GridView: Create dummy grids only when no apps to populate

meson.build

@@ -45,6 +45,7 @@ json_glib_dep = dependency('json-glib-1.0')
 switchboard_dep = dependency('switchboard-3')
 libhandy_dep = dependency('libhandy-1', version: '>= 0.83.0')
 wingpanel_dep = dependency('wingpanel', version: '>=2.1.0')
+math_dep = meson.get_compiler('c').find_library('m')
 posix_dep = meson.get_compiler('vala').find_library('posix')
 
 zeitgeist_dep = []

src/Views/GridView.vala

@@ -7,6 +7,7 @@
 public class Slingshot.Widgets.Grid : Gtk.Box {
     private const int PAGE_ROWS = 3;
     private const int PAGE_COLUMNS = 5;
+    private const int MAX_APPS_IN_PAGE = (PAGE_ROWS * PAGE_COLUMNS);
 
     private Hdy.Carousel paginator;
     private Gtk.EventControllerKey key_controller;
@@ -75,35 +76,54 @@ public class Slingshot.Widgets.Grid : Gtk.Box {
             paginator.remove (child);
         }
 
-        var grid = add_new_grid ();
-        // Where to insert new app button
-        var next_row_index = 0;
-        var next_col_index = 0;
+        var apps = app_system.get_apps_by_name ();
+        var num_apps = apps.length ();
 
-        foreach (Backend.App app in app_system.get_apps_by_name ()) {
-            var app_button = new Widgets.AppButton (app);
-            app_button.app_launched.connect (() => ((Gtk.Popover) get_ancestor (typeof (Gtk.Popover))).popdown ());
+        // e.g. Number of pages needed to show 33 apps is 3; 2 pages with fully apps and 1 additional page
+        var num_pages = (int) Math.ceil ((double) num_apps / MAX_APPS_IN_PAGE);
 
-            if (next_col_index == PAGE_COLUMNS) {
-                next_col_index = 0;
-                next_row_index++;
-            }
+        for (uint page_idx = 0; page_idx < num_pages; page_idx++) {
+            // Number of total apps populated after dealing with this page
+            // clamp is used to handle last page correctly; has no effect for other pages
+            var num_apps_populated = ((page_idx + 1) * MAX_APPS_IN_PAGE).clamp (1, num_apps);
 
-            if (next_row_index == PAGE_ROWS) {
-                grid = add_new_grid ();
-                next_row_index = 0;
-                next_col_index = 0;
-            }
+            // Number of apps in this page, in range of 1 to MAX_APPS_IN_PAGE
+            // Subtract 1 before calculating modulo and finally adds 1 to prevent the result becomes 0
+            var num_apps_in_page = ((num_apps_populated - 1) % MAX_APPS_IN_PAGE) + 1;
 
-            grid.attach (app_button, (int)next_col_index, (int)next_row_index);
-            next_col_index++;
+            populate_page (apps.nth (page_idx * MAX_APPS_IN_PAGE), num_apps_in_page);
         }
 
         show_all ();
         // Show first page after populating the carousel
         set_page (0);
     }
 
+    private void populate_page (SList<Backend.App> apps, uint num_apps) {
+        var grid = add_new_grid ();
+
+        for (var row = 0; row < PAGE_ROWS; row++) {
+            for (var column = 0; column < PAGE_COLUMNS; column++) {
+                Gtk.Widget widget_to_attach;
+
+                var app_idx = (row * PAGE_COLUMNS) + column;
+                if (app_idx < num_apps) {
+                    unowned var app = apps.nth_data (app_idx);
+
+                    var app_button = new Widgets.AppButton (app);
+                    app_button.app_launched.connect (() => ((Gtk.Popover) get_ancestor (typeof (Gtk.Popover))).popdown ());
+
+                    widget_to_attach = app_button;
+                } else {
+                    // Fake grid in case there are not enough apps to fill the page
+                    widget_to_attach = new Gtk.Grid ();
+                }
+
+                grid.attach (widget_to_attach, column, row);
+            }
+        }
+    }
+
     private Gtk.Grid add_new_grid () {
         var grid = new Gtk.Grid () {
             hexpand = true,
@@ -116,13 +136,6 @@ public class Slingshot.Widgets.Grid : Gtk.Box {
             column_spacing = 0
         };
 
-        // Fake grids in case there are not enough apps to fill the grid
-        for (var row = 0; row < PAGE_ROWS; row++) {
-            for (var column = 0; column < PAGE_COLUMNS; column++) {
-                grid.attach (new Gtk.Grid (), column, row, 1, 1);
-            }
-        }
-
         paginator.add (grid);
 
         return grid;

src/meson.build

@@ -82,6 +82,7 @@ dependencies = [
     zeitgeist_dep,
     wingpanel_dep,
     libhandy_dep,
+    math_dep,
     posix_dep,
 ]