Question

public class CheckedTextView extends TextView implements Checkable {
    private boolean mChecked;
    private int mCheckMarkResource;
    private Drawable mCheckMarkDrawable;
    private int mBasePaddingRight;
    private int mCheckMarkWidth;

    private static final int[] CHECKED_STATE_SET = {
        R.attr.state_checked
    };

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

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

    public CheckedTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        TypedArray a = context.obtainStyledAttributes(attrs,
                R.styleable.CheckedTextView, defStyle, 0);

        Drawable d = a.getDrawable(R.styleable.CheckedTextView_checkMark);
        if (d != null) {
            setCheckMarkDrawable(d);
        }

        boolean checked = a.getBoolean(R.styleable.CheckedTextView_checked, false);
        setChecked(checked);

        a.recycle();
    }

    public void toggle() {
        setChecked(!mChecked);
    }

    @ViewDebug.ExportedProperty
    public boolean isChecked() {
        return mChecked;
    }

    /**
     * <p>Changes the checked state of this text view.</p>
     *
     * @param checked true to check the text, false to uncheck it
     */
    public void setChecked(boolean checked) {
        if (mChecked != checked) {
            mChecked = checked;
            refreshDrawableState();
        }
    }


    /**
     * Set the checkmark to a given Drawable, identified by its resourece id. This will be drawn
     * when {@link #isChecked()} is true.
     * 
     * @param resid The Drawable to use for the checkmark.
     */
    public void setCheckMarkDrawable(int resid) {
        if (resid != 0 && resid == mCheckMarkResource) {
            return;
        }

        mCheckMarkResource = resid;

        Drawable d = null;
        if (mCheckMarkResource != 0) {
            d = getResources().getDrawable(mCheckMarkResource);
        }
        setCheckMarkDrawable(d);
    }

    /**
     * Set the checkmark to a given Drawable. This will be drawn when {@link #isChecked()} is true.
     *
     * @param d The Drawable to use for the checkmark.
     */
    public void setCheckMarkDrawable(Drawable d) {
        if (mCheckMarkDrawable != null) {
            mCheckMarkDrawable.setCallback(null);
            unscheduleDrawable(mCheckMarkDrawable);
        }
        if (d != null) {
            d.setCallback(this);
            d.setVisible(getVisibility() == VISIBLE, false);
            d.setState(CHECKED_STATE_SET);
            setMinHeight(d.getIntrinsicHeight());

            mCheckMarkWidth = d.getIntrinsicWidth();
            mPaddingRight = mCheckMarkWidth + mBasePaddingRight;
            d.setState(getDrawableState());
        } else {
            mPaddingRight = mBasePaddingRight;
        }
        mCheckMarkDrawable = d;
        requestLayout();
    }

    @Override
    public void setPadding(int left, int top, int right, int bottom) {
        super.setPadding(left, top, right, bottom);
        mBasePaddingRight = mPaddingRight;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        final Drawable checkMarkDrawable = mCheckMarkDrawable;
        if (checkMarkDrawable != null) {
            final int verticalGravity = getGravity() & Gravity.VERTICAL_GRAVITY_MASK;
            final int height = checkMarkDrawable.getIntrinsicHeight();

            int y = 0;

            switch (verticalGravity) {
                case Gravity.BOTTOM:
                    y = getHeight() - height;
                    break;
                case Gravity.CENTER_VERTICAL:
                    y = (getHeight() - height) / 2;
                    break;
            }

            int right = getWidth();
            checkMarkDrawable.setBounds(
                    right - mCheckMarkWidth - mBasePaddingRight, 
                    y, 
                    right - mBasePaddingRight, 
                    y + height);
            checkMarkDrawable.draw(canvas);
        }
    }

    @Override
    protected int[] onCreateDrawableState(int extraSpace) {
        final int[] drawableState = super.onCreateDrawableState(extraSpace + 1);
        if (isChecked()) {
            mergeDrawableStates(drawableState, CHECKED_STATE_SET);
        }
        return drawableState;
    }

    @Override
    protected void drawableStateChanged() {
        super.drawableStateChanged();

        if (mCheckMarkDrawable != null) {
            int[] myDrawableState = getDrawableState();

            // Set the state of the Drawable
            mCheckMarkDrawable.setState(myDrawableState);

            invalidate();
        }
    }

    @Override
    public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
        boolean populated = super.dispatchPopulateAccessibilityEvent(event);
        if (!populated) {
            event.setChecked(mChecked);
        }
        return populated;
    }
}

As indicated above, checkMarkDrawable is Gravity position in the Canvas to determine the location.
My question is: How can change checkMarkDrawable the location, for example to set checkMarkDrawable in a TextView on the left.

Answer 1

Use drawableRight instead of checkMarkDrawable in xml.