View的Touch事件分发以及源码分析

2017-07-27

Touch事件分发中有两个主角:ViewGroup和View。
为了方便理解，今天我们先单独讲View的Touch事件分发，我们先看下实例代码

首先，我们自定义一个view

public class TouchView extends View {
    private  Context context;
    private  AttributeSet attrs;

    public TouchView(Context context) {
        super(context);
    }

    public TouchView(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        this.attrs = attrs;
    }

    public TouchView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        addTextView("onTouchEvent-->"+event.getAction(),(LinearLayout)getParent());
        return super.onTouchEvent(event);
    }

    /**
     * 用来做事件分发
     * @param event
     * @return
     */
    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        addTextView("dispatchTouchEvent-->"+event.getAction(),(LinearLayout)getParent());
        return super.dispatchTouchEvent(event);
    }

    public void addTextView(String tag, ViewGroup viewGroup){
        TextView textView=new TextView(context);
        textView.setText(tag);
        textView.setTextSize(18);
        textView.setTextColor(Color.BLACK);
        viewGroup.addView(textView);
        TextView text=new TextView(context);
        text.setText("↓");
        viewGroup.addView(text);
    }
}

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