复合颜色：iPhone 上的 CALayer 和混合模式

发布于 2024-08-09 09:58:19 字数 1020 浏览 3 评论 0原文

我正在尝试在 iPhone 上使用核心图像。我可以使用石英合成颜色来绘制 uiview，但我想将每个组件分离到 CALayer 中（UIview 消耗更多资源）。

所以我有一个白色蒙版，我想用它来过滤背景位图，并且我想尝试不同的混合模式。不幸的是，这些图层只是“添加”它们的颜色。

这是我的代码：

@implementation WhiteLayerHelper

    - (void)drawLayer:(CALayer *)theLayer
            inContext:(CGContextRef)myContext
    {
        // draw a white overlay, with special blending and alpha values, so that the saturation can be animated
        CGContextSetBlendMode(myContext,kCGBlendModeSaturation);
        CGContextSetRGBFillColor(myContext,1.0,1.0,1.0,0.9);
        CGContextFillRect(myContext,[UIScreen mainScreen].bounds);

    }

@end

这是主视图 drawrect 代码，我在其中使用 CALayer：

- (void)drawRect:(CGRect)rect {
    //get the drawing context
    CGContextRef myContext = UIGraphicsGetCurrentContext();
    // draw the background
    [self fillContext:myContext withBounds:m_overlayRect withImage:m_currentImage];
    [whiteLayer renderInContext:myContext];

}

有什么问题吗？

原文

I'm trying to use core image on the iphone. I'm able to composite my colors using quartz to draw an uiview, but I want to separate each component into CALayer (UIview consume more resources).

So I have a white mask I want to use to filter a background bitmap, and I want to try different blending mode. Unfortunately, the layers are only "adding" their colors.

Here is my code:

@implementation WhiteLayerHelper

    - (void)drawLayer:(CALayer *)theLayer
            inContext:(CGContextRef)myContext
    {
        // draw a white overlay, with special blending and alpha values, so that the saturation can be animated
        CGContextSetBlendMode(myContext,kCGBlendModeSaturation);
        CGContextSetRGBFillColor(myContext,1.0,1.0,1.0,0.9);
        CGContextFillRect(myContext,[UIScreen mainScreen].bounds);

    }

@end

And here is the main view drawrect code, where I use my CALayer:

- (void)drawRect:(CGRect)rect {
    //get the drawing context
    CGContextRef myContext = UIGraphicsGetCurrentContext();
    // draw the background
    [self fillContext:myContext withBounds:m_overlayRect withImage:m_currentImage];
    [whiteLayer renderInContext:myContext];

}

Is there something wrong?

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送舟行 2024-08-16 09:58:19

我设法通过将多个 CALayer 直接绘制到 UIView 的图形上下文中来获得合成多个 CALayer 的效果。

-(void)drawRect:(CGRect)rect {
 CGContextRef c = UIGraphicsGetCurrentContext();
 CGContextSetBlendMode(c, kCGBlendModeDifference);
 [myLayer drawInContext:c];
}

顺便说一句，我没有将图层添加为视图图层的子图层（也就是说，我从未调用过 [myView.layer addSublayer:myLayer]）

I managed to get the affect of compositing multiple CALayers by drawing them directly into a UIView's graphics context.

-(void)drawRect:(CGRect)rect {
 CGContextRef c = UIGraphicsGetCurrentContext();
 CGContextSetBlendMode(c, kCGBlendModeDifference);
 [myLayer drawInContext:c];
}

BTW, I did not add the layers as sublayers of the view's layer (that is I never called [myView.layer addSublayer:myLayer])

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