如何在Android画布上设置路径动画 [英] How to animate a path on an Android Canvas

问题描述

是否可以将动画师附加到路径？

是否有其他方法可以在画布上绘制动画线？

我在发帖前搜索了一下，但什么也找不到。在另外两个帖子Draw a path as animation on Canvas in Android和How to draw a path on an Android Canvas with animation中，有一些解决方案对我不起作用。

我在onDraw方法内部发布代码以指定我到底想要什么。

paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeWidth(2);
    paint.setColor(Color.BLACK);

    Path path = new Path();
    path.moveTo(10, 50);   // THIS TRANSFORMATIONS TO BE ANIMATED!!!!!!!!
    path.lineTo(40, 50);
    path.moveTo(40, 50);
    path.lineTo(50, 40);
    // and so on...

    canvas.drawPath(path, paint);

推荐答案

您可以按时间转换画布，即：

class MyView extends View {

    int framesPerSecond = 60;
    long animationDuration = 10000; // 10 seconds

    Matrix matrix = new Matrix(); // transformation matrix

    Path path = new Path();       // your path
    Paint paint = new Paint();    // your paint

    long startTime;

    public MyView(Context context) {
        super(context);

        // start the animation:
        this.startTime = System.currentTimeMillis();
        this.postInvalidate(); 
    }

    @Override
    protected void onDraw(Canvas canvas) {

        long elapsedTime = System.currentTimeMillis() - startTime;

        matrix.postRotate(30 * elapsedTime/1000);        // rotate 30° every second
        matrix.postTranslate(100 * elapsedTime/1000, 0); // move 100 pixels to the right
        // other transformations...

        canvas.concat(matrix);        // call this before drawing on the canvas!!

        canvas.drawPath(path, paint); // draw on canvas

        if(elapsedTime < animationDuration)
            this.postInvalidateDelayed( 1000 / framesPerSecond);
    }

}

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