I'm still trying to learn vala and I am having a problem with GtkButton Signals.
I want to connect a function void refresh () to a GtkButton. When the Button is clicked the function should be called and set the Label of a GtkLabel. So I write GtkButton.clicked.connect (this.function);. This should call the function when I click on the button, right?
My function is very simple for testing and should change the text of a GtkLabel. So I get void function () { GtkLabel.label = "New Text"; }.
When I test this litte program clicking on the button does nothing or at least I can't see anything.
What am I missing?
Here is my code:
namespace Zeiterfassunggtk {
[GtkTemplate (ui = "/org/gnome/Zeiterfassunggtk/window.ui")]
public class Window : Gtk.ApplicationWindow {
[GtkChild]
Gtk.Button refreshbutton;
Gtk.Button menubuttonrefresh;
void refresh () {
label1.label = "Clicked";
}
public Window (Gtk.Application app) {
Object (application: app);
refreshbutton.clicked.connect (this.refresh);
menubuttonrefresh.clicked.connect (this.refresh);
this.show_all ();
}
}
}
you can look at the full code at github.com
You need [GtkChild] on every field if they are in the template. Right now, menurefresh contains null and won't be connected to anything. label1 is also null, so changing its label won't do anything.
The correct code is:
namespace Zeiterfassunggtk {
[GtkTemplate (ui = "/org/gnome/Zeiterfassunggtk/window.ui")]
public class Window : Gtk.ApplicationWindow {
[GtkChild]
Gtk.Button refreshbutton;
[GtkChild]
Gtk.Button menubuttonrefresh;
[GtkChild]
Gtk.Label label1;
void refresh () {
label1.label = "Clicked";
}
public Window (Gtk.Application app) {
Object (application: app);
refreshbutton.clicked.connect (this.refresh);
menubuttonrefresh.clicked.connect (this.refresh);
this.show_all ();
}
}
}
Related
Pretty new to vala and Gtk.
I am unable to call Gtk.Entry's set_text method, to set text from another method. Here is the sample code which I tried. I am able to set_text while in the activate() method, but just not from the tryThis() method.
using Gtk;
public class MyApplication : Gtk.Application {
public MyApplication () {
Object(application_id: "testing.my.application",
flags: ApplicationFlags.FLAGS_NONE);
}
protected override void activate () {
Gtk.ApplicationWindow window = new Gtk.ApplicationWindow (this);
window.set_default_size (800, 600);
window.window_position = WindowPosition.CENTER;
window.set_border_width(10);
Gtk.HeaderBar headerbar = new Gtk.HeaderBar();
headerbar.show_close_button = true;
headerbar.title = "Window";
window.set_titlebar(headerbar);
//Entry is initialized here
Gtk.Entry entry = new Gtk.Entry();
entry.set_text ("Before button click");
//Button is initialized and connect to method
Gtk.Button but = new Gtk.Button.with_label("Click me");
but.clicked.connect(tryThis);
Gtk.Box vbox = new Gtk.Box(Gtk.Orientation.VERTICAL, 0);
vbox.pack_start(entry, false, false, 10);
vbox.pack_start(but, false, false, 20);
window.add(vbox);
window.show_all ();
}
private void tryThis() {
Gtk.Entry entry = new Gtk.Entry();
//This is not working!!
entry.set_text ("After button click");
message("%s -", "I am here");
}
public static int main (string[] args) {
MyApplication app = new MyApplication ();
return app.run (args);
}
}
The problem is a problem of scope. So activate creates an entry within the scope of that method, not the whole class. tryThis creates a new instance of Gtk.Entry and assigns it to a variable entry in the scope of that method, not the whole class.
This example fixes your problem, but is not the best solution, as discussed after the example:
using Gtk;
public class MyApplication : Gtk.Application {
Gtk.Entry entry;
public MyApplication () {
Object(application_id: "testing.my.application",
flags: ApplicationFlags.FLAGS_NONE);
}
protected override void activate () {
Gtk.ApplicationWindow window = new Gtk.ApplicationWindow (this);
window.set_default_size (800, 600);
window.window_position = WindowPosition.CENTER;
window.set_border_width(10);
Gtk.HeaderBar headerbar = new Gtk.HeaderBar();
headerbar.show_close_button = true;
headerbar.title = "Window";
window.set_titlebar(headerbar);
//Entry is initialized here
entry = new Gtk.Entry();
entry.set_text ("Before button click");
//Button is initialized and connect to method
Gtk.Button but = new Gtk.Button.with_label("Click me");
but.clicked.connect(tryThis);
Gtk.Box vbox = new Gtk.Box(Gtk.Orientation.VERTICAL, 0);
vbox.pack_start(entry, false, false, 10);
vbox.pack_start(but, false, false, 20);
window.add(vbox);
window.show_all ();
}
private void tryThis() {
entry.set_text ("After button click");
message("%s -", "I am here");
}
public static int main (string[] args) {
MyApplication app = new MyApplication ();
return app.run (args);
}
}
You should notice that:
entry is brought in to the scope of the whole class with Gtk.Entry entry; at the beginning of the class definition
entry = new Gtk.Entry (); has been removed from tryThis because the entry has already been instantiated when activate is called
This works, but for the longer term it is better to separate the window from the application. So use activate to instantiate a new MainApplicationWindow for example. Also Vala includes code generation routines for Gtk templates. This allows you to define the window and its child widgets using XML or the GUI tool Glade and then attach the Vala code with the Vala attributes [GtkTemplate], [GtkChild] and [GtkCallback].
So I am currently working on an app for elementary os and encountered a problem.
I have a window which has a Granite.Sourcelistview on the left and a stack holding the different views on the right. My problem is that when pressing a button on one of the screens (the project settings screen i created), the stack should change the current view to a different one but it doesn't. The current view stays and is not changed.
This is the window:
public class MainWindow : Gtk.Window {
private SourceListStackView srcl_view {get; set;}
construct {
var header = new Gtk.HeaderBar ();
header.show_close_button = true;
//this is the source list view
srcl_view = new SourceListStackView ();
var paned = new Gtk.Paned (Gtk.Orientation.HORIZONTAL);
paned.position = 130;
paned.pack1 (srcl_view, false, false);
paned.add2 (srcl_view.stack);
add(paned);
set_titlebar (header);
}
public static int main(string[] args) {
Gtk.init (ref args);
MainWindow app = new MainWindow ();
app.show_all ();
Gtk.main ();
return 0;
}
}
This is the sourcelistview class that i created:
public class SourceListStackView : Granite.Widgets.SourceList {
public Gtk.Stack stack {get; set;}
public SourceListStackView () {
var project_page = new ProjectSettings ();
stack = new Gtk.Stack ();
var project = new Granite.Widgets.SourceList.ExpandableItem("Root");
this.root.add(project);
stack.add_named(project_page, "hello");
//here depending on what item of the sourcelist is created,
//the view with the same name as the item
//should be displayed (not the best mechanism but works)
this.item_selected.connect ((item) => {
if(item != null){
stack.visible_child_name = item.name;
}
});
//problematic part is here: This won't change the current view..why?
//The button should add another item to the
// source list view and change the current view
// to the newly created Welcome Screen but it doesn't do that..
project_page.button.clicked.connect(() => {
project.add(new Granite.Widgets.SourceList.Item ("Welcome"));
stack.add_named(new Granite.Widgets.Welcome("bla bli blu", "bla"), "Welcome");
stack.set_visible_child_name("Welcome");
});
}
}
This is the view with the button that should trigger the change of the view:
public class ProjectSettings : Granite.SimpleSettingsPage {
public Gtk.Button button {get; set;}
public ProjectSettings () {
Object (
activatable: false,
description: "This is a screen",
header: "",
icon_name: "preferences-system",
title: "Screen"
);
}
construct {
var project_name_label = new Gtk.Label ("Name");
project_name_label.xalign = 1;
var project_name_entry = new Gtk.Entry ();
project_name_entry.hexpand = true;
project_name_entry.placeholder_text = "Peter";
content_area.attach (project_name_label, 0, 0, 1, 1);
content_area.attach (project_name_entry, 1, 0, 1, 1);
button = new Gtk.Button.with_label ("Save Settings");
action_area.add (button);
}
}
The part that does not work is this one:
//problematic part is here: This won't change the current view.. why?
project_page.button.clicked.connect(() => {
project.add(new Granite.Widgets.SourceList.Item ("Welcome"));
stack.add_named(new Granite.Widgets.Welcome("bla bli blu", "bla"), "Welcome");
stack.set_visible_child_name("Welcome");
});
I do not know why it wont change the view. I specifically tell it to set the visible child to "Welcome" (and that is exactly how i named it one line above), but it just won't appear. Can someone explain to me why?
I can easily change the stack's visible child outside of the signal/event but inside of it won't do the trick..
Thanks a lot
Update: The issue was solved through José Fonte's comment down below: I instantiated the view, called the show_all () method on it and then added it to the stack and set the visible child to it.
I have made an AR app in Unity using Vuforia. I have some Virtual Buttons in the scene. The problem I am facing is that the virtual button is getting pressed on their own. I am not able to figure out what I am doing wrong. All the buttons are in a layer named "Buttons". Here is the virtual Button handler script:
private List<GameObject> vbtns= new List<GameObject>();
// Use this for initialization
void Start () {
var goArray = FindObjectsOfType<GameObject>();
for(var i=0; i<goArray.Length; i++)
{
if(goArray[i].GetComponent<VirtualButtonBehaviour>())
{
//Debug.Log("The game component is " + goArray[i]);
goArray[i].GetComponent<VirtualButtonBehaviour>().RegisterEventHandler(this);
vbtns.Add(goArray[i]);
}
}
}
// Update is called once per frame
void Update () {
}
public void OnButtonPressed(VirtualButtonAbstractBehaviour vb)
{
Debug.Log("Button Pressed.");
Debug.Log("The name of the vbutton is "+ vb.VirtualButtonName);
SceneManager.LoadScene("scene_"+vb.VirtualButtonName,LoadSceneMode.Single);
}
public void OnButtonReleased(VirtualButtonAbstractBehaviour vb)
{
Debug.Log("Button Released");
}
Please suggest what could be the reason for this. I have attached the screenshot of the game view below. Thanks in advance.
Please help me, as I will go mad with this soon:
When I run the code, on first occasion loadNewPoint() is executed and displays some data from global variable - allPointsAndPlaces
However when I click a button (from a child class), the same method loadNewPoint() gives me null pointer for allPointsAndPlaces.
I have changed the code structure a lot from an original trying to solve this issue, and moved this method (loadNewPoint()) to a parent class to see, if it would solve the issue.
Parent class:
public class CabbieApp implements EntryPoint {
private GetLocationsServiceAsync getAllLocationsService = GWT.create(GetLocationsService.class);
CabbiePoint[] allPointsAndPlaces;
PointsQuiz quiz;
/**
* Entry point method.
*/
public void onModuleLoad() {
//Get all the required data from DB
getAllPointsAndLocations();
}
private void loadAppPages(){
// Associate the Main panel with the HTML host page.
RootPanel rootPanel = RootPanel.get("pointsList");
quiz = new PointsQuiz();
rootPanel.setStyleName("GWTapp");
rootPanel.add(quiz.getMainPanel());
loadNewPoint();
}
private void getAllPointsAndLocations() {
// Initialize the service proxy.
if (getAllLocationsService == null) {
getAllLocationsService = GWT.create(GetLocationsService.class);
}
// Set up the callback object.
AsyncCallback<CabbiePoint[]> callback = new AsyncCallback<CabbiePoint[]>() {
public void onFailure(Throwable caught) {
System.out.println(caught.getMessage());
}
public void onSuccess(CabbiePoint[] result) {
//allPointsAndPlaces = result;
System.out.println(result.length);
allPointsAndPlaces = result;
loadAppPages();
}
};
// Make the call to the service.
getAllLocationsService.getLocations(callback);
}
void loadNewPoint(){
int r = Random.nextInt(allPointsAndPlaces.length);
quiz.CurrentPlace = allPointsAndPlaces[r].getPlaceName();
quiz.CurrentLocation = allPointsAndPlaces[r].getPlaceLocation();
quiz.point.setText(quiz.CurrentPlace);
quiz.location.setText(quiz.CurrentLocation);
quiz.location.setStyleName("invisibleText");
}
}
Child class:
public class PointsQuiz extends CabbieApp{
VerticalPanel mainPanel = new VerticalPanel();
HorizontalPanel navigation = new HorizontalPanel();
TextBox point = new TextBox();
TextBox location = new TextBox();
Button showLocation = new Button("Show Location");
Button nextPoint = new Button("Next Point");
String CurrentPlace, CurrentLocation;
public PointsQuiz() {
// Assemble Add Stock panel.
navigation.add(showLocation);
navigation.add(nextPoint);
navigation.setCellHorizontalAlignment(nextPoint, HasHorizontalAlignment.ALIGN_RIGHT);
navigation.addStyleName("addPanel");
mainPanel.setSpacing(5);
mainPanel.setStyleName("body");
mainPanel.setVerticalAlignment(HasVerticalAlignment.ALIGN_MIDDLE);
mainPanel.setHorizontalAlignment(HasHorizontalAlignment.ALIGN_CENTER);
// Assemble Main panel.
mainPanel.add(point);
point.setWidth("200px");
mainPanel.add(location);
location.setWidth("200px");
mainPanel.add(navigation);
navigation.setWidth("200px");
// Move cursor focus to the input box.
showLocation.setFocus(true);
// Listen for mouse events on the show location button.
showLocation.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
showCurrentLocation();}
});
// Listen for mouse events on the next point button.
nextPoint.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
loadNewPoint();
}
});
}
private void showCurrentLocation(){
location.setStyleName("visibleText");
}
public VerticalPanel getMainPanel() {
return mainPanel;
}
}
I managed to find a solution to this problem with Bhumika's help.
To make this work I had to change CabbiePoint[] allPointsAndPlaces to static.
This would solve the reference problem one way - from child to parent.
Also I managed to find out trough debugging, that this reference
quiz = new PointsQuiz();
is also null on a second run of loadNewPoint(). So this child reference (PointsQuiz quiz;) and any other references to children were set also to static.
You are getting null pointer error because of allPointsAndPlaces is null. As per your coding The value of allPointsAndPlaces is assigned after completion of RPC call in getAllPointsAndLocations() method. so the allPointsAndPlaces has some assigned values.
Here you try to directly access loadNewPoint() method in child class. At a time, allPointsAndPlaces is not assigned.
Within a XAML user control, the Frame object is null:
this.Frame.Navigate(typeof(FaxPropertiesPage));
How do I navigate between pages with a Windows 8 XAML User Control? I have placed the control within a Callisto Flyout on a XAML page.
The search button below must navigate the user to another XAML page.
I've successfully used the code from app.xaml.cs
Frame frame = Window.Current.Content as Frame;
and then used the standard Navigate code.
There's the nice way and the not-so-nice way:
Both of them start with a navigation service:
public interface INavigationService
{
bool CanGoBack { get; }
void GoBack();
void GoForward();
bool Navigate<T>(object parameter = null);
bool Navigate(Type source, object parameter = null);
void ClearHistory();
event EventHandler<NavigatingCancelEventArgs> Navigating;
}
public class NavigationService : INavigationService
{
private readonly Frame _frame;
public NavigationService(Frame frame)
{
_frame = frame;
frame.Navigating += FrameNavigating;
}
#region INavigationService Members
public void GoBack()
{
_frame.GoBack();
}
public void GoForward()
{
_frame.GoForward();
}
public bool Navigate<T>(object parameter = null)
{
Type type = typeof (T);
return Navigate(type, parameter);
}
So, where do I get the Frame? In App.xaml.cs
protected async override void OnLaunched(LaunchActivatedEventArgs args)
{
// Do not repeat app initialization when already running, just ensure that
// the window is active
if (args.PreviousExecutionState == ApplicationExecutionState.Running)
{
Window.Current.Activate();
return;
}
// Create a Frame to act as the navigation context and navigate to the first page
var rootFrame = new Frame();
if (DesignMode.DesignModeEnabled)
SimpleIoc.Default.Register<INavigationService, DesignTimeNavigationService>();
else
SimpleIoc.Default.Register<INavigationService>(() => new NavigationService(rootFrame));
I'm using MVVM Light here. This makes life easy because all my viewmodels get created using dependency injection and have their services injected into them.
If you're not using something like MVVM Light and rely on code-behind then you can still make this work: Just make the navigation service static
public class NavigationService : INavigationService
{
public static INavigationService Current{
get;set;}
blah blah blah
}
And change App.xaml.cs to:
protected async override void OnLaunched(LaunchActivatedEventArgs args)
{
// Do not repeat app initialization when already running, just ensure that
// the window is active
if (args.PreviousExecutionState == ApplicationExecutionState.Running)
{
Window.Current.Activate();
return;
}
// Create a Frame to act as the navigation context and navigate to the first page
var rootFrame = new Frame();
NavigationService.Current= new NavigationService(rootFrame));
}
And you can then access your main Frame anywhere in the app by saying:
NavigationService.Current.Navigate<MyView>();
simple code ( may not be 100% efficient) is :
Frame frame = new Frame();
frame.Navigate(typeof(ExerciseAddPage)