jQuery Drag/Resize with CSS Transform Scale

Question

I am applying a CSS transform (and the browser specific -webkit, -o etc):

transform: matrix(0.5 , 0 , 0, 0.5, 0 , 0);

to a div then using jQuery\'s draggable

Answer 1

It's been a while since this question was asked. I have found (actually created) an answer. All it requires is setting callback handlers. No editing jquery-ui needed!

Note: zoomScale in this example is a global variable and the transform is set using animate (aided by jquery.transform.js) like so:

target.animate({
    transform: 'scale(' + zoomScale + ')'
});

Take a look at this:

transform scale() fix for resizable:

$(this).resizable({
    minWidth: -(contentElem.width()) * 10,  // these need to be large and negative
    minHeight: -(contentElem.height()) * 10, // so we can shrink our resizable while scaled
    resize: function(event, ui) {

        var changeWidth = ui.size.width - ui.originalSize.width; // find change in width
        var newWidth = ui.originalSize.width + changeWidth / zoomScale; // adjust new width by our zoomScale

        var changeHeight = ui.size.height - ui.originalSize.height; // find change in height
        var newHeight = ui.originalSize.height + changeHeight / zoomScale; // adjust new height by our zoomScale

        ui.size.width = newWidth;
        ui.size.height = newHeight;

    }
});

transform scale() fix for draggable:

$(this).draggable({
    handle: '.drag-handle',
    start: function(event, ui) {
        ui.position.left = 0;
        ui.position.top = 0;
    },
    drag: function(event, ui) {

        var changeLeft = ui.position.left - ui.originalPosition.left; // find change in left
        var newLeft = ui.originalPosition.left + changeLeft / (( zoomScale)); // adjust new left by our zoomScale

        var changeTop = ui.position.top - ui.originalPosition.top; // find change in top
        var newTop = ui.originalPosition.top + changeTop / zoomScale; // adjust new top by our zoomScale

        ui.position.left = newLeft;
        ui.position.top = newTop;

    }
});

Let me know if you find any problems or further improvements on this. :)

Reference: jQuery-UI resizable/draggable with transform: scale() set

Answer 2

I found I could just wrap the scaled element with another div and set draggable on it instead.

Answer 3

I had the same problem, and the easiest way for me was NOT to use the jquery-ui's draggable functionality since it does not support CSS3 transform properties.

What worked for me really good was to implement an own draggable functionality: http://css-tricks.com/snippets/jquery/draggable-without-jquery-ui/

I know it does not solve your problem 100%, since you still want to use the jquery-ui draggable functionality, but it could help others.

Answer 4

I would add this as a comment to the accepted answer from Gung Foo but I don't have the rep to comment.

I found Gung's answered worked perfectly for me however the resizable fix only worked when dragging from the bottom-right corner. I also have handles on the other three corners and found the element would shift so I had to add the fix from draggable to the resizable functions.

Maybe there's a better way, or I missed something, but I found the modified resizable below worked for me from all handles:

$(this).resizable({
    minWidth: -(contentElem.width()) * 10,  // these need to be large and negative
    minHeight: -(contentElem.height()) * 10, // so we can shrink our resizable while scaled

    // adjust the initial position to accomodate for the scale
    start: function(event, ui){
        ui.position.left = Math.round(ui.position.left/zoomScale);
        ui.position.top = Math.round(ui.position.top/zoomScale);
        ui.originalPosition.left = ui.position.left;
        ui.originalPosition.top = ui.position.top;
    },

    resize: function(event, ui) {

        var changeWidth = ui.size.width - ui.originalSize.width; // find change in width
        var newWidth = ui.originalSize.width + changeWidth / zoomScale; // adjust new width by our zoomScale

        var changeHeight = ui.size.height - ui.originalSize.height; // find change in height
        var newHeight = ui.originalSize.height + changeHeight / zoomScale; // adjust new height by our zoomScale

        ui.size.width = newWidth;
        ui.size.height = newHeight;

        // if the position is changed by a NW,NE,SW handle resize adjust for the scale
        var changeWidth = ui.size.width - ui.originalSize.width; // find change in width
        var newWidth = ui.originalSize.width + changeWidth / zoomScale; // adjust new width by our zoomScale

        var changeHeight = ui.size.height - ui.originalSize.height; // find change in height
        var newHeight = ui.originalSize.height + changeHeight / zoomScale; // adjust new height by our zoomScale

        ui.size.width = newWidth;
        ui.size.height = newHeight;

    }
});

Answer 5

Another approach would be to add a plugin that compensate for the transformation ( remember to add "transform : true" to the plugin initialization.

The ui.draggable need to be passed via a inverse matrix of the transformation in order to position the element in the un-transformed space which the browser later transform on display.

For "draggable" the following worked for me ( jqueryui 1.10 ) ( the matrix calculation I have taken from jquery.panzoom):

var Matrix = function(a, b, c, d, e, f, g, h, i) {
    if ($.type(a) === 'array') {
        this.elements = [
            +a[0], +a[2], +a[4],
            +a[1], +a[3], +a[5],
                0,     0,     1
        ];
    } else {
        this.elements = [
            a, b, c,
            d, e, f,
            g || 0, h || 0, i || 1
        ];
    }
};

Matrix.prototype = {
    /**
     * Multiply a 3x3 matrix by a similar matrix or a vector
     * @param {Matrix|Vector} matrix
     * @return {Matrix|Vector} Returns a vector if multiplying by a vector
     */
    x: function(matrix) {
        var isVector = matrix instanceof Vector;

        var a = this.elements,
            b = matrix.elements;

        if (isVector && b.length === 3) {
            // b is actually a vector
            return new Vector(
                a[0] * b[0] + a[1] * b[1] + a[2] * b[2],
                a[3] * b[0] + a[4] * b[1] + a[5] * b[2],
                a[6] * b[0] + a[7] * b[1] + a[8] * b[2]
            );
        } else if (b.length === a.length) {
            // b is a 3x3 matrix
            return new Matrix(
                a[0] * b[0] + a[1] * b[3] + a[2] * b[6],
                a[0] * b[1] + a[1] * b[4] + a[2] * b[7],
                a[0] * b[2] + a[1] * b[5] + a[2] * b[8],

                a[3] * b[0] + a[4] * b[3] + a[5] * b[6],
                a[3] * b[1] + a[4] * b[4] + a[5] * b[7],
                a[3] * b[2] + a[4] * b[5] + a[5] * b[8],

                a[6] * b[0] + a[7] * b[3] + a[8] * b[6],
                a[6] * b[1] + a[7] * b[4] + a[8] * b[7],
                a[6] * b[2] + a[7] * b[5] + a[8] * b[8]
            );
        }
        return false; // fail
    },
    /**
     * Generates an inverse of the current matrix
     * @returns {Matrix}
     */
    inverse: function() {
        var d = 1 / this.determinant(),
            a = this.elements;
        return new Matrix(
            d * ( a[8] * a[4] - a[7] * a[5]),
            d * (-(a[8] * a[1] - a[7] * a[2])),
            d * ( a[5] * a[1] - a[4] * a[2]),

            d * (-(a[8] * a[3] - a[6] * a[5])),
            d * ( a[8] * a[0] - a[6] * a[2]),
            d * (-(a[5] * a[0] - a[3] * a[2])),

            d * ( a[7] * a[3] - a[6] * a[4]),
            d * (-(a[7] * a[0] - a[6] * a[1])),
            d * ( a[4] * a[0] - a[3] * a[1])
        );
    },
    /**
     * Calculates the determinant of the current matrix
     * @returns {Number}
     */
    determinant: function() {
        var a = this.elements;
        return a[0] * (a[8] * a[4] - a[7] * a[5]) - a[3] * (a[8] * a[1] - a[7] * a[2]) + a[6] * (a[5] * a[1] - a[4] * a[2]);
    }
};

var Vector = function (x, y, z) {
    this.elements = [ x, y, z ];
};

/**
 * Get the element at zero-indexed index i
 * @param {Number} i
 */
Vector.prototype.e = Matrix.prototype.e = function(i) {

    if( this.elements[ i ] != undefined ){
        return this.elements[ i ];    
    }

    return this.elements;
};    

$.ui.plugin.add("draggable", "transform", {

    start: function( event, ui ) {

        if(!$(this).data('ui-draggable')){
            return false;
        }            

        var inst = $(this).data("ui-draggable");

        inst.matrix = new Matrix(function(matrix){

            var rmatrix = new RegExp(
                    '^matrix\\(' +
                    '(\\-?[\\d\\.e]+)' + '\\,?\\s*' +
                    '(\\-?[\\d\\.e]+)' + '\\,?\\s*' +
                    '(\\-?[\\d\\.e]+)' + '\\,?\\s*' +
                    '(\\-?[\\d\\.e]+)' + '\\,?\\s*' +
                    '(\\-?[\\d\\.e]+)' + '\\,?\\s*' +
                    '(\\-?[\\d\\.e]+)' + '\\)$'
            );                

            var matrix = rmatrix.exec( matrix );
            if (matrix) {
                matrix.shift();
            }
            return matrix || [ 1, 0, 0, 1, 0, 0 ];

        }([$(this).parents('[style*="transform"]').css('transform')]));            
    },
    drag: function( event, ui ) {

        if(!$(this).data('ui-draggable')){
            return false;
        }            

        var inst = $(this).data("ui-draggable");

        var t_pos = inst.matrix.inverse().x(new Vector(ui.position.left, ui.position.top, 0));

        ui.position.left = t_pos.e(0);
        ui.position.top = t_pos.e(1);                   

        if(inst.options.grid) {
            ui.position.left = ui.position.left - ui.position.left % inst.options.grid[0];
            ui.position.top  = ui.position.top - ui.position.top % inst.options.grid[1];                
        }

        if( inst.containment ){

            if( ui.position.left < inst.containment[0] ){
                ui.position.left = inst.containment[0];
            }

            if( ui.position.left > inst.containment[2] ){
                ui.position.left = inst.containment[2];
            }                

            if( ui.position.top < inst.containment[1] ){
                ui.position.top = inst.containment[1];
            }  

            if( ui.position.top > inst.containment[3] ){
                ui.position.top = inst.containment[3];
            }
        }
    },     
});

Answer 6

The top answer was working for me till i've found a glitch on draggable :(

When the containment itself is also scaled:

• it can't be fully dragged within its containment box if scaled < 1
• it can be dragged outside the containment box if scaled > 1

Luckily, i've found a solution here