android - my Custom View gets drawn only when added in onCreate

Question

I made a "GraphBar" custom view that is a RelativeLayout with a TextView on the bottom and an ImageView, varying in height, above that. Here is the code:

public class GraphBar extends RelativeLayout {

    private int mAvailHeight; // space for the bar (component minus label)
    private float mBarHeight; // 0.0-1.0 value

    public GraphBar(Context context) {
        this(context, null);
    }

    public GraphBar(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public GraphBar(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        LayoutInflater.from(context).inflate(R.layout.graphbar, this, true);
        setId(R.id.graphBar); // defined in <merge> but not assigned (?)
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        mAvailHeight = getHeight()-findViewById(R.id.label).getHeight();
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        super.onLayout(changed, l, t, r, b);

        View bar2 = findViewById(R.id.smallBar);
        RelativeLayout.LayoutParams llp2 = (RelativeLayout.LayoutParams) bar2.getLayoutParams();
        llp2.height = Math.round((float)mAvailHeight * mBarHeight);
    }

    public void setBarHeight(float value, float max) {
        mBarHeight = value / max;
        findViewById(R.id.smallBar).requestLayout();
    }

    public void setLabel(CharSequence c) {
        ((TextView) findViewById(R.id.label)).setText(c);
    }
}

While adding these GraphBars and setting their height in onCreate() works well, if I create them onClickSomething or call again setBarHeight() on the created bars, the only way to see changes is Load View Hierarchy. I've been told here that it means I need to call somewhere requestLayout(). Where else than after modifying mBarHeight? Any help? I tried everywhere, and with invalidate() too.

Thank you, Andrea

(if you need I can post the activity with which i do my tests and the graphbar.xml)

---

I've found it's probably a bug. The workaround should be, again, calling requestLayout(). Still i don't understand where i can put the call.

Answer 1

I've finally found a way to call again requestLayout(). I called setWillNotDraw(false) in the constructor so that in onDraw() (that is after onLayout()) I can call the extra requestLayout(). This generates a stupid cycle but solves the problem aesthetically.

If anyone knows a better solution, let me know... here the new code (modifies are next to comments):

//...
    public GraphBar(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        LayoutInflater.from(context).inflate(R.layout.graphbar, this, true);
        setWillNotDraw(false); // WORKAROUND: onDraw will be used to make the
                                // redundant requestLayout() call
        setId(R.id.graphBar);
    }
//...
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        // i think it's one of the worst workaround one could think of.
        // luckily android is smart enough to stop the cycle...
        findViewById(R.id.smallBar).requestLayout();
    }

    public void setBarHeight(float value, float max) {
        mBarHeight = value / max;
        View bar =   findViewById(R.id.smallBar);

        bar.requestLayout(); // because when we create this view onDraw is called...
        bar.invalidate();    // ...but not when we modify it!!!
                            //so we need to invalidate too
    }
//...