如何平铺CALayer的内容？ [英] How to tile the contents of a CALayer?

问题描述

示例代码：

$ b $

我想在CALayer b

  self.background = [UIImage imageNamed：@Background.png]; 
 [documentDisplay.layer setContents：self.background.CGImage]; 
  

如果可以，我想避免子类化。

解决方案

您可以使用图案图片创建颜色，并将其设置为图层的背景颜色。

你需要将 CGImage 包装在 CGPattern 中，并创建一个 CGColor 从它。

  //回调CreateImagePattern。 
 static void drawPatternImage（void * info，CGContextRef ctx）
 {
 CGImageRef image =（CGImageRef）info; 
 CGContextDrawImage（ctx，
 CGRectMake（0,0，CGImageGetWidth（image），CGImageGetHeight（image）），
 image）; 
} 
 
 // CreateImagePattern的回调。 
 static void releasePatternImage（void * info）
 {
 CGImageRelease（（CGImageRef）info）; 
} 
 
 //假设图像是你想要分配为图层背景的CGImage 
 int width = CGImageGetWidth（image）; 
 int height = CGImageGetHeight（image）; 
 static const CGPatternCallbacks callbacks = {0，& drawPatternImage，& releasePatternImage}; 
 CGPatternRef pattern = CGPatternCreate（image，
 CGRectMake（0，0，width，height），
 CGAffineTransformMake（1,0,0,1,0,0），
 width ，
 height，
 kCGPatternTilingConstantSpacing，
 true，
& callbacks）; 
 CGColorSpaceRef space = CGColorSpaceCreatePattern（NULL）; 
 CGFloat components [1] = {1.0}; 
 CGColorRef color = CGColorCreateWithPattern（space，pattern，components）; 
 CGColorSpaceRelease（space）; 
 CGPatternRelease（pattern）; 
 yourLayer.backgroundColor = color; //将图层的背景设置为图片
 CGColorRelease（color）; 
  

此代码是从GeekGameBoard示例代码修改的。

I would like to tile a CGImage across a CALayer, but it seems to only want to stretch it.

The example code:

 self.background = [UIImage imageNamed: @"Background.png"];
 [documentDisplay.layer setContents: self.background.CGImage];

I would like to avoid subclassing if I could.

解决方案

You can create a color with a pattern image and set that as the background color of the layer.

To do that you need wrap your CGImage in a CGPattern and make a CGColor from it.

// callback for CreateImagePattern.
static void drawPatternImage (void *info, CGContextRef ctx)
{
    CGImageRef image = (CGImageRef) info;
    CGContextDrawImage(ctx, 
                       CGRectMake(0,0, CGImageGetWidth(image),CGImageGetHeight(image)),
                       image);
}

// callback for CreateImagePattern.
static void releasePatternImage( void *info )
{
    CGImageRelease((CGImageRef)info);
}

//assume image is the CGImage you want to assign as the layer background
int width = CGImageGetWidth(image);
int height = CGImageGetHeight(image);
static const CGPatternCallbacks callbacks = {0, &drawPatternImage, &releasePatternImage};
CGPatternRef pattern = CGPatternCreate (image,
                        CGRectMake (0, 0, width, height),
                        CGAffineTransformMake (1, 0, 0, 1, 0, 0),
                        width,
                        height,
                        kCGPatternTilingConstantSpacing,
                        true,
                        &callbacks);
CGColorSpaceRef space = CGColorSpaceCreatePattern(NULL);
CGFloat components[1] = {1.0};
CGColorRef color = CGColorCreateWithPattern(space, pattern, components);
CGColorSpaceRelease(space);
CGPatternRelease(pattern);
yourLayer.backgroundColor = color; //set your layer's background to the image
CGColorRelease(color);

This code is modified from the GeekGameBoard sample code.

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