Only process updates when the view is visible

demo/demo.qml

@@ -123,6 +123,9 @@ ApplicationWindow {
                     onClicked: {
                         processSelection.select(index, ItemSelectionModel.ToggleCurrent);
                     }
+                    Component.onCompleted: {
+                        processes.active = Qt.binding(function() { return visible; });
+                    }
                     width: parent.width
                     anchors.top: processFilterInput.bottom
                     anchors.bottom: parent.bottom
@@ -138,12 +141,12 @@ ApplicationWindow {
                         role: "name"
                     }
                     TableViewColumn {
-                        title: "pid"
-                        role: "pid"
+                        title: "cpu"
+                        role: "cpuUsage"
                     }
                     TableViewColumn {
-                        title: "cpu"
-                        role: "cpu"
+                        title: "memory"
+                        role: "memory"
                     }
                     onSortIndicatorColumnChanged: sort()
                     onSortIndicatorOrderChanged: sort()

demo/processes.json

@@ -10,6 +10,10 @@
         "Processes": {
             "type": "UniformTree",
             "properties": {
+                "active": {
+                    "type": "bool",
+                    "write": true
+                }
             },
             "itemProperties": {
                 "pid": {

demo/rust/src/processes_implementation.rs

@@ -22,7 +22,8 @@ pub struct Processes {
     emit: ProcessesEmitter,
     model: ProcessesUniformTree,
     p: ProcessTree,
-    incoming: Arc<Mutex<Option<ProcessTree>>>
+    incoming: Arc<Mutex<Option<ProcessTree>>>,
+    active: bool
 }
 
 fn check_process_hierarchy(parent: Option<pid_t>, processes: &HashMap<pid_t,Process>) {
@@ -250,7 +251,8 @@ impl ProcessesTrait for Processes {
             emit: emit.clone(),
             model: model,
             p: ProcessTree::default(),
-            incoming: Arc::new(Mutex::new(None))
+            incoming: Arc::new(Mutex::new(None)),
+            active: true
         };
         update_thread(emit, p.incoming.clone());
         p
@@ -276,7 +278,7 @@ impl ProcessesTrait for Processes {
         self.get(item).process.parent.map(|pid| pid as usize)
     }
     fn can_fetch_more(&self, item: Option<usize>) -> bool {
-        if item.is_some() {
+        if item.is_some() || !self.active {
             return false;
         }
         if let Ok(ref incoming) = self.incoming.try_lock() {
@@ -286,7 +288,7 @@ impl ProcessesTrait for Processes {
         }
     }
     fn fetch_more(&mut self, item: Option<usize>) {
-        if item.is_some() {
+        if item.is_some() || !self.active {
             return;
         }
         let new = if let Ok(ref mut incoming) = self.incoming.try_lock() {
@@ -334,4 +336,10 @@ impl ProcessesTrait for Processes {
     fn cmd(&self, item: usize) -> String {
         self.process(item).cmd.join(" ")
     }
+    fn get_active(&self) -> bool {
+        self.active
+    }
+    fn set_active(&mut self, active: bool) {
+        self.active = active
+    }
 }

demo/rust/src/processes_interface.rs

@@ -79,6 +79,7 @@ pub struct ProcessesQObject {}
 #[derive (Clone)]
 pub struct ProcessesEmitter {
     qobject: Arc<Mutex<*const ProcessesQObject>>,
+    active_changed: fn(*const ProcessesQObject),
     new_data_ready: fn(*const ProcessesQObject, item: usize, valid: bool),
 }
 
@@ -88,6 +89,12 @@ impl ProcessesEmitter {
     fn clear(&self) {
         *self.qobject.lock().unwrap() = null();
     }
+    pub fn active_changed(&self) {
+        let ptr = *self.qobject.lock().unwrap();
+        if !ptr.is_null() {
+            (self.active_changed)(ptr);
+        }
+    }
     pub fn new_data_ready(&self, item: Option<usize>) {
         let ptr = *self.qobject.lock().unwrap();
         if !ptr.is_null() {
@@ -134,6 +141,8 @@ impl ProcessesUniformTree {
 pub trait ProcessesTrait {
     fn create(emit: ProcessesEmitter, model: ProcessesUniformTree) -> Self;
     fn emit(&self) -> &ProcessesEmitter;
+    fn get_active(&self) -> bool;
+    fn set_active(&mut self, value: bool);
     fn row_count(&self, Option<usize>) -> usize;
     fn can_fetch_more(&self, Option<usize>) -> bool { false }
     fn fetch_more(&mut self, Option<usize>) {}
@@ -152,6 +161,7 @@ pub trait ProcessesTrait {
 
 #[no_mangle]
 pub extern "C" fn processes_new(processes: *mut ProcessesQObject,
+        active_changed: fn(*const ProcessesQObject),
         new_data_ready: fn(*const ProcessesQObject, item: usize, valid: bool),
         data_changed: fn(*const ProcessesQObject, usize, usize),
         begin_reset_model: fn(*const ProcessesQObject),
@@ -167,6 +177,7 @@ pub extern "C" fn processes_new(processes: *mut ProcessesQObject,
         -> *mut Processes {
     let processes_emit = ProcessesEmitter {
         qobject: Arc::new(Mutex::new(processes)),
+        active_changed: active_changed,
         new_data_ready: new_data_ready,
     };
     let model = ProcessesUniformTree {
@@ -188,6 +199,16 @@ pub unsafe extern "C" fn processes_free(ptr: *mut Processes) {
     Box::from_raw(ptr).emit().clear();
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn processes_active_get(ptr: *const Processes) -> bool {
+    (&*ptr).get_active()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn processes_active_set(ptr: *mut Processes, v: bool) {
+    (&mut *ptr).set_active(v);
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn processes_row_count(ptr: *const Processes, item: usize, valid: bool) -> c_int {
     if valid {

demo/src/Processes.cpp

@@ -44,6 +44,10 @@ namespace {
         int row;
         quintptr id;
     };
+    inline void processesActiveChanged(Processes* o)
+    {
+        emit o->activeChanged();
+    }
 
 }
 typedef void (*qstring_set)(QString*, qstring_t*);
@@ -210,7 +214,7 @@ bool Processes::setData(const QModelIndex &index, const QVariant &value, int rol
     return set;
 }
 extern "C" {
-    Processes::Private* processes_new(Processes*,
+    Processes::Private* processes_new(Processes*, void (*)(Processes*),
         void (*)(const Processes*, quintptr, bool),
         void (*)(Processes*, quintptr, quintptr),
         void (*)(Processes*),
@@ -220,6 +224,8 @@ extern "C" {
         void (*)(Processes*, option<quintptr>, int, int),
         void (*)(Processes*));
     void processes_free(Processes::Private*);
+    bool processes_active_get(const Processes::Private*);
+    void processes_active_set(Processes::Private*, bool);
 };
 
 Processes::Processes(bool /*owned*/, QObject *parent):
@@ -232,6 +238,7 @@ Processes::Processes(bool /*owned*/, QObject *parent):
 Processes::Processes(QObject *parent):
     QAbstractItemModel(parent),
     m_d(processes_new(this,
+        processesActiveChanged,
         [](const Processes* o, quintptr id, bool valid) {
             if (valid) {
                 int row = processes_row(o->m_d, id);
@@ -287,3 +294,10 @@ Processes::~Processes() {
         processes_free(m_d);
     }
 }
+bool Processes::active() const
+{
+    return processes_active_get(m_d);
+}
+void Processes::setActive(bool v) {
+    processes_active_set(m_d, v);
+}

demo/src/Processes.h

@@ -15,10 +15,13 @@ public:
 private:
     Private * m_d;
     bool m_ownsPrivate;
+    Q_PROPERTY(bool active READ active WRITE setActive NOTIFY activeChanged FINAL)
     explicit Processes(bool owned, QObject *parent);
 public:
     explicit Processes(QObject *parent = nullptr);
     ~Processes();
+    bool active() const;
+    void setActive(bool v);
 
     int columnCount(const QModelIndex &parent = QModelIndex()) const override;
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
@@ -36,5 +39,6 @@ signals:
     // new data is ready to be made available to the model with fetchMore()
     void newDataReady(const QModelIndex &parent) const;
 signals:
+    void activeChanged();
 };
 #endif // PROCESSES_H