javascript - 如何使用 JavaScript 和 Raphael 旋转之前拖动的 SVG 对象？

Question

我正在使用 Raphael 库来旋转和拖动图像。我正确地拖动了它，并且我有一个按钮，每次按下它时它都会正确旋转 90 度。但是，当我旋转图像、拖动它然后再次尝试旋转时，我遇到了问题。

HTML 中仅有的元素是用于放置 Raphael Canvas 的 div 和用于旋转图像的按钮。 JavaScript 在这里:

var gboard;
var piece;

window.onload = function () 
{
    gboard = Raphael("gameboard", 800, 500);    
    // piece = gboard.rect(100, 100, 50, 50).attr({fill: "#0CF", "fill-opacity": 1, stroke: "none", cursor: "move"});
    piece = gboard.image("piece.gif", 100, 100, 50, 50).attr({cursor: "move"});
    piece.drag(dragMove, dragStart, dragStop);  
    var angle = 0;

    document.getElementById('btn').onclick = function () {
        angle += 90;
        var cx = piece.attr('x') + 25;
        var cy = piece.attr('y') + 25;
        piece.animate({transform: "R" + angle + ", " + cx + ", " + cy + ""}, 500, "<>");
        // piece.transform("R90," + cx + "," + cy);
    };

}

// Set up the object for dragging
function dragStart() 
{
    this.ox = this.attr("x");
    this.oy = this.attr("y");
}

// Clean up after dragging ends
function dragStop() {}

/**
 * Handle the moving of objects when dragging 
 * Check the current angle to compensate for rotated coordinate system.
 */
function dragMove(dx, dy) 
{
    var angle = getAngle(this._['deg']);
    if (angle == 90)
        this.attr({x: this.ox + dy, y: this.oy - dx});
    else if (angle == 180)
        this.attr({x: this.ox - dx, y: this.oy - dy});
    else if (angle == 270)
        this.attr({x: this.ox - dy, y: this.oy + dx});
    else // angle == 0
        this.attr({x: this.ox + dx, y: this.oy + dy});
}

/** 
 * Get the simplified equivalent angle (0 <= angle <= 360) for the given angle. 
 *
 * @param deg   The angle in degrees
 * @return  The equivalent angle between 0 and 360
 */
function getAngle(deg)
{
    if (deg % 360 == 0)
        return 0;   
    else if (deg < 0)
    {
        while (deg < 0)
            deg += 360;
    }
    else if (deg > 360)
    {
        while (deg > 360)
            deg -= 360;
    }

    return deg;
}

Answer 1

我通过在值更改时重新应用所有转换来解决这个问题。

http://alias.io/raphael/free_transform/

来源:https://github.com/ElbertF/Raphael.FreeTransform