CALayer小记1

CALayer小记1

  今天有闲情逸致,再来一篇

1.contents填充图片时,如果加圆角,图片会超出圆角框,即还是直角,得加一句masksToBounds(imageView加圆角则没有这样的问题):

layer.masksToBounds =YES;

2.transform.rotation旋转,直接setValue forKeyPath:

摘自文档:

You can not specify a structure field key path using Objective-C 2.0 properties. This will not work:

myLayer.transform.rotation.x=0;

Instead you must use setValue:forKeyPath: or valueForKeyPath: as shown below:

[myLayer setValue:[NSNumber numberWithInt:0] forKeyPath:@"transform.rotation.x"];

注意:当设置y坐标时,直接赋值会有问题,应该先hold住当前状态,再改变(x/z则没问题),我这用的UISlider测试:

CALayer *layer=[window.layer.sublayersobjectAtIndex:0];

//hold住当前状态

layer.transform =CATransform3DIdentity; 

//用slider来改变,如果没hold住,当大于90度时,慢慢划动会导致一正一反反复出现…

[layer setValue:[NSNumbernumberWithFloat:DegreesToRadians(slider.value)]forKeyPath:@"transform.rotation.y"];  

3.进一步,摘自文档:

Modifying a Transform Using Key Paths

Core Animation extends the key-value coding protocol to allow getting and setting of the common values of a layer'sCATransform3D matrix through key paths. Table 4 describes the key paths for which a layer’stransform and sublayerTransform properties are key-value coding and observing compliant.

Table 4  CATransform3D key paths

Field Key Path

Description

rotation.x

The rotation, in radians, in the x axis.

rotation.y

The rotation, in radians, in the y axis.

rotation.z

The rotation, in radians, in the z axis.

rotation

The rotation, in radians, in the z axis. This is identical to setting therotation.z field.

scale.x

Scale factor for the x axis.

scale.y

Scale factor for the y axis.

scale.z

Scale factor for the z axis.

scale

Average of all three scale factors.

translation.x

Translate in the x axis.

translation.y

Translate in the y axis.

translation.z

Translate in the z axis.

translation

Translate in the x and y axis. Value is an NSSize or CGSize.

(1)setValue的时候这些keyPath需加前缀transform,如transform.rotation, transform.scale,不然不反应

(2)scale在改变时,x/y同时变,二维z不变,最好也hold,slider的min值最好不要为0(或者检测到0的时候特殊处理),因为scale 0的话会导致layer不见了,那之后的改变都不可见:

slider.minimumValue=0.0;

slider.maximumValue=2.0;

slider.value=1.0;

//scale,出现0值需特殊处理

if(slider.value<0.001){

layer.hidden=YES;

return;

}else{

layer.hidden=NO;

}

layer.transform =CATransform3DIdentity;

[layer setValue:[NSNumbernumberWithFloat:slider.value] forKeyPath:@"transform.scale"];

(3)transform.rotation是默认改变的z,而不是三个坐标一起变

(4)transform.translation是改变位置,x为正向右移,y为正向下移(和二维坐标一致),二维时z无变化

修正:并非无变化(google:iphone transform.translation.z

找到http://stackoverflow.com/questions/4150105/my-calayer-is-not-appearing 有一句有用:.m34 is for z-axis transforms)

这样的话,加入下面这句就可以改变Z坐标:

CATransform3D transform =CATransform3DIdentity;

transform.m34 =1.0 / -100;

layer.transform = transform;

加上setValue,Z改变量随m34的值变化而不同,暂时不知道m34和translation.z的关系…

[layer setValue:[NSNumbernumberWithFloat:slider.value] forKeyPath:@"transform.translation.z"];