Your Court.onDraw() function will not get called by default for
efficiency. You need to call setWillNotDraw(false) to enable it.
--
Jack Ha
Open Source Development Center
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On Jul 7, 5:30 am, Carl <carl...@gmail.com> wrote:
> I'm trying to do some simple UI stuff in a game (Basketball).
>
> I've created my own Court class (which extends ViewGroup) and I want
> to add a Ball (extends View) to the court.
>
> Unfortunately my ball doesn't show up on the court, and in fact the
> court doesn't draw either.
>
> What have I done wrong?
>
> package test.com;
>
> import android.app.Activity;
> import android.os.Bundle;
> import android.view.ViewGroup.LayoutParams;
> import android.widget.FrameLayout;
> import android.widget.LinearLayout;
>
> public class test extends Activity
> {
> /** Constants */
> final int FPAR = LinearLayout.LayoutParams.FILL_PARENT;
>
> private FrameLayout main;
>
> /** Called when the activity is first created. */
> @Override
> public void onCreate(Bundle savedInstanceState)
> {
> super.onCreate(savedInstanceState);
> this.addContentView(new Court(this), new LayoutParams(FPAR,
> FPAR));
> }
>
> }
>
> package test.com;
>
> import android.content.Context;
> import android.graphics.Canvas;
> import android.graphics.Color;
> import android.graphics.Paint;
> import android.graphics.Rect;
> import android.view.ViewGroup;
>
> public class Court extends ViewGroup
> {
> // court dimensions
> private int height = 0;
> private int width = 0;
> private Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
>
> // ball
> Ball ball;
>
> public Court(Context context)
> {
> super(context);
> }
>
> @Override
> public void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
> {
> super.onMeasure(widthMeasureSpec, heightMeasureSpec);
>
> // fix the sizes here
> height = this.getMeasuredHeight();
> width = this.getMeasuredWidth();
> this.layout(0, 0, width, height);
>
> // create a new ball
> ball = new Ball(this, 100, 100, 20, Color.RED);
>
> // put a ball on the court
> this.addView(ball);
> }
>
> @Override
> public void onDraw(Canvas canvas)
> {
> paint.setColor(Color.RED);
> Rect rect = new Rect(this.getLeft(), this.getTop(), width,
> height);
> canvas.drawRect(rect, paint);
> // tell the ball to draw itself
> ball.draw(canvas);
> }
>
> @Override
> protected void onLayout(boolean changed, int l, int t, int r, int b)
> {
> // TODO Auto-generated method stub
> }
>
> }
>
> package test.com;
>
> import android.graphics.Canvas;
> import android.graphics.Paint;
> import android.view.MotionEvent;
> import android.view.View;
>
> public class Ball extends View
> {
> private int x;
> private int y;
> private int r;
> private Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
>
> public Ball(Court court, int x, int y, int r, int color)
> {
> super(court.getContext());
> mPaint.setColor(color);
> this.x = x;
> this.y = y;
> this.r = r;
> this.layout(this.x, this.y, this.x + (r * 2), this.y + (2 *
> r));
> this.setOnTouchListener(this.ballTouchListener);
> }
>
> private OnTouchListener ballTouchListener = new OnTouchListener()
> {
> @Override
> public boolean onTouch(View view, MotionEvent event)
> {
> // get the location of the click
> int X = (int)event.getRawX();
> int Y = (int)event.getRawY();
>
> Ball ball = (Ball)view;
>
> // do stuff, depending on what type of touch motion
> is occurring
> switch (event.getAction())
> {
> case MotionEvent.ACTION_DOWN:
> break;
> case MotionEvent.ACTION_MOVE:
> ball.layout(X, Y, X +
> ball.getWidth(), Y + ball.getHeight());
> break;
> case MotionEvent.ACTION_UP:
> break;
> }
> return true;
> }
> };
>
> @Override
> protected void onDraw(Canvas canvas)
> {
> super.onDraw(canvas);
> canvas.drawCircle(this.getLeft(), this.getTop(), this.r,
> mPaint);
> }
>
> }
>
>
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