My question is very close to this one:
How can I switch tabs programatically from within my ViewModel?
But what I want to do is just switch tabs as a courtesy to the user, and not make it binding. (When the user starts a 'scan', I would like to switch to the 'monitoring' tab, but not prevent him changing tabs just because the scan is still running).
I've worked out that setting mode=OneWay will avoid the user stopping the scan by changing tabs, but my original idea of binding to 'Scanning' doesn't work great because when that gets set to 'false', the tab goes to 'not selected' and I just get a blank rectangle. I could only invoke the 'property changed' when it goes from false to true, but that seems very wrong.
I ended up deciding that code behind was the best way to go. It's a UI convenience for the user and the ViewModel doesn't need to know anything about it. So I hook into the 'Start' button and switch tabs when it's clicked.
Related
I'm trying to use toggles on an inactive screen as a replacement for functions (and thus help code reuse), however I'm stuck as my toggle won't activate unless I visit the page it's on. I found plenty of working examples online but somehow can't get it to work for me.
Overview:
I have a button on screen1 and a toggle on screen2.
During my button's OnSelect event, a variable varSendData is being set to true like so:
Set (varSendData, true)
The toggle has its Default property set to varSendData.
The OnCheck property of the toggle contains the code to be executed:
Notify("This works")
Problem:
While the variable varSendData is correctly being set to true, nothing happens while I'm on the screen1 with the button. Only when I visit the screen2 with the toggle (even if in edit mode only) does the toggle change state and execute the code in the OnCheck property. I tried using the OnChange property of the toggle, however that has the same effect/limitation.
Furthermore, if I set the variable (varSendData) back to false before visiting screen2 then nothing happens from which I conclude that the toggle is only triggered (changed) if the page it's on is visible/active.
Any ideas on how I could get the toggle to change state even if I'm not screen2? Or any other ideas on how I could reuse the same code from different screens?
It's a limitation of the method the actual code is calling. In order to allow the HTML to refresh from this "Notify("This Works"). You would need to also have a function that refreshes the HTML in the screen your currently viewing.
I was able to get this to work by adding a label and setting its text property to be If(Toggle6.Value = true, "yes", "no").
Literally adding this in allowed the notification to pop up. Nothing extra.
Is there a property that tells if a form is deactivated by other form ShowModal procedure ?
EDIT :
My program has a tray icon that brings to front the main form when it's clicked. I want to disable this when another window is shown in modal state. Because not doing so the main form (which is disable) will cover the modal form and completly block my program.
This behaviour is to be expected. When a modal form is shown, the other forms are disabled. You don't need to disable anything at all, the framework already handles it all for you. The beep is sounding because you are attempting to interact with a disabled form.
If you want to be notified when your window has been disabled, for any reason, not just because a modal form has been shown, listen to the WM_ENABLE message. To test whether or not your main form has been disabled. Do that by calling the IsWindowEnabled Win32 function.
Having said that I feel that it is likely you've not diagnosed the issue correctly. It sounds like you might be suffering from window ownership problems, which are common in Delphi 6. Or perhaps you are attempting to restore the application incorrectly from your notification icon code. Use Application.BringToFront for that.
The VCL's handling of modal dialogs seem very mixed up. When you show a system provided modal dialog, e.g. MessageBox, windows are disabled whether or not they are visible. However, the VCL only disables visible windows when ShowModal is called. What's more, you cannot use Enabled to test whether or not the window is disabled, you must use the IsWindowEnabled Win32 function.
You can test Application.ModalLevel at any point in time to find out if there's a modal form. E.g.:
if Application.ModalLevel = 0 then
MainForm.Visible := True;
Note that non-TCustomForm descendants will not set modal level, API dialogs like a file open dialog or MessageBox for instance. If there's a possibility of such a thing, you might surround code that runs those dialogs with ModalStarted and ModalFinished.
It doesn't seem necessary in your case, but if you somehow need to be notified that a form/dialog is going modal, you can attach a handler to Application.OnModalBegin and Application.OnModalEnd events. You can use an TApplicationEvents component for that.
What is the proper way to use the SDK to make a dialog (which is not anchored to the add-on bar, etc. but shows centered on screen)? It doesn't seem like there is any API for this important capability. I do see windows/utils has open but I have two problems with that:
The dialog opening seems to require "chrome" privs to get it to be centered on the screen (and I'd be expectant of add-on reviewers complaining of chrome privs, and even if not, I'd like to try to stick to the SDK way).
While I can get the DOM window reference of the new window/utils' open() dialog, I'm not sure how to attach a content script so I can respond to user interaction in a way that prompts (and can respond to) privileged behavior ala postMessage or port.emit (without again, directly working with chrome privs).
Ok, this answer should have been pretty obvious for anyone with a little experience with the SDK. I realized I can just use a panel. In my defense, the name "panel" is not as clear as "dialog" in conjuring up this idea, and I am so used to using panels with widgets, that it hadn't occurred to me that I could use it independently!
Edit
Unfortunately, as per Bug 595040, these dialogs are not persistent, meaning if the panel loses focus, the "dialog" is gone... So panel looks like it is not a suitable candidate after all... :(
Edit 2
I've since moved on and have gotten things working mostly to my satisfaction with sdk/window/utils and openDialog on whose returned window I add a load listener and then call tabs.activeTab.on('ready', and then set tabs.activeTab.url to my add-on local HTML file so the ready event will get a tab to which I can attach a worker. There is still the problem with chrome privs I suppose, but at least the main communications are using SDK processes.
Update to Edit 2:
Code sample provided by request:
var data = require('sdk/self').data,
tabs = require('sdk/tabs');
var win = require('sdk/window/utils').openDialog({
// No "url" supplied here in this case as we add it below (in order to have a ready listener in place before load which can give us access to the tab worker)
// For more, see https://developer.mozilla.org/en-US/docs/Web/API/window.open#Position_and_size_features
features: Object.keys({
chrome: true, // Needed for centerscreen per docs
centerscreen: true, // Doesn't seem to be working for some reason (even though it does work when calling via XPCOM)
resizable: true,
scrollbars: true
}).join() + ',width=850,height=650',
name: "My window name"
// parent:
// args:
});
win.addEventListener('load', function () {
tabs.activeTab.on('ready', function (tab) {
var worker = tab.attach({
contentScriptFile: ....
// ...
});
// Use worker.port.on, worker.port.emit, etc...
});
tabs.activeTab.url = data.url('myHTMLFile.html');
});
if the panel loses focus, the "dialog" is gone...
It doesn't get destroyed, just hides, right? If so, depending on why it's getting hidden, you can just call show() on it again.
You'd want to make sure it's not being hidden for a good reason before calling show again. If there's a specific situation in which it's losing focus where you don't want it to, create a listener for that situation, then call if (!panel.isShown) panel.show();
For example, if it's losing focus because a user clicks outside the box, then that's probably the expected behaviour and nothing should be done. If it's losing focus when the browser/tab loses focus, just register a tab.on('activate', aboveFunction)
Simply adding ",screenX=0,screenY=0" (or any values, the zeroes seem to be meaningless) to the features screen seems to fix centerscreen.
Where exactly is the limit to adopt VM so it can suite better a particular View? Example:
There should be a command in UI (ex button) that should allow adding new item. Additional requirement can be that new item should be selected, ensured that its visible on control (lets say TreeView control), and to begin edit on the newly added item (in order to change predefined value that was set in VM). Lets assume that control doesn't have automatic mechanism to achieve this, so we need to do it manually. So the execution flow looks like this:
invoke add command on VM - done is View's xaml.
set SelectedItem to new item (usually we bind control's SelectedItem property to VM's CurrentItem property, and then just assign new item to CurrentItem.
ensure that new item is visible on control - this must be done in View's code behind.
Start editing - this must be done in View's code behind.
Now, since everywhere on net there are articles on using messages for almost everything, a question:
What do I break if I do it in the simple old fashion way? I use Click event instead of Command binding on adding new item, and in the method I do this:
// in View's Click event handler
ViewModel.AddCommand.Execute(null);
EnsureVisibleSelectedItem();
BeginEdit();
.. clean and clear! And what do I gain if I do it using messages:
// in ViewModel's AddCommand
AddNewItem();
SetCurrentItem();
SendMessageToEnsureVisibleSelectedItem();
SendMessageToBeginEditSelectedItem();
... where View has registered to receive these two messages.
Any light on this is greatly appreciated. To my opinion, UI can change, and VM should be able to adopt new UI without making changes to itself, so I dont quite understand current MVVM policy that is preached on internet.
I would say "make it simple".
What's really important in MVVM is:
what doesn't depend on the view should go in the ViewModel (your ViewModel must not be aware of the view in any way - not just by object reference)
everything else in the View and its code-behind.
Yes, in its code-behind. There's nothing wrong in writing code-behind if it is code that is related to the view, not logic. For instance, drag & drop management should be written in the code-behind.
To answer your question, you do not break anything in writing:
// in View's Click event handler
ViewModel.AddCommand.Execute(null);
EnsureVisibleSelectedItem();
BeginEdit();
Everything that is not related to the view is in the ViewModel, everything else in the View/code-behind. That's just fine.
No if I look at your second example:
// in ViewModel's AddCommand
AddNewItem();
SetCurrentItem();
SendMessageToEnsureVisibleSelectedItem();
SendMessageToBeginEditSelectedItem();
AddNewItem is OK (not related to the view), SetCurrentItem is OK (not related to the view), but what about SendMessageToEnsureVisibleSelectedItem and SendMessageToBeginEditSelectedItem?
EnsureVisible is typically useful for a treeview, but what if your view wasn't built with a treeview? What if the control would automatically make the new selected item visible? Of course you could ignore the message, but you would have written some useless code in ViewModel because you thought your view would need it for UI display.
You have typically written here some code in the ViewModel that is aware of how the View should be working. Yes, you have reduced the number of lines in the code-behind, but you definitely have broken the pattern.
Your "old fashion way" is actually a good way for your needs. Your ViewModel is not aware of the view, that's what's important.
I have a site with five tabs using jquery-ui. Each loads an individual jQuery script. Now when I have loaded the second tab and go to the third tab the js out of the second tab still remains active and disturbs my actions in the third tab space.
Can someone explain me why the js out of the second tab still stays active when changing to the third tab and how I can avoid such behaviour?
Once you have loaded a script onto the page, it remains active until the page refreshes.
I don't know about unloading, but you can certainly disable the actions of a certain script depending on what it is. Could you post an example of the script causing the issues?
EDIT:
For example, if you have a script that is dependent on the tab you are in, you can condition the actions in the script with the tabs being at a certain index. A demo syntax:
//will only execute action if you are in current tab
if(tabs_ui_index == 0){
//do something
}
to get that variable (tabs_ui_index) you can do something like this:
$('#mytabs').bind('tabsselect', function(event, ui) {
tabs_ui_index = ui.index;
});
This code binds a "tabsselect" event to the element that is tabbed and sets the variable to the currently indexed tab every time a user changes a tab.
Also, you can unbind events, if you loaded a script that set a click event for a button that no longer exists, or that you are using for a different purpose now:
$("#mybutton").unbind("click");
I hope this helps. Let me know if you have any other questions.