android - 如何绘制平滑的位图路径，没有任何中断

Question

我正在开发一个绘图应用程序，我想绘制一个位图路径 我的代码是这样的:

	private void onCanvasInitialization() {
		// Main_Activity.paintButton.setEnabled(true);

		mPaint = new Paint();
		BlurMaskFilter bmf = new BlurMaskFilter(2, Blur.OUTER);
		mPaint.setAntiAlias(true);
		mPaint.setDither(true);
		mPaint.setFilterBitmap(true);
		mPaint.setColor(Main_Activity.colorchanger);
		mCanvas = new Canvas();
		mPath = new Path();
		mPaint.setStyle(Paint.Style.STROKE);
	mPaint.setMaskFilter(bmf);
		mPaint.setStrokeJoin(Paint.Join.ROUND);
		mPaint.setStrokeCap(Paint.Cap.ROUND);
		mPaint.setAlpha(255);
		bmp = Bitmap.createScaledBitmap(bmp, 30, 30, false);
		bmp = bmp.copy(Config.ARGB_8888, true);
	}

	@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);

		mCanvas = new Canvas(mBitmap);
	}

	public boolean onTouch(View arg0, MotionEvent event) {
		float x = event.getX();
		float y = event.getY();
		if (true)
			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;
	}

	private void touch_start(float x, float y) {
		Random rand = new Random();
		float r = rand.nextFloat();
		float g = rand.nextFloat();
		float b = rand.nextFloat();
		Random rnd = new Random();
		mPaint.setColor(Color.rgb(rnd.nextInt(256), rnd.nextInt(256),
				rnd.nextInt(256)));

		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;
			arrX[i] = mX;
			arrY[i] = mY;
			i++;
		}
	}


	@Override
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		for (int k = 0; k < i; k++) {
			canvas.drawBitmap(bmp, arrX[k], arrY[k], mPaint);

		}
	}

由此我可以在 Canvas 上绘制位图，但流程不流畅，它看起来不像一条线。两个连续的位图之间有间隙。我希望它看起来像一条路径。

Answer 1

为什么在每个 case: 中调用 invalidate() 方法，尝试调用它 ot switch。

例如

public boolean onTouch(View arg0, MotionEvent event) {
        float x = event.getX();
        float y = event.getY();
        if (true)
            switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                touch_start(x, y);
                break;
            case MotionEvent.ACTION_MOVE:
                touch_move(x, y);                   
                break;
            case MotionEvent.ACTION_UP:
                touch_up();
                break;
            }
          invalidate();
        return true;
    }