draw - Kinetic JS - 使用鼠标在行首和行尾绘制箭头

Question

我正在尝试在我使用鼠标绘制的线条的开头和结尾添加箭头，这是我绘制线条的脚本：

    document.getElementById('dLine').onclick = function() {
    layer.on("mousedown", function () {
        if (moving) {
            moving = false;
            layer.draw();
        } else {
            var mousePos = stage.getMousePosition();
            x1 = mousePos.x;
            y1 = mousePos.y;
            line = new Kinetic.Line({
                points: [0, 0, 50, 50],
                stroke: "red"
            });
            layer.add(line);
            line.getPoints()[0].x = mousePos.x;
            line.getPoints()[0].y = mousePos.y;
            line.getPoints()[1].x = mousePos.x;
            line.getPoints()[1].y = mousePos.y;
            moving = true;
            layer.drawScene();
        }
    });

    layer.on("mousemove", function () {
        if (moving) {
            var mousePos = stage.getMousePosition();
            var x = mousePos.x;
            var y = mousePos.y;
            line.getPoints()[1].x = mousePos.x;
            line.getPoints()[1].y = mousePos.y;
            moving = true;
            layer.drawScene();
        }
    });

    layer.on("mouseup", function () {
        moving = false;
        var mousePos = stage.getMousePosition();
        x2 = mousePos.x;
        y2 = mousePos.y;
        $("#distance").val(calculateDistance(x1, y1, x2, y2));

    });
};

我会很感激你的建议。

Answer 1

您可以使用此函数绘制箭头：

function canvas_arrow(fromx, fromy, tox, toy){
    var headlen = 20;   // how long you want the head of the arrow to be, you could calculate this as a fraction of the distance between the points as well.
    var angle = Math.atan2(toy-fromy,tox-fromx);

    line = new Kinetic.Line({
        points: [fromx, fromy, tox, toy, tox-headlen*Math.cos(angle-Math.PI/6),toy-headlen*Math.sin(angle-Math.PI/6),tox, toy, tox-headlen*Math.cos(angle+Math.PI/6),toy-headlen*Math.sin(angle+Math.PI/6)],
        stroke: "red"
    });
}

编辑：jsfiddle.net/cmcculloh/M56w4 - 在评论中提供