Android small counter next to a button

Question

I would like to add a small counter next to a button to show the remaining quantity for some items, for example, the remaining number of tips remaining unused. Targeted layout w

Answer 1

set Button's background Drawable to a custom Drawable like this one:

public class DecoratedTextViewDrawable extends LayerDrawable {
    private int mCnt = 0;
    private Paint mPaint;
    private TextView mParent;
    private ColorStateList mColors;
    private Rect mBounds;

    public DecoratedTextViewDrawable(TextView tv, Drawable[] layers, int cnt) {
        super(layers);
        mParent = tv;
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setTextAlign(Align.CENTER);
        mPaint.setTextSize(tv.getTextSize());
        mPaint.setTypeface(Typeface.DEFAULT_BOLD);
        int[][] states = {
                {android.R.attr.state_pressed}, {android.R.attr.state_focused}, {}
        };
        int[] colors = {
                0xff0000aa, 0xff880000, 0xff00aa00
        };
        mColors = new ColorStateList(states, colors);
        mBounds = new Rect();
        setCnt(cnt);
    }

    public void setCnt(int cnt) {
        mCnt = cnt;
        String s = Integer.toString(cnt);
        mPaint.getTextBounds(s, 0, s.length(), mBounds);
        invalidateSelf();
    }

    @Override
    protected boolean onStateChange(int[] state) {
        invalidateSelf();
        return super.onStateChange(state);
    }

    @Override
    public boolean isStateful() {
        return true;
    }

    @Override
    public void draw(Canvas canvas) {
        super.draw(canvas);

        float x = mPaint.getTextSize() * 1.5f;
        float r = mPaint.getTextSize() * 0.9f;
        int base = mParent.getBaseline();
        int[] stateSet = getState();
//        Log.d(TAG, "draw " + StateSet.dump(stateSet));
        int color = mColors.getColorForState(stateSet, 0xff000000);
        mPaint.setColor(color);
        canvas.drawCircle(x, base + mBounds.top + mBounds.height() / 2, r, mPaint);
        mPaint.setColor(0xffeeeeee);
        canvas.drawText(Integer.toString(mCnt), x, base, mPaint);
    }
}

you can use it like this:

// Activity.onCreate method
LinearLayout ll = new LinearLayout(this);
ll.setOrientation(LinearLayout.VERTICAL);

int NUM = 5;
final int[] cnt = new int[NUM];
Random r = new Random();
for (int i = 0; i < NUM; i++) {
    cnt[i] = r.nextInt(20);
    Button b = new Button(this);
    b.setText("Click me");
    b.setTextSize(18);
    b.setTag(i);

    Drawable[] layers = {b.getBackground()};
    Drawable d = new DecoratedTextViewDrawable(b, layers, cnt[i]);
    b.setBackgroundDrawable(d);
    OnClickListener l = new OnClickListener() {
        @Override
        public void onClick(View v) {
            DecoratedTextViewDrawable  d = (DecoratedTextViewDrawable) v.getBackground();
            int idx = (Integer) v.getTag();
            d.setCnt(++cnt[idx]);
        }
    };
    b.setOnClickListener(l);
    ll.addView(b);
}
setContentView(ll);