1. 首先要声明一下ConstraintSet对象
private val set = ConstraintSet()复制代码
2. 其次需要复制一份父布局的约束,方法有三个如下:
set.clone(constraintLayout: ConstraintLayout);set.clone(set: ConstraintSet);set.clone(context: Context, constraintLayoutId: Int);复制代码
简单说明一下,如果要修改一个TextView的约束,需要找到TextView的父布局,然后调用上述方法clone一份
这里需要注意一下,在调用clone()方法的时候,必须保证这个父布局的所有子布局都设置了 id,不然会报如下错误:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.liuniukeji.lightlanguage/com.mufeng.light.ui.activity.CurriculumClassifyActivity}: java.lang.RuntimeException: All children of ConstraintLayout must have ids to use ConstraintSet at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892) at android.app.ActivityThread.-wrap11(Unknown Source:0) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593) at android.os.Handler.dispatchMessage(Handler.java:105) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread.main(ActivityThread.java:6541) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767) Caused by: java.lang.RuntimeException: All children of ConstraintLayout must have ids to use ConstraintSet at android.support.constraint.ConstraintSet.clone(ConstraintSet.java:688)复制代码 3. 第三步就需要去设置组件之间的约束了,常用方法有:
set.connect(startID: Int, startSide: Int, endID: Int, endSide: Int, margin: Int)set.connect(startID: Int, startSide: Int, endID: Int, endSide: Int)复制代码
例如: 修改一个id为text的TextView的约束,相依赖的约束组件为一个id为btn的Button,修改为text的左边和btn的左边对其,边距margin为20px:
set.connect(R.id.text,ConstraintSet.LEFT,ConstraintSet.R.id.btn,ConstraintSet.LEFT,20)复制代码
设置text水平剧中于父布局parent
set.centerHorizontally(R.id.text, ConstraintSet.PARENT_ID)复制代码
设置text的高度为10px
set.constrainHeight(R.id.text, 10);复制代码
4.第四步 设置一个动画,并且要求api版本为19及以上
TransitionManager.beginDelayedTransition(rootLayout)复制代码
5.最后一步 ,apply一下使设置生效
set.applyTo(rootLayout)复制代码