How to have an image with a dynamic text in it, all in a drawable, like the “today” action item on Google Calendar app?

Question

Background

Google Calendar app has an action item that dynamically change according to the current day (\"today\"):

I\'m required to do a very similar

Answer 1

Reference is made to your other question "How to fully mimic Action item view in the toolbar, for a customized one?"

I have incorporated the approach in my answer to the above-referenced question into your implementation of a custom drawable in your answer to this question. Below is a new version of TextDrawable.java that dynamically builds a boxed TextView for display as the desired icon for a menu item. It avoids drawing caches and simply manages a TextView internally for display.

TextDrawable.java

public class TextDrawable extends Drawable {
    private final int mIntrinsicSize;
    private final TextView mTextView;

    public TextDrawable(Context context, CharSequence text) {
        mIntrinsicSize = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, DRAWABLE_SIZE,
                                                         context.getResources().getDisplayMetrics());
        mTextView = createTextView(context, text);
        mTextView.setWidth(mIntrinsicSize);
        mTextView.setHeight(mIntrinsicSize);
        mTextView.measure(mIntrinsicSize, mIntrinsicSize);
        mTextView.layout(0, 0, mIntrinsicSize, mIntrinsicSize);
    }

    private TextView createTextView(Context context, CharSequence text) {
        TextView textView = new TextView(context);
//        textView.setId(View.generateViewId()); // API 17+
        LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
            LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
        lp.gravity = Gravity.CENTER;
        textView.setLayoutParams(lp);
        textView.setGravity(Gravity.CENTER);
        textView.setBackgroundResource(R.drawable.ic_backtodate);
        textView.setTextColor(Color.WHITE);
        textView.setTextSize(TypedValue.COMPLEX_UNIT_DIP, DEFAULT_TEXT_SIZE);
        textView.setText(text);
        return textView;
    }

    public void setText(CharSequence text) {
        mTextView.setText(text);
        invalidateSelf();
    }

    @Override
    public void draw(@NonNull Canvas canvas) {
        mTextView.draw(canvas);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.OPAQUE;
    }

    @Override
    public int getIntrinsicWidth() {
        return mIntrinsicSize;
    }

    @Override
    public int getIntrinsicHeight() {
        return mIntrinsicSize;
    }

    @Override
    public void setAlpha(int alpha) {
    }

    @Override
    public void setColorFilter(ColorFilter filter) {
    }

    private static final int DRAWABLE_SIZE = 32; // device-independent pixels (DP)
    private static final int DEFAULT_TEXT_SIZE = 12; // device-independent pixels (DP)
}

Invoke this custom Drawable as follows (Kotlin):

mTextDrawable = TextDrawable(this, "1")
menu.add("goToToday").setIcon(mTextDrawable).setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS)

To change the displayed date (Kotlin):

mTextDrawable?.setText(i.toString())