[Android ] SurfaceView-Vẽ hình tròn khi chạm lên màn hình
1.Tạo 1 project android với tên “GraphicsDrawPointSurfaceView”
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6. Tạo 1 class mới tên PaintSurface src/in/wptrafficanalyzer/graphicsdrawpointsurfaceview/PaintSurface.java với nội dung như sau.
7. file res/layout/activity_main.xml
8. src/in/wptrafficanalyzer/graphicsdrawpointsurfaceview/MainActivity.java
9.Ảnh chụp Demo
Figure 1 : Create new Android application project
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Figure 2 : Configure the project
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Figure 3 : Design application launcher icon
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Figure 4 : Create a blank activity
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Figure 5 : Enter MainActivity details
6. Tạo 1 class mới tên PaintSurface src/in/wptrafficanalyzer/graphicsdrawpointsurfaceview/PaintSurface.java với nội dung như sau.
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| package in.wptrafficanalyzer.graphicsdrawpointsurfaceview;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.SurfaceHolder;import android.view.SurfaceView;import android.view.View;import android.view.View.OnTouchListener;public class PaintSurface extends SurfaceView implements Runnable, OnTouchListener{ // Surface holder allows to control and monitor the surface private SurfaceHolder mHolder; // A thread where the painting activities are taking place private Thread mThread; // A flag which controls the start and stop of the repainting of the SurfaceView private boolean mFlag = false; // X coordinate of the touched position private float mX; // Y Coordinate of the touched position private float mY; // Paint private Paint mPaint; public PaintSurface(Context context, AttributeSet attrs) { super(context, attrs); // Getting the holder mHolder = getHolder(); // Initializing the X position mX = -100; // Initializing the Y position mY = -100; // Initializing the paint object mPaint mPaint = new Paint(); // Setting the color for the paint object mPaint.setColor(Color.BLUE); } public void resume(){ // Instantiating the thread mThread = new Thread(this); // setting the mFlag to true for start repainting mFlag = true; // Start repaint the SurfaceView mThread.start(); } public void pause(){ mFlag = false; } @Override public boolean onTouch(View v, MotionEvent event) { switch(event.getAction()){ case MotionEvent.ACTION_DOWN: // Getting the X-Coordinate of the touched position mX = event.getX(); // Getting the Y-Coordinate of the touched position mY = event.getY(); break; } return true; } @Override public void run() { while(mFlag){ // Check whether the object holds a valid surface if(!mHolder.getSurface().isValid()) continue; // Start editing the surface Canvas canvas = mHolder.lockCanvas(); // Draw a background color canvas.drawARGB(255, 255, 255, 255); // Draw a circle at (mX,mY) with radius 5 canvas.drawCircle(mX, mY, 5, mPaint); // Finish editing the canvas and show to the user mHolder.unlockCanvasAndPost(canvas); } }} |
7. file res/layout/activity_main.xml
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| android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" > <in.wptrafficanalyzer.graphicsdrawpointsurfaceview.PaintSurface android:id="@+id/paint_surface" android:layout_width="fill_parent" android:layout_height="fill_parent" /></RelativeLayout> |
8. src/in/wptrafficanalyzer/graphicsdrawpointsurfaceview/MainActivity.java
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| package in.wptrafficanalyzer.graphicsdrawpointsurfaceview;import android.app.Activity;import android.os.Bundle;import android.view.Menu;public class MainActivity extends Activity { PaintSurface mPaintSurface; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Getting reference to the PaintView mPaintSurface = (PaintSurface)findViewById(R.id.paint_surface); // Setting the touch listener mPaintSurface.setOnTouchListener(mPaintSurface); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } @Override protected void onResume() { super.onResume(); mPaintSurface.resume(); } @Override protected void onPause() { super.onPause(); mPaintSurface.pause(); }} |
9.Ảnh chụp Demo
Figure 6 : Screenshot of the application in execution
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