在 Android XML 布局中，我可以使用子视图或视图组为父视图的一部分背景着色吗？

Question

I currently have the following layout as part of my XML file:

LinearLayout (orientation: vertical)
+---TextView (title)
+---LinearLayout (orientation: horizontal)
    +---ConstraintLayout
        +---...
    +---ConstraintLayout
        +---...
    +---ConstraintLayout
        +---...

The parent LinearLayout has a background that is a drawable.

My intention is to have the child TextView and child LinearLayout tint a part of said parent LinearLayout 's background each with different colors.

I've tried the backgroundTint and foregroundTint attributes in both the child layouts, but neither changed the parent LinearLayout 's drawable in any way.

So, is there any way I can do what I asked in the title, or am I stuck subclassing the LinearLayout and overriding the onDraw function?

Answer 1

Yup, I'm stuck with using the ViewGroup 's onDraw function:

public class PartialTintedRoundedRectLinearLayout extends LinearLayout {

    Context ctx;
    RectF topPartitionRect, botPartitionRect;
    RectF topBandAidRect, botBandAidRect;
    Paint bgTopPaint, bgBotPaint;

    int defaultCornerRadius;
    float material30sdp;

    public PartialTintedRoundedRectLinearLayout(Context c) {
        super(c);
        init(c);
    }

    public PartialTintedRoundedRectLinearLayout(Context c, AttributeSet a) {
        super(c, a);
        init(c);
    }

    public PartialTintedRoundedRectLinearLayout(Context c, AttributeSet a, int dsAttr) {
        super(c, a, dsAttr);
        init(c);
    }

    private void init(Context c) {
        setWillNotDraw(false);
        ctx = c;
        defaultCornerRadius = (int)(20 * ctx.getResources().getDisplayMetrics().density);
        material30sdp = ctx.getResources().getDimension(R.dimen._30sdp);
        bgTopPaint = new Paint(); bgTopPaint.setColor(ContextCompat.getColor(ctx, R.color.blue_700));
        bgBotPaint = new Paint(); bgBotPaint.setColor(ContextCompat.getColor(ctx, R.color.blue_500));
        getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                topPartitionRect = new RectF(0, 0, getWidth(), material30sdp);
                topBandAidRect = new RectF(0, defaultCornerRadius, getWidth(), material30sdp);
                botPartitionRect = new RectF(0, material30sdp, getWidth(), getHeight());
                botBandAidRect = new RectF(0, material30sdp, getWidth(), getHeight() - defaultCornerRadius);
                invalidate();
                getViewTreeObserver().removeOnGlobalLayoutListener(this);
            }
        });
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawRoundRect(topPartitionRect, defaultCornerRadius, defaultCornerRadius, bgTopPaint);
        canvas.drawRoundRect(botPartitionRect, defaultCornerRadius, defaultCornerRadius, bgBotPaint);
        canvas.drawRect(topBandAidRect, bgTopPaint);
        canvas.drawRect(botBandAidRect, bgBotPaint);
    }
}

I'll have to figure out how to make it more general, since this was made for one specific use-case.