0 ] * data->range.green;

    out[ 2 ] = data->start.blue + in[ 0 ] * data->range.blue;

    // always 100% alpha  CGShading alpha isn't working in Jaguar right now

    // anyway, so if it does start working, the behavior won't change.

    out[ 3 ] = 1;

}

// -----------------------------------------------------------------------------

//  ShadeRectColor

// -----------------------------------------------------------------------------

//

OSStatus ShadeRectColor(

    const CGRGB*        inStartColor,

    const CGRGB*        inEndColor,

    const HIRect*       inRect,

    CGContextRef        inContext )

{

    OSStatus            err = noErr;

    CGColorSpaceRef     colorSpace;

    CGFunctionCallbacks callbacks = { 0, ColorGradientEvaluate, NULL };

    CGFunctionRef       function;

    CGShadingRef        shading;

    ColorShadeData      data;

    // Warning: this stuff is sitting on the stack.  Be careful if you move

    // the shading code around.

    data.start = *inStartColor;

    data.range.red = inEndColor->red - inStartColor->red;

    data.range.green = inEndColor->green - inStartColor->green;

    data.range.blue = inEndColor->blue - inStartColor->blue;

    CGContextSaveGState( inContext );

    CGContextClipToRect( inContext, *inRect );

    colorSpace = CGColorSpaceCreateDeviceRGB();

    require_action( colorSpace != NULL, CantCreateColorSpace, err = memFullErr );

    function = CGFunctionCreate(

            &data,          // info

            1,              // domainDimension

            NULL,           // input domain NULL == no range clipping

            4,              // rangeDimension,

            NULL,           // output domain NULL == no range clipping

            &callbacks );   // CGFunctionCallbacks

    require_action( function != NULL, CantCreateFunction, err = memFullErr );

    shading = CGShadingCreateAxial(

            colorSpace,

            inRect->origin, // start

            CGPointMake( CGRectGetMinX( *inRect ), CGRectGetMaxY( *inRect ) ),  // end

            function,

            false,          // extendStart

            false );        // extendEnd

    require_action( colorSpace != NULL, CantCreateShading, err = memFullErr );

    CGContextDrawShading( inContext, shading);

CantCreateFunction:

    CGShadingRelease( shading );

CantCreateShading:

    CGColorSpaceRelease( colorSpace );

CantCreateColorSpace:

    CGContextRestoreGState( inContext );

    return err;

}