lots of fixes to pdfs and link following.

1 files changed, 30 insertions, 0 deletions

diff --git a/src/Utils.ts b/src/Utils.ts
index 4fac53c7d..2b00a6530 100644
--- a/src/Utils.ts
+++ b/src/Utils.ts
@@ -307,4 +307,34 @@ export function PostToServer(relativeRoute: string, body: any) {
         body: body
     };
     return requestPromise.post(options);
+}
+
+const easeInOutQuad = (currentTime: number, start: number, change: number, duration: number) => {
+    let newCurrentTime = currentTime / (duration / 2);
+
+    if (newCurrentTime < 1) {
+        return (change / 2) * newCurrentTime * newCurrentTime + start;
+    }
+
+    newCurrentTime -= 1;
+    return (-change / 2) * (newCurrentTime * (newCurrentTime - 2) - 1) + start;
+};
+
+export default function smoothScroll(duration: number, element: HTMLElement, to: number) {
+    const start = element.scrollTop;
+    const change = to - start;
+    const startDate = new Date().getTime();
+
+    const animateScroll = () => {
+        const currentDate = new Date().getTime();
+        const currentTime = currentDate - startDate;
+        element.scrollTop = easeInOutQuad(currentTime, start, change, duration);
+
+        if (currentTime < duration) {
+            requestAnimationFrame(animateScroll);
+        } else {
+            element.scrollTop = to;
+        }
+    };
+    animateScroll();
 }
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