Question

我正在使用Raphael库来旋转和拖动图像。我正确拖动它，我有一个按钮，每按一次就能正确旋转90度。但是，当我旋转图像，拖动它然后再次尝试旋转它时，我遇到了问题。

HTML中唯一的元素是用于存放Raphael画布的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此问题。

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

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

Answer 2

不是使用x / y属性操作位置，而是使用变换操作旋转，而是使用变换工具来处理两者，从而简化项目。

由于我们在翻译中使用大写'T'，忽略了同一字符串中的先前翻译命令，因此我们不再需要担心拖动时的当前角度。

var gboard, 
    piece;

gboard = Raphael("gameboard", 800, 500);    

var angle = 0,
    x = 100,
    y = 100;

//note that this now starts at 0,0 and is immediately translated to 100,100
piece = gboard.image("piece.gif", 0, 0, 50, 50).attr({cursor: "move", transform: "R" + angle + "T" + x + "," + y });

piece.drag(dragMove, dragStart, dragStop);

document.getElementById('btn').onclick = function () {  
  angle += 90;
  piece.animate({transform: "R" + angle + "T" + x + "," + y}, 500, "<>");
};

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

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

//Since we're using a capital 'T' in the translation, which ignores previous translation commands in the same string, we no longer have to worry about the current angle here    
function dragMove(dx, dy) {
  x = this.ox + dx;
  y = this.oy + dy;
  piece.attr({ transform: "R" + angle + "T" + x + "," + y });
}

jsFiddle

Answer 3

好奇;它看起来像旋转实际上改变了x和y值。因此，如果您旋转90度，将框向右移动100像素实际上会将其移动100像素向上，然后将其转换为向右移动。这会抛出cx和cy值，这决定了旋转盒子的点。

要查看我的意思，请旋转一次，然后在检查器中观察X和Y值的同时拖动该框。

我可以看到两种方法来解决它：你可以做数学运算来重新计算每次旋转的“真实”x和y，或者你可以通过附加数据属性（你自己跟踪x和y）是我推荐的）。祝你好运！

如何使用JavaScript和Raphael旋转以前拖动的SVG对象？

3 个答案: