From d2cb4aceb42397b63c2485ebc86c9ad69bf22ede Mon Sep 17 00:00:00 2001
From: ratatoeskr666 <erik.finnork@hotmail.de>
Date: Sat, 5 Aug 2023 14:54:29 +0000
Subject: [PATCH] Only capture pointer when a certain threshold is exceeded
 Only invoke window.move() once every 5ms to prevent performance issues

---
 src/api/window.ts | 42 +++++++++++++++++++++++++++++++++++-------
 1 file changed, 35 insertions(+), 7 deletions(-)

diff --git a/src/api/window.ts b/src/api/window.ts
index c1386da..ea111d5 100644
--- a/src/api/window.ts
+++ b/src/api/window.ts
@@ -102,6 +102,9 @@ export function setDraggableRegion(domElementOrId: string | HTMLElement): Promis
                                                     domElementOrId : document.getElementById(domElementOrId);
         let initialClientX: number = 0;
         let initialClientY: number = 0;
+        let absDragMovementDistance: number = 0; 
+        let isPointerCaptured = false;
+        let lastMoveTimestamp = performance.now();
 
         if (!draggableRegion) {
             return reject({
@@ -122,19 +125,44 @@ export function setDraggableRegion(domElementOrId: string | HTMLElement): Promis
 
         draggableRegions.set(draggableRegion, { pointerdown: startPointerCapturing, pointerup: endPointerCapturing });
 
-        async function onPointerMove(evt: PointerEvent) {
-            await move(
-                evt.screenX - initialClientX,
-                evt.screenY - initialClientY
-            );
+        async function onPointerMove(evt: PointerEvent) {            
+
+            if (isPointerCaptured) {                                        
+
+                const currentMilliseconds = performance.now();
+                const timeTillLastMove = currentMilliseconds - lastMoveTimestamp;
+                // Limit move calls to 1 per every 5ms - TODO: introduce constant instead of magic number?
+                if (timeTillLastMove < 5) {
+                    // Do not execute move more often than 1x every 5ms or performance will drop 
+                    return;
+                }
+
+                // Store current time minus the offset
+                lastMoveTimestamp = currentMilliseconds - (timeTillLastMove - 5);
+
+                await move(
+                    evt.screenX - initialClientX,
+                    evt.screenY - initialClientY
+                );
+
+                return;
+            }
+
+            // Add absolute drag distance 
+            absDragMovementDistance = Math.sqrt(evt.movementX * evt.movementX + evt.movementY * evt.movementY);
+            // Only start pointer capturing when the user dragged more than a certain amount of distance 
+            // This ensures that the user can also click on the dragable area, e.g. if the area is menu / navbar
+            if (absDragMovementDistance >= 10) { // TODO: introduce constant instead of magic number? 
+                isPointerCaptured = true;
+                draggableRegion.setPointerCapture(evt.pointerId);
+            }
         }
 
         function startPointerCapturing(evt: PointerEvent) {
             if (evt.button !== 0) return;
             initialClientX = evt.clientX;
             initialClientY = evt.clientY;
-            draggableRegion.addEventListener('pointermove', onPointerMove);
-            draggableRegion.setPointerCapture(evt.pointerId);
+            draggableRegion.addEventListener('pointermove', onPointerMove);            
         }
 
         function endPointerCapturing(evt: PointerEvent) {