Open source Pull_to_refresh controls use

Learning Knowledge points

1. onTouchThe event delivery mechanism.
2. LisenterListening
3. ImageViewThe src background scaleType display of different properties.
4. onTouchThe slide lifted up the call MotionEvent.ACTION_CANCEL is not MotionEvent.ACTION_UP

Development steps

① Creating Activity Layout
② Inherit Viewpager Create Autoscrollviewpager
③ Display points
④ adding monitoring Onpagechangedlistener
⑤ Automatic scrolling
⑥ Stop scrolling when manual scrolling

Inherit Viewpager Create Autoscrollviewpager

public  Span class= "Hljs-class" >class  autoscrollviewpager  extends  viewpager   {
 
 //. xml  
 public  Span class= "Hljs-title" >autoscrollviewpager   (context context, AttributeSet attrs)   {
 super  (context, attrs); 
} 
 <com.itheima.autoscroll.view.autoscrollviewpager 
 Android:id= "@+id/sroll_ Viewpager " 
 Android:layout_width=" match_parent " 
 Android:layout_ Height= "match_parent"  
 Android:background= "# 47659E "/> 
  

Set dot

//Selector: Selector objects that manage footage display different pictures depending on the state of the press
 //Select=true false
 //view.setslected ()
 Privatelist<imageview> dots =NewArraylist<imageview> ();
 Public   void init(int pagenumber, linearlayout layoutdot) {
 //3
PageCount = pagenumber;
 //. XML
 //. Java
  for(inti =0; i < pagenumber; i++) {
ImageView img =NewImageView (GetContext ());
Img.setbackgroundresource (R.drawable.dot_selector);
Img.setselected (false);//Red
 //. XML Layout_width layout_height
 //. Java linearlayout.layoutparams Layout Parameters
Linearlayout.layoutparams p =NewLinearlayout.layoutparams (//
LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
 //. XML MarginRight
 //. Java rightMargin
P.rightmargin =6;
Layoutdot.addview (IMG, p);
Dots.add (IMG);
}
Dots.get (0). setselected (true);
 //Set content
Pageradapter adpater =NewImageviewadapter ();
  This. Setadapter (Adpater);//Pageadpater fragmentpageadapter

 //④ Adding monitoring Onpagechangedlistener
 //⑤ Auto-Scroll hold point synchronization
 //⑥ Stop Scrolling when manual scrolling
Onpagechangelistener listener =NewMyonpagechangelistener ();
  This. Setonpagechangelistener (listener);//Onpagechangelistener monitor swipe to page
}

Add a page Select Listen listen 同步

ViewPagecontrol the page's title and Dot synchronization by checking the status

Private  class Myonpagechangelistener implements Onpagechangelistener {
 @Override
 Public   void onpagescrollstatechanged(int arg0) {

}
 @Override
 Public   void onpagescrolled(int arg0, float arg1, int ARG2) {

}

 //Slide The first few pages
 @Override
 Public   void onpageselected(int arg0) {

 //3
 //0 1 2 3 4 5
 //Take -out operation
 //0 1 2->0 1 2
 //Old dot not lit
 if(islooping) {
Dots.get (currpageindex% pagecount). setselected (false);
 //New Point highlighting
Currpageindex = arg0;
Dots.get (currpageindex% pagecount). setselected (true);
}Else{
Dots.get (Currpageindex). setselected (false);
 //New Point highlighting
Currpageindex = arg0;
Dots.get (Currpageindex). setselected (true);
}

}

}

Private intCurrpageindex =0;

 Private  class imageviewadapter extends pageradapter {

 //Pages
 @Override
 Public   int getcount() {
 if(islooping) {
 returnInteger.max_value;
}Else{
 returnPageCount;
}
}

 @Override
 Public   boolean isviewfromobject(View arg0, Object arg1) {
 returnarg0 = = Arg1;
}

 //Current display view
 @Override
 Public   Object instantiateitem(ViewGroup container, int position) {
 //Create a displayed page is a picture
ImageView imag =NewImageView (GetContext ());
Imag.setbackgroundresource (R.drawable.home_scroll_default);
 //. XML Layout_width layout_height
 //. Java viewpager.layoutparams
Viewpager.layoutparams p =NewViewpager.layoutparams ();
P.width = ViewPager.LayoutParams.MATCH_PARENT;
P.height = ViewPager.LayoutParams.MATCH_PARENT;
Container.addview (Imag, p);


 returnImag
}

 //Remove display

 @Override
 Public   void destroyitem(ViewGroup container, int position, object object)  {
Container.removeview ((ImageView) object);
}

}

Automatic Carousel

principle: by Handle sending a delay message. Implementations similar to recursion

2.4. Auto Scroll
//Support unlimited sliding
 Private BooleanIslooping =false;
 Public   void setlooping(boolean flag) {
islooping = Flag;
}
 PrivateHandler Handler =NewHandler () {
 ///callback function: 1. Override 2. System or other object invocation
 // on
 Public   void handlemessage(android.os.Message msg) {
 if(Msg.what = =1) {
LOG.I ("WZX","Switch to next page");
 //Switch to next page
 intCurr = Getcurrentitem ();
++curr;
Setcurrentitem (Curr);//Display specified page
 //Rewrite to send a message to yourself
 //Message msg=new message ();
Message MSG2 = Handler.obtainmessage ();//Obtain=get is an optimized notation
 //Internally Find reusable message if there is no reuse to create new. 
Msg2.what =1;
Handler.sendmessagedelayed (MSG2, the);//---->handlemessage
 //Cyclic transmission of interest
}
};
};

 //Support auto Play
 //exposed to outside calls. 
 Public   void startscroll() {
 //
 //Message msg=new message ();
Message msg = Handler.obtainmessage ();//Obtain=get is an optimized notation
 //Internally Find reusable message if there is no reuse to create new. 
Msg.what =1;
Handler.sendmessagedelayed (MSG, the);//---->handlemessage

}

 /**
* Stop Playing
*/
 Public   void stopscroll() {
 //Clear All messages Handlemessage will not execute
 //Use callback function without condition to satisfy
Handler.removecallbacksandmessages (NULL);//

}

Stop scrolling when manual scrolling

Ontouchlistener listener =NewMyontouchlistener ();
Imag.setontouchlistener (listener);

 Private  class Myontouchlistener implements Ontouchlistener {

 Private intDownx =0;
 Private LongDowntime =0;

 //Motionevent location Change small rocket
 @Override
 Public   boolean onTouch(View V, motionevent event) {
 Switch(Event.getaction ()) {//Get Action
  CaseMotionevent.action_down://Press
Stopscroll ();
Downx = (int) Event.getx ();//Get on the inferior
Downtime = System.currenttimemillis ();//Save press time
LOG.I ("WZX","Action_down");
  Break;
  CaseMotionevent.action_move://Mobile
LOG.I ("WZX","Action_move");
  Break;
  CaseMOTIONEVENT.ACTION_UP://Filed
LOG.I ("WZX","Action_up");
 intUpX = (int) Event.getx ();
 if(Downx = = UpX && system.currenttimemillis ()-Downtime < -) {

 //Use command design mode to add an interface as a listener
 //1. Creating interface
 //2. Abstract method (extract code to remove method body)
 //3. Adding listeners
 //4. The listener is to be called. 
 //Let the developer write the code in the Listener (outside the control)
//Onitemclick ();
 if(listener!=NULL)
{
Listener.onitemclick ();//code inside the method
}
}
Startscroll ();
  Break;
  CaseMotionevent.action_cancel://Cancel
LOG.I ("WZX","Action_cancel");
Startscroll ();
  Break;
}
 return true;//Return value handling this event returns True
}


}

Stand-alone callback CommandDesign Patterns

principle:

1. Setting the listener interface, defining the method

private OnViewClickListener listener ;
publicinterface OnViewClickListener 
 {
public void onViewClick();
}

2. Setting the Listening method

public void setOnViewClickListener(OnViewClickListener listener)
 {
this.listener = listener;
}

3. ACTION_UPinvoke callback method on touch

case MotionEvent.ACTION_UP:
startScroll();
//保证是单机，
if(dowx == event.getX() & System.currentTimeMillis() - mDownTimel<300)
{
//回调事件
listener.onViewClick();
}

break;

Open source Pull_to_refresh controls use