How to make a surface draggable.

[PankajJatav]

Hi Everyone,
I am new to famous, So i don't know, my code is either wrong or right.
I just apply logic that if user touchmove them i will set the modifier origin.

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I just created a surface
{{#Modifier}}
{{>Surface template="image" align="[0.5,0.5]" origin="[0.5, 0.5]" size="[200,200]"}
{{/Modifier}}

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In my js file add a event like this.
touchmove':function(evt, tpl){
tpl.modifier.setOrigin(
evt.changedTouches[0].clientX/($( window ).width()), evt.changedTouches[0].clientY/$( window ).height()
);

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thanks in advanced.