Manipulating Layers

Setting layer properties

Using the setLayer() method, you can set the properties of a layer. The method’s arguments include:

1. The name or index of the layer, or the layer itself
2. The object of properties to set.

Note that this method does not automatically redraw the canvas.

$('canvas')
  .setLayer('myBox', {
    fillStyle: '#36b',
    rotate: 30,
    x: '+=100', y: '-=100'
  })
  .drawLayers();

Note that the you can use the '+=" and "-=" strings to increment and decrement numbers, respectively.

You can also set properties on all layers using the setLayers() method.

// Set properties of all layers
$('canvas')
  .setLayers({
    fillStyle: '#36b',
    rotate: 30
  })
  .drawLayers();

Note that the setLayers() method also accepts a callback function as s second argument, which filters the layers.

// Set properties of all draggable layers
$('canvas')
  .setLayers(
    {
      fillStyle: '#36b',
      rotate: 30
    },
    function (layer) {
      return layer.draggable === true;
    }
  )
  .drawLayers();

Setting layer group properties

Using the setLayerGroup() method, you can set any properties of all layers in the group. The method accepts the same arguments as setLayer().

Also note that this method does not automatically redraw the canvas.

// Set properties for all layers
// in the group 'myBoxes'
$('canvas')
  .setLayerGroup('myBoxes', {
    fillStyle: '#36b',
    rotate: 30
  })
  .drawLayers();

Moving layers

Using the moveLayer() method, you can move a layer to a new index in the layers array. Please note that the canvas does not change until you redraw it.

The method accepts a layer ID (name, index, or object), and the new index to which the layer is to be moved.

Also note that this method does not automatically redraw the canvas.

// Move the layer with the name 'box' to index 1
$('canvas').moveLayer('box', 1);

Removing layers

jCanvas provides a removeLayer() method for removing one layer from the jCanvas layers array.

Also note that this method does not automatically redraw the canvas.

// Removes the layer at index 0
$('canvas').removeLayer(0);

// Removes the layer with the name 'myBox'
$('canvas').removeLayer('myBox');

Furthermore, you can remove all layers using the removeLayers() method.

// Remove all layers
$('canvas').removeLayers();

As with the getLayers() and setLayers() methods, the removeLayers() method also accepts a callback function.

// Remove all draggable layers
$('canvas').removeLayers(function (layer) {
  return layer.draggable === true;
});

Removing layer groups

Using the removeLayerGroup() method, You can remove any layers from the layers array which are in the same layer group.

// Remove all layers in the group 'myBoxes'
$('canvas').removeLayerGroup('myBoxes');

To dynamically remove an existing layer from a group, use the removeLayerFromGroup() method.

// Remove the layer with the name 'box'
// from the group 'myBoxes'
$('canvas').removeLayerFromGroup('box', 'myBoxes');

Notes

None of the above methods redraw the canvas after being called. Therefore, you will need to redraw the canvas using the drawLayers() method to see the changes visually.