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Fix flickering issue at certain rotation angles.

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This commit is contained in:
Antoine Vandecreme 2015-12-13 11:49:58 -05:00
parent 4a6d31ae37
commit 2dcd40afc6
1 changed files with 31 additions and 3 deletions
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34
src/point.js
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@ -185,9 +185,37 @@ $.Point.prototype = /** @lends OpenSeadragon.Point.prototype */{
*/
rotate: function (degrees, pivot) {
pivot = pivot || new $.Point(0, 0);
var angle = degrees * Math.PI / 180.0;
var cos = Math.cos(angle);
var sin = Math.sin(angle);
var cos;
var sin;
// Avoid float computations when possible
if (degrees % 90 === 0) {
var d = degrees % 360;
if (d < 0) {
d += 360;
}
switch (d) {
case 0:
cos = 1;
sin = 0;
break;
case 90:
cos = 0;
sin = 1;
break;
case 180:
cos = -1;
sin = 0;
break;
case 270:
cos = 0;
sin = -1;
break;
}
} else {
var angle = degrees * Math.PI / 180.0;
cos = Math.cos(angle);
sin = Math.sin(angle);
}
var x = cos * (this.x - pivot.x) - sin * (this.y - pivot.y) + pivot.x;
var y = sin * (this.x - pivot.x) + cos * (this.y - pivot.y) + pivot.y;
return new $.Point(x, y);