Change boolean variable in function

Hi, i’m new with Vue,
i have this configuration:

<panZoom :options="{minZoom: 0.27,maxZoom: 10,initialZoom: 0.273,transformOrigin: null,
beforeWheel: false,
beforeMouseDown: false
}">
<vue-draggable-resizable @dragging="onDrag" ref="draggable" :active="true">
</panZoom>

When onDrag i have to set beforeWheel & beforeMouseDown → true

methods: {
onDrag: function(){ ???
},
beforeWheel: function(e) {
var shouldIgnore = !e.altKey;
return shouldIgnore;
},
beforeMouseDown: function(e) {
var shouldIgnore = !e.altKey;
return shouldIgnore;
},

}

how can I do? Thanks in advance