Button Screen Change in Android Mono using delegates - c#

The following code is from the C# portion of my Android Mono application. It is going to eventually be the GUI for a multimeter simulator, but right now just displays text. It is rather straight forward:
-Click one of the buttons to go to that meter (voltmeter, ammeter, ohmmeter)
-Click the "re-scan" button and a TextView tells you how many times you clicked that button.
-Click one of the other meter buttons or the home button to switch views
That much is working flawlessly. Unfortunately, once I switch views, the buttons cease to work. Below is the code for the Ohm button and the Amp button. The Ohm button is the 'complete' one that brings up views of all of the other screens. For testing purposes, I was going to the amp screen but when I go there, its re-scan button does nothing. None of the buttons do anything.
I am fairly certain that the issue is my use of the delegate commands, but none of my research has led me in any way towards a solution.
I can provide more of the main code and the XML code if needed.
ampButton.Click += delegate
{
SetContentView(Resource.Layout.AmpScreen);
Button ampButtonData = FindViewById<Button>(Resource.Id.CurrentButtonamp);
TextView ampData = FindViewById<TextView>(Resource.Id.ampdata);
ampButtonData.Click += delegate
{
ampData.Text = string.Format("{0} clicks!", count2++);
};
Button amp2volt = FindViewById<Button>(Resource.Id.Amp2VoltButton);
Button amp2ohm = FindViewById<Button>(Resource.Id.Amp2OhmButton);
Button amp2home = FindViewById<Button>(Resource.Id.Amp2HomeButton);
};
ohmButton.Click += delegate
{
SetContentView(Resource.Layout.OhmScreen);
Button ohmButtonData = FindViewById<Button>(Resource.Id.CurrentButtonohm);
TextView ohmData = FindViewById<TextView>(Resource.Id.ohmdata);
ohmButtonData.Click += delegate
{
ohmData.Text = string.Format("{0} clicks!", count3++);
};
Button ohm2amp = FindViewById<Button>(Resource.Id.Ohm2AmpButton);
Button ohm2volt = FindViewById<Button>(Resource.Id.Ohm2VoltButton);
Button ohm2home = FindViewById<Button>(Resource.Id.Ohm2HomeButton);
ohm2amp.Click += delegate
{
SetContentView(Resource.Layout.AmpScreen);
};
ohm2volt.Click += delegate
{
SetContentView(Resource.Layout.VoltScreen);
};
ohm2home.Click += delegate
{
SetContentView(Resource.Layout.Main);
};
};

I think your problem is that you are replacing the entire view each time - so the button instances are changing.
What happens inside SetContentView is that the InflatorService gets asked to create a brand new set of UI objects based on the passed in XML, the existing UI is wiped clean and then those new UI objects are put in their place.
It doesn't matter if the new UI objects happen to have the same resource identifiers as the old objects - they are still separate instances.
If you want to continue using your current approach, then you need to rewire all your events after each SetContentView - e.g.
ohm2amp.Click += delegate
{
SetContentView(Resource.Layout.AmpScreen);
RewireEvents();
};
with
private void RewireEvents()
{
var ohm2home = FindViewById<Button>(Resource.Id.ohm2home);
ohm2home.Click += { /* todo */ };
// etc
}
alternatively, maybe consider a different UI:
e.g. you could change the Visibility on different child layouts rather than calling SetContentView to replace everything
e.g. or you could use multiple activities (or tabs) instead of a single activity
Hope that helps

Related

Functionality to treat floating tabs as separate from main window

Context: I launch my main window. Within that window I create three new tabs. I float two of the tabs and leave the other within the main window. There are two problems I am currently trying to tackle:
I want to be able to minimize the main window without hiding my other floating tabs as well.
When shifting focus to another program (e.g. Chrome) then clicking back on my floating tab, I don't want all my other floating tabs + the main window to be brought back to front, in effect hiding my other program.
I believe this should be possible since the Visual Studio UI is built using WPF and I can achieve this functionality using floating tabs in VS.
Yes you can do this. The reason why it is being minimized is because the default owner of the floating window is the main window. so you have to set the floatingWindow.Owner = null; then you will also be able to put the main window in front of the floating window. if you want to switch between floating window and main window you can set floatingWindow.ShowInTaskbar = true;.
In my code i put it in a selectionChanged event handler so when i pop out a document it fires the selectionChanged event.
Document creation
private void userItem_Click(object sender, RoutedEventArgs e)
{
LayoutDocument ld = new LayoutDocument();
ld.Title = "All Users";
ld.ToolTip = "Manage all users";
//selection changed event
ld.IsSelectedChanged += Ld_IsSelectedChanged;
ld.IsActiveChanged += Ld_IsSelectedChanged;
Users users = new Users(ld);
ld.Content = users;
LayoutDocumentPane pane = ((todaysPayments.FindParent<LayoutDocumentPane>() ?? (panal.Children?[0] as LayoutDocumentPane)) ?? new LayoutDocumentPane());
pane.Children.Add(ld);
if (panal.ChildrenCount == 0)
{
panal.Children.Add(pane);
}
ld.IsSelected = true;
}
And the event handler
public void Ld_IsSelectedChanged(object sender, EventArgs e)
{
//get the floating windows from the DockingManager
manager.FloatingWindows.ToList().ForEach(floatingWindow =>
{
floatingWindow.Owner = null;
floatingWindow.ShowInTaskbar = true;
var fw = floatingWindow.Model as LayoutDocumentFloatingWindow;
floatingWindow.Title = fw?.RootDocument?.Title ?? "";
});
}

MS Band SDK - Button pressed event handler not being called

I've set up my tile and page layout with a button in my app but when I press the button the event handler does not get called. I tried with the tile open event handler but that doesn't work either. My code is as follows:
private async void OnConnectToBand()
{
IBandInfo[] pairedBands = await BandClientManager.Instance.GetBandsAsync();
try
{
using (IBandClient bandClient = await BandClientManager.Instance.ConnectAsync(pairedBands[0]))
{
//add tile, create page layout with button and add content with button
//subscribe to listeners
bandClient.TileManager.TileButtonPressed += EventHandler_TileButtonPressed;
// Start listening for events
bandClient.TileManager.StartReadingsAsync();
}
}
catch(BandException ex)
{
//handle a Band connection exception
}
}
void EventHandler_TileButtonPressed(object sender, BandTileEventArgs<IBandTileButtonPressedEvent> e)
{
// handle event
}
The tile and page get created fine but the button doesn't trigger the event handler. Any ideas why it's not being called?
UPDATE: I just went through my code and the SDK doco again and remembered I'm doing something different which is why it might not be working. The doco has the following for adding the button to the layout which doesn't compile:
// create the content to assign to the page
PageData pageContent = new PageData
(
pageGuid,
0, // index of our (only) layout
new Button(
TilePageElementId.Button_PushMe,
“Push Me!”)
);
The compiler says there isn't a constructor for Button that takes in 2 arguments.
I assumed there was an error in the sample code and changed it to TextButtonData which compiles fine but now I'm wondering if that is why the event handler isn't working? Code is:
PageData pageContent = new PageData(
pageGuid,
0, // index of our (only) layout
new TextButtonData(
(short)TilePageElementId.Button_PushMe, "Push"));
Any ideas?
This is great to see someone developing on the MS Band.... heres a few links that discuss the OnConnectToBand and its setup
void EventHandler_TileButtonPressed(object sender,
BandTileEventArgs<IBandTileButtonPressedEvent> e)
{
// This method is called when the user presses the
// button in our tile’s layout.
//
// e.TileEvent.TileId is the tile’s Guid.
// e.TileEvent.Timestamp is the DateTimeOffset of the event.
// e.TileEvent.PageId is the Guid of our page with the button.
// e.TileEvent.ElementId is the value assigned to the button
// in our layout (i.e.,
// TilePageElementId.Button_PushMe).
//
// handle the event
}
Section 9- Handling custom events
http://developer.microsoftband.com/Content/docs/Microsoft%20Band%20SDK.pdf
Talks about adding, clicking, removing tiles
http://www.jayway.com/2015/03/04/first-impression-of-microsoft-band-developing-2/
Try adding a dialog(below is windows code, for ios or android have a look at the above mentioned manual) to respond to the event (in your code above there is nothing in your event handler? this to see if it actually does something?
using Microsoft.Band.Notifications;
try
{
// send a dialog to the Band for one of our tiles
await bandClient.NotificationManager.ShowDialogAsync(tileGuid,
"Dialog title", "Dialog body");
}
catch (BandException ex)
{
// handle a Band connection exception
}
You can only receive events from the Band while you have an active IBandClient instance (i.e. an active connection to the Band). In your code above, the bandClient instance is disposed of immediately after StartReadingsAsync() is called, due to the use of the using() {} block. When an IBandClient instance is disposed, it causes the application to disconnect from the Band.
You need to hold onto the IBandClient instance for the length of time during which you wish to receive events, and dispose of the instance only after that time.

How to properly send different parameters down for a standard Button Click

I know this has to have an easy answer, but I'm utterly failing to fathom the wealth of information on custom events, event handlers, and delegates. I have a custom messagebox class. I am trying to add the capability to do something based off of the state of a check box if the OK button is clicked. The buttons and the checkbox are added dynamically based upon input into a static Show method somewhat like the following:
if (!String.IsNullOrWhiteSpace(suicideCheckboxID))
{
suicideCheckBox = new CheckBox();
suicideCheckBox.AutoSize = true;
suicideCheckBox.Text = "Do not show this message again.";
suicideCheckBox.Location = new Point(xMargin, label.Bottom + yMargin);
suicideCheckBox.Checked = false;
suicideCheckBoxHeight = suicideCheckBox.Height;
form.Controls.Add(suicideCheckBox);
}
Button okButton = NewButton(DialogResult.OK, scaleFactor);
int x = (form.Width - okButton.Width) / 2;
okButton.Location = new Point(x, buttonYPosition);
form.Controls.Add(okButton);
form.AcceptButton = okButton;
form.CancelButton = okButton;
That's not the exact code, but it's fairly representative. My impulse is to use okButton.Clicked += new EventHandler(OKButton_clicked), but if I do that, the event generated only carries arguments for object sender and EventArgs e and I really need it to operate off of the state of the checkbox and an additional piece of text to indicate which messagebox is being shown so that the values can be stored in the registry.
My first attempt was to do something like okButton.Clicked += processSuicideCheckbox(suicideCheckboxID, suicideCheckBox);, but that seems to just process the contents and allow one to return an EventHandler that points to a method with the signature of object sender and EventArgs e. What am I missing here? What is the best way to pass in the arguments actually relevant to me?
You don't get to choose what is in the event handler for the Click event. Microsoft has already done that. You are stuck with the (object sender, EventArgs e) signature.
You do have a couple options:
Simply store the state in the class itself; the event handler will have access to it because it is inside the class.
Utilize a closure to do the same thing:
myButton.Click += (s, e) => ActualFunction(checkBox1.Checked);
Note that using the closure (via a lambda expression) is just hiding the details of maintaining this state (creating the class-level variables).

Managing EventHandlers within a large Form

I'm developing a WinForm application and I've done a pretty bad job thus far of managing the size and contents. I was hoping someone could give me an example of how to break out some of the logic that I have within the main form cs file.
Here is an example of an EventHandler function that I have within my MainWindow.cs:
private void GroupBoxRequestTypeCheckedChanged(object pSender, EventArgs pEventArgs)
{
RadioButton vRadioButton = pSender as RadioButton;
if (vRadioButton != null)
{
this.fSelectedButton = vRadioButton.Checked ? vRadioButton : null;
if (vRadioButton.Equals(this.RadioButton_Copy) || vRadioButton.Equals(this.RadioButton_Delete) || vRadioButton.Equals(this.RadioButton_Download)
|| vRadioButton.Equals(this.RadioButton_Move) || vRadioButton.Equals(this.RadioButton_Upload))
{
this.GroupBox_Files.Enabled = true;
this.GroupBox_Variables.Enabled = false;
}
else
{
this.GroupBox_Files.Enabled = false;
this.GroupBox_Variables.Enabled = true;
}
if (this.fSelectedButton != null)
{
if (this.fSelectedButton.Equals(this.RadioButton_Delete))
{
this.TextBox_DestinationFile.Enabled = false;
this.Button_DestinationBrowse.Enabled = false;
}
else
{
this.TextBox_DestinationFile.Enabled = true;
this.Button_DestinationBrowse.Enabled = true;
}
}
}
}
So this is simply one of many EventHandler's that I have within a Form. I created a MainForm which has a Tabbed Pane and has a collection of Tabs which have buttons, textboxes, checkboxes etc in each tab. All of the events that I handle go into the MainForm.cs file and now I've got close to 1,000 lines in this one file.
Can someone give me a simple example (or a article/document) detailing good structure? Can I define my EventHandler functions in a separate class (if so, how would this work...) Do I create some sort of static Helper class where I simply pass the instance of the objects i need to manipulate? I.E.
private void GroupBoxRequestTypeCheckedChange(object pSender, EventArgs pEventArgs)
{
HelperClass.HandleGroupBoxRequestTypeCheckedChanged(pSender, pEventArgs, this);
}
Where 'this' is the Form itself which has all the references to the objects I need to manipulate?
It's probably worth noting that I've learned a good bit about the Cross-Thread calls and I've started making Extension methods for many instances that I need which are simplistic.
Another question - I notice that the Visual Designer automatically makes all Components created with it private by default, is it in general a bad idea to make these internal and use the form object to reference these components as needed from outside the class? If it is not a good idea, what is better?
First I would suggest to separate independent user-interface parts into UserControls or Components. Then - if needed - wire them using Events (eg. your own specialized events and properties.
For example you can place your main content (the TabControl / Container) in a UserControl and place that user control in the main form. All tab-/page-switching logic/UI etc. then belongs to that user control. In that UserControl you can define for example your own Event that gets fired when the user switches a tab. The main form then can register to this event - just like it can for other Winforms-control-events - and do its stuff (eg. change the window title to represent the currently active tab).
Then next you can move the content of each tab to its own user-control and use these user-controls within your new tabs-usercontrol. Move the logic down to the UserControl which is responsible for the given task.
A form/controls hierarchy from some typical application could look like this:
MainForm (Form)
MainTabContainerControl (UserControl)
Page1Control (UserControl)
Page2Control (UserControl)
MyImprovedDbRowGridControl (UserControl or Component)
Page3Control (UserControl)
SidebarControl (UserControl)
SearchControl (UserControl)
MyImprovedDbRowGridControl (UserControl or Component)
QuickHelpControl (UserControl)
Next thing is so keep all the UI-eventhandlers as small as possible and doing only UI stuff. Move other logic like business- or dataaccess-logic to other classes outside of the user-interface.
If you have combinations of the controls that are needed more then once in the application: move them to a re-usable UserControl. (eg. breadcrum).
Regarding your sample code you can make it more compact and therefore maintainable by simplyfing its logic:
if (this.fSelectedButton.Equals(this.RadioButton_Delete))
{
this.TextBox_DestinationFile.Enabled = false;
this.Button_DestinationBrowse.Enabled = false;
}
else
{
this.TextBox_DestinationFile.Enabled = true;
this.Button_DestinationBrowse.Enabled = true;
}
...could be:
var delete = fSelectedButton == RadioButton_Delete;
this.TextBox_DestinationFile.Enabled = !delete;
this.Button_DestinationBrowse.Enabled = !delete;
Update:
When it comes to refactoring and code-cleanup a very usefull tool is Resharper (R#). I can highly recommend it.
Hope this gives you some ideas where to start.

Prevent events from firing multiple times from single action

How can I prevent the firing of multiple events of the same kind triggered by a single action?
For example, I have a ListView containing some items. When I select or deselect all items, the SelectedIndexChanged event is fired once for each item. Rather, I would like to receive a single event indication the user's action (selection/deselection of items), regardless of the number of items.
Is there any way to achieve this?
You can't change the ListView code, and subclassing it doesn't provide many options.
I would suggest that you simply add a small delay (200ms or similar) to your code - i.e. you only do the calculation a little while after the last update. Something like:
using System;
using System.Windows.Forms;
static class Program {
[STAThread]
static void Main() {
Application.EnableVisualStyles();
ListView list;
TextBox txt;
Timer tmr = new Timer();
tmr.Interval = 200;
Form form = new Form {
Controls = {
(txt = new TextBox { Dock = DockStyle.Fill, Multiline = true}),
(list = new ListView { Dock = DockStyle.Right, View = View.List,
Items = { "abc", "def" , "ghi", "jkl", "mno" , "pqr"}})
}
};
list.SelectedIndexChanged += delegate {
tmr.Stop();
tmr.Start();
};
tmr.Tick += delegate {
tmr.Stop();
txt.Text += "do work on " + list.SelectedItems.Count + " items"
+ Environment.NewLine;
};
Application.Run(form);
}
}
Only by by coming at the problem from a slightly different direction. E.g. subscribe loss of focus.
In the end, the application or runtime cannot raise an event on "all selection changes done" without actually using something else because there is no way for the application to predict whether the user will perform another click on the control while it retains focus.
Even using focus, the user could switch back to that control.
If your ListView is in virtual mode, you could use the
VirtualItemsSelectionRangeChanged event. This event will be fired only once for the user's action (selection/deseclection).

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