I'm in the process of teaching myself WPF, and I have run into a small issue that I can't find the answer to.
My test app allows image files to be dropped into a StackPanel. Once an image is dropped, a new user control is added to the stack, and displays some meta-data about the file. All is working correctly, and I can iterate through the child controls to retrieve the values.
What I'd prefer to be able to do is allow the user to persist this data to a file, so they can suspend working on the data. The obvious way for me to do this is to store the data in a DataTable and serialise/deserialise it to xml. However, I don't know how to drive the collection of user controls from a DataTable or DataSet object - in fact, I don't even know if this is the right way to go about it in a WPF app. I am more than willing to admit my ignorance here and take better suggestions if there are any.
Summary of the app logic.
1) File is dropped (from Win explorer) onto a StackPanel
2) File triggers creation of a new user control, which is added to the StackPanel
3) Data is populated in the user control
4) Processing data involves iterating through the control collection.
What I'd like
1) File is dropped (from Win explorer) onto a StackPanel
2) File data is inserted into some persistable object (data table?)
3) updated data table drives the generation of the user control to be added to the displayed collection.
4) save / load functionality persists the data for re-use later.
Thanks in advance
You're on the right track with the second approach, what you need to look at is the ItemsControl - that's a thing which can have items added to it. It's the base for ListBox etc, and you can template it to work as you require. Then there's the DataTemplate which handles which controls are displayed and data binding to those controls when an item is added to the underlying data structure. There are quite a few examples around on the net, try Dr WPF.
In order to make everything work the underlying data structure must support change notification. As everything happens automagically, once the Xaml is setup, you can find yourself in an odd situation. You've added data to a data structure, which in turn has caused controls and data to appear in your ItemsControl. How do you link the data items and their visual controls. The answer is to use some built in static methods ItemFromContainer which links from the graphic to your underlying data item, useful to handle click events, and ContainerFromItem which does the reverse.
Related
I have been tasked with creating a like for like user interface for a product replacement.
One of the components of the old system was a container that displayed properties in a hierarchy (think treeview like) where each property had a label and value (value could be a textbox, drop down, checkbox, file browse etc)
This is the component that I need to replace and one of the conditions being imposed on me is to front load it with about 5000 items, some of which will be made visible depending on usage context.
My first attempt has been to use a FlowLayoutPanel as the main container populated by TableLayoutPanels indented on left margin that each hold label and edit control.
I hit the problem of the 10,000 control handles limit.
Any suggestions on an alterantive approach to get round this limitation that will allow for the front loading of the 5000 items?
Thanks in advance.
Consider the following guidelines:
1. Do not load all the records at once. Load the data page by page as per request, and render each page of data.
2. Do not show all the records at once. You have a limited window size, even if you load all the data, just show the part that should be visible in the view port. Show the rest of the data when the user scrolls. This way you can dispose the previous elements.
3. Do not use a lot of handles. You can use a control which uses just 1 control handle, like a TreeView or DataGridView or even a custom control for yourself. The key is keeping data in view mode and just show the edit controls when the user focus on a specific item to edit.
Example: DataGridView and ListView controls support virtual mode for loading data. You can also simulate nested data by padding the first cell/item. Also the Treeview control supports events like BeforeExpand which allows you to load child data when the user requests.
For all above examples you can just show the edit controls when the user wants to edit the cell.
Is it normal in a WPF app to create a lot of user controls in order to separate concerns that would otherwise be crammed in a single window with a huge XAML hierarchy? I'm finding that I keep making new user controls, even though I don't intend to reuse them, just so that each of my sub-components has a separate task. I'm also giving each of them their own view model, instead of binding things to properties on one master view model.
Is this normal? I feel like from a code cleanliness perspective I'm doing the right thing. But from a WPF perspective, I feel that this can't be right.
For example, let's say you have a list on the left side of the window, and when you select an item, it changes what's displayed on the right side. There are also buttons above your list to manipulate it, adding and deleting items for example. I would be inclined to pull that whole list out as a UserControl, which would contain just the list and the control buttons above it. Then the main window would just include my new control.
Am I going overboard?
I'm working on an app, that displayes huge (10000+ elements) graphs in a wpf canvas.
I'd like a feature like in Visual Studio, when you can split the view of an editor (so I can view two distant part of the same graph at the same time).
I have some constraints:
data binding (creating the bindings) of graph elements makes the loading of big graphs very slow, so I'm not using MVVM, the "VM" knows about the view and updates it directly when needed
the children of the canvas are frameworkelements, since I use the Tag property
because of the number of graph elements, I don't want to keep two different view for each element for the two part of the split view
So it should be like displaying multiple parts of the same canvas in different places. You can't set two parents for the FrameworkElements in WPF, so the easiest way is out of question :(
What are my options? Should I reconsider my constraints or there is some workaround for this?
Let me know if you need any more details (it's a big application, so I can't give you every information).
Edit: duplicating with visual brush is not an option since I need proper input event notifications, so both view must be editable.
Options:
Bind the same data to two controls.
Use a visual brush and duplicate input on the real control.
Create a custom graphing control that can output two parts of the graph at once.
If binding to two controls is too slow, then I think you need to rethink your application. The very fact that you have so much data displayed at once that you need a dual view to see separate parts is disturbing. That should raise a red flag. The red flag would notify you that, "What I need, and what I have is different." And you should go back to the drawing board and find out what you really need.
Otherwise, it might be best to create a custom control. The graph is rendering in its entirety even though you only need small portions displayed. If you had your own custom control you could speed up the entire app by rendering only visible portions at a time, and splitting within the control.
I am eager to find some solid (free, Open Source, or tutorial/example) code to make a WPF Combobox do autocomlete/autofilter as the user types. But everything I've tried so far has had some sort of problem...
A Reusable WPF Autocomplete TextBox came close, but I can't get it to work with more than one filter (more info here).
WPF autocomplete textbox/combobox doesn't work for me because it inherits from UserControl, and thus doesn't support the DataTemplates I need (for showing/selecting the value of one property for an object with multiple properties).
Automatically Filtering a ComboBox in WPF didn't work because it doesn't seem to ever find the EditableTextBox portion of the inherited ComboBox code (via (TextBox)base.GetTemplateChild("PART_EditableTextBox") which seems to always returns null).
Building a Filtered ComboBox for WPF just gets stuck in a refresh loop then overflows the stack after I type just a few letters.
Other things I've considered:
I know that Windows Forms' Combobox control has AutoCompleteMode and I could embed it in WPF, but I can't imagine it would play very well with my WPF data bindings.
Perhaps it is too complex and I need to simplify, maybe by building one-dimensional (single-property) ObservableCollections for the ComboBoxen... However, the challenge of applying multiple filters (one set by another control's value, and one from what the user is typing) to multiple controls using different views of the same DataSet would require a ridiculous amount of processing power to destroy and rebuild the list every time the user types a character!
So... I'm at wit's end. Any suggestions?
If your Combobox has some data source attached to it ,
just make
1-IsTextSearchEnabled = true.
2-IsEditable = true.
you are good to go
Try this one:
http://blogs.windowsclient.net/dragonz/archive/2010/02/23/autocomplete-textbox-control-for-wpf.aspx
I want to create a table representing data I have, but I want each row to have a custom display. I have developed a little custom control that represents a row and has a few items in it (text box, check box, progress bar), however how do I now in the main form create multiple instances of this for the data I have?
e.g. is there a winforms control I can use to do this? or do I have to take a panel or something and programmatically do it?
I do need to somehow take responses back. So if someone clicks on the button in the 4th row say then I'll need to be able to tell which row it was from.
As an aside would then be a way to BIND the above mentioned visualization of my data to the data itself, say housed in an Array?
thanks
I see two options here:
You can use a DataRepeater. This control can be found in the Microsoft Visual Basic Powerpack. It allows you to place controls on a template which gets copied for each item in the databound collection.
You can create a custom control and manually place one instance of it for each item in a collection, re-creating databinding for the controls in it. This requires you to either expose the controls inside publicly or as properties of the user control.
However, above options are mostly useful for non-tabular data. If your layout is strictly tabular (i. e. rectangular cells in a grid) then you can create a custom DataGridViewCell which takes some time to understand but not too much code. Putting a progress bar into such a cell shouldn't prove too difficult.