View mode scroll fix

view-mode/function/function.js

@@ -522,3 +522,33 @@ function replaceAll(str, find, replace) {
 	}
 	return str
 }
+
+// Function to get the earliest planned start date among all tasks
+function getEarliestTaskDate() {
+	var earliestDate = null;
+	gantt.eachTask(function (task) {
+		var taskStartDate = task.planned_start || task.start_date;
+		if (!earliestDate || task.planned_start < earliestDate) {
+			earliestDate = taskStartDate;
+			if (task.start_date < earliestDate) {
+				earliestDate = task.start_date;
+			}
+		}
+	});
+	return earliestDate;
+}
+
+// Function to get the latest planned end date among all tasks
+function getLatestTaskDate() {
+	var latestDate = null;
+	gantt.eachTask(function (task) {
+		var taskEndDate = task.planned_end || task.end_date;
+		if (!latestDate || task.planned_end > latestDate) {
+			latestDate = taskEndDate;
+			if (task.end_date > latestDate) {
+				latestDate = task.end_date;
+			}
+		}
+	});
+	return latestDate;
+}

view-mode/function/ganttEvent.js

@@ -97,4 +97,34 @@ gantt.attachEvent("onGanttRender", function(){
     }else{
         gantt.config.readonly = true;
     }
+});
+
+gantt.attachEvent("onGanttScroll", function (left, top){
+  var left_date = gantt.dateFromPos(left)
+  var right_date = gantt.dateFromPos(left + gantt.$task.offsetWidth)
+  
+  let taskCount = gantt.getTaskCount();
+  if (taskCount > 0) {
+    gantt.config.start_date = gantt.config.start_date || gantt.getState().min_date;
+    gantt.config.end_date = gantt.config.end_date || gantt.getState().max_date;
+    
+    var min_allowed_date = gantt.date.add(gantt.config.start_date, 1, "day");
+    var max_allowed_date = gantt.date.add(gantt.config.end_date, -1, "day");
+    
+    var repaint = false;
+      if (earliest && +left_date <= +min_allowed_date && +left_date >= +earliest){
+        gantt.config.start_date = gantt.date.add(gantt.config.start_date, -1, "day");
+        repaint = true;
+    }
+      if (latest && +right_date >= +max_allowed_date && +right_date <= +latest){
+        gantt.config.end_date = gantt.date.add(gantt.config.end_date, 1, "day");
+        repaint = true;
+    }
+    
+    if (repaint) {
+        setTimeout(function(){
+            gantt.render()
+        },20)
+    }
+}
 });

view-mode/function/restActivityLink.js

@@ -1,4 +1,6 @@
 var parts = [];
+let latest;
+let earliest;
 window.parent.postMessage({ action: 'getUrl' }, '*');
 window.addEventListener('message', function(event) {
   if (event.data && event.data.action === 'sendUrl') {
@@ -40,6 +42,8 @@ gantt.ajax.get({
     if(!parts[2]){
       gantt.silent(function () {
         gantt.parse(data);
+        earliest = getEarliestTaskDate();
+        latest = getLatestTaskDate();
       });
     }
 });
@@ -62,6 +66,8 @@ function refresData(id){
         if(!parts[2]){
           gantt.silent(function () {
             gantt.parse(data);
+            earliest = getEarliestTaskDate();
+            latest = getLatestTaskDate();
           });
         }
         if(id){