Android Multi-Touch (Image Zoom Demo)

This article mainly describes the Android multi-touch, using a picture scaling example, to better explain its principle. You need to implement the Ontouchlistener interface, overriding the Ontouch method.

Realize:

Source:

Layout file:

Activity_main:

<relativelayout xmlns:android= "http://schemas.android.com/apk/res/android"    xmlns:tools= "http// Schemas.android.com/tools "    android:id=" @+id/layout "    android:layout_width=" Match_parent "    android: layout_height= "Match_parent" >    <imageview        android:id= "@+id/imageview"        android:layout_width= " Wrap_content "        android:layout_height=" wrap_content "        android:src=" @drawable/ic_launcher "/></ Relativelayout>

Code:

Package Com.multitouch;import Android.app.activity;import Android.os.bundle;import android.util.log;import Android.view.motionevent;import Android.view.view;import Android.view.view.ontouchlistener;import Android.widget.imageview;import Android.widget.relativelayout;import Android.widget.RelativeLayout.LayoutParams /** * Multi-Touch Demo instance: Image zoom. * */public class Mainactivity extends Activity {private Relativelayout layout;protected String TAG = "Zhongyao";p rivate I Mageview imageview;private float currentdistance;private float lastdistance =-1; @Overrideprotected void OnCreate ( Bundle savedinstancestate) {super.oncreate (savedinstancestate); Setcontentview (r.layout.activity_main); layout = ( Relativelayout) Findviewbyid (r.id.layout); ImageView = (ImageView) Findviewbyid (R.id.imageview); Layout.setontouchlistener (New Ontouchlistener () {@Overridepublic Boolean onTouch (View V, motionevent event) {switch ( Event.getaction ()) {/** * finger press */case motionevent.action_down:log.d (TAG, "down!!!"); break;/** * FingerMobile */case MOTIONEVENT.ACTION_MOVE:LOG.D (TAG, "Move!!!"); * * * First to determine whether the number of fingers is greater than two. * If greater than two, do the following (that is, the zoom action of the picture). */if (Event.getpointercount () >= 2) {Float OffsetX = event.getx (0)-event.getx (1); float OffsetY = event.gety (0)-even T.gety (1);/** * Distance difference between origin and sliding point */currentdistance = (float) math.sqrt (OffsetX * offsetx+ OffsetY * OffsetY); if (Lastdistance & Lt 0) {lastdistance = currentdistance;} else {/** * If the current sliding distance (currentdistance) is greater than 5 inches (or other dimensions) compared to the last recorded distance (lastdistance). * Then real picture magnification */if (Currentdistance-lastdistance > 5) {log.d (TAG, "Zoom In!!! "); Relativelayout.layoutparams LP = (layoutparams) imageview.getlayoutparams ();/** * The picture is enlarged one time to 1.1 times times the original picture (and of course, it can be a different value). */lp.width = (int) (Imageview.getwidth () * 1.1); lp.height = (int) (Imageview.getheight () * 1.1); IMAGEVIEW.SETLAYOUTPARAMS (LP); lastdistance = currentdistance;/** * If the last recorded distance (lastdistance) is less than 5 inches compared to the current sliding distance (currentdistance), * then the picture shrinks. */} else if (Lastdistance-currentdistance > 5) {log.d (TAG, "Zoom Out!!! "); Relativelayout.layoutparams LP = (Layoutparams) imageview.getlayoutparams ();/** * Picture width is 0.9 times times smaller than the original picture. */lp.width = (int) (Imageview.getwidth () * 0.9); lp.height = (int) (Imageview.getheight () * 0.9); IMAGEVIEW.SETLAYOUTPARAMS (LP); lastdistance = Currentdistance;}}} break;/** * Finger lift */case motionevent.action_up:log.d (TAG, "UP!!!"); break;} return true;}});}}

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