Think about a WPF program that has 2 pages which you navigate between. (Upload and Crop)
In the first page, you load an image using a button, select the image, and your image appears in the WPF Image control. Then, you press the "Crop" button. That sends the navigation to the second page, which you can crop the image.
Then, you crop the image in the second page. Then you press "next". Next button must redirect you to the first page, but wait a minute, the image you loaded no longer exist in the page. Because it's a new page.
Dim CropPage As New Crop(Crop_Bmp, Crop_BmpSource)
Me.NavigationService.Navigate(CropPage)
You may think it's okay. Because we pass the parameters and we can refill the WPF Image controls using that parameters. But, there is actually 8 upload panels in the page 1. So, other ones are important.
Or think about another method I found. Instead of using a new page instance, navigate back that you used.
Upload.Crop_Bmp = Crop_Bmp
Upload.Crop_BmpSource = Crop_BmpSource
Me.NavigationService.GoBack()
Upload.Crop()
But in the second one, it throws errors.
"Reference to a non-shared member requires an object reference."
Then, back to the Upload page, I made the variables and functions "Shared". But then, more problems come up. Because you cannot edit the local variables unless you also make them Shared. So, all of the variables and functions need to be "Shared".
I'm searching about a solution for a few days and I could not get rid of them. What method should I use? Redirecting back, or opening a new instance?
In old-type applications, it was very easy. All was that:
Form1.Crop_Bmp = Crop_Bmp
Me.Hide()
Form1.Crop()
And it was working perfectly. Because the forms were not instances like WPF pages. That's the reason I find WPF quite weird.
I found it a way to do this. When navigating to the Crop page, I sent the Upload page as a parameter to Crop Page.
Dim CropPage As New Crop(Crop_Bmp, Crop_BmpSource, Me)
Me.NavigationService.Navigate(CropPage)
Then, in Crop:
Public Sub New(ByVal Crop_Bitmap_ As Bitmap, ByVal Crop_BitmapSource_ As BitmapSource, ByVal pg As Upload)
' This call is required by the designer.
InitializeComponent()
UploadPage = pg
Then, in the Crop page, I accessed that parameter to modify its elements. For example:
Me.NavigationService.Navigate(UploadPage)
UploadPage.Crop()
This sounds like a bad use-case for the Pages metaphor. Pages are for loosely coupled peer screens (E.G. A separate page for each department), but you are using them in a tightly coupled parent-child relationship. (The "Crop" page is the child of the "Upload" page) For what you are doing, launching the crop screen as modal dialog might be more fitting.
If you want to keep everything in the same window, you can keep both functions in the same window, and toggle their visibility as needed.
Related
I am currently a little bit troubled by the following problem. I have a user interface which basically shows a graphic (a canvas made of Lines, Circles, ... these are all WPF objects). Depending on the selection a user makes in the menu, some items get deleted and some get added. So the basic image looks the same, but a few modifications are made.
The user has the possibility to select - say - 10 different "pages" by clicking a Next/Previous Button.
I am using MVVM Light and my ViewModel contains all the items of the graphic (all Lines, ...).
Now I would like to print that graphic to multiple pages. The first page should contain the graphic with changes from page 1, the second page contains the graphic with changes from page 2 and so on. The actual number of pages is dynamic. I track this with a property CurrentPage and a property PagesTotal.
Whenever I push the "Next" button, this causes a command to be executed which will change the variable CurrentPage and also makes sure that the correct items are displayed.
Now I would like to print this but this is where I'm stuck. I dont' mind leaving the MVVM zone and doing some dirty work in code-behind but I would refuse to draw everything again like in the old GDI days.
Any ideas are really welcome.
Create a UserControl containing your display logic (you graphic, for instance). Grab you ViewModel list and project then in UserControls, setting each ViewModel as each UserControl's DataContext.
Force each one to render calling Measure with infinite value and then Arrange with the resulting DesiredHeight and Width. Then follow the procedures to print WPF visuals (link link link).
Essentially, this should be quite simple if and only if your views work independently; i.e. your ViewModel doesn't contain UiElements that are placed into your View.
Simple solution is to basically print your visual root. If need be encapsulate your Views in a user control first.
PrintDialog printDlg = new PrintDialog();
UserControl1 uc = new UserControl1();
printDlg.PrintVisual(uc, "User Control Printing.");
Reference
Alright, I have to admin that I now switched back to doing the printing through code only. I would have really liked doing it "WPF-style" but handling the multiple pages issue was just too much trouble.
Anyway, there is still one issue regarding the printout left but this will be another question.
I want to make a program by WPF which includes several pages.
I have a Window and several Pages now.
In order to navigate, I use
this.Content = new Page1();
in the main window (from Window to Page), and
((Window)this.Parent).Content = new Page1();
between pages (from Page to Page), because Page can only be sub-element of Window or Frame.
However, the second line of code above looks quite ugly.
Is there a better way to achieve the same goal?
I have coded from several Windows Phone applications before, and I think it might be better to navigate between Pages rather than hide/show elements (such as Grids).
If your navigation code is on your Page class, either :
move it to the window class
create an event in the Page class, and react to it on the Window class.
Is there any reason why you can't just put a Frame in your Window ?
You could use NavigationService.
http://msdn.microsoft.com/en-us/library/ms750478.aspx
http://www.paulstovell.com/wpf-navigation
Maybe this could help:
http://azerdark.wordpress.com/2010/04/23/multi-page-application-in-wpf/
I'm new to using WPF. I have the following program I want to create:
-Application opens up with one button
-User clicks button and it takes them to a new page with various input.
I'm confused about how I need to do this. I tried opening a new window, but I don't want a window to open up, I want it to be all one Window. I tried creating a new page and navigating to it using NavigationService but couldn't get it to work.
Basically I want to create a workflow where the user enters some stuff, clicks the next button and is taken to a new page to enter some more information. Can anyone point me in the right direction?
Use Pages in your application and use NavigationService to switch between them.
For example, if you have two pages in your paplication, "Page1" and "Page2" you can include the following in Page1.xaml:
<Button Content="Next" Click="NextClicked" />
and this in your Page1.xaml.cs:
void NextClicked(object sender, RoutedEventArgs e)
{
NavigationService.Navigate(new Page2());
}
Alternatively you could use this:
NavigationService.Navigate(new Uri("Page2.xaml", UriKind.Relative));
Generally it is easier to do the first, because you can also set properties of Page2. For example, if Page2 has a public "CurrentItem" property you could say:
NavigationService.Navigate(new Page2 { CurrentItem = this.Something });
You can't do that with the Uri-based syntax.
You can also create instances of various pages (Page1, Page2, etc) and store them in your Application object, then switch to them like this:
NavigationService.Navigate(App.Page2);
This way if you ever navigate to Page2 later you will get exactly the same Page2 object. Alternatively you could use NavigationService's Journaling feature to help with this.
Initially there doesn't seem to be much of a difference in the preference of what should be used: Pages or Windows. However, looking at the intended goal of the application, I would suggest using UserControls instead of Pages, as Pages seem to focus on Web related content, though they can be used in stand alone applications as well. Another argument that has been made in another post is referring to the MSDN-documentation, and points out that in using a Page the NavigationWindow that it is hosted in does not remember the instance of the content that is navigated to and thus other WPF-techniques are needed to store that content in your navigation history.
NavigationWindow does not store an instance of a content object in navigation history. Instead, NavigationWindow creates a new instance of the content object each time it is navigated to by using navigation history. This behavior is designed to avoid excessive memory consumption when large numbers and large pieces of content are being navigated to. Consequently, the state of the content is not remembered from one navigation to the next. However, WPF provides several techniques by which you can store a piece of state for a piece of content in navigation history.
If you use a UserControl, you wouldn't have that problem if your goal is to create a native application anyway. You can download this template as an example to use UserControls instead.
The use of the NavigationService is the right way to do that. You have to add a frame to your windows to show your pages, then navigating between them with the NavigationService.
You can change your application object's MainWindow reference to another Window object.
Application.Current.MainWindow = new SecondWindowToBeDisplayed();
I've come across a strange scenario where a frame refuses to refresh its content.
I can kinda understand what's happening but the solution is not coming to me.
I have a page that has a frame (Frame1) and several buttons. When I click on a button a page is loaded into the frame. This works perfectly in most situations.
Private Sub btnIncidents_Click(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles btnIncidents.Click
Frame1.Source = New System.Uri("/Incident/Incidents.xaml", UriKind.Relative)
End Sub
However, I have a situation where I need to select the button that was previously clicked to effectively do a Refresh on the Uri. The problem is it simply does nothing because the Uri hasn't changed. That makes sense but it's not what I want, I need to call it again.
My first solution was to introduce Frame1.Refresh which initially did the trick. But once a page was Refreshed, none of the Buttons could load a different page.
It was as if by calling Frame1.Refresh I'd broken the Frames ability to navigate to other pages.
My second idea was to set the Frame source to Nothing (Null) and then set the source to the URI but that didn't work either. ie Frame1.Source = Nothing
Has anyone else come across this or maybe have some suggestions? I just need to Refresh/Reload the Frames page without breaking the Frame!
I had the similar problem - with html though. Resolved it with
frame.NavigationService.Refresh();
apparently will clear navigation history, but in my case I do not really care.
Got the answer from http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/8fc6bd83-2803-4820-a22b-d4d87638c4e2
I tried the Visual C# Kicks code for an alpha-blended form. This works (as soon as I remove the TransparencyKey property); that is, I can use the W3C's PNG alpha test image and see other windows underneath, but makes all controls on the form invisible. Presumably, they simply aren't painted, as OnPaint is overridden. I tried calling the superclass's OnPaint:
Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
UpdateFormDisplay()
MyBase.OnPaint(e)
End Sub
, but this didn't change anything. (Calling MyBase.OnPaint first doesn't make any difference either.)
Unfortunately most articles about alpha-blended forms focus on pure splash screens without any controls on them — but we need a panel which first shows sign-in fields, then a progress bar.
The controls, by the way, do not need transparency; it's only on the outer edges that the PNG's transparency truly matters. So faking this by adding another form on top of this all (with the two always moving in tandem) might suffice, but I'd prefer a smoother solution.
Try putting this in your form ctor after InitializeComponents();
base.SetStyle(ControlStyles.OptimizedDoubleBuffer | ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint, true);