防止画布对象发生碰撞或交叉

我正在画布上绘制 n 个矩形。矩形是可拖动和可缩放的。 我想防止它们重叠或相交。最好的情况是，如果它们只是相互咬合。

我想办法检查一下十字路口。在我的示例中，我将触摸对象的不透明度设置为 0.1。

巧合的是，在我尝试解决这个问题时，我的对象在接触另一个对象时无法释放。看http://jsfiddle.net/gcollect/jZw7P/ http://jsfiddle.net/gcollect/jZw7P/这是因为第 91 行警报没有执行。alert(math.abs(distx));

实际上这是一种解决方案，但绝对不是一个优雅的解决方案。

有任何想法吗？

这是基于 gco 的答案，已更新以与 FabricJS 1.5.0 配合使用，并进行了以下改进：

• 形状不重叠。
• 捕捉更加灵敏。
• 形状包含在画布内。

JSFiddle：https://jsfiddle.net/aphillips8/31qbr0vn/1/ https://jsfiddle.net/aphillips8/31qbr0vn/1/

var canvas = new fabric.Canvas('canvas'),
canvasWidth = document.getElementById('canvas').width,
canvasHeight = document.getElementById('canvas').height,
counter = 0,
rectLeft = 0,
snap = 20; //Pixels to snap

canvas.selection = false;
plusrect();
plusrect();
plusrect();

function plusrect(top, left, width, height, fill) {
    var rect = new fabric.Rect({
        top: 300,
        name: 'rectangle ' + counter,
        left: 0 + rectLeft,
        width: 100,
        height: 100,
        fill: 'rgba(' + (Math.floor(Math.random() * 256)) + ',' + (Math.floor(Math.random() * 256)) + ',' + (Math.floor(Math.random() * 256)) + ', 0.75)',
        lockRotation: true,
        originX: 'left',
        originY: 'top',
        cornerSize: 15,
        hasRotatingPoint: false,
        perPixelTargetFind: true,
        minScaleLimit: 1,
        maxWidth: canvasWidth,
        maxHeight: canvasHeight
    });

    rect.custom = {};
    rect.custom.counter = counter;

    canvas.add(rect);
    counter++;
    rectLeft += 200;
}

function findNewPos(distX, distY, target, obj) {
    // See whether to focus on X or Y axis
    if(Math.abs(distX) > Math.abs(distY)) {
        if (distX > 0) {
            target.setLeft(obj.getLeft() - target.getWidth());
        } else {
            target.setLeft(obj.getLeft() + obj.getWidth());
        }
    } else {
        if (distY > 0) {
            target.setTop(obj.getTop() - target.getHeight());
        } else {
            target.setTop(obj.getTop() + obj.getHeight());
        }
    }
}

canvas.on('object:moving', function (options) {
    // Sets corner position coordinates based on current angle, width and height
    options.target.setCoords();

    // Don't allow objects off the canvas
    if(options.target.getLeft() < snap) {
        options.target.setLeft(0);
    }

    if(options.target.getTop() < snap) {
        options.target.setTop(0);
    }

    if((options.target.getWidth() + options.target.getLeft()) > (canvasWidth - snap)) {
        options.target.setLeft(canvasWidth - options.target.getWidth());
    }

    if((options.target.getHeight() + options.target.getTop()) > (canvasHeight - snap)) {
        options.target.setTop(canvasHeight - options.target.getHeight());
    }

    // Loop through objects
    canvas.forEachObject(function (obj) {
        if (obj === options.target) return;

        // If objects intersect
        if (options.target.isContainedWithinObject(obj) || options.target.intersectsWithObject(obj) || obj.isContainedWithinObject(options.target)) {

            var distX = ((obj.getLeft() + obj.getWidth()) / 2) - ((options.target.getLeft() + options.target.getWidth()) / 2);
            var distY = ((obj.getTop() + obj.getHeight()) / 2) - ((options.target.getTop() + options.target.getHeight()) / 2);

            // Set new position
            findNewPos(distX, distY, options.target, obj);
        }

        // Snap objects to each other horizontally

        // If bottom points are on same Y axis
        if(Math.abs((options.target.getTop() + options.target.getHeight()) - (obj.getTop() + obj.getHeight())) < snap) {
            // Snap target BL to object BR
            if(Math.abs(options.target.getLeft() - (obj.getLeft() + obj.getWidth())) < snap) {
                options.target.setLeft(obj.getLeft() + obj.getWidth());
                options.target.setTop(obj.getTop() + obj.getHeight() - options.target.getHeight());
            }

            // Snap target BR to object BL
            if(Math.abs((options.target.getLeft() + options.target.getWidth()) - obj.getLeft()) < snap) {
                options.target.setLeft(obj.getLeft() - options.target.getWidth());
                options.target.setTop(obj.getTop() + obj.getHeight() - options.target.getHeight());
            }
        }

        // If top points are on same Y axis
        if(Math.abs(options.target.getTop() - obj.getTop()) < snap) {
            // Snap target TL to object TR
            if(Math.abs(options.target.getLeft() - (obj.getLeft() + obj.getWidth())) < snap) {
                options.target.setLeft(obj.getLeft() + obj.getWidth());
                options.target.setTop(obj.getTop());
            }

            // Snap target TR to object TL
            if(Math.abs((options.target.getLeft() + options.target.getWidth()) - obj.getLeft()) < snap) {
                options.target.setLeft(obj.getLeft() - options.target.getWidth());
                options.target.setTop(obj.getTop());
            }
        }

        // Snap objects to each other vertically

        // If right points are on same X axis
        if(Math.abs((options.target.getLeft() + options.target.getWidth()) - (obj.getLeft() + obj.getWidth())) < snap) {
            // Snap target TR to object BR
            if(Math.abs(options.target.getTop() - (obj.getTop() + obj.getHeight())) < snap) {
                options.target.setLeft(obj.getLeft() + obj.getWidth() - options.target.getWidth());
                options.target.setTop(obj.getTop() + obj.getHeight());
            }

            // Snap target BR to object TR
            if(Math.abs((options.target.getTop() + options.target.getHeight()) - obj.getTop()) < snap) {
                options.target.setLeft(obj.getLeft() + obj.getWidth() - options.target.getWidth());
                options.target.setTop(obj.getTop() - options.target.getHeight());
            }
        }

        // If left points are on same X axis
        if(Math.abs(options.target.getLeft() - obj.getLeft()) < snap) {
            // Snap target TL to object BL
            if(Math.abs(options.target.getTop() - (obj.getTop() + obj.getHeight())) < snap) {
                options.target.setLeft(obj.getLeft());
                options.target.setTop(obj.getTop() + obj.getHeight());
            }

            // Snap target BL to object TL
            if(Math.abs((options.target.getTop() + options.target.getHeight()) - obj.getTop()) < snap) {
                options.target.setLeft(obj.getLeft());
                options.target.setTop(obj.getTop() - options.target.getHeight());
            }
        }
    });

    options.target.setCoords();

    // If objects still overlap

    var outerAreaLeft = null,
    outerAreaTop = null,
    outerAreaRight = null,
    outerAreaBottom = null;

    canvas.forEachObject(function (obj) {
        if (obj === options.target) return;

        if (options.target.isContainedWithinObject(obj) || options.target.intersectsWithObject(obj) || obj.isContainedWithinObject(options.target)) {

            var intersectLeft = null,
            intersectTop = null,
            intersectWidth = null,
            intersectHeight = null,
            intersectSize = null,
            targetLeft = options.target.getLeft(),
            targetRight = targetLeft + options.target.getWidth(),
            targetTop = options.target.getTop(),
            targetBottom = targetTop + options.target.getHeight(),
            objectLeft = obj.getLeft(),
            objectRight = objectLeft + obj.getWidth(),
            objectTop = obj.getTop(),
            objectBottom = objectTop + obj.getHeight();

            // Find intersect information for X axis
            if(targetLeft >= objectLeft && targetLeft <= objectRight) {
                intersectLeft = targetLeft;
                intersectWidth = obj.getWidth() - (intersectLeft - objectLeft);

            } else if(objectLeft >= targetLeft && objectLeft <= targetRight) {
                intersectLeft = objectLeft;
                intersectWidth = options.target.getWidth() - (intersectLeft - targetLeft);
            }

            // Find intersect information for Y axis
            if(targetTop >= objectTop && targetTop <= objectBottom) {
                intersectTop = targetTop;
                intersectHeight = obj.getHeight() - (intersectTop - objectTop);

            } else if(objectTop >= targetTop && objectTop <= targetBottom) {
                intersectTop = objectTop;
                intersectHeight = options.target.getHeight() - (intersectTop - targetTop);
            }

            // Find intersect size (this will be 0 if objects are touching but not overlapping)
            if(intersectWidth > 0 && intersectHeight > 0) {
                intersectSize = intersectWidth * intersectHeight;
            }

            // Set outer snapping area
            if(obj.getLeft() < outerAreaLeft || outerAreaLeft == null) {
                outerAreaLeft = obj.getLeft();
            }

            if(obj.getTop() < outerAreaTop || outerAreaTop == null) {
                outerAreaTop = obj.getTop();
            }

            if((obj.getLeft() + obj.getWidth()) > outerAreaRight || outerAreaRight == null) {
                outerAreaRight = obj.getLeft() + obj.getWidth();
            }

            if((obj.getTop() + obj.getHeight()) > outerAreaBottom || outerAreaBottom == null) {
                outerAreaBottom = obj.getTop() + obj.getHeight();
            }

            // If objects are intersecting, reposition outside all shapes which touch
            if(intersectSize) {
                var distX = (outerAreaRight / 2) - ((options.target.getLeft() + options.target.getWidth()) / 2);
                var distY = (outerAreaBottom / 2) - ((options.target.getTop() + options.target.getHeight()) / 2);

                // Set new position
                findNewPos(distX, distY, options.target, obj);
            }
        }
    });
});