Remember, MainWindow. Also, you will notice that, there is no other designer. Here is a sample code that i got after dragging a textbox, a label and a button:. You see!! How simple the generated code is!!!
If we compare this to the traditional win form application, following the code samples that generated when doing the same tasks in a win form project:. However, wpf provides a lot more rich features to improve the user experience than win form application. But, in that case you should know which tag to use for which controls. Let's break down this XAML code to understand it better.
NET code. There are eight attributes declared, and they generally belong to three categories:. The main xmlns attribute imports the XML namespace for the entire file, and in this case, maps to the types declared by WPF.
For example, the xmlns:local namespace declares the local prefix and maps to the objects declared by your project, the ones declared in the Names code namespace. MainWindow class. Any normal attribute declared on the XAML object sets a property of that object.
In this case, the Title attribute sets the Window. Title property. First, run the project and see the default output. You'll see a window that pops up, without any controls, and a title of MainWindow :. For our example app, this window is too large, and the title bar isn't descriptive. Change the title and size of the window by changing the appropriate attributes in the XAML to the following values:.
WPF provides a powerful layout system with many different layout controls. Layout controls help place and size child controls, and can even do so automatically. The Grid control lets you define rows and columns, much like a table, and place controls within the bounds of a specific row and column combination. You can have any number of child controls or other layout controls added to the Grid.
For example, you can place another Grid control in a specific row and column combination, and that new Grid can then define more rows and columns and have its own children. A grid always has a single row and column declared, meaning, the grid by default is a single cell. That doesn't really give you much flexibility in placing controls.
This insets the grid from the window and makes it look a little nicer. Now that the grid has been created, we can start adding controls to it.
First, start with the label control. Some controls understand how to handle content, others don't. The content of a control maps to the Content property. Both ways accomplish the same thing, setting the content of the label to display the text Names.
We have a problem though, the label takes up half the window as it was automatically assigned to the first row and column of the grid. For our first row, we don't need that much space because we're only going to use that row for the label. The Auto value automatically sizes the grid row to the size of its contents, in this case, the label control.
Notice that the designer now shows the label occupying a small amount of the available height. There's now more room for the next row to occupy.
Most controls define some sort of height and width value that they should occupy that looks best for them. All the samples have been retargeted to. NET Core 3. You can also find an archive of samples targeting. NET 4. The samples in this repo are generally about illustrating specific concepts and may go against accessibility best practices. However, the team has spent some time illustrating accessibility best practices in a subset of these samples.
Please note that the documentation on the repo is still being updated, so all links might not point to the right location. Unless otherwise mentioned, the samples are released under the MIT license. Help us improve out samples by sending us a pull-request or opening a GitHub Issue.
These samples require Visual Studio to build, test, and deploy, and also require the. WPF on. Note: If you are using the latest version of Visual Studio You can find installers for the. The easiest way to use these samples without using Git is to download the zip file containing the current version using the link below or by clicking the "Download ZIP" button on the repo page.
You can then unzip the entire archive and use the samples in Visual Studio For more info about the programming models, platforms, languages, and APIs demonstrated in these samples, please refer to the guidance available in MSDN.
These samples are provided as-is in order to indicate or demonstrate the functionality of the programming models and feature APIs for WPF.
Skip to content. Objects that implement this interface are validated on demand, rather than each time their state changes. For a discussion of how this can make your business objects more useable, the article Fort Knox Business Objects makes interesting reading. They also have the advantage that they are able to validate state which depends on multiple properties; there is clearly a synergy here with BindingGroup s.
The following example is a business object that shares similar constraints to the previous Person object; however, this object has a further rule that StartDate must be before EndDate. This rule iterates over all of the items within the binding group i. In this case, the IDataErrorInfo. Error property is used for object level validation. Note also that because the validation error does not relate to an individual property of our business object, none of the DataGrid cells are highlighted.
In order to make the failure more obvious, the style of the row has been modified to add a red border. This can be automatically added to the validation rules for a binding via the ValidatesOnDataError property. This works fine when editing an existing row; however, when a new row is added, for some reason, validation is applied to the newly created object, and re-validation attempts fail to remove the error. I delved into the implementation of BindingExpression , but got rather lost along the way!
A simple solution is to implement a validation rule which uses the IDataErrorInfo interface, but simply probes for the error of the bound property, as follows:. With the above rule associated with our column bindings, you can now give feedback regarding which cell has a validation error in the case where the validation error relates to an individual object property :. The WPF DataGrid is able to perform an atomic commit of the contents of an individual row, or alternatively, dispose of any changes made if the user hits the Escape key.
This functionality is made possible when the bound objects implement the IEditableObject interface. When a DataTable is bound to the DataGrid , the view associated with the table is bound. This exposes the rows via the DataRowView wrapper class which implements this interface.
To have this behaviour in your own business objects, you have to implement IEditableObject yourself; however, there are a few simple patterns that can be applied; see, for example, this method which uses an object state snapshot.
When a new row or changes to an existing row is committed to a DataTable , constraints are checked e. It would make sense to catch these exceptions and display the problem as a validation error to the DataGrid user. EndEdit is invoked. The workaround given here uses validation to ensure that all the DataTable constraints are satisfied before the updates are committed.
The following slightly lengthy validation rule can be applied at cell and row level. The rule will check a column or all the row's columns for length, unique, and null constraints. The example in the attached source code presents a UI for editing the Customer table. One other subtlety of this example is that the primary key is read only, because the generated DataSet 's update methods assume that the primary key has not been modified.
However, when the data grid selection changes to the empty row at the bottom, the column's read-only state is toggled to allow the user to add a new Customer row.
It should be noted that the validation method detailed above is quite inefficient. Also, it has only been tested on a rather small set of column types.
However, the approach could be extended further. Hopefully, in the. Many of the grid's properties such as CellStyle and RowStyle are quite obvious. Rather than exhaustively cover all the various styling properties, this section will cover some of the DataGrid specific features, and also how to style some of the more tricky parts of the grid. If these column types do not fulfill your needs, either in read-only mode or when the cells are in edit mode, then you can define your own column type using templates.
Users of the ASP. NET GridView will find this approach very familiar; you simply define a DataTemplate for rendering your data in read-only or edit mode. The following example uses the DatePicker control, which is also part of the WPF Toolkit, to provide a more intuitive interface for selecting a date:. Note also that the read-only view of this cell uses the StringFormat property of the Binding class to specify a format which matches that which is used by the DatePicker. The standard validation error indicator is a red exclamation mark which is displayed at the left hand side of the row.
With the example given below, the exclamation mark is rendered within a red circle in order to give it a more striking appearance. Also, a tooltip is defined that displays the validation error message. The templated control which displays the error indicator is a child of the DataGridRow ; therefore, we can obtain the validation errors from the row via a FindAncestor RelativeSource binding.
You can use the RowDetailsVisibilityMode property of the DataGrid to specify whether to display details just for the selected rows or for all the rows. The RowDetails displays the image thumbnail and its associated tags:.
0コメント