[Rust] Port the ListView demo (#198)

* [Rust] Ported the listview demo

* Improve the comment on Cell usage

* small comment change

* Update src/List View/code.rs

Fix the language

Co-authored-by: Hofer-Julian <[email protected]>

* Update src/List View/code.rs

Missed this one glib::clone

Co-authored-by: Hofer-Julian <[email protected]>

* Update src/List View/code.rs

Fixed comment

Co-authored-by: Hofer-Julian <[email protected]>

* Update src/List View/code.rs

English too hard

Co-authored-by: Hofer-Julian <[email protected]>

* Update src/List View/code.rs

Co-authored-by: Hofer-Julian <[email protected]>

* Update src/List View/code.rs

Remove unnecessary debugging output

Co-authored-by: Hofer-Julian <[email protected]>

* Apply suggestions from code review

Co-authored-by: Hofer-Julian <[email protected]>

* Strings_model => string_model

---------

Co-authored-by: Ondrej Kolin <[email protected]>
Co-authored-by: Hofer-Julian <[email protected]>

src/List View/code.rs

@@ -0,0 +1,81 @@
+use crate::workbench;
+use gtk;
+use gtk::glib;
+use gtk::prelude::*;
+use std::cell::Cell;
+
+pub fn main() {
+    // Required by gtk::StringList::new(), otherwise crashes
+    gtk::init().unwrap();
+
+    let list_view: gtk::ListView = workbench::builder().object("list_view").unwrap();
+    let add: gtk::Button = workbench::builder().object("add").unwrap();
+    let remove: gtk::Button = workbench::builder().object("remove").unwrap();
+
+    // https://doc.rust-lang.org/std/cell/struct.Cell.html
+    // "A mutable memory location."
+    // Makes it possible to access and change values from within signal handlers
+    let item = Cell::new(1);
+
+    // Model
+    let string_model =
+        gtk::StringList::new(&["Default Item 1", "Default Item 2", "Default Item 3"]);
+    let model = gtk::SingleSelection::new(Some(string_model.clone()));
+
+    // View
+    string_model.connect_items_changed(move |_model, position, removed, added| {
+        println!(
+            "position: {}, Item removed? {}, Item added? {}",
+            position,
+            removed > 0,
+            added > 0
+        )
+    });
+
+    model.connect_selection_changed(move |model, _position, _n_items| {
+        let selected_item = model.selected();
+        println!(
+            "Model item selected from view: {}",
+            model
+                .item(selected_item) // Get the item
+                .unwrap() // Make sure it exists
+                .downcast::<gtk::StringObject>() // It's a member of GStringList
+                .unwrap() // Make sure it's really a StringObject
+                .string() // Read the string value
+        )
+    });
+
+    add.connect_clicked(glib::clone!(
+    // Copy the reference, so it's accessible from the closure
+        // https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/macro.clone.html
+    @weak model => move |_| {
+        // Get the item counter value
+        let value = item.get();
+        // Access the underlying gtk::StringList
+        let string_model = model
+            .model()
+            .unwrap()
+            .downcast::<gtk::StringList>()
+            .unwrap();
+        string_model.append(format!("New item {}", item.get()).as_str());
+        // Increase the counter
+        item.set(value + 1);
+    }));
+
+    remove.connect_clicked(gtk::glib::clone!(
+    // Copy the reference, so it's accessible from the closure
+    // https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/macro.clone.html
+    @weak model => move |_| {
+      let selected_item = model.selected();
+      // In order to delete values we need to access the
+      // actual StringList model, we've created.
+      let string_model = model
+        .model()
+        .unwrap()
+        .downcast::<gtk::StringList>()
+        .unwrap();
+      string_model.remove(selected_item);
+    }));
+
+    list_view.set_model(Some(&model));
+}