Android custom components automatically draw circles with your fingers

First, customize a view subclass:

Package Com.example.androidtest0.myview;import Android.content.context;import android.graphics.canvas;import Android.graphics.color;import Android.graphics.paint;import Android.util.attributeset;import Android.view.motionevent;import Android.view.View; Public classDrawview extends View { Public floatCurrentX = +;  Public floatCurrentY = -; //define, and create brushesPaint p =NewPaint ();  PublicDrawview (Context context) {super (context); }     PublicDrawview (Context context, AttributeSet Attrs) {Super (context, attrs); } @Overrideprotected voidOnDraw (canvas canvas) {super.ondraw (canvas); //set the color of a brushP.setcolor (color.red); //draw a small ballCanvas.drawcircle (CurrentX, CurrentY, the, p); }        /** * Override event handling method for touch event of this component*/@Override PublicBoolean ontouchevent (motioneventEvent) {        //Modify CurrentX, currenty two propertiesCurrentX =Event. GetX (); CurrentY=Event. GetY (); //notifies the current component to redraw itselfinvalidate (); return true; }}

Main interface xml:

Custom_layout.xml

<pre name="Code" class="Java"><?xml version="1.0"encoding="Utf-8"? ><linearlayout xmlns:android="http://schemas.android.com/apk/res/android"Android:layout_width="match_parent"Android:layout_height="match_parent"Android:id="@+id/root"android:orientation="Vertical"></LinearLayout>

The main activity file is as follows:

Package Com.example.androidtest0;import Com.example.androidtest0.myview.drawview;import android.app.Activity; Import Android.os.bundle;import android.widget.LinearLayout;  Public class CustomView extends Activity {    @Override    protectedvoid  onCreate (Bundle Savedinstancestate) {        super.oncreate (savedinstancestate);        Setcontentview (r.layout.custom_layout);    }}

Effect:

Besides:

It can also be done in XML: It is also the first subclass of a view, as in the above. Then the main interface XML is as follows:

<?xml version="1.0"encoding="Utf-8"? ><linearlayout xmlns:android="http://schemas.android.com/apk/res/android"Android:layout_width="match_parent"Android:layout_height="match_parent"Android:id="@+id/root"android:orientation="Vertical"> <Com.example.androidtest0.myView.DrawView android:layout_width="match_parent"android:layout_height="match_parent"/></linearlayout>

The main activity file is as follows:

Package Com.example.androidtest0;import Com.example.androidtest0.myview.drawview;import android.app.Activity; Import Android.os.bundle;import android.widget.LinearLayout;  Public class CustomView extends Activity {    @Override    protectedvoid  onCreate (Bundle Savedinstancestate) {        super.oncreate (savedinstancestate);        Setcontentview (r.layout.custom_layout);    }}

Android custom components automatically draw circles with your fingers