使用自定义视图以编程方式向布局添加按钮会隐藏按钮

Question

我有一个自定义视图，我必须用手指绘制（就像在FingerPaint示例中一样）。

我尝试通过制作一个LinearLayout并向其添加所需的视图，以编程方式在此视图下方添加一个按钮。

但是，我看不到按钮本身。

我理解这是由于我实现了onMeasure而导致的问题，因为如果我恢复为默认值，则会显示按钮，但视图不会显示。

MainActivity Class

public class FingerPaintActivity extends Activity implements ColorPickerDialog.OnColorChangedListener
{

    MyView mv;
    AlertDialog dialog;
    ArrayList<Integer> colorList;
    private LinearLayout.LayoutParams params;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        LinearLayout layout = new LinearLayout(this);

        params = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);

        layout.setLayoutParams(params);

        Button submitButton = new Button(this);

        params = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);

        submitButton.setLayoutParams(params);
        submitButton.setGravity(Gravity.CENTER);
        submitButton.setText("Done");

        mv = new MyView(this);

        params = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT);

        mv.setLayoutParams(params);
        mv.setDrawingCacheEnabled(true);
        mv.setAdjustViewBounds(true);

        layout.addView(mv);
        layout.addView(submitButton);

        setContentView(layout);

        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
        mPaint.setColor(0xFFFF0000);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeWidth(6);

    }
    private Paint mPaint;

    @Override
    public void colorChanged(int color)
    {
        mPaint.setColor(color);
        Log.i("COLOR", color + "");
    }

    public class MyView extends ImageView
    {

        private Bitmap mBitmap, originalBitmap, originalNonResizedBitmap;
        private Canvas mCanvas;
        private Path mPath;
        private Paint mBitmapPaint;
        Context context;
        private BitmapFactory.Options options = new BitmapFactory.Options();

        public MyView(Context c)
        {
            super(c);
            context = c;
            mPath = new Path();
            mBitmapPaint = new Paint(Paint.DITHER_FLAG);
            options.inMutable = true;

            originalNonResizedBitmap = Bitmap.createBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.amsler_boundary, options));

            originalNonResizedBitmap = getResizedBitmap(originalNonResizedBitmap);

            originalBitmap = originalNonResizedBitmap.copy(Bitmap.Config.ARGB_8888, true);
            mBitmap = originalBitmap.copy(Bitmap.Config.ARGB_8888, true);

            mCanvas = new Canvas(mBitmap);

        }
        public MyView(Context context, AttributeSet attrs)
        {
            super(context, attrs);
        }

        @Override
        protected void onSizeChanged(int w, int h, int oldw, int oldh)
        {
            super.onSizeChanged(w, h, oldw, oldh);
            // mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);

            // mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
            mCanvas = new Canvas(mBitmap);

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

            canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);

            canvas.drawPath(mPath, mPaint);

        }

        private float mX, mY;
        private static final float TOUCH_TOLERANCE = 4;

        private void touch_start(float x, float y)
        {

            mPath.reset();
            mPath.moveTo(x, y);
            mX = x;
            mY = y;

        }
        private void touch_move(float x, float y)
        {
            float dx = Math.abs(x - mX);
            float dy = Math.abs(y - mY);
            if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE)
            {
                mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
                mX = x;
                mY = y;
            }
        }
        private void touch_up()
        {
            mPath.lineTo(mX, mY);
            // commit the path to our offscreen
            mCanvas.drawPath(mPath, mPaint);
            // kill this so we don't double draw
            mPath.reset();
            mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SCREEN));
            // mPaint.setMaskFilter(null);
        }

        @Override
        public boolean onTouchEvent(MotionEvent event)
        {
            float x = event.getX();
            float y = event.getY();

            switch (event.getAction())
            {
                case MotionEvent.ACTION_DOWN :

                    touch_start(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_MOVE :

                    touch_move(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_UP :
                    touch_up();
                    // Need to set null or clogs the Paint
                    mPaint.setXfermode(null);
                    invalidate();

                    break;
            }
            return true;
        }

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
        {

            int newWidthMeasure = MeasureSpec.makeMeasureSpec(mBitmap.getWidth(), MeasureSpec.EXACTLY);
            int newHeightMeasure = MeasureSpec.makeMeasureSpec(mBitmap.getHeight(), MeasureSpec.EXACTLY);

            setMeasuredDimension(newWidthMeasure, newHeightMeasure);

            // super.setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec),
            // MeasureSpec.getSize(heightMeasureSpec));
            // super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
        public void clearScreen()
        {
            mCanvas.drawColor(Color.TRANSPARENT);
            mCanvas.drawBitmap(originalBitmap, 0, 0, mBitmapPaint);
            invalidate();
        }

        public Rect getCoordinateRect()
        {
            return new Rect(0, 0, mBitmap.getWidth(), mBitmap.getHeight());
        }

    }

    public Bitmap getResizedBitmap(Bitmap bm)
    {
        int width = bm.getWidth();
        int height = bm.getHeight();

        WindowManager wm = (WindowManager) this.getSystemService(Context.WINDOW_SERVICE);
        Display display = wm.getDefaultDisplay();
        Point size = new Point();
        display.getSize(size);

        int newDimen = size.x;

        float scaleWidth = ((float) newDimen) / width;
        float scaleHeight = ((float) newDimen) / height;

        Matrix matrix = new Matrix();
        matrix.postScale(scaleWidth, scaleHeight);

        Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, false);
        return resizedBitmap;

    }

这是上面代码的布局：