Question

我必须生成一个图像 < a href=" "http:// developmenter.apple.com/library/mac/#document/Graphicsimage/Reference/CoreImageFilterReference/Reference/Reference/ reference.html#//apple_ref/doc/filter/ci/CIRadialGradient" rel="nofollown norefererr", 和这里在CIRadialGradient苹果文档中找到的 :

"https://i.sstatic.net/UoH89.gif" alt="CIRadialGradient"/> https://i.sstatic.net/UoH89.gif" alt="CIRadial Gradient"/>

我尝试了很多方法,最后却说:

+(NSImage*)radialGradientWithR0:(float)r0 r1:(float)r1 c0:(NSColor*)c0 c1:(NSColor*)c1 imageDimensionPx:(int)imageDimension
{
    CIColor* cc0 = [[CIColor alloc]initWithColor:c0];
    CIColor* cc1 = [[CIColor alloc]initWithColor:c1];
    CIVector* civ = [CIVector vectorWithX:imageDimension/2 Y:imageDimension/2];

    CIFilter* filter = [CIFilter filterWithName:@"CIRadialGradient"];
    [filter setDefaults];
    [filter setValue:civ forKey:@"inputCenter"];
    [filter setValue:[NSNumber numberWithFloat:r0] forKey:@"inputRadius0"];
    [filter setValue:[NSNumber numberWithFloat:r0] forKey:@"inputRadius1"];
    [filter setValue:cc0 forKey:@"inputColor0"];
    [filter setValue:cc1 forKey:@"inputColor1"];

    CIImage* outputImage = [filter valueForKey:@"outputImage"];

    NSRect outputImageRect = NSRectFromCGRect([outputImage extent]);
    NSImage* blurredImage = [[NSImage alloc]
                             initWithSize:NSMakeSize(imageDimension,  imageDimension)];

    [blurredImage lockFocus];
    [blurredImage drawAtPoint:NSZeroPoint fromRect:NSMakeRect(0, 0, imageDimension, imageDimension) operation:NSCompositeSourceOver fraction:1.0];
    [blurredImage unlockFocus];

    return blurredImage;
}

但我只能得到一个空虚的图像。

帮帮我吧

谢谢谢谢

菲利克斯

Answer 1

您的代码中有一些错误, 阻止它工作 :

typo in the arguments: r1 is not used in the second call

您需要更改第二行:

 [filter setValue:[NSNumber numberWithFloat:r0] forKey:@"inputRadius0"];
 [filter setValue:[NSNumber numberWithFloat:r0] forKey:@"inputRadius1"];

您不需要这个 : NSRect 输出图像矩形 = NSRectfromCGRect ([产出范围]);
[blurredImaage lockFocus]; 之后是 [blurredImaage drawAtpoint: 基本上意指类似的东西: 自己绘制图像。您的意思是: [utimage drawAtpoint:.]

以下是一个方法, 做你想做的事 :

-(NSImage *) radialGradientWithR0:(float)r0 r1:(float)r1 c0:(NSColor*)c0 c1:(NSColor*)c1 imageDimensionPx:(int)imageDimension {

    CIColor* cc0 = [[CIColor alloc]initWithColor:c0];
    CIColor* cc1 = [[CIColor alloc]initWithColor:c1];
    CIVector* civ = [CIVector vectorWithX:imageDimension/2 Y:imageDimension/2];

    CIFilter* filter = [CIFilter filterWithName:@"CIRadialGradient"];

    [filter setValue:civ forKey:@"inputCenter"];
    [filter setValue:[NSNumber numberWithFloat:r0] forKey:@"inputRadius0"];
    [filter setValue:[NSNumber numberWithFloat:r1] forKey:@"inputRadius1"];
    [filter setValue:cc0 forKey:@"inputColor0"];
    [filter setValue:cc1 forKey:@"inputColor1"];

    NSImage * res = [[NSImage alloc] initWithSize:NSMakeSize(imageDimension, imageDimension)];
    [res lockFocus];
    [[filter valueForKey:@"outputImage"]
     drawAtPoint:NSZeroPoint 
     fromRect:NSMakeRect(0, 0, imageDimension, imageDimension)                   
     operation:NSCompositeDestinationAtop  fraction:1.0];
    [res unlockFocus];
    return res;
}

"https://i.sstatic.net/Xr6Wt.png" alt="NSImage Wells 显示半径梯度"/ >

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