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authortoasted-nutbread <toasted-nutbread@users.noreply.github.com>2019-09-15 17:52:30 -0400
committertoasted-nutbread <toasted-nutbread@users.noreply.github.com>2019-09-27 21:41:00 -0400
commit946e577e42db9df43169d8547d4536fe8edd6748 (patch)
tree3ca1d83d1d5bedcd113d71235f507411a49239c2 /ext/mixed/js/scroll.js
parent9fc69395c5a3c66a9289c73d412f8b92d9bc4b31 (diff)
Implement custom window scroll
Diffstat (limited to 'ext/mixed/js/scroll.js')
-rw-r--r--ext/mixed/js/scroll.js100
1 files changed, 100 insertions, 0 deletions
diff --git a/ext/mixed/js/scroll.js b/ext/mixed/js/scroll.js
new file mode 100644
index 00000000..824fd92b
--- /dev/null
+++ b/ext/mixed/js/scroll.js
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2019 Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+class WindowScroll {
+ constructor() {
+ this.animationRequestId = null;
+ this.animationStartTime = 0;
+ this.animationStartX = 0;
+ this.animationStartY = 0;
+ this.animationEndTime = 0;
+ this.animationEndX = 0;
+ this.animationEndY = 0;
+ this.requestAnimationFrameCallback = (t) => this.onAnimationFrame(t);
+ }
+
+ toY(y) {
+ this.to(this.x, y);
+ }
+
+ toX(x) {
+ this.to(x, this.y);
+ }
+
+ to(x, y) {
+ this.stop();
+ window.scroll(x, y);
+ }
+
+ animate(x, y, time) {
+ this.animationStartX = this.x;
+ this.animationStartY = this.y;
+ this.animationStartTime = window.performance.now();
+ this.animationEndX = x;
+ this.animationEndY = y;
+ this.animationEndTime = this.animationStartTime + time;
+ this.animationRequestId = window.requestAnimationFrame(this.requestAnimationFrameCallback);
+ }
+
+ stop() {
+ if (this.animationRequestId === null) {
+ return;
+ }
+
+ window.cancelAnimationFrame(this.animationRequestId);
+ this.animationRequestId = null;
+ }
+
+ onAnimationFrame(time) {
+ if (time >= this.animationEndTime) {
+ window.scroll(this.animationEndX, this.animationEndY);
+ this.animationRequestId = null;
+ return;
+ }
+
+ const t = WindowScroll.easeInOutCubic((time - this.animationStartTime) / (this.animationEndTime - this.animationStartTime));
+ window.scroll(
+ WindowScroll.lerp(this.animationStartX, this.animationEndX, t),
+ WindowScroll.lerp(this.animationStartY, this.animationEndY, t)
+ );
+
+ this.animationRequestId = window.requestAnimationFrame(this.requestAnimationFrameCallback);
+ }
+
+ get x() {
+ return window.scrollX || window.pageXOffset;
+ }
+
+ get y() {
+ return window.scrollY || window.pageYOffset;
+ }
+
+ static easeInOutCubic(t) {
+ if (t < 0.5) {
+ return (4.0 * t * t * t);
+ } else {
+ t = 1.0 - t;
+ return 1.0 - (4.0 * t * t * t);
+ }
+ }
+
+ static lerp(start, end, percent) {
+ return (end - start) * percent + start;
+ }
+}