Delete multiple Objects at once on a fabric.js canvas in html5

问题

I'm actually working on a html5 canvas project which uses the fabric.js Framework for the canvas interactions. Now I'm struggeling with the deletion of multiple objects. The following code does not seem to track the selected objects, but tracks all objects on the canvas.

var deleteSelectedObject = document.getElementById('delete-item');
deleteSelectedObject.onclick = function(){
    var curSelectedObjects = new Array();
    curSelectedObjects = canvas.getObjects(canvas.getActiveGroup);
    canvas.discardActiveGroup();
    for (var i = 0; i < curSelectedObjects.length; i++){
        canvas.setActiveObject(curSelectedObjects[i]);
        canvas.remove(canvas.getActiveObject());
    }
};

Don't get my failure.

回答1:

Due to @Kangax comment which solved most of the problem, I found the following solution to delete the currently selected objects from the canvas.

var deleteSelectedObject = document.getElementById('delete-item');
deleteSelectedObject.onclick = function()
{
if(canvas.getActiveGroup()){
      canvas.getActiveGroup().forEachObject(function(o){ canvas.remove(o) });
      canvas.discardActiveGroup().renderAll();
    } else {
      canvas.remove(canvas.getActiveObject());
    }
};

The function checks whether a group is selected. If a group is selected every object of the group gets removed. If no group is selected the function tries to remove a selected object. If nothing is selected, the canvas is not changed.

回答2:

Your code seems like it is selecting and then de-selecting the objects.

This may work better:

var deleteSelectedObject = document.getElementById('delete-item');
deleteSelectedObject.onclick = function()
{
    var curSelectedObjects = canvas.getObjects(canvas.getActiveGroup);

    canvas.discardActiveGroup();
    for (var i = 0; i < curSelectedObjects.length; i++)
    {
        canvas.remove(curSelectedObjects[i]);
    }
};

Good information link:

https://github.com/kangax/fabric.js/wiki/Tutorial-2#wiki-modifying-objects

回答3:

You can check any object property and can remove

var objects = canvas.getObjects();

for (var i = 0; i < objects.length; ) {
  if (objects[i].name == 'cropArea' || objects[i].name == 'bleedLine') {
    canvas.remove(objects[i]);
    i = 0;
  } else {
    i++;
  }
}

回答4:

I done this:

  var selectedObj = canvas.getObjects(canvas.getActiveGroup()) 

return me the array of the selected objects. :) the last function paranthesis is missing in your code snippet

回答5:

None of the solutions above (or anywhere elese on stackoverflow) worked for me except for this one solution I found on jsfiddle:

function deleteObjects(){
var activeObject = canvas.getActiveObject(),
activeGroup = canvas.getActiveGroup();
if (activeObject) {
    if (confirm('Are you sure?')) {
        canvas.remove(activeObject);
    }
}
else if (activeGroup) {
    if (confirm('Are you sure?')) {
        var objectsInGroup = activeGroup.getObjects();
        canvas.discardActiveGroup();
        objectsInGroup.forEach(function(object) {
        canvas.remove(object);
        });
    }
}
}

http://jsfiddle.net/beewayne/z0qn35Lo/

来源：https://stackoverflow.com/questions/11829786/delete-multiple-objects-at-once-on-a-fabric-js-canvas-in-html5