Harden icon cache concurrency (T-606)

app-modern/ui/gio/shell.go

@@ -103,14 +103,19 @@ func (shell *AppShell) SetItems(items []application.CatalogListItem) {
 	shell.model.SetItems(items)
 
 	nextRows := make(map[string]*rowControls, len(items))
+	nextIcons := make(map[string]paint.ImageOp, len(items))
 	for _, item := range items {
 		controls := shell.rows[item.ID]
 		if controls == nil {
 			controls = new(rowControls)
 		}
 		nextRows[item.ID] = controls
+		if icon, exists := shell.icons[item.ID]; exists {
+			nextIcons[item.ID] = icon
+		}
 	}
 	shell.rows = nextRows
+	shell.icons = nextIcons
 
 	nextCategories := make(map[string]*widget.Clickable)
 	for _, category := range append([]string{""}, shell.model.Categories()...) {

app-modern/ui/gio/shell_test.go

@@ -61,6 +61,8 @@ func TestAppShellKeepsRowControlsByAppID(t *testing.T) {
 	}
 	shell := NewAppShell("Modern", items...)
 	original := shell.rows["app-two"]
+	shell.ApplyIcon("app-one", image.NewNRGBA(image.Rect(0, 0, 16, 16)))
+	shell.ApplyIcon("app-two", image.NewNRGBA(image.Rect(0, 0, 24, 24)))
 
 	shell.model.SetCategory("图像")
 	shell.Layout(testContext(image.Pt(1080, 720)), NewTheme())
@@ -77,6 +79,16 @@ func TestAppShellKeepsRowControlsByAppID(t *testing.T) {
 	if _, exists := shell.rows["app-one"]; exists {
 		t.Fatal("removed app retained row controls")
 	}
+	if _, exists := shell.icons["app-one"]; exists {
+		t.Fatal("removed app retained prepared icon")
+	}
+	icon, exists := shell.icons["app-two"]
+	if !exists {
+		t.Fatal("retained app lost its prepared icon")
+	}
+	if icon.Size() != image.Pt(24, 24) {
+		t.Fatalf("retained app icon size = %v", icon.Size())
+	}
 }
 
 func TestAppShellRendersSelectedDetailAndAppliedIcon(t *testing.T) {