dtlaunch: add global dtlaunch object

The global dtlaunch object contains function and information to restore
the page between instances of dtlaunch.

apps/dtlaunch/app-b2.js

@@ -33,8 +33,12 @@
     s.writeJSON("launch.cache.json", launchCache);
   }
   let apps = launchCache.apps;
-  let page = (Bangle.dtHandlePagePersist&&Bangle.dtHandlePagePersist()) ?? (parseInt(s.read("dtlaunch.page")) ?? 0);
-  for (let i = page*4; i < Math.min(page*4+4, apps.length); i++) { // Initially only load icons for the current page.
+  let page = (global.dtlaunch&&dtlaunch.HandlePagePersist()) ??
+    (parseInt(s.read("dtlaunch.page")) ?? 0);
+
+  const INIT_PAGE_APP_ZEROTH = page*4;
+  const INIT_PAGE_APP_LAST = Math.min(page*5-1, apps.length-1)
+  for (let i = INIT_PAGE_APP_ZEROTH; i <= INIT_PAGE_APP_LAST; i++) { // Initially only load icons for the current page.
     if (apps[i].icon)
       apps[i].icon = s.read(apps[i].icon); // should just be a link to a memory area
   }
@@ -102,26 +106,27 @@
   drawPage(page);
 
   for (let i = 0; i < apps.length; i++) { // Load the rest of the app icons that were not initially.
-    if (i >= page*4 && i < Math.min(page*4+4, apps.length)) continue;
+    if (i >= INIT_PAGE_APP_ZEROTH && i <= INIT_PAGE_APP_LAST) continue;
     if (apps[i].icon)
       apps[i].icon = s.read(apps[i].icon); // should just be a link to a memory area
   }
 
-  if (!Bangle.dtHandlePagePersist) {
-    Bangle.dtHandlePagePersist = (page) => {
+  if (!global.dtlaunch) {
+    global.dtlaunch = {};
+    dtlaunch.HandlePagePersist = (page) => {
       // Function for persisting the active page when leaving dtlaunch.
-      if (page===undefined) {return this.page||0;}
+      if (page===undefined) {return dtlaunch.page||0;}
 
-      if (!this.killHandler) { // Only register kill listener once.
-        this.killHandler = () => {
-          s.write("dtlaunch.page", this.page.toString());
+      if (!dtlaunch.killHandler) { // Only register kill listener once.
+        dtlaunch.killHandler = () => {
+          s.write("dtlaunch.page", dtlaunch.page.toString());
         };
-        E.on("kill", this.killHandler); // This is intentionally left around after fastloading into other apps. I.e. not removed in uiRemove.
+        E.on("kill", dtlaunch.killHandler); // This is intentionally left around after fastloading into other apps. I.e. not removed in uiRemove.
       }
 
-      this.page = page;
+      dtlaunch.page = page;
     };
-    Bangle.dtHandlePagePersist(page);
+    dtlaunch.HandlePagePersist(page);
   }
 
   let swipeListenerDt = function(dirLeftRight, dirUpDown){
@@ -160,7 +165,7 @@
               drawIcon(page,selected,false);
             } else {
               buzzLong();
-              Bangle.dtHandlePagePersist(page);
+              dtlaunch.HandlePagePersist(page);
               load(apps[page*4+i].src);
             }
           }
@@ -183,7 +188,7 @@
     touch : touchListenerDt,
     remove : ()=>{
       if (timeoutToClock) {clearTimeout(timeoutToClock);}
-      Bangle.dtHandlePagePersist(page);
+      dtlaunch.HandlePagePersist(page);
     }
   });