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var cur_section = Symbol();
export class ActivePage {
constructor(appName) {
// The idea behind this property that it could basically anything, but
// whoever inherits this class must override next(), prev(), and display() methods,
// if necessary; just in the end, its value probably corresponds to the IDs of the
// individual elements in the page.
this[cur_section] = null;
this.swipe_pos_x = 0;
this.swipe_pos_y = 0;
this.app_record = null;
// Swipe event handlers
document.body.addEventListener("dblclick",
() => {
this.display();
}, false);
document.body.addEventListener("mousedown",
(evt) => {
this.swipe_pos_x = evt.screenX;
this.swipe_pos_y = evt.screenY;
}, false);
document.body.addEventListener("mouseup",
(evt) => {
this.handle_move(this.swipe_pos_x - evt.screenX,
this.swipe_pos_y - evt.screenY);
}, false);
document.body.addEventListener("touchstart",
(evt) => {
this.swipe_pos_x = evt.changedTouches[0].screenX;
this.swipe_pos_y = evt.changedTouches[0].screenY;
}, false);
document.body.addEventListener("touchend",
(evt) => {
var end_pos = evt.changedTouches[evt.changedTouches.length - 1];
// We want't opposite direction to Mouse gestures here
// so the difference should be opposite
this.handle_move(end_pos.screenX - this.swipe_pos_x,
end_pos.screenY - this.swipe_pos_y);
}, false);
document.body.addEventListener("touchcancel",
() => {
this.swipe_pos_x = 0;
this.swipe_pos_y = 0;
}, false);
applicationCache.addEventListener("updateready",
() => { location.reload(); }
);
this.display();
}
/**
* Display current item
*
* @param new_date String with ISO formatted date (optional)
* or Number with the relative distance of the day from the date
* currently displayed.
*
* Displays the Losungen for the given date (or today if not defined)
*/
display() {
// first scroll then switch to avoid blinking of the page
window.scroll(0, 0);
var visibleElems = document.getElementsByClassName("visible");
Array.prototype.forEach.call(visibleElems, function(e) {
e.classList.remove("visible");
});
}
/**
* react to the discovered distance of swipe
*
* @param distX Number distance in points in direction X
* @param distY Number distance in points in direction Y
*
* There is a preference for the horizontal swipe; if that doesn't
* happen (i.e., the distance travelled horizontally is less than
* negligible), then the vertical swipe (in either direction) means
* jump to today.
*/
handle_move(distX, distY) {
var negligible = 100;
if (distX < -negligible) {
this.next();
}
else if (distX > negligible) {
this.prev();
}
}
next() {
this.cur_section += 1;
this.display();
}
prev() {
this.cur_section -= 1;
this.display();
}
}
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