search: Replace IconGrid from grid search results

Replace the usage of IconGrid in the grid search results by
a custom layout manager that only allocates as many children
as the actor can fit.

This new layout manager does not implement changing the icon
size depending on the screen size.

https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1265

data/theme/gnome-shell-sass/widgets/_search-results.scss

@@ -54,6 +54,10 @@
   @extend %status_text;
 }
 
+.grid-search-results {
+  spacing: $base_spacing * 6;
+}
+
 // Search results with icons
 .grid-search-result {
   @extend %app-well-app;

js/ui/search.js

@@ -13,7 +13,6 @@ const Util = imports.misc.util;
 const SEARCH_PROVIDERS_SCHEMA = 'org.gnome.desktop.search-providers';
 
 var MAX_LIST_SEARCH_RESULTS_ROWS = 5;
-var MAX_GRID_SEARCH_RESULTS_ROWS = 1;
 
 var MaxWidthBox = GObject.registerClass(
 class MaxWidthBox extends St.BoxLayout {
@@ -349,18 +348,140 @@ class ListSearchResults extends SearchResultsBase {
     }
 });
 
+var GridSearchResultsLayout = GObject.registerClass({
+    Properties: {
+        'spacing': GObject.ParamSpec.int('spacing', 'Spacing', 'Spacing',
+            GObject.ParamFlags.READWRITE, 0, GLib.MAXINT32, 0),
+    },
+}, class GridSearchResultsLayout extends Clutter.LayoutManager {
+    _init() {
+        super._init();
+        this._spacing = 0;
+    }
+
+    vfunc_set_container(container) {
+        this._container = container;
+    }
+
+    vfunc_get_preferred_width(container, forHeight) {
+        let minWidth = 0;
+        let natWidth = 0;
+        let first = true;
+
+        for (let child of container) {
+            if (!child.visible)
+                continue;
+
+            const [childMinWidth, childNatWidth] = child.get_preferred_width(forHeight);
+
+            minWidth = Math.max(minWidth, childMinWidth);
+            natWidth += childNatWidth;
+
+            if (first)
+                first = false;
+            else
+                natWidth += this._spacing;
+        }
+
+        return [minWidth, natWidth];
+    }
+
+    vfunc_get_preferred_height(container, forWidth) {
+        let minHeight = 0;
+        let natHeight = 0;
+
+        for (let child of container) {
+            if (!child.visible)
+                continue;
+
+            const [childMinHeight, childNatHeight] = child.get_preferred_height(forWidth);
+
+            minHeight = Math.max(minHeight, childMinHeight);
+            natHeight = Math.max(natHeight, childNatHeight);
+        }
+
+        return [minHeight, natHeight];
+    }
+
+    vfunc_allocate(container, box, flags) {
+        const width = box.get_width();
+
+        const childBox = new Clutter.ActorBox();
+        childBox.x1 = 0;
+        childBox.y1 = 0;
+
+        let first = true;
+        for (let child of container) {
+            if (!child.visible)
+                continue;
+
+            if (first)
+                first = false;
+            else
+                childBox.x1 += this._spacing;
+
+            const [childWidth] = child.get_preferred_width(-1);
+            const [childHeight] = child.get_preferred_height(-1);
+            childBox.set_size(childWidth, childHeight);
+
+            if (childBox.x1 + childWidth > width)
+                return;
+
+            child.allocate(childBox, flags);
+
+            childBox.x1 += childWidth;
+        }
+    }
+
+    columnsForWidth(width) {
+        if (!this._container)
+            return -1;
+
+        const [minWidth] = this.get_preferred_width(this._container, -1);
+
+        if (minWidth === 0)
+            return -1;
+
+        let nCols = 0;
+        while (width > minWidth) {
+            width -= minWidth;
+            if (nCols > 0)
+                width -= this._spacing;
+            nCols++;
+        }
+
+        return nCols;
+    }
+
+    get spacing() {
+        return this._spacing;
+    }
+
+    set spacing(v) {
+        if (this._spacing === v)
+            return;
+        this._spacing = v;
+        this.layout_changed();
+    }
+});
+
 var GridSearchResults = GObject.registerClass(
 class GridSearchResults extends SearchResultsBase {
     _init(provider, resultsView) {
         super._init(provider, resultsView);
 
-        this._grid = new IconGrid.IconGrid({ rowLimit: MAX_GRID_SEARCH_RESULTS_ROWS,
-                                             xAlign: St.Align.START });
+        this._grid = new St.Widget({ style_class: 'grid-search-results' });
+        this._grid.layout_manager = new GridSearchResultsLayout();
 
-        this._bin = new St.Bin({ x_align: Clutter.ActorAlign.CENTER });
-        this._bin.set_child(this._grid);
+        this._grid.connect('style-changed', () => {
+            const node = this._grid.get_theme_node();
+            this._grid.layout_manager.spacing = node.get_length('spacing');
+        });
 
-        this._resultDisplayBin.set_child(this._bin);
+        this._resultDisplayBin.set_child(new St.Bin({
+            child: this._grid,
+            x_align: Clutter.ActorAlign.CENTER,
+        }));
     }
 
     _onDestroy() {
@@ -400,12 +521,11 @@ class GridSearchResults extends SearchResultsBase {
         if (width == 0)
             return -1;
 
-        let nCols = this._grid.columnsForWidth(width);
-        return nCols * this._grid.getRowLimit();
+        return this._grid.layout_manager.columnsForWidth(width);
     }
 
     _clearResultDisplay() {
-        this._grid.removeAll();
+        this._grid.remove_all_children();
     }
 
     _createResultDisplay(meta) {
@@ -414,13 +534,14 @@ class GridSearchResults extends SearchResultsBase {
     }
 
     _addItem(display) {
-        this._grid.addItem(display);
+        this._grid.add_child(display);
     }
 
     getFirstResult() {
-        if (this._grid.visibleItemsCount() > 0)
-            return this._grid.getItemAtIndex(0);
-        else
+        for (let child of this._grid) {
+            if (child.visible)
+                return child;
+        }
         return null;
     }
 });