Android 事件分发 系列文章目录
【Android 事件分发】事件分发源码分析 ( 驱动层通过中断传递事件 | WindowManagerService 向 View 层传递事件 )
【Android 事件分发】事件分发源码分析 ( Activity 中各层级的事件传递 | Activity -> PhoneWindow -> DecorView -> ViewGroup )
【Android 事件分发】事件分发源码分析 ( ViewGroup 事件传递机制 一 )
【Android 事件分发】事件分发源码分析 ( ViewGroup 事件传递机制 二 )
文章目录
Android 事件分发 系列文章目录前言一、获取触摸索引值二、按照 Z 轴深度排序组件三、ViewGroup 事件分发相关源码前言
接上一篇博客 【Android 事件分发】事件分发源码分析 ( ViewGroup 事件传递机制 一 ) , 继续分析 ViewGroup 的事件分发机制后续代码 ;
一、获取触摸索引值
首先在 动作事件不是取消操作 , 且不拦截事件 , 的前提下 , 才能执行后续操作 , 判定代码如下 :
// 此处判定 , 是否拦截 // 假定不取消 , 也不拦截 // canceled 和 intercepted 二者都是 false , 才不能拦截 ; if (!canceled && !intercepted) {
凡是涉及到 Accessibility 功能的 , 直接忽略 , 与当前分析的事件分发无关 ;
View childWithAccessibilityFocus = ev.isTargetAccessibilityFocus()? findChildWithAccessibilityFocus() : null;
再次判定是否是按下操作 ;
// 判断是否是按下操作 if (actionMasked == MotionEvent.ACTION_DOWN|| (split && actionMasked == MotionEvent.ACTION_POINTER_DOWN)|| actionMasked == MotionEvent.ACTION_HOVER_MOVE) {
如果是按下操作 , 则获取触摸索引值 , 从 0 开始计数 ;
// 获取触摸索引值 final int actionIndex = ev.getActionIndex(); // always 0 for down
ViewGroup | dispatchTouchEvent 方法相关源码 :
@UiThreadpublic abstract class ViewGroup extends View implements ViewParent, ViewManager {@Overridepublic boolean dispatchTouchEvent(MotionEvent ev) {...// 此处判定 , 是否拦截 // 假定不取消 , 也不拦截 // canceled 和 intercepted 二者都是 false , 才不能拦截 ; if (!canceled && !intercepted) {// If the event is targeting accessibility focus we give it to the// view that has accessibility focus and if it does not handle it// we clear the flag and dispatch the event to all children as usual.// We are looking up the accessibility focused host to avoid keeping// state since these events are very rare.// 无障碍 辅助功能 View childWithAccessibilityFocus = ev.isTargetAccessibilityFocus()? findChildWithAccessibilityFocus() : null;// 判断是否是按下操作 if (actionMasked == MotionEvent.ACTION_DOWN|| (split && actionMasked == MotionEvent.ACTION_POINTER_DOWN)|| actionMasked == MotionEvent.ACTION_HOVER_MOVE) {// 获取触摸索引值 final int actionIndex = ev.getActionIndex(); // always 0 for downfinal int idBitsToAssign = split ? 1 << ev.getPointerId(actionIndex): TouchTarget.ALL_POINTER_IDS;// Clean up earlier touch targets for this pointer id in case they// have become out of sync.removePointersFromTouchTargets(idBitsToAssign);...}}
源码路径 :/frameworks/base/core/java/android/view/ViewGroup.java
二、按照 Z 轴深度排序组件
先计算 ViewGroup 父容器下面有多少个子 View 组件 ;
// 计算 ViewGroup 父容器下面有多少个子 View 组件 ; final int childrenCount = mChildrenCount;
如果子组件个数为 0 , 则不走下一段代码 , 如果子组件个数大于 0 , 则执行下一段代码 ; 说明下面的代码块中处理的是 ViewGroup 中子组件的事件分发功能 ;
在子组件个数不为 0 的情况下 , 继续向后执行 ;
获取手指触摸的 x, y 坐标值 ;
// 获取单个手指的 x,y 坐标 final float x = ev.getX(actionIndex);final float y = ev.getY(actionIndex);
子组件排序 :按照 Z 轴排列的层级 , 从上到下进行排序 , 控件会相互重叠 , Z 轴的排列次序上 , 顶层的组件优先获取到触摸事件 ;
// TouchTarget newTouchTarget = null; 在上面声明为空 , 此处肯定为 null ; // childrenCount 子组件个数不为 0 // 如果子组件个数为 0 , 则不走下一段代码 , 如果子组件个数大于 0 , 则执行下一段代码 ; // 说明下面的代码块中处理的是 ViewGroup 中子组件的事件分发功能 ; if (newTouchTarget == null && childrenCount != 0) {// 获取单个手指的 x,y 坐标 final float x = ev.getX(actionIndex);final float y = ev.getY(actionIndex);// Find a child that can receive the event.// Scan children from front to back.// 子组件排序 , 按照 Z 轴排列的层级 , 从上到下进行排序 , // 控件会相互重叠 , Z 轴的排列次序上 , // 顶层的组件优先获取到触摸事件 final ArrayList<View> preorderedList = buildTouchDispatchChildList();
ViewGroup | buildTouchDispatchChildList 方法是排序的核心方法 ;
获取当前所有组件的子组件的 Z 轴的深度 , 按照 Z 轴深度进行排序 , Z 轴方向上 , 对于事件传递 , 上面的组件优先级高于被覆盖的下面的组件优先级 ;
下面的代码是组件遍历排序的核心逻辑 :
// 下面的组件排序的核心逻辑 // 获取当前所有组件的子组件的 Z 轴的深度 // 按照 Z 轴深度进行排序 // Z 轴方向上 , 对于事件传递 , 上面的组件优先级高于被覆盖的下面的组件优先级for (int i = 0; i < childrenCount; i++) {// add next child (in child order) to end of listfinal int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);final View nextChild = mChildren[childIndex];final float currentZ = nextChild.getZ();// insert ahead of any Views with greater Z// 计算当前遍历的组件应该被放到的索引位置int insertIndex = i;while (insertIndex > 0 && mPreSortedChildren.get(insertIndex - 1).getZ() > currentZ) {insertIndex--;}// 将当前遍历的组件插入到指定索引位置上 mPreSortedChildren.add(insertIndex, nextChild);}
ViewGroup | dispatchTouchEvent / buildOrderedChildList 方法相关源码 :
@UiThreadpublic abstract class ViewGroup extends View implements ViewParent, ViewManager {@Overridepublic boolean dispatchTouchEvent(MotionEvent ev) {...// 计算 ViewGroup 父容器下面有多少个子 View 组件 ; final int childrenCount = mChildrenCount;// TouchTarget newTouchTarget = null; 在上面声明为空 , 此处肯定为 null ; // childrenCount 子组件个数不为 0 // 如果子组件个数为 0 , 则不走下一段代码 , 如果子组件个数大于 0 , 则执行下一段代码 ; // 说明下面的代码块中处理的是 ViewGroup 中子组件的事件分发功能 ; if (newTouchTarget == null && childrenCount != 0) {// 获取单个手指的 x,y 坐标 final float x = ev.getX(actionIndex);final float y = ev.getY(actionIndex);// Find a child that can receive the event.// Scan children from front to back.// 子组件排序 , 按照 Z 轴排列的层级 , 从上到下进行排序 , // 控件会相互重叠 , Z 轴的排列次序上 , // 顶层的组件优先获取到触摸事件 final ArrayList<View> preorderedList = buildTouchDispatchChildList();final boolean customOrder = preorderedList == null&& isChildrenDrawingOrderEnabled();final View[] children = mChildren;...}/*** Provide custom ordering of views in which the touch will be dispatched.* 按照事件传递的顺序进行组件排序 ** This is called within a tight loop, so you are not allowed to allocate objects, including* the return array. Instead, you should return a pre-allocated list that will be cleared* after the dispatch is finished.* @hide*/public ArrayList<View> buildTouchDispatchChildList() {return buildOrderedChildList();}/*** Populates (and returns) mPreSortedChildren with a pre-ordered list of the View's children,* sorted first by Z, then by child drawing order (if applicable). This list must be cleared* after use to avoid leaking child Views.** Uses a stable, insertion sort which is commonly O(n) for ViewGroups with very few elevated* children.*/ArrayList<View> buildOrderedChildList() {final int childrenCount = mChildrenCount;if (childrenCount <= 1 || !hasChildWithZ()) return null;if (mPreSortedChildren == null) {mPreSortedChildren = new ArrayList<>(childrenCount);} else {// callers should clear, so clear shouldn't be necessary, but for safety...mPreSortedChildren.clear();mPreSortedChildren.ensureCapacity(childrenCount);}final boolean customOrder = isChildrenDrawingOrderEnabled();// 下面的组件排序的核心逻辑 // 获取当前所有组件的子组件的 Z 轴的深度 // 按照 Z 轴深度进行排序 // Z 轴方向上 , 对于事件传递 , 上面的组件优先级高于被覆盖的下面的组件优先级for (int i = 0; i < childrenCount; i++) {// add next child (in child order) to end of listfinal int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);final View nextChild = mChildren[childIndex];final float currentZ = nextChild.getZ();// insert ahead of any Views with greater Z// 计算当前遍历的组件应该被放到的索引位置int insertIndex = i;while (insertIndex > 0 && mPreSortedChildren.get(insertIndex - 1).getZ() > currentZ) {insertIndex--;}// 将当前遍历的组件插入到指定索引位置上 mPreSortedChildren.add(insertIndex, nextChild);}return mPreSortedChildren;}// 获取排序后的子组件的索引值private int getAndVerifyPreorderedIndex(int childrenCount, int i, boolean customOrder) {final int childIndex;if (customOrder) {final int childIndex1 = getChildDrawingOrder(childrenCount, i);if (childIndex1 >= childrenCount) {throw new IndexOutOfBoundsException("getChildDrawingOrder() "+ "returned invalid index " + childIndex1+ " (child count is " + childrenCount + ")");}childIndex = childIndex1;} else {childIndex = i;}return childIndex;}}
源码路径 :/frameworks/base/core/java/android/view/ViewGroup.java
三、ViewGroup 事件分发相关源码
ViewGroup 事件分发相关源码 :下面的代码中 , 逐行注释分析了 ViewGroup 的 dispatchTouchEvent 事件分发操作 ;
@UiThreadpublic abstract class ViewGroup extends View implements ViewParent, ViewManager {// First touch target in the linked list of touch targets.private TouchTarget mFirstTouchTarget;@Overridepublic boolean dispatchTouchEvent(MotionEvent ev) {// 辅助功能 , 残疾人相关辅助 , 跨进程调用 无障碍 功能if (mInputEventConsistencyVerifier != null) {mInputEventConsistencyVerifier.onTouchEvent(ev, 1);}// If the event targets the accessibility focused view and this is it, start// normal event dispatch. Maybe a descendant is what will handle the click.// 判断产生事件的目标组件是可访问性的 , 那么按照普通的事件分发进行处理 ; // 可能由其子类处理点击事件 ; // 判断当前是否正在使用 无障碍 相关功能产生事件 if (ev.isTargetAccessibilityFocus() && isAccessibilityFocusedViewOrHost()) {ev.setTargetAccessibilityFocus(false);}// 是否按下操作 , 最终的对外返回结果 , 该方法的最终返回值 boolean handled = false;if (onFilterTouchEventForSecurity(ev)) {final int action = ev.getAction();final int actionMasked = action & MotionEvent.ACTION_MASK;// Handle an initial down.// 判断是否是第一次按下 , 如果是第一次按下 , 则执行下面的业务逻辑 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);// 如果是第一次按下 , 那么重置触摸状态 resetTouchState();}// Check for interception.// 判定是否拦截 // 用于多点触控按下操作的判定 final boolean intercepted;if (actionMasked == MotionEvent.ACTION_DOWN|| mFirstTouchTarget != null) {// 判断是否需要拦截 , 可以使用 requestDisallowInterceptTouchEvent 方法进行设置final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;if (!disallowIntercept) {// 进行事件拦截 // 该 onInterceptTouchEvent 方法只返回是否进行事件拦截 , 返回一个布尔值 , 没有进行具体的事件拦截 // 是否进行拦截 , 赋值给了 intercepted 局部变量 // 该值决定是否进行拦截 intercepted = onInterceptTouchEvent(ev);ev.setAction(action); // restore action in case it was changed} else {// 不进行事件拦截 intercepted = false;}} else {// There are no touch targets and this action is not an initial down// so this view group continues to intercept touches.intercepted = true;}// If intercepted, start normal event dispatch. Also if there is already// a view that is handling the gesture, do normal event dispatch.if (intercepted || mFirstTouchTarget != null) {ev.setTargetAccessibilityFocus(false);}// Check for cancelation.// 检查是否取消操作 , 手指是否移除了组件便捷 ; // 一般情况默认该值是 false ; final boolean canceled = resetCancelNextUpFlag(this)|| actionMasked == MotionEvent.ACTION_CANCEL;// Update list of touch targets for pointer down, if needed.final boolean split = (mGroupFlags & FLAG_SPLIT_MOTION_EVENTS) != 0;// 注意此处 newTouchTarget 为空 TouchTarget newTouchTarget = null;boolean alreadyDispatchedToNewTouchTarget = false;// 此处判定 , 是否拦截 // 假定不取消 , 也不拦截 // canceled 和 intercepted 二者都是 false , 才不能拦截 ; if (!canceled && !intercepted) {// If the event is targeting accessibility focus we give it to the// view that has accessibility focus and if it does not handle it// we clear the flag and dispatch the event to all children as usual.// We are looking up the accessibility focused host to avoid keeping// state since these events are very rare.// 无障碍 辅助功能 View childWithAccessibilityFocus = ev.isTargetAccessibilityFocus()? findChildWithAccessibilityFocus() : null;// 判断是否是按下操作 if (actionMasked == MotionEvent.ACTION_DOWN|| (split && actionMasked == MotionEvent.ACTION_POINTER_DOWN)|| actionMasked == MotionEvent.ACTION_HOVER_MOVE) {// 获取触摸索引值 final int actionIndex = ev.getActionIndex(); // always 0 for downfinal int idBitsToAssign = split ? 1 << ev.getPointerId(actionIndex): TouchTarget.ALL_POINTER_IDS;// Clean up earlier touch targets for this pointer id in case they// have become out of sync.removePointersFromTouchTargets(idBitsToAssign);// 计算 ViewGroup 父容器下面有多少个子 View 组件 ; final int childrenCount = mChildrenCount;// TouchTarget newTouchTarget = null; 在上面声明为空 , 此处肯定为 null ; // childrenCount 子组件个数不为 0 // 如果子组件个数为 0 , 则不走下一段代码 , 如果子组件个数大于 0 , 则执行下一段代码 ; // 说明下面的代码块中处理的是 ViewGroup 中子组件的事件分发功能 ; if (newTouchTarget == null && childrenCount != 0) {// 获取单个手指的 x,y 坐标 final float x = ev.getX(actionIndex);final float y = ev.getY(actionIndex);// Find a child that can receive the event.// Scan children from front to back.// 子组件排序 , 按照 Z 轴排列的层级 , 从上到下进行排序 , // 控件会相互重叠 , Z 轴的排列次序上 , // 顶层的组件优先获取到触摸事件 final ArrayList<View> preorderedList = buildTouchDispatchChildList();final boolean customOrder = preorderedList == null&& isChildrenDrawingOrderEnabled();final View[] children = mChildren;... return handled;}@Overridepublic void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {// disallowIntercept 存在一个默认值 , 如果值为默认值 , 直接退出 if (disallowIntercept == ((mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0)) {// We're already in this state, assume our ancestors are tooreturn;}// 如果不是默认值 , 则进行相应更改 // 最终的值影响 mGroupFlags 是 true 还是 false if (disallowIntercept) {mGroupFlags |= FLAG_DISALLOW_INTERCEPT;} else {mGroupFlags &= ~FLAG_DISALLOW_INTERCEPT;}// Pass it up to our parentif (mParent != null) {mParent.requestDisallowInterceptTouchEvent(disallowIntercept);}}public boolean onInterceptTouchEvent(MotionEvent ev) {// 该方法只返回是否进行事件拦截 , 返回一个布尔值 , 没有进行具体的事件拦截 if (ev.isFromSource(InputDevice.SOURCE_MOUSE)&& ev.getAction() == MotionEvent.ACTION_DOWN&& ev.isButtonPressed(MotionEvent.BUTTON_PRIMARY)&& isOnScrollbarThumb(ev.getX(), ev.getY())) {return true;}return false;}/*** Provide custom ordering of views in which the touch will be dispatched.* 按照事件传递的顺序进行组件排序 ** This is called within a tight loop, so you are not allowed to allocate objects, including* the return array. Instead, you should return a pre-allocated list that will be cleared* after the dispatch is finished.* @hide*/public ArrayList<View> buildTouchDispatchChildList() {return buildOrderedChildList();}/*** Populates (and returns) mPreSortedChildren with a pre-ordered list of the View's children,* sorted first by Z, then by child drawing order (if applicable). This list must be cleared* after use to avoid leaking child Views.** Uses a stable, insertion sort which is commonly O(n) for ViewGroups with very few elevated* children.*/ArrayList<View> buildOrderedChildList() {final int childrenCount = mChildrenCount;if (childrenCount <= 1 || !hasChildWithZ()) return null;if (mPreSortedChildren == null) {mPreSortedChildren = new ArrayList<>(childrenCount);} else {// callers should clear, so clear shouldn't be necessary, but for safety...mPreSortedChildren.clear();mPreSortedChildren.ensureCapacity(childrenCount);}final boolean customOrder = isChildrenDrawingOrderEnabled();// 下面的组件排序的核心逻辑 // 获取当前所有组件的子组件的 Z 轴的深度 // 按照 Z 轴深度进行排序 // Z 轴方向上 , 对于事件传递 , 上面的组件优先级高于被覆盖的下面的组件优先级for (int i = 0; i < childrenCount; i++) {// add next child (in child order) to end of listfinal int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);final View nextChild = mChildren[childIndex];final float currentZ = nextChild.getZ();// insert ahead of any Views with greater Z// 计算当前遍历的组件应该被放到的索引位置int insertIndex = i;while (insertIndex > 0 && mPreSortedChildren.get(insertIndex - 1).getZ() > currentZ) {insertIndex--;}// 将当前遍历的组件插入到指定索引位置上 mPreSortedChildren.add(insertIndex, nextChild);}return mPreSortedChildren;}}
源码路径 :/frameworks/base/core/java/android/view/ViewGroup.java