elm-core-sources-1.0.0: src/Native/Window.js

Elm.Native = Elm.Native || {};
Elm.Native.Window = {};
Elm.Native.Window.make = function(localRuntime) {

    localRuntime.Native = localRuntime.Native || {};
    localRuntime.Native.Window = localRuntime.Native.Window || {};
    if (localRuntime.Native.Window.values) {
        return localRuntime.Native.Window.values;
    }

    var Signal = Elm.Signal.make(localRuntime);
    var NS = Elm.Native.Signal.make(localRuntime);
    var Tuple2 = Elm.Native.Utils.make(localRuntime).Tuple2;

    function getWidth() {
        return localRuntime.node.clientWidth;
    }
    function getHeight() {
        if (localRuntime.isFullscreen()) {
            return window.innerHeight;
        }
        return localRuntime.node.clientHeight;
    }

    var dimensions = NS.input(Tuple2(getWidth(), getHeight()));
    dimensions.defaultNumberOfKids = 2;

    // Do not move width and height into Elm. By setting the default number of kids,
    // the resize listener can be detached.
    var width  = A2(Signal.map, function(p){return p._0;}, dimensions);
    width.defaultNumberOfKids = 0;

    var height = A2(Signal.map, function(p){return p._1;}, dimensions);
    height.defaultNumberOfKids = 0;

    function resizeIfNeeded() {
        // Do not trigger event if the dimensions have not changed.
        // This should be most of the time.
        var w = getWidth();
        var h = getHeight();
        if (dimensions.value._0 === w && dimensions.value._1 === h) return;

        setTimeout(function () {
            // Check again to see if the dimensions have changed.
            // It is conceivable that the dimensions have changed
            // again while some other event was being processed.
            var w = getWidth();
            var h = getHeight();
            if (dimensions.value._0 === w && dimensions.value._1 === h) return;
            localRuntime.notify(dimensions.id, Tuple2(w,h));
        }, 0);
    }
    localRuntime.addListener([dimensions.id], window, 'resize', resizeIfNeeded);

    return localRuntime.Native.Window.values = {
        dimensions: dimensions,
        width: width,
        height: height,
        resizeIfNeeded: resizeIfNeeded
    };

};