PercentLayoutHelper

public class PercentLayoutHelper
extends Object

Helper用于支持基于百分比的尺寸的布局。

该类收集涉及提取基于百分比的维度属性并将其应用于ViewGroup的子项的实用程序方法。 如果您想要实现支持基于百分比的维度的布局，则需要执行以下几个步骤：

1. You need a ViewGroup.LayoutParams subclass in your ViewGroup that implements PercentLayoutHelper.PercentLayoutParams.
2. In your LayoutParams(Context c, AttributeSet attrs) constructor create an instance of PercentLayoutHelper.PercentLayoutInfo by calling getPercentLayoutInfo(Context, AttributeSet). Return this object from public PercentLayoutHelper.PercentLayoutInfo getPercentLayoutInfo() method that you implemented for PercentLayoutHelper.PercentLayoutParams interface.
3. Override setBaseAttributes(TypedArray, int, int) with a single line implementation PercentLayoutHelper.fetchWidthAndHeight(this, a, widthAttr, heightAttr);
4. In your ViewGroup override generateLayoutParams(AttributeSet) to return your LayoutParams.
5. In your onMeasure(int, int) override, you need to implement following pattern:

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        mHelper.adjustChildren(widthMeasureSpec, heightMeasureSpec);
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (mHelper.handleMeasuredStateTooSmall()) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }
    

6. In your onLayout(boolean, int, int, int, int) override, you need to implement following pattern:

    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        mHelper.restoreOriginalParams();
    }
    

Summary

Inherited methods

From class java.lang.Object Object clone() 创建并返回此对象的副本。 boolean equals(Object obj) 指示其他某个对象是否“等于”这一个。 void finalize() 当垃圾收集确定没有更多对该对象的引用时，由对象上的垃圾回收器调用。 final Class<?> getClass() 返回此 Object的运行时类。 int hashCode() 返回对象的哈希码值。 final void notify() 唤醒正在等待该对象监视器的单个线程。 final void notifyAll() 唤醒在该对象监视器上等待的所有线程。 String toString() 返回对象的字符串表示形式。 final void wait(long millis, int nanos) 导致当前线程等待，直到另一个线程为该对象调用 notify()方法或 notifyAll()方法，或者某个其他线程中断当前线程或经过一定的实时时间。 final void wait(long millis) 导致当前线程等待，直到另一个线程调用此对象的 notify()方法或 notifyAll()方法或经过了指定的时间量。 final void wait() 导致当前线程等待，直到另一个线程调用此对象的 notify()方法或 notifyAll()方法。

Public constructors

PercentLayoutHelper (ViewGroup host)

Public methods

void adjustChildren (int widthMeasureSpec, 
                int heightMeasureSpec)

void fetchWidthAndHeight (ViewGroup.LayoutParams params, 
                TypedArray array, 
                int widthAttr, 
                int heightAttr)

PercentLayoutHelper.PercentLayoutInfo getPercentLayoutInfo (Context context, 
                AttributeSet attrs)

boolean handleMeasuredStateTooSmall ()

void restoreOriginalParams ()