Tips for Android Event distribution

@Override public boolean OnTouch (View V, Final motionevent event) {Checkablebutton cb = (Checkablebutton) v;if (CB. Iseditable()) {int action = Event. Getaction();Rect outrect = new Rect ();Getactivity (). GetWindow(). Findviewbyid(Window. ID_android_content). Getdrawingrect(Outrect);ScreenWidth = Outrect. Width();ScreenHeight = Outrect. Height();Switch (action) {case motionevent. ACTION_down:startx = V. GetLeft();Starty = V. GetTop();EndX = V. GetRight();EndY = V. Getbottom();Log. I(TAG,"Action_down:startx ="+ StartX);Log. I(TAG,"Action_down:starty ="+ starty);LASTX = (int) event. GETRAWX();Lasty = (int) event. Getrawy();                     Break;Case Motionevent. ACTION_move:v. GetParent(). Requestdisallowintercepttouchevent(true);if (islongclickmodule) {int dx = (int) event. GETRAWX()-Lastx;int dy = (int) event. Getrawy()-Lasty;Log. I(TAG,"ONTOUCH:DX ="+ dx);Log. I(TAG,"Ontouch:dy ="+ dy);int left = V. GetLeft() + DX;int top = V. GetTop() + dy;int right = V. GetRight() + DX;int bottom = V. Getbottom() + dy;if (left <0) {left =0;right = left + V. GetWidth();} if (right > ScreenWidth) {right = ScreenWidth;left = Right-v. GetWidth();} if (Top <0) {top =0;Bottom = top + V. GetHeight();} if (Bottom > screenheight) {bottom = ScreenHeight;top = Bottom-v. GetHeight();} V. Layout(left, top, right, bottom);LASTX = (int) event. GETRAWX();Lasty = (int) event. Getrawy();Dealing with bottomfragment float px = getresources (). Getdimension(R. Dimen. Bottomfrag_bar_height);int heightpixels = getactivity (). Getresources(). Getdisplaymetrics(). Heightpixels;if (Lasty > heightpixels-px) {mcallbacks. Ondragtoloction(Getresources (). getString(R. String. FA_trash_o));IsDeleted = True;}else{Mcallbacks. Ondragtoloction(Getresources (). getString(R. String. FA_floppy_o));IsDeleted = False;} Log. I(TAG,"ONTOUCH:LASTX ="+ lastx);Log. I(TAG,"ontouch:lasty ="+ lasty);} Break;Case Motionevent. ACTION_up:v. Layout(StartX, Starty, EndX, EndY);Islongclickmodule = False;if (isDeleted) {DELETECB (CB);} Log. I(TAG,"action_up:scrolly ="+ Mscrollview. getscrolly());Timer. Cancel();                     Break;This event is triggered when your finger (or other) moves the screen, such as when your finger drags a ListView or a scrollview on the screen instead of pressing the button above to trigger the event//Because the trigger starts at the root of the view tree, so Add v when you move.. GetParent(). Requestdisallowintercepttouchevent(true); this sentenceCase Motionevent. ACTION_cancel:islongclickmodule = False;V. Layout(StartX, Starty, EndX, EndY);if (isDeleted) {DELETECB (CB);}//timer. Cancel();                     Break;}} return False;}

1. 当ontouch return false的时候onTouch执行后会继续执行Onclick，onLongClick之类的函数，return true时就不会执行了，所以ACTION_DOWN的优先级是高于click的
2. 事件的派发总是自顶向下即先父布局在子布局，如果不想让父布局接受事件需要在恰当的位置添加v.getParent().requestDisallowInterceptTouchEvent(true);这样一句话
3.当你的手指（或者其它）移动屏幕的时候会触发这个事件，比如当你的手指在屏幕上拖动一个listView或者一个ScrollView而不是去按上面的按钮时会触发这个事件。

Tips for Android event distribution