Flex:在形状之间绘制连接线

Question

我正在使用Adobe Flex 3构建图表工具.我即将实现连接线,我有一个问题.

想象一下,我在画布上的随机位置有2个正方形.我需要在它们之间画一条箭头连接线.我需要它倾向于目标广场的中心,但结束于它的边界.替代文字http://i44.tinypic.com/25tw4n4.jpg

如何找出绘制线的确切点？

谢谢

Answer 1

这是一个做你想要的例子.

package
{
    import flash.display.Shape;
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.geom.Matrix;
    import flash.geom.Point;
    import flash.ui.Mouse;

    /**
     * Sample class to draw squares and arrows between them.
     */
    public class SquareArrows extends Sprite
    {
        /**
         * Initialize the scene as soon as we can.
         */
        public function SquareArrows()
        {
            if(stage) {
                init();
            }
            else {
                addEventListener(Event.ADDED_TO_STAGE, init);
            }
        }

        /**
         * Draw two squares and an arrow between them.
         */
        private function init(e : Event = null) : void
        {
            if(hasEventListener(Event.ADDED_TO_STAGE)) {
                removeEventListener(Event.ADDED_TO_STAGE, init);
            }

            // Drawing random-sized squares.
            var squareOne : Shape =
                    getSquareShape((Math.random() * 50) + 20, 0xBBBBBB);
            var squareTwo : Shape =
                    getSquareShape((Math.random() * 50) + 20, 0xDDDDDD);
            addChild(squareOne);
            addChild(squareTwo);

            // Draw the connector.
            var connector : Shape = getConnectorShape(squareOne, squareTwo);
            addChild(connector);
        }

        /**
         * Draw a connector arrow between two square shapes.
         */
        private function getConnectorShape(connectFrom : Shape, connectTo : Shape) : Shape
        {
            // Getting the center of the first square.
            var centerFrom : Point = new Point();
            centerFrom.x = connectFrom.x + (connectFrom.width / 2);
            centerFrom.y = connectFrom.y + (connectFrom.height / 2);

            // Getting the center of the second square.
            var centerTo : Point = new Point();
            centerTo.x = connectTo.x + (connectTo.width / 2);
            centerTo.y = connectTo.y + (connectTo.height / 2);

            // Getting the angle between those two.
            var angleTo : Number =
                Math.atan2(centerTo.x - centerFrom.x, centerTo.y - centerFrom.y);
            var angleFrom : Number =
                Math.atan2(centerFrom.x - centerTo.x, centerFrom.y - centerTo.y);

            // Getting the points on both borders.
            var pointFrom : Point = getSquareBorderPointAtAngle(connectFrom, angleTo);
            var pointTo : Point = getSquareBorderPointAtAngle(connectTo, angleFrom);

            // Calculating arrow edges.
            var arrowSlope : Number = 30;
            var arrowHeadLength : Number = 10;
            var vector : Point =
                new Point(-(pointTo.x - pointFrom.x), -(pointTo.y - pointFrom.y));

            // First edge of the head...
            var edgeOneMatrix : Matrix = new Matrix();
            edgeOneMatrix.rotate(arrowSlope * Math.PI / 180);
            var edgeOneVector : Point = edgeOneMatrix.transformPoint(vector);
            edgeOneVector.normalize(arrowHeadLength);
            var edgeOne : Point = new Point();
            edgeOne.x = pointTo.x + edgeOneVector.x;
            edgeOne.y = pointTo.y + edgeOneVector.y;

            // And second edge of the head.
            var edgeTwoMatrix : Matrix = new Matrix();
            edgeTwoMatrix.rotate((0 - arrowSlope) * Math.PI / 180);
            var edgeTwoVector : Point = edgeTwoMatrix.transformPoint(vector);
            edgeTwoVector.normalize(arrowHeadLength);
            var edgeTwo : Point = new Point();
            edgeTwo.x = pointTo.x + edgeTwoVector.x;
            edgeTwo.y = pointTo.y + edgeTwoVector.y;

            // Drawing the arrow.
            var arrow : Shape = new Shape();
            with(arrow.graphics) {
                lineStyle(2);
                // Drawing the line.
                moveTo(pointFrom.x, pointFrom.y);
                lineTo(pointTo.x, pointTo.y);

                // Drawing the arrow head.
                lineTo(edgeOne.x, edgeOne.y);
                moveTo(pointTo.x, pointTo.y);
                lineTo(edgeTwo.x, edgeTwo.y);
            }
            return arrow;
        }

        /**
         * Utility method to get a point on a square border at a certain angle.
         */
        private function getSquareBorderPointAtAngle(square : Shape, angle : Number) : Point
        {
            // Calculating rays of inner and outer circles.
            var minRay : Number = Math.SQRT2 * square.width / 2;
            var maxRay : Number = square.width / 2;

            // Calculating the weight of each rays depending on the angle.
            var rayAtAngle : Number = ((maxRay - minRay) * Math.abs(Math.cos(angle * 2))) + minRay;

            // We have our point.
            var point : Point = new Point();
            point.x = rayAtAngle * Math.sin(angle) + square.x + (square.width / 2);
            point.y = rayAtAngle * Math.cos(angle) + square.y + (square.height / 2);
            return point;
        }

        /**
         * Utility method to draw a square of a given size in a new shape.
         */
        private function getSquareShape(edgeSize : Number, fillColor : Number) : Shape
        {
            // Draw the square.
            var square : Shape = new Shape();
            with(square.graphics) {
                lineStyle(1);
                beginFill(fillColor);
                drawRect(0, 0, edgeSize, edgeSize);
                endFill();
            }

            // Set a random position.
            square.x = Math.random() * (stage.stageWidth - square.width);
            square.y = Math.random() * (stage.stageHeight - square.height);

            return square;
        }
    }
}

此代码未完全优化.这个想法更多的是解释它是如何工作的.基本上,我们定义了两个(随机)方块,并在它们之间描绘了一条线.为了跟踪线,我们计算从第一个正方形的中心到第二个正方形的中心的角度,我们使用一个特殊的方法(getSquareBorderPointAtAngle)来在正确的方向上提取方形边界上的一个点.

此方法是此代码段的第一个关键点.我们使用简单的圆几何计算,稍微复杂化我们如何使点匹配边框而不是匹配方形周围或内部的圆.

然后,我们画一个箭头.为此,我们正在使用Flash Matrix类,因为这种方式比从头开始计算要容易得多.

在这里我们已经完成了.