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Fix lightbox zoom issues. 

This fixes the lightbox zoom issues that occurred on some browsers
due to the units of `deltaY` being in lines rathern than pixels,
making it incredibly slow to zoom.
This commit is contained in:
Brock Whittaker 2017-08-02 13:39:20 -07:00 committed by Tim Abbott
parent 48815204e4
commit e22920bef6
1 changed files with 18 additions and 0 deletions
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18
static/js/lightbox_canvas.js
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@ -41,6 +41,14 @@ var LightboxCanvas = (function () {
attachEvents: function (canvas, context, meta) { attachEvents: function (canvas, context, meta) {
var mousedown = false; var mousedown = false;
// wheelEvent.deltaMode is a value that describes what the unit is
// for the `deltaX`, `deltaY`, and `deltaZ` properties.
const DELTA_MODE = {
PIXEL: 0,
LINE: 1,
PAGE: 2,
};
// give object structure in `mousedown`, because its props are only // give object structure in `mousedown`, because its props are only
// ever set once `mousedown` + `mousemove` is triggered. // ever set once `mousedown` + `mousemove` is triggered.
var lastPosition = {}; var lastPosition = {};
@ -69,6 +77,16 @@ var LightboxCanvas = (function () {
// this is to reverese scrolling directions for the image. // this is to reverese scrolling directions for the image.
var delta = meta.direction * e.deltaY; var delta = meta.direction * e.deltaY;
if (e.deltaMode === DELTA_MODE.LINE) {
// the vertical height in pixels of an approximate line.
delta *= 15;
}
if (e.deltaMode === DELTA_MODE.PAGE) {
// the vertical height in pixels of an approximate page.
delta *= 300;
}
// this is calculated as the user defined speed times the normalizer // this is calculated as the user defined speed times the normalizer
// (which just is what it takes to take the raw delta and transform // (which just is what it takes to take the raw delta and transform
// it to a normal speed), multiply it against the current zoom. // it to a normal speed), multiply it against the current zoom.