GPS: introduce an app structure

src/app.rs

@@ -0,0 +1,238 @@
+// app.rs
+//
+// Copyright 2021 Stéphane Cerveau <scerveau@collabora.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+// SPDX-License-Identifier: GPL-3.0-only
+use gtk::cairo::Context;
+use gtk::glib;
+use gtk::prelude::*;
+use gtk::{
+    AboutDialog, AccelFlags, AccelGroup, ApplicationWindow, Builder, Button, DrawingArea, EventBox,
+    FileChooserDialog, MenuItem, ResponseType, Viewport, WindowPosition,
+};
+use std::cell::RefCell;
+use std::rc::{Rc, Weak};
+use std::{error, ops};
+
+use crate::pipeline::Pipeline;
+use crate::pluginlistwindow;
+
+#[derive(Debug)]
+pub struct GPSAppInner {
+    pub window: gtk::ApplicationWindow,
+    pub builder: Builder,
+    pipeline: Pipeline,
+}
+
+// This represents our main application window.
+#[derive(Debug, Clone)]
+pub struct GPSApp(Rc<GPSAppInner>);
+
+// Deref into the contained struct to make usage a bit more ergonomic
+impl ops::Deref for GPSApp {
+    type Target = GPSAppInner;
+
+    fn deref(&self) -> &GPSAppInner {
+        &*self.0
+    }
+}
+
+// Weak reference to our application struct
+//
+// Weak references are important to prevent reference cycles. Reference cycles are cases where
+// struct A references directly or indirectly struct B, and struct B references struct A again
+// while both are using reference counting.
+pub struct GPSAppWeak(Weak<GPSAppInner>);
+impl GPSAppWeak {
+    // Upgrade to a strong reference if it still exists
+    pub fn upgrade(&self) -> Option<GPSApp> {
+        self.0.upgrade().map(GPSApp)
+    }
+}
+
+#[derive(Debug, Clone, Default)]
+struct Element {
+    name: String,
+    position: (f64, f64),
+    size: (f64, f64),
+}
+fn draw_elements(elements: &Vec<Element>, c: &Context) {
+    for element in elements {
+        c.rectangle(element.position.0, element.position.1, 80.0, 45.0);
+        c.fill().expect("Can not draw into context");
+    }
+}
+
+impl GPSApp {
+    fn new(application: &gtk::Application) -> anyhow::Result<GPSApp, Box<dyn error::Error>> {
+        let glade_src = include_str!("gps.ui");
+        let builder = Builder::from_string(glade_src);
+        let window: ApplicationWindow = builder.object("mainwindow").expect("Couldn't get window");
+        window.set_application(Some(application));
+        window.set_title("GstPipelineStudio");
+        window.set_position(WindowPosition::Center);
+        window.set_size_request(800, 600);
+        let pipeline = Pipeline::new().expect("Unable to initialize the pipeline");
+
+        let app = GPSApp(Rc::new(GPSAppInner {
+            window,
+            builder,
+            pipeline,
+        }));
+        Ok(app)
+    }
+    pub fn on_startup(application: &gtk::Application) {
+        // Create application and error out if that fails for whatever reason
+        let app = match GPSApp::new(application) {
+            Ok(app) => app,
+            Err(_err) => {
+                /*                 utils::show_error_dialog(
+                    true,
+                    format!("Error creating application: {}", err).as_str(),
+                ); */
+                return;
+            }
+        };
+
+        // When the application is activated show the UI. This happens when the first process is
+        // started, and in the first process whenever a second process is started
+        let app_weak = app.downgrade();
+        application.connect_activate(move |_| {
+            let app = upgrade_weak!(app_weak);
+            app.build_ui();
+        });
+
+        let app_container = RefCell::new(Some(app));
+        application.connect_shutdown(move |_| {
+            let app = app_container
+                .borrow_mut()
+                .take()
+                .expect("Shutdown called multiple times");
+            app.drop();
+        });
+    }
+
+    pub fn build_ui(&self) {
+        let drawing_area = DrawingArea::new();
+        let view_port: Viewport = self
+            .builder
+            .object("drawing_area")
+            .expect("Couldn't get window");
+        let event_box = EventBox::new();
+        event_box.add(&drawing_area);
+        view_port.add(&event_box);
+        let elements: Rc<RefCell<Vec<Element>>> = Rc::new(RefCell::new(vec![]));
+        let e_clone = elements.clone();
+        drawing_area.connect_draw(move |w, c| {
+            println!("w: {} c:{} e: {:?}", w, c, e_clone);
+            draw_elements(&e_clone.borrow().to_vec(), c);
+            gtk::Inhibit(false)
+        });
+
+        event_box.connect_button_release_event(move |_w, evt| {
+            let mut elements = elements.borrow_mut();
+            let mut element: Element = Default::default();
+            element.position.0 = evt.position().0;
+            element.position.1 = evt.position().1;
+            elements.push(element);
+            drawing_area.queue_draw();
+            gtk::Inhibit(false)
+        });
+        let window = &self.window;
+
+        window.show_all();
+
+        let quit: MenuItem = self
+            .builder
+            .object("menu-quit")
+            .expect("Couldn't get window");
+        let about: MenuItem = self
+            .builder
+            .object("menu-about")
+            .expect("Couldn't get window");
+        let about_dialog: AboutDialog = self
+            .builder
+            .object("dialog-about")
+            .expect("Couldn't get window");
+        about.connect_activate(move |_| {
+            about_dialog.connect_delete_event(|dialog, _| {
+                dialog.hide();
+                gtk::Inhibit(true)
+            });
+
+            about_dialog.show_all();
+        });
+
+        // Create a dialog to select GStreamer elements.
+        let add_button: Button = self
+            .builder
+            .object("button-add-plugin")
+            .expect("Couldn't get app_button");
+        let app_weak = self.downgrade();
+        add_button.connect_clicked(glib::clone!(@weak window => move |_| {
+            let app = upgrade_weak!(app_weak);
+            let elements = Pipeline::elements_list().expect("Unable to obtain element's list");
+            pluginlistwindow::build_plugin_list(&app, &elements);
+        }));
+        // Create a dialog to open a file
+        let open_button: Button = self
+            .builder
+            .object("button-open-file")
+            .expect("Couldn't get app_button");
+        let open_dialog: FileChooserDialog = self
+            .builder
+            .object("dialog-open-file")
+            .expect("Couldn't get window");
+        open_button.connect_clicked(glib::clone!(@weak window => move |_| {
+            // entry.set_text("Clicked!");
+            open_dialog.connect_response(|dialog, _| dialog.close());
+            open_dialog.add_buttons(&[
+                ("Open", ResponseType::Ok),
+                ("Cancel", ResponseType::Cancel)
+            ]);
+            open_dialog.set_select_multiple(true);
+            open_dialog.connect_response(|open_dialog, response| {
+                if response == ResponseType::Ok {
+                    let files = open_dialog.filenames();
+                    println!("Files: {:?}", files);
+                }
+                open_dialog.close();
+            });
+            open_dialog.show_all();
+        }));
+
+        let accel_group = AccelGroup::new();
+        window.add_accel_group(&accel_group);
+
+        quit.connect_activate(glib::clone!(@weak window => move |_| {
+            window.close();
+        }));
+
+        // `Primary` is `Ctrl` on Windows and Linux, and `command` on macOS
+        // It isn't available directly through `gdk::ModifierType`, since it has
+        // different values on different platforms.
+        let (key, modifier) = gtk::accelerator_parse("<Primary>Q");
+        quit.add_accelerator("activate", &accel_group, key, modifier, AccelFlags::VISIBLE);
+    }
+
+    // Downgrade to a weak reference
+    pub fn downgrade(&self) -> GPSAppWeak {
+        GPSAppWeak(Rc::downgrade(&self.0))
+    }
+
+    // Called when the application shuts down. We drop our app struct here
+    fn drop(self) {}
+}

src/macros.rs

@@ -0,0 +1,14 @@
+// Macro for upgrading a weak reference or returning the given value
+//
+// This works for glib/gtk objects as well as anything else providing an upgrade method
+macro_rules! upgrade_weak {
+    ($x:ident, $r:expr) => {{
+        match $x.upgrade() {
+            Some(o) => o,
+            None => return $r,
+        }
+    }};
+    ($x:ident) => {
+        upgrade_weak!($x, ())
+    };
+}

src/main.rs

@@ -17,12 +17,15 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 //
 // SPDX-License-Identifier: GPL-3.0-only
-mod mainwindow;
+#[macro_use]
+mod macros;
+mod app;
 mod pipeline;
 mod pluginlistwindow;
 
 use gtk::prelude::*;
 
+use crate::app::GPSApp;
 fn main() {
     //    gio::resources_register_include!("compiled.gresource").unwrap();
 
@@ -30,8 +33,9 @@ fn main() {
         Some("com.github.gtk-rs.examples.menu_bar"),
         Default::default(),
     );
-
-    application.connect_activate(mainwindow::build_ui);
+    application.connect_startup(|application| {
+        GPSApp::on_startup(application);
+    });
 
     application.run();
 }

src/mainwindow.rs

@@ -1,116 +0,0 @@
-use gtk::cairo::Context;
-use gtk::glib;
-use gtk::prelude::*;
-use gtk::{
-    AboutDialog, AccelFlags, AccelGroup, ApplicationWindow, Builder, Button, Dialog, DrawingArea,
-    EventBox, FileChooserDialog, MenuItem, ResponseType, Viewport, WindowPosition,
-};
-use std::cell::RefCell;
-use std::rc::Rc;
-
-use crate::pipeline::Pipeline;
-use crate::pluginlistwindow;
-#[derive(Debug, Clone, Default)]
-struct Element {
-    name: String,
-    position: (f64, f64),
-    size: (f64, f64),
-}
-
-fn draw_elements(elements: &Vec<Element>, c: &Context) {
-    for element in elements {
-        c.rectangle(element.position.0, element.position.1, 80.0, 45.0);
-        c.fill().expect("Can not draw into context");
-    }
-}
-
-pub fn build_ui(application: &gtk::Application) {
-    let glade_src = include_str!("gps.ui");
-    let builder = Builder::from_string(glade_src);
-
-    let window: ApplicationWindow = builder.object("mainwindow").expect("Couldn't get window");
-    window.set_application(Some(application));
-
-    window.set_title("GstPipelineStudio");
-    window.set_position(WindowPosition::Center);
-    window.set_size_request(800, 600);
-
-    let drawing_area = DrawingArea::new();
-    let view_port: Viewport = builder.object("drawing_area").expect("Couldn't get window");
-    let event_box = EventBox::new();
-    event_box.add(&drawing_area);
-    view_port.add(&event_box);
-    let elements: Rc<RefCell<Vec<Element>>> = Rc::new(RefCell::new(vec![]));
-    let e_clone = elements.clone();
-    drawing_area.connect_draw(move |w, c| {
-        println!("w: {} c:{} e: {:?}", w, c, e_clone);
-        draw_elements(&e_clone.borrow().to_vec(), c);
-        gtk::Inhibit(false)
-    });
-
-    event_box.connect_button_release_event(move |_w, evt| {
-        let mut elements = elements.borrow_mut();
-        let mut element: Element = Default::default();
-        element.position.0 = evt.position().0;
-        element.position.1 = evt.position().1;
-        elements.push(element);
-        drawing_area.queue_draw();
-        gtk::Inhibit(false)
-    });
-    window.show_all();
-
-    let quit: MenuItem = builder.object("menu-quit").expect("Couldn't get window");
-    let about: MenuItem = builder.object("menu-about").expect("Couldn't get window");
-    let about_dialog: AboutDialog = builder.object("dialog-about").expect("Couldn't get window");
-    about.connect_activate(move |_| {
-        about_dialog.show();
-    });
-    // Create a dialog to select GStreamer elements.
-    let add_button: Button = builder
-        .object("button-add-plugin")
-        .expect("Couldn't get app_button");
-
-    add_button.connect_clicked(glib::clone!(@weak window => move |_| {
-        // entry.set_text("Clicked!");
-        let pipeline = Pipeline::new();
-        let elements = Pipeline::get_elements_list().expect("cocuou");
-        pluginlistwindow::build_plugin_list(&window, &elements);
-    }));
-    // Create a dialog to open a file
-    let open_button: Button = builder
-        .object("button-open-file")
-        .expect("Couldn't get app_button");
-    let open_dialog: FileChooserDialog = builder
-        .object("dialog-open-file")
-        .expect("Couldn't get window");
-    open_button.connect_clicked(glib::clone!(@weak window => move |_| {
-        // entry.set_text("Clicked!");
-        open_dialog.connect_response(|dialog, _| dialog.close());
-        open_dialog.add_buttons(&[
-            ("Open", ResponseType::Ok),
-            ("Cancel", ResponseType::Cancel)
-        ]);
-        open_dialog.set_select_multiple(true);
-        open_dialog.connect_response(|open_dialog, response| {
-            if response == ResponseType::Ok {
-                let files = open_dialog.filenames();
-                println!("Files: {:?}", files);
-            }
-            open_dialog.close();
-        });
-        open_dialog.show_all();
-    }));
-
-    let accel_group = AccelGroup::new();
-    window.add_accel_group(&accel_group);
-
-    quit.connect_activate(glib::clone!(@weak window => move |_| {
-        window.close();
-    }));
-
-    // `Primary` is `Ctrl` on Windows and Linux, and `command` on macOS
-    // It isn't available directly through `gdk::ModifierType`, since it has
-    // different values on different platforms.
-    let (key, modifier) = gtk::accelerator_parse("<Primary>Q");
-    quit.add_accelerator("activate", &accel_group, key, modifier, AccelFlags::VISIBLE);
-}

src/pipeline.rs

@@ -37,6 +37,7 @@ impl Default for ElementInfo {
     }
 }
 
+#[derive(Debug)]
 pub struct Pipeline {
     initialized: bool,
 }

src/pluginlistwindow.rs

@@ -1,3 +1,4 @@
+use crate::app::GPSApp;
 use crate::pipeline::ElementInfo;
 use gtk::{
     glib::{self, clone},
@@ -6,8 +7,7 @@ use gtk::{
 };
 
 use gtk::{
-    ApplicationWindow, CellRendererText, Dialog, Label, ListStore, Orientation, TreeView,
-    TreeViewColumn, WindowPosition,
+    CellRendererText, Label, ListStore, Orientation, TreeView, TreeViewColumn, WindowPosition,
 };
 
 fn create_and_fill_model(elements: &Vec<ElementInfo>) -> ListStore {
@@ -45,10 +45,10 @@ fn create_and_setup_view() -> TreeView {
     tree
 }
 
-pub fn build_plugin_list(window: &ApplicationWindow, elements: &Vec<ElementInfo>) {
+pub fn build_plugin_list(app: &GPSApp, elements: &Vec<ElementInfo>) {
     let dialog = gtk::Dialog::with_buttons(
         Some("Edit Item"),
-        Some(window),
+        Some(&app.window),
         gtk::DialogFlags::MODAL,
         &[("Close", ResponseType::Close)],
     );