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POHow to draw ball using onDraw() in android
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copied!<p>This class use to draw ball but its onDraw() function not call so ball not draw</p> <pre><code>package com.bounce.app; import org.jbox2d.collision.AABB; import org.jbox2d.collision.shapes.CircleDef; import org.jbox2d.collision.shapes.PolygonDef; import org.jbox2d.common.Vec2; import org.jbox2d.dynamics.Body; import org.jbox2d.dynamics.BodyDef; import org.jbox2d.dynamics.World; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Paint.Style; import android.util.Log; import android.view.MotionEvent; import android.view.SurfaceHolder; import android.view.SurfaceView; public class PhysicsWorld extends SurfaceView implements SurfaceHolder.Callback { private AABB worldAABB; private World world; private PolygonDef groundShapeDef; public int W_width, W_height; private static final String TAG = PhysicsWorld.class.getSimpleName(); protected static final int GUIUPDATEIDENTIFIER = 0x231; public int targetFPS = 40; public float timeStep = (10.0f/targetFPS); public int iterations = 5; private int count=0; private Body[] theBodies ; private Paint paint; private float radius = 10; public PhysicsWorld(Context context, int width, int height) { super(context); getHolder().addCallback(this); W_width = width; W_height = height; worldAABB = new AABB(); Vec2 min = new Vec2(-50, -50); Vec2 max = new Vec2(W_width+50, W_height+50); worldAABB.lowerBound.set(min); worldAABB.upperBound.set(max); Vec2 gravity = new Vec2((float) 0.0, (float) -9.8); boolean doSleep = true; world = new World(worldAABB, gravity, doSleep); BodyDef groundBodyDef = new BodyDef(); groundBodyDef.position.set(new Vec2((float) 0.0, (float) -10.0)); Body groundBody = world.createBody(groundBodyDef); groundShapeDef = new PolygonDef(); groundShapeDef.setAsBox(W_width, 10); groundBody.createShape(groundShapeDef); // up : groundBodyDef = new BodyDef(); groundBodyDef.position.set(new Vec2((float) 0.0, (float) (W_height + 10.0))); groundBody = world.createBody(groundBodyDef); groundShapeDef = new PolygonDef(); groundShapeDef.setAsBox(W_width, 10); groundBody.createShape(groundShapeDef); // left : groundBodyDef = new BodyDef(); groundBodyDef.position.set(new Vec2(-10, (float) 0.0)); groundBody = world.createBody(groundBodyDef); groundShapeDef = new PolygonDef(); groundShapeDef.setAsBox(10, W_height); groundBody.createShape(groundShapeDef); // right : groundBodyDef = new BodyDef(); groundBodyDef.position.set(new Vec2((float) W_width + 10, (float) 0.0)); groundBody = world.createBody(groundBodyDef); groundShapeDef = new PolygonDef(); groundShapeDef.setAsBox(10, W_height); groundBody.createShape(groundShapeDef); theBodies = new Body[50]; paint = new Paint(); paint.setStyle(Style.FILL); paint.setColor(Color.RED); } public void addBall(int x, int y) { // Create Dynamic Body BodyDef bodyDef = new BodyDef(); bodyDef.position.set(x, y); Log.d(TAG,"Ball Created At: " + Integer.toString(x) + "," + Integer.toString(y)); theBodies[count] = world.createBody(bodyDef); // Create Shape with Properties CircleDef circle = new CircleDef(); circle.radius = radius; circle.density = (float) 1.0; circle.restitution = 0.5f; theBodies[count].createShape(circle); theBodies[count].setMassFromShapes(); count+=1; } public void update() { world.step(timeStep, iterations); postInvalidate(); } @Override protected void onDraw(Canvas canvas) { Log.v("@@@@*****", "draw ball"); paint = new Paint(); paint.setStyle(Style.FILL); paint.setColor(Color.RED); for (int j = 0; j < count; j++) { canvas.drawCircle(theBodies[j].getPosition().x, W_height - theBodies[j].getPosition().y, radius, paint); Log.v("@@@@*****", "draw ball"); } } @Override public boolean onTouchEvent(MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: Log.v("@@@@*****", "Add ball"); addBall((int)event.getX(),(int)event.getY()); } return true; } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { // TODO Auto-generated method stub } @Override public void surfaceCreated(SurfaceHolder holder) { Log.d(TAG,"Surface Created"); } @Override public void surfaceDestroyed(SurfaceHolder holder) { // TODO Auto-generated method stub } } </code></pre>

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