CoordinatorLayout源码解析和手动实现.zip

package com.dongnao.lsn_16_classdemo.design; import android.content.Context; import android.content.res.TypedArray; import android.support.v4.view.NestedScrollingParent; import android.util.AttributeSet; import android.view.View; import android.view.ViewGroup; import android.view.ViewTreeObserver; import android.widget.RelativeLayout; import com.dongnao.lsn_16_classdemo.R; import java.lang.reflect.Constructor; @SuppressWarnings("all") public class CoordinatorLayout extends RelativeLayout implements NestedScrollingParent, ViewTreeObserver.OnGlobalLayoutListener { float lastX; float lastY; public CoordinatorLayout(Context context) { super(context); } public CoordinatorLayout(Context context, AttributeSet attrs) { super(context, attrs); } public LayoutParams generateLayoutParams(AttributeSet attrs) { return new LayoutParams(getContext(), attrs); } @Override protected void onFinishInflate() { super.onFinishInflate(); getViewTreeObserver().addOnGlobalLayoutListener(this); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); for (int i = 0; i < getChildCount(); i++) { View v = getChildAt(i); LayoutParams lp = (LayoutParams) v.getLayoutParams(); if (lp.behavior != null) lp.behavior.onSizeChanged(this, v, w, h, oldw, oldh); } } @Override public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) { return true; } //当NestedScrollingChild发生滑动时，会调用此方法来通知NestedScrollingParent滑动了多少距离 //最常见的情景是，NestedScrollView通知CoordinatorLayout //target：一般为NestedScrollView //dyConsumed：NestedScrollView单次已消费滑动距离 //dyUnconsumed：NestedScrollView单次未消费滑动距离 //未消费的滑动距离是指，ScrollView已经滑动到顶端，手继续往下拉，但是控件内容缺没有继续滑动，手额外拉的这部分距离就是未消费的滑动距离 @Override public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) { for (int i = 0; i < getChildCount(); i++) { View v = getChildAt(i); LayoutParams lp = (LayoutParams) v.getLayoutParams(); //关键代码，转发滑动事件 if (lp.behavior != null) lp.behavior.onNestedScroll(target, v, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed); } } @Override public void onGlobalLayout() { for (int i = 0; i < getChildCount(); i++) { View v = getChildAt(i); LayoutParams lp = (LayoutParams) v.getLayoutParams(); if (lp.behavior != null) lp.behavior.onLayoutFinish(this, v); } } public class LayoutParams extends RelativeLayout.LayoutParams { protected Behavior behavior; public LayoutParams(Context context, AttributeSet attributeSet) { super(context, attributeSet); TypedArray a = context.obtainStyledAttributes(attributeSet, R.styleable.MyCoordinatorLayout); String clazzName = a.getString(R.styleable.MyCoordinatorLayout_behavior); behavior = parseBehaivor(context, attributeSet, clazzName); a.recycle(); } public LayoutParams(int w, int h) { super(w, h); } public LayoutParams(ViewGroup.LayoutParams source) { super(source); } public LayoutParams(MarginLayoutParams source) { super(source); } public LayoutParams(RelativeLayout.LayoutParams source) { super(source); } protected Behavior parseBehaivor(Context context, AttributeSet attrs, String name) { try { Class<?> aClass = Class.forName(name, true, context.getClassLoader()); Constructor c = aClass.getConstructor(new Class[]{Context.class, AttributeSet.class}); c.setAccessible(true); return (Behavior) c.newInstance(context, attrs); } catch (Throwable e) { e.printStackTrace(); } return null; } } }