记录并存储曲线形状的路径

Question

我想在我的绘图应用程序中记录用户的输入。它可以画出任何他想要的东西，而不仅仅是直线形状。我怎样才能在一条路径上记录用户在绘制时所做的所有动作，例如，一个特定的圆圈？这是我的方法，其中 System.out.println() 是我将推送方法以保存路径的地方。

    public boolean onTouchEvent(MotionEvent event) {
        float touchX = event.getX();
        float touchY = event.getY();
        //respond to down, move and up events
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                drawPath.moveTo(touchX, touchY);
                break;
            case MotionEvent.ACTION_MOVE:
                drawPath.lineTo(touchX, touchY);
                break;
            case MotionEvent.ACTION_UP:
                drawPath.lineTo(touchX, touchY);
                System.out.println(touchX +", " +touchY);
                drawCanvas.drawPath(drawPath, drawPaint);
                drawPath.reset();
                break;
            default:
                return false;
        }
        //redraw
        invalidate();
        return true;
    }```

Answer 1

只需存储 (x,y) 点，并在以后需要时 'redraw' 存储它们。

(x,y)，我指的是 event getX 和 getY 值。将所有值存储在 ArrayList 中，然后您可以使用存储的值重绘形状。基本上，我建议你按照以下几行做一些事情，

创建点数组

ArrayList<Pair<Float,Float>> points = new ArrayList<>();

在数组中存储触摸点

public boolean onTouchEvent(MotionEvent event) {
    float touchX = event.getX();
    float touchY = event.getY();
    //respond to down, move and up events
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            drawPath.moveTo(touchX, touchY);
            points.add(new Pair<Float, Float>(touchX, touchY));
            break;
        case MotionEvent.ACTION_MOVE:
            drawPath.lineTo(touchX, touchY);
            points.add(new Pair<Float, Float>(touchX, touchY));
            break;
        case MotionEvent.ACTION_UP:
            drawPath.lineTo(touchX, touchY);
            System.out.println(touchX +", " +touchY);

            points.add(new Pair<Float, Float>(touchX, touchY));
            //At this point you might want to
            //store this array somewhere 
            //so you can use it to redraw later if needed

            drawCanvas.drawPath(drawPath, drawPaint);
            drawPath.reset();
            break;
        default:
            return false;
    }
    //redraw
    invalidate();
    return true;
}

需要的时候可以用数组重画形状

public void drawFromArrayList(ArrayList<Pair<Float,Float>> points) {
    int pointCount = points.size();
    if (pointCount < 2) {
        return;
    }
    for (int i=0;i<pointCount;i++) {
        float touchX = points.get(i).first, touchY = points.get(i).second;
        if(i==0) {
            drawPath.moveTo(touchX, touchY);
        }
        drawPath.lineTo(touchX, touchY);
        if(i==pointCount-1) {
            drawCanvas.drawPath(drawPath, drawPaint);
            drawPath.reset();
        }
    }
}

记录并存储曲线形状的路径

Record and store a path of a curved shape

java

android

record

shapes