使用Canvas和SurfaceView绘制速度非常慢

Question

我创建了一个Android 5.1应用程序，我可以使用SurfaceView和Canvas在平板电脑上使用手写笔编写。你可以在下面找到我的代码。不幸的是，写作速度非常慢，特别是当写入大量文本时，它开始变慢。我认为问题是它是用软件渲染的。当然，加速的可能性是使用OpenGL，但我不知道它，我认为这对我来说有一个太陡峭的学习曲线。

然而，是否有可能加速我的代码（即在写作时使其更负责任）？或者将代码更改为OpenGL很容易吗？

public class DrawingView extends SurfaceView implements OnTouchListener {
    private Bitmap mBitmap;
    private Canvas m_Canvas;
    private Path m_Path;
    private Paint m_Paint;
    private ArrayList<Pair<Path, Paint>> paths = new ArrayList<>();
    private float mX, mY;
    private static final float TOUCH_TOLERANCE = 4;
    private boolean isEraserActive = false;
    private int pathCount = 0;
    private View rectangleView;

    public DrawingView(Context context, AttributeSet attr) {
        super(context, attr);

        setFocusable(true);
        setFocusableInTouchMode(true);
        setBackgroundColor(Color.TRANSPARENT);
        this.setOnTouchListener(this);
        onCanvasInitialization();
        setAlpha(0.99f);
    }

    public void onCanvasInitialization() {
        m_Paint = new Paint();
        m_Paint.setAntiAlias(true);
        m_Paint.setDither(true);
        m_Paint.setColor(Color.parseColor("#000000"));
        m_Paint.setStyle(Paint.Style.STROKE);
        m_Paint.setStrokeJoin(Paint.Join.ROUND);
        m_Paint.setStrokeCap(Paint.Cap.ROUND);
        m_Paint.setStrokeWidth(2);

        m_Path = new Path();
        Paint newPaint = new Paint(m_Paint);
        paths.add(new Pair<>(m_Path, newPaint));
    }

    @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_4444);
        m_Canvas = new Canvas(mBitmap);
    }

    @Override
    public boolean onTouch(View arg0, MotionEvent event) {
        float x = event.getX();
        float y = event.getY();

        if (rectangleView != null) {
            ConstraintLayout.LayoutParams params = (ConstraintLayout.LayoutParams) rectangleView.getLayoutParams();
            params.leftMargin = (int) x;
            params.topMargin = (int) y;
            rectangleView.setLayoutParams(params);
            return true;
        } else {
            if (event.getToolType(0) == MotionEvent.TOOL_TYPE_ERASER) {
                isEraserActive = true;
            } else {
                isEraserActive = false;
            }

            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();
                    invalidate();
                    break;
            }
            return true;
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        for (Pair<Path, Paint> p : paths) {
            canvas.drawPath(p.first, p.second);
        }
    }

    private void touch_start(float x, float y) {
        if (isEraserActive) {
            m_Paint.setStrokeWidth(20);
            m_Paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
            Paint newPaint = new Paint(m_Paint);
            paths.add(new Pair<>(m_Path, newPaint));
        } else { 
            m_Paint.setColor(Color.BLACK);
            m_Paint.setStrokeWidth(2);
            m_Paint.setXfermode(null);
            Paint newPaint = new Paint(m_Paint);
            paths.add(new Pair<>(m_Path, newPaint));
            pathCount++;
        }

        m_Path.reset();
        m_Path.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) {
            m_Path.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
            mX = x;
            mY = y;
        }
    }

    private void touch_up() {
        m_Path.lineTo(mX, mY);
        m_Canvas.drawPath(m_Path, m_Paint);
        m_Path = new Path();
        Paint newPaint = new Paint(m_Paint);
        paths.add(new Pair<>(m_Path, newPaint));
    }

    public void reset() {
        for (Pair<Path, Paint> p : paths) {
            p.first.reset();
        }
        paths.clear();
        pathCount = 0;
        mBitmap.eraseColor(Color.TRANSPARENT);
        invalidate();
    }
}