View绘制流程(2)----绘制过程及事件冲突
Touch的传递机制（Intercept不一定每次都调用）
当一个点击事件产生后，它的传递过程遵循如下顺序：Activity->Window->View即事件总是先传递Activity，Activity再传递给Window，最后Window再传递给顶级View,顶级View接收到事件后，就会按照事件分发机制去分发事件
（1）ViewGroup默认不拦截任何事件，Android源码中ViewGroup的onInterceptTouchEvent方法默认返回false
（2）View的enable属性不影响onTouchEvent的默认返回值。哪怕一个view是disable状态的，只要他的clicklable或者longClickable有一个为true,那么他的onTouchEvent就返回True
（3）如果View不消耗ACTION_DOWN事件（onTouchEvent返回了false）,那么同一个事件序列中的其他事件都不会再交给它来处理，并且事件将重新交给它的父元素去处理，即父元素的onTouchEvent会被调用。（打个比方如果交给下属一件小事都没处理好，那就不会继续把更大的事交给它处理）
（4）某个view一旦决定拦截，那么这一个事件序列都只能由它来处理（如果事件序列能够传递给他的话），并且它的onInterceptTouchEvent不会再被调用（当一个view决定拦截一个事件后，那么系统会把同一个事件序列内的其他方法都直接交给它来处理，因此就不用在调用这个view的onInterceptTouchEvent去询问他是否要拦截了）
（5）事件传递过程是由外向内的，即事件总是先传递给父元素，然后再由父元素分发给子view,通过requestDisallowInterceptTouchEvent方法可以在子元素中干预父元素的事件分发过程，但是ACTION_DOWN事件除外
当面对ACTION_DOWN事件时，ViewGroup总是会调用自己的onInterceptTouchEvent方法来询问自己是否要拦截事件，可以从源码看出来了
public boolean dispatchTouchEvent(MotionEvent ev) {
。。。。。。
boolean handled = false;
if (onFilterTouchEventForSecurity(ev)) {
final int action = ev.getAction();
final int actionMasked = action & MotionEvent.ACTION_MASK;
// Handle an initial down.
if (actionMasked == MotionEvent.ACTION_DOWN) {
// Throw away all previous state when starting a new touch gesture.
// The framework may have dropped the up or cancel event for the previous gesture
// due to an app switch, ANR, or some other state change.
cancelAndClearTouchTargets(ev);
resetTouchState();//会对FLAG_DISALLOW_INTERCEPT充值
}
。。。。。。
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因此子View调用requestDisallowInterceptTouchEvent方法并不能影响ViewGroup对ACTION_DOWN对事件的处理
(7)通过setClickable和setLongClickabe分别改变view的CLICKABLE和LONG_CLICKABLE属性，另外，setOnClickListener会自动将View的CLICKABLE设为true,setOnLongClickListener则会自动将View的LONG_CLICKABLE设为True
自最后的滑动的冲突事件的解决 用MySlideMenu(已写完)加上zhbj的框架做例子（未写完）
//SlideMenuView.java
/**
* Created by Administrator on 2015/12/13 0013.
*/
public class SlideMenuView extends RelativeLayout {
private LinearLayout mLeft;
private LinearLayout mContent;
private int mLeftMeasureWidth;
private float startX;
private float downX;
private float moveX;
private float downY;
private float moveY;
private Scroller mScroller;
boolean isLeftOpened = false;
private int downX2;
private int downY2;
public SlideMenuView(Context context) {
super(context);
}
public SlideMenuView(Context context, AttributeSet attrs) {
super(context, attrs);
mScroller = new Scroller(context);
}
public SlideMenuView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
/**
* Finalize inflating a view from XML. This is called as the last phase of inflation,
* after all child views have been added.
*/
@Override
protected void onFinishInflate() {
super.onFinishInflate();
mLeft = (LinearLayout) getChildAt(0);
mContent = (LinearLayout) getChildAt(1);
//获取left的宽度
mLeftMeasureWidth = mLeft.getLayoutParams().width;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
//slideMenu是一个viewgroup
//所以要先写子view的measure
//1.conent的宽高跟父容器（也就是slidemenu一样）
mContent.measure(widthMeasureSpec, heightMeasureSpec);
//2.mleft的宽是80dp,高和父容器一样
//好像还有一种就是upspecified 也就是布局文件写多少就是多少？？？？？？
int mLeftMeasureSpec = MeasureSpec.makeMeasureSpec(mLeftMeasureWidth, MeasureSpec.EXACTLY);
mLeft.measure(mLeftMeasureSpec, heightMeasureSpec);
//3.最后就到自己了
int measuredWidth = MeasureSpec.getSize(widthMeasureSpec);
int measuredHeight = MeasureSpec.getSize(heightMeasureSpec);
setMeasuredDimension(measuredWidth, measuredHeight);
// 因为自己的大小没有变可以直接写下面的就行，但是这里暂时写上面的
// super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// super.onLayout(changed, l, t, r, b);
//1.先放置mLeftView
// mLeft.layout(-mLeft.getMeasuredWidth() + 100, 0, 100, mLeft.getMeasuredHeight());//这样可以露一点
// mContent.layout(100, 0, mContent.getMeasuredWidth()+100, mContent.getMeasuredHeight());
mLeft.layout(-mLeft.getMeasuredWidth(), 0, 0, mLeft.getMeasuredHeight());
//2.在放置mContent
mContent.layout(0, 0, mContent.getMeasuredWidth(), mContent.getMeasuredHeight());
}
/**
* 避免滑动出现的几种极端情况
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
System.out.println("xcqw onTouchEvent ACTION_DOWN");
downX = event.getRawX();
downY = event.getRawY();
break;
case MotionEvent.ACTION_MOVE:
moveX = event.getRawX();
moveY = event.getRawY();
System.out.println("xcqw ACTION_MOVE");
float dx = downX - moveX;
//The left edge of the displayed part of your view, in pixels
//可以理解就是现在窗体的位置
int verteX = getScrollX();
System.out.println("xcqw verteX" + verteX);
System.out.println("xcqw dx" + dx);
//情况1 就是窗体最多移动-mLeft.getMeasuredWidth()
if (verteX + dx < -mLeft.getMeasuredWidth()) {
//窗体直接移到-mLeft.getMeasuredWidth()！！！
//Set the scrolled position of your view
scrollTo(-mLeft.getMeasuredWidth(), 0);
System.out.println("xcqw 移到最左边");
} else if (verteX + dx > 0) {
//情况2 就是窗体右移最多智能移到mContent.getMeasureWidth
System.out.println("xcqw 移到Content");
scrollTo(0, 0);
} else {
//在原有位置上移动
System.out.println("xcqw 在当前位置移动");
scrollBy((int) dx, 0);
}
//更新坐标
downX = moveX;
downY = moveY;
break;
case MotionEvent.ACTION_UP:
System.out.println("xcqw ACTION_UP");
//根据移动到的位置来做自动开关
//如果打开位置小于一半就关上 or 大于一半 就自动打开
System.out.println("xcqw action_up 开还是关" + (getScrollX() < -mLeft.getMeasuredWidth() / 2));
judgeOpenOrClose(getScrollX() < -mLeft.getMeasuredWidth() / 2);
break;
}
return true;
//深究一下为什么会是return false
// return super.onTouchEvent(event);
}
private void judgeOpenOrClose(boolean open) {
isLeftOpened = open;
if (open) {
//如果大于二分之一，就自动打开
//The left edge of the displayed part of your view, in pixels.
int startX = getScrollX();
//The top edge of the displayed part of your view, in pixels.
int startY = getScrollY();
int endX = -mLeft.getMeasuredWidth();
int endY = 0;
int dx = endX - startX;
int dy = endY - startY;
//根据移动的px来设定滑动的速度（控制总共的时间），这样体验比较好
int duration = Math.abs(dx) * 10;
if (duration > 500) {
duration = 500;
}
mScroller.startScroll(startX, startY, dx, dy, duration);
} else {
//如果小于二分之一，就自动关闭
//The left edge of the displayed part of your view, in pixels.
int startX = getScrollX();
//The top edge of the displayed part of your view, in pixels.
int startY = getScrollY();
int endX = 0;
int endY = 0;
int dx = endX - startX;
int dy = endY - startY;
//根据移动的px来设定滑动的速度（控制总共的时间），这样体验比较好
int duration = Math.abs(dx) * 10;
if (duration > 500) {
duration = 500;
}
mScroller.startScroll(startX, startY, dx, dy, duration);
}
//重新绘制 draw-->ondraw
invalidate();
}
@Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
scrollTo(mScroller.getCurrX(), 0);
postInvalidate();
}
}
public void openLeft() {
//打开左边菜单
judgeOpenOrClose(true);
}
public void closeLeft() {
//关闭左边菜单
judgeOpenOrClose(false);
}
//避免left的scroll吃掉左右滑动事件
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
downX = getX();
downY = getY();
System.out.println("xcqw onInterceptTouchEvent ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
moveX = getX();
moveY = getY();
float dx = downX - moveX;
float dy = downY - moveY;
if (Math.abs(dx) > Math.abs(dy)) {
//如果x方向移动大于y方向
//不分发了//自己处理
return true;
}
break;
case MotionEvent.ACTION_UP:
break;
}
return super.onInterceptTouchEvent(ev);
}
//为了解决当left全部脱出时点击content区域关闭left（也就是让他缩回去）
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
downX2 = (int) event.getX();
//这里如果写downY会有问题 downY 跟 upY差太多//因为前面有个donwnY = moveY
downY2 = (int) event.getY();
System.out.println("xcqw dispatchTouchEvent ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
break;
case MotionEvent.ACTION_UP:
float upX = event.getX();
float upY = event.getY();
System.out.println("xcqw dispatchTouchEvent ACTION_UP" + isLeftOpened);
if (isLeftOpened) {
//因为像素点很小不可能每次按都是按同一个像素点，所以要给一个误差范围
System.out.println("xcqw dispatchTouchEvent ACTION_UP upX-" + upX + "-downX-" + downX);
System.out.println("xcqw dispatchTouchEvent ACTION_UP upY-" + upY + "-downY-" + downY);
System.out.println("xcqw dispatchTouchEvent ACTION_UP upX-" + upX + "-downX2-" + downX2);
System.out.println("xcqw dispatchTouchEvent ACTION_UP upY-" + upY + "-downY2-" + downY2);
if ((upX < downX2 + 4) && (upX > downX2 - 4) && upY < downY2 + 4 && upY > downY2 - 4) {
System.out.println("xcqw dispatchTouchEvent ACTION_UP x1");
//排除用户按住滑动然后放手
//点击位置跟弹起位置在一定范围内就认为是点了不是移动
//这样就可以排除了按着滑动一定距离的情况
//关闭left
if (upX > mLeft.getMeasuredWidth()) {
//这样是在left全部展开的情况点击关闭
//关闭左侧
System.out.println("xcqw dispatchTouchEvent ACTION_UP x2");
judgeOpenOrClose(false);
//自己就把他处理，不要别人来处理
return true;
}
}
}
break;
}
return super.dispatchTouchEvent(event);
}
public boolean isLeftOpen() {
return isLeftOpened;
}
}
Activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<com.dx.text.myslidemenu.SlideMenuView
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<include layout="@layout/left"/>
<include layout="@layout/content"/>
</com.dx.text.myslidemenu.SlideMenuView>
</RelativeLayout>