Adding a thumbnail view & navigation to the PdfViewer control

If you’ve used the PdfViewer control you’ll know that it provides an easy way to display PDF documents within¬† your WinForms application. Currently, you can select text, manipulate a file (via the PdfDocumentProccessor non-visual component) and even fill out PDF forms. The 14.2.5 release even allows the ability to programmatically fill in PDF forms–pretty useful stuff for those of you processing electronic documents and working towards the dream of a paperless office.

One feature that I find lacking in the PdfViewer control is a good thumbnail navigation system. Adobe Reader offers this ability with a simple thumbnail navigation system; each page of the document is displayed as a small image which users can quickly scroll through. Double-clicking on a thumbnail opens the corresponding page and end users can even change the size of the thumbnail images.

Screenshot of Adobe Reader's thumbnail navigation
Screenshot of Adobe Reader’s thumbnail navigation

The DevExpress PdfViewer will display thumbnails for pages if you zoom out to about the 10-20% zoom level, but the functionality ends there. You can’t double-click one of the pages and have the viewer navigate to that particular page. How can we implement a system similar to Adobe Reader ourselves?

DevExpress's non-functional thumbnail mode.
DevExpress’s non-functional thumbnail mode.

To mimic Adobe Reader’s thumbnail function, I immediately though of a few controls that might make our job easier:

  • GalleryControl – This could easily organize and display our thumbnail images. We don’t really need any grouping functionality but that’s easy to ignore.
  • GridControl – This tends to be my default go-to for displaying a list of items/records. But that’s only the first half of the equation–after that, we’d have to decide which view type to use. The LayoutView in a single column mode would work well, but honestly, I hate the layout editor.

In the end, I decided to use the GridControl, but with the WinExplorerView instead of the LayoutView. The WinExplorerView mimics the various ways you might view a folder in Windows Explorer–details, large icons, small icons etc… This is all controlled via the OptionsViewStyles property, so we can even allow the user to toggle between styles at runtime.

At the end of this exercise, we’ll end up with something like this:

Our semi-finished product: a PdfViewer control with a sidebar of page thumbnails.
Our semi-finished product: a PdfViewer control with a sidebar of page thumbnails.

To being, we’ll create a form and place a LayoutControl onto the form. Dock the LayoutControl to fill the form, and then drop a GridControl onto the LayoutControl, followed by a PdfViewer control to the right. The GridControl can be placed in a LayoutControlGroup and the PdfViewer can just be contained within a standard LayoutControlItem. I also changed the view type of the GridControl from the default GridView to the WinExplorerView type.

The thumbnail logic is all going to be contained within a class I’ve called PdfPage. Let’s have a look at it:

namespace PdfThumbnails
{
    /// <summary>
    /// Encapsulates the properties and methods of a PdfPage
    /// </summary>
    sealed public class PdfPage
    {

        #region Public properties

        /// <summary>
        /// Gets or sets the number of this Pdf Page
        /// </summary>
        public int PageNumber
        {
            get;
            set;
        }

        /// <summary>
        /// Gets the thumbnail image for this Pdf Page
        /// </summary>
        public Image Thumbnail
        {
            get;
            private set;
        }

        #endregion


        /// <summary>
        /// Initializes a new instance of the PdfPage class
        /// </summary>
        public PdfPage()
        {

        }



        /// <summary>
        /// Sets the thumbnail image for the current PdfPage
        /// </summary>
        /// <param name="DocumentViewer">PdfViewer control responsible for displaying the PdfPage</param>
        public void SetThumbnailImage(PdfViewer DocumentViewer)
        {
            int PageWidth = 0;
            int PageHeight = 0;
            int PagePixelWidth = 0;
            int PagePixelHeight = 0;

            using (Graphics graphics = DocumentViewer.CreateGraphics())
            {
                //Get the page dimensions
                PageWidth = (int)DocumentViewer.GetPageSize(PageNumber).Width;
                PageHeight = (int)DocumentViewer.GetPageSize(PageNumber).Height;

                //Convert the page dimensions into screen pixels
                PagePixelWidth = (PageWidth * (int)graphics.DpiX);
                PagePixelHeight = (PageHeight * (int)graphics.DpiY);

                Thumbnail = DocumentViewer.CreateBitmap(PageNumber, Math.Max(PagePixelWidth, PagePixelHeight));

            }   //End the using() statement

        }   //End the SetThumbnailImage class



    }   //End the PdfPage class
}   //End the PdfThumbnails namespace

The class is pretty sparse in and of itself–just two properties. One to keep track of the page number within the document and another to hold the thumbnail image. The important part is the SetThumbnailImage method, which is in charge of creating a thumbnail for this page.

The method requires an instance of the PdfViewer control because unfortunately, the control doesn’t offer a way to get an instance of a single visual page. Luckily, having an instance of the PdfViewer control allows to use its CreateGraphics method to get a reference to the drawing surface which will be useful for generating that thumbnail. And it is useful because the PdfViewer’s GetPageSize method returns the page’s dimensions in inches, not in pixels.

I think this was a poor decision on the part of DevExpress, because it’s not mentioned in the documentation that SizeF struct returned from the method is measured in inches and I have no clue how useful that information would be in metric-based countries. Our demonstration PDF will return 8 & 11 for the page’s width and height, respectively. Since we don’t want to create an 8px X 11px Bitmap, we need to convert these dimensions into pixels.

I’m not a graphics programmer, but I do know that DPI settings will influence the conversion between inches and pixels–after all, its name implies how many dots-per-inch there are on our display! Because of this, we can’t just multiply the page dimensions by some magic number. We have to take this DPI into account and multiply by that instead.

Once we have the page and screen dimensions, it’s a matter of using the PdfViewer’s CreateBitmap method to generate a Bitmap image of current page.

I then create a BindingSource component on the Form and set its DataSource property the PdfThumb class. After that, I set the GridControl’s DataSource to this BindingSource component. The GridControl will automatically read the scheme from this data source, but because we’re using the GridControl with a WinExplorerView there aren’t any columns. Instead, there’s a ColumnSet, which maps properties of the data source to the predefined properties of the WinExplorerView.

Since a future version of this application may allow a user to toggle between thumbnail sizes, we’ll set the values for SmallImageColumn, MediumImageColumnn, LargeImageColumn and ExtraLargeImageColumn members of that ColumnSet property. These are all set to the PdfPage’s ThumbnailImage property, and we’ll set the ColumnSet’s Description andTextColumn properties to the PageNumber property.

At this point, we have a PdfViewer control capable of displaying our PDF, a GridControl capable of displaying page thumbnails and a class capable of generating those thumbnails. The only thing we need to do is actually tell our application to generate those thumbnails at runtime when a PDF is loaded into the viewer.

Create a handler for the the PdfViewer’s DocumentChanged event as this will be fired every time a document is loaded into the PdfViewer control. After that, it’s just a matter of looping through the pages of the PdfViewer and creating an instance of the PdfPage class for each:

/// <summary>
/// Document changed event handler for the PdfViewer control
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void pdfViewer1_DocumentChanged(object sender, DevExpress.XtraPdfViewer.PdfDocumentChangedEventArgs e)
{
    IList<PdfPage> documentPages = new List<PdfPage>(pdfViewer1.PageCount);

    for (int i = 1; i <= pdfViewer1.PageCount; i++)
    {
        PdfPage documentPage = new PdfPage();
        documentPage.PageNumber = i;
        documentPage.SetThumbnailImage(pdfViewer1);

        documentPages.Add(documentPage);

    }   //End the for() loop

    bindingSource1.DataSource = documentPages;

}   //End the pdfViewer1_DocumentChanged() method

Once that’s done, our GridControl will automatically show those page thumbnails when the application is run and a Pdf is loaded into the viewer.

The final step is to handle the WinExplorerView’s DoubleClick event:

/// <summary>
/// Double click event handler for the Thumbnails WinExplorerView
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void wvThumbnails_DoubleClick(object sender, EventArgs e)
{
    PdfPage currentPage = (wvThumbnails.GetFocusedRow() as PdfPage);

    pdfViewer1.CurrentPageNumber = currentPage.PageNumber;

}   //End the wvThumbnails_DoubleClick() method

This code simply takes the current row (thumbnail) from the thumbnail grid and casts it to an instance of our PdfPage class. Since the class is nice enough to keep track of its page number on our behalf, we can tell the PdfViewer to navigate to corresponding page.

And that’s all there is to it! Once small class, a couple of event handlers and we’re done. In an upcoming post, we’ll look at adding a few additional features to this application such as:

  • Allowing the user to change the thumbnail size
  • Synchronizing the thumbnail sidebar scroll position to the PdfViewer scroll position
  • Showing a magnified image of the thumbnail when the user hovers over a thumbnail image

And don’t worry, we’ll also get back to the DxContactList Xpo tutorial soon! In the meantime, here is the full source code for this tutorial: PdfThumbnails.

Adding a thumbnail view & navigation to the PdfViewer control

Creating a sample WinForms application, part two: the data access layer

In part one of this series I provided you with an overview of what I hope to accomplish. We’ll be starting our sample application with an Xpo back-end that will reside as its own project without our overall solution. The nice thing about Xpo is that your classes, data access and UI don’t all need to reside within the same project or namespace. Because of this flexibility, I like to segregate my data access layer (or DAL for short) to its own project so that it could be changed easily to take advantage of the the different ways Xpo can connect to your data store (or even what data store Xpo connects to).

Xpo has a default data layer, known as XpoDefault.Session. If you choose to use this, all newly created Xpo objects will automatically use and share this default data layer. Of course, this method isn’t recommended by DevExpress and won’t really work well in multi-threaded or ASP.NET applications.

Instead of relying on XpoDefault.Session, we’ll create an XpoDefault.DataLayer instance and actually set the XpoDefault.Session to null to ensure that it’s never used. It’s safe to use the XpoDefault.DataLayer static instance, but you could choose to provide a reference to your data layer when instantiating a Session or UnitOfWork object if you wanted.

We have two options to choose from when it comes to creating this XpoDefault.DataLayer:

  • SimpleDataLayer – Used by default.Use this DAL if you need to modify the object metadata at runtime.
  • ThreadSafeDataLayerUse this DAL if multiple threads are allowed to access data in a data store.

Source: IDataLayer documentation

We’ll choose to use the ThreadSafeDataLayer in the event that we want to use threading in our application.

Beyond that, we need to provide a Data Store–namely our database server. We can provide a connection string to the ThreadSafeDataLayer constructor so that it knows where it’s getting and saving our data to/from:

/// <summary>
/// Sets the application's default data layer
/// </summary>
internal override void SetDataLayer()
{
    string ConnectionString = "Data Source=MySqlServer\\sqlexpress;integrated security=SSPI;initial catalog=DxContactList";

    XPDictionary dictionary = MetaDataDictionary.GetMetaDataDictionary();
    XpoDefault.DataLayer = new ThreadSafeDataLayer(dictionary, XpoDefault.GetConnectionProvider(ConnectionString, AutoCreateOption.DatabaseAndSchema));
    XpoDefault.Session = null;

}   //End the SetDataLayer() method

We’ll invoke that method from the Program class when the application starts up, and we’re essentially done at this point. Any new Session or UnitOfWork component used within our application will automatically connect via this data layer.

In part three of this series, we’ll begin building our Xpo business class objects.

Creating a sample WinForms application, part two: the data access layer

Visualizing data with the XtraMap control

One important tool in my company’s flagship software offers users the ability to search for trucks and visualize that information on map to see what is available and where it is. It’s easy to display results to a grid control, but looking at tabular data over and over can be a little boring. Mixing in another control, such as the XtraMap control provides us with the ability to visualize these results in an easy-to-understand & interactive manner.

Here’s a basic overview of how it might look in my software:

XtraMap example
XtraMap example

There’s a basic set of editors in which a user can enter some search criteria and then search results are displayed with a GridControl to the left, and an XtraMap to the right. Clicking on a row show zoom us to the selected result marker on the map and vice versa. We should also make use of the tooltip ability for map markers to display some additional information when a user hovers over a marker.

To simplify things, I’ve provided a basic Xml data source with the project file that will have our “search” results. To get started, we’ll first drop an XtraLayoutControl onto the form to help us with arranging our controls.

I’ve created a LayoutGroup at the top of the form to arrange where our search criteria controls would (we’ll just execute the search with a button since our results are hardcoded), and the bottom portion of the form will have another LayoutGroup containing the GridControl and XtraMap control. Drop both of these onto your form via the VS toolbox–both are contained within the Data & Analytics tab. At this point, we have the skeleton of our interface:

form1Out of the box, the XtraMap control offers the ability to connect to 2 different map providers: Bing Maps and OpenStreetMap. I’d advise you to consult both of these providers to learn the terms and conditions of using their services. Bing Maps will require a developer account; OpenStreetMap will work immediately without the need for an account. For this reason, will choose OpenStreetMap as our provider for this example.

One common topic that pops up on the DevExpress Support Center concerns the ability to connect the XtraMap control to Google Maps. While it’s technically possible (after all, the XtraMap control simply issues an HttpWebRequest to retrieve map tiles and then displays them), it does violate Google’s terms of service for their mapping service and is beyond the scope of this example.

To connect to OpenStreetMap, click on the MapControl’s Smart Tag and click on the “Connect to OpenStreetMap Server” link:

connecttoopenmapAt this point, your XtraMap control is fully operational. Start your project and you will see that map tiles are loaded and you have the ability to pan and zoom your map. When you connected to OpenStreetMap, the XtraMap control automatically generated an Image Tiles Layer for your control. This single layer is responsible for arranging the images returned from OpenStreetMap and draws our map.

From here, we’ll handle the SimpleButton’s Click event, load the Xml into a DataSet and assign it to the GridControl’s DataSource property. We now have a grid with search results, but that’s only half of what we want. We’d like to display a little icon in the map that corresponds to each of the results, so how is that accomplished?

First, we need add another layer to our MapControl. For our purposes, we’ll use the VectorItemsLayer type. I’d recommend reviewing the Layers documentation to see a quick overview of the various layer types available and when & how you should use them.

This can be done via the designer or at runtime; we’ll choose the latter just so we can see what is happening:

/// <summary>
/// Creates a Vector Items Layer on which to display equipment icons
/// </summary>
private void CreateVectorLayer()
{
    VectorItemsLayer itemsLayer = new VectorItemsLayer();
    ListSourceDataAdapter dataAdapter = new ListSourceDataAdapter();

    dataAdapter.Mappings.Latitude = "OriginLatitude";
    dataAdapter.Mappings.Longitude = "OriginLongitude";
    itemsLayer.ItemImageIndex = 0;

    //Map the attributes used for the tooltip
    dataAdapter.AttributeMappings.Add(new MapItemAttributeMapping() { Member = "CompanyName", Name = "CompanyName" });
    dataAdapter.AttributeMappings.Add(new MapItemAttributeMapping() { Member = "MCNumber", Name = "MCNumber" });
    dataAdapter.AttributeMappings.Add(new MapItemAttributeMapping() { Member = "MatchID", Name = "MatchID" });
    dataAdapter.AttributeMappings.Add(new MapItemAttributeMapping() { Member = "CompanyContact.ContactMethodValue", Name = "ContactMethod" });

    //Set up the tooltip pattern for the truck icons
    itemsLayer.ToolTipPattern = "<b>{CompanyName}</b>\r\nMC/DOT #{MCNumber}\r\n{ContactMethod}";
    itemsLayer.Data = dataAdapter;
    mapControl1.Layers.Add(itemsLayer);

}   //End the CreateVectorLayer() method

Let’s break it down:

As expected, we create an instance of the VectorItemsLayer class and additionally an instance of the ListSourceDataAdapter class. The ListSourceDataAdapter is what is responsible for providing data to the XtraMap and shares the GridControl’s data source. Before we provide all that, we’ll see at basic properties to tell it what to do with that data that it will be receiving:

  • Mappings.Latitude – We set this the property in our data source (remember that Xml file?) which contains the latitude co-ordinates.
  • Mappings.Longitude – Similar to above, we set this to the property in the data source containing the longitude co-ordinates.
  • ItemImageIndex – I’ve created an ImageCollection component containing any images that I’d like to draw onto the map. Right now this is just a single png image and I’ve set the XtraMap control’s ImageList property to this ImageCollection. I then tell the VectorItemsLayer which image within the collection is going to correspond to our data source items.
  • I create a collection of MapItemAttributeMapping objects which maps items in the data source to attributes of a MapItem. It’s a little confusingly named since we’re dealing with Maps and mappings. We can create as many attributes as we’d like and connect them to a property in the data source. The Member property needs to match a property/field in the data source, and the Name property is what the VectorItemsLayer will use to identify it.
  • We create a tooltip pattern to be used when our users hover over one of these map items. Some limited HTML is supported (you’ll need to use a ToolTipController component for this) and we place our MapItemAttribute names within { } brackets as placeholders to be populated at runtime when the tooltip is created.
  • Finally, we set the data source for the VectorItemsLayer to this ListSourceDataAdapter and add it all to the MapControl.

We’ll invoke this method from the SimpleButton’s click handler after we set the GridControl’s data source. If we run the application now we’d expect both the GridControl and the XtraMap control to show the search results. This doesn’t happen though, because we never actually set the data source for the ListSourceDataAdapter! We told it WHAT to display and we told the VectorImageLayer HOW to display it, but we’re missing that one last link:

(itemsLayer.Data as ListSourceDataAdapter).DataSource = (grdResults.DataSource);

The GridView’s DataSourceChanged event is a good place to use that code to provide data for the layer’s data adapter.

Now when we run the application, our truck image appears for each of the results and the tooltips are nicely formatted to match the ToolTipPattern we created.

Let’s add in that synchronization between the map and grid that we talked about in the beginning. The first thing we want to handle is when a user clicks on an item in the MapControl. The MapControl exposes a MapItemClick event that will be fired when a user clicks on the truck icons. I’ll handle this event, find the item in the GridControl that matches what the user clicks on and focus that.

/// <summary>
/// Map Item click event handler
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void mapControl1_MapItemClick(object sender, MapItemClickEventArgs e)
{
    if (IsItemSelecting == true)
        return;

    string MatchID = e.Item.Attributes["MatchID"].Value.ToString();
    int RowHandle = gvResults.LocateByDisplayText(0, gvResults.Columns["MatchID"], MatchID);

    if (gvResults.IsValidRowHandle(RowHandle))
    {
        IsItemSelecting = true;
        gvResults.ClearSelection();
        gvResults.FocusedRowHandle = RowHandle;
        gvResults.SelectRow(RowHandle);
        gvResults.MakeRowVisible(RowHandle);
        gvResults.Focus();
        IsItemSelecting = false;
    }

}   //End the mapControl1_MapItemClick() method

The IsItemSelecting property is a simple Boolean flag that I created and its use will be apparent in just a bit. The important take-away from the above snippet is that we want to have some sort of unique ID for each search result/map item so that we can find it within the GridControl and focus it. The flip-side to this is focusing a map item when a user clicks on a grid row. First, wire up a FocusedRowChanged event handler for the results GridView:

/// <summary>
/// Focused Row Changed event handler for the results GridView
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void gvResults_FocusedRowChanged(object sender, DevExpress.XtraGrid.Views.Base.FocusedRowChangedEventArgs e)
{
    if (IsItemSelecting == true)
        return;

    DataRow selectedResult = gvResults.GetFocusedDataRow();

    IsItemSelecting = true;

    SelectEquipmentIcon(selectedResult);

    IsItemSelecting = false;

}   //End the gvResults_FocusedRowChanged() method

In here we first check that IsItemSelecting flag. If a user clicks on an item from the map control, this event would be fired and vice versa resulting in an infinite loop. We want to make sure that don’t keep going back and forth like this, thus the need for that Boolean flag.

We’ll retrieve the DataRow object that corresponds to the selected row and pass this to the SelectEquipmentIcon method to zoom in on the truck that goes with the selected row:

/// <summary>
/// Selects the provided truck on the map
/// </summary>
/// <param name="selectedResult">A DataRow corresponding to the selected Grid row</param>
public void SelectEquipmentIcon(DataRow selectedResult)
{
    double SelectedLatitude = 0.0d;
    double SelectedLongitude = 0.0d;

    SelectedLatitude = Convert.ToDouble(selectedResult["OriginLatitude"]);
    SelectedLongitude = Convert.ToDouble(selectedResult["OriginLongitude"]);

    mapControl1.Zoom(1, true);
    mapControl1.CenterPoint = new GeoPoint(SelectedLatitude, SelectedLongitude);
    mapControl1.Zoom(10, true);

    VectorItemsLayer itemsLayer = mapControl1.Layers[1] as VectorItemsLayer;

    itemsLayer.SelectedItem = itemsLayer.GetMapItemBySourceObject(selectedResult);

}   //End the SelectEquipmentIcon class

And with that, we have a finished product! As always, the source code is provided with this post: XtraMapSearchResults

Visualizing data with the XtraMap control

Extending XtraEditors for fun and profit

One question that I see pop up every now and then in the DevExpress Support Center deals with changing the default behavior of the various controls offered in the XtraEditors suite. Many people are looking for a static property that can override the default settings of the controls so that they don’t need to constantly set the same properties for controls that are used over and over again. While there are some static properties and methods that can control behavior, for the most part you’re on your own when it comes to changing how the editors work on an application-wide basis.

To make things easier, I often find myself extending the DevExpress controls to suit my own requirements. The various controls offered in the XtraEditors suite are for the most part descendants of the standard .NET controls offered in System.Windows.Forms namespace; for instance, the XtraEditors TextEdit is just a descendant of the System.Windows.Forms.TextBox control, albeit with a lot of additional functionality and styling added.

The simplest method of building our own extended control library would be to just create a class that derives from one of the DevExpress controls:

public class MyTextEdit : DevExpress.XtraEditors.TextEdit
{
    public MyTextEdit() : base() { }
}

So with that, we have the beginnings of a basic extension of the TextEdit.

I’ve come to embrace the idea of changing user-input into upper case for the sake of consistency. To handle this, the TextEdit control offers a nifty feature in the form of the CharacterCasing property. You can set this property to CharacterCasing.Upper for each instance of the TextEdit control to automatically change the user’s input to upper case regardless of their CAPS LOCK setting.

Doing this is easy enough, but it kind of violates the principle we’re trying to establish here. If you have a dozen forms, each containing 10 TextEdit controls, do you really want to repetitively change the same property over and over? Instead, let’s build a basic TextEdit descendant that automatically defaults to upper case!

    /// <summary>
    /// A TextEdit control which defaults to upper case text editing
    /// </summary>
    [ToolboxItem(true)]
    [Description("Creates a TextEdit control which defaults to upper case text editing")]
    public class UpperCaseTextEdit : TextEdit
    {

        /// <summary>
        /// Initializes a new instance of the UpperCaseTextEdit class
        /// </summary>
        public UpperCaseTextEdit()
            : base()
        {
        }



        /// <summary>
        /// OnCreateControl event handler
        /// </summary>
        protected override void OnCreateControl()
        {
            base.OnCreateControl();

            Properties.CharacterCasing = System.Windows.Forms.CharacterCasing.Upper;

        }   //End the OnCreateControl() method


    }   //End the UppercaseTextEdit class

Let’s have a look at what’s going on here.

First, we’ve decorated our class with the [ToolboxItem(true)] attribute. This tells Visual Studio that the control should be made available in the toolbox window. Visual Studio is also nice enough to automatically look through your solution for any controls which have this attribute and place them in the toolbox for immediate use.

Aside from that, the most important thing to do is to place your default behavior within the control’s OnCreateControl event handler. If you don’t, you may find that your settings are just overwritten at runtime.

This is all and good, but many times we edit our data within a GridControl. If we want our new UpperCaseTextEdit control to be usable as a GridControl repository item, we’ll need to define our own repository item type.


    /// <summary>
    /// 
    /// </summary>
    [UserRepositoryItem("Register")]
    public class RepositoryItemUpperCaseTextEdit : RepositoryItemTextEdit
    {

        #region Internal members

        /// <summary>
        /// Editor name
        /// </summary>
        internal const string EditorName = "UpperCaseTextEdit";

        #endregion

        #region Public accessors

        /// <summary>
        /// Gets the EditorTypeName of this RepositoryItemTextEdit editor
        /// </summary>
        public override string EditorTypeName
        {
            get { return EditorName; }
        }

        #endregion


        /// <summary>
        /// Static constructor
        /// </summary>
        static RepositoryItemUpperCaseTextEdit()
        {
            Register();
        }


        /// <summary>
        /// Initializes a new instance of the RepositoryItemUpperCaseTextEdit class
        /// </summary>
        public RepositoryItemUpperCaseTextEdit()
            : base()
        {

        }


        public override System.Windows.Forms.CharacterCasing CharacterCasing
        {
            get
            {
                return System.Windows.Forms.CharacterCasing.Upper;
            }
            set
            {
                base.CharacterCasing = value;
            }
        }


        /// <summary>
        /// Registers this editor with the designer
        /// </summary>
        public static void Register()
        {
            EditorRegistrationInfo.Default.Editors.Add
                (
                    new EditorClassInfo(EditorName, typeof(UpperCaseTextEdit),
                    typeof(RepositoryItemUpperCaseTextEdit), typeof(TextEditViewInfo),
                    new TextEditPainter(), true, null)
                );

        }   //End the Register() method

    }   //End the RepositoryItemUpperCaseTextEdit class

Most of this code is going to be pretty boiler-plate as you build your own extended control library. You must provide an EditorTypeName, register it in a static constructor and provide an implementation of the Register method. The Register method is going need to know the name of the editor, the type (this is your control class) and what DevExpress ViewInfo and Painter to use. How do I know which ViewInfo or Painter to use? For the most part, it’s pretty self-explanatory, but there are some caveats. For instance, a LookUpEdit descendant needs to use the ButtonEditPainter. Lucky for us, DevExpress provides a handy chart viewable in the Custom Editors documentation.

One more thing of note: you’ll notice that I’ve overrode the CharacterCasing property in the RepositoryItemUpperCaseTextEdit class to have it return CharacterCasing.Upper by default. This is a better solution than setting the property in the OnCreateControl event.

What if we’d like to create a control with some additional properties? When my users need to enter a location address, I present them with a drop-down list containing the abbreviations of the US and Mexican states as well as Canadian provinces. After all, who can remember that “MI” is Michigan and not Missouri? To simply this data entry, let’s create a ComboBoxEdit descendant which is pre-filled with these abbreviations and has some additional properties to determine if we want to show Mexican states or Canadian provinces.

We’ll start by creating a control that derives from the ComboBoxEdit class and we’ll add in a few new members:


        /// <summary>
        /// Include USA flag
        /// </summary>
        private bool _IncludeUSA;

        /// <summary>
        /// Include Canada flag
        /// </summary>
        private bool _IncludeCanada;

        /// <summary>
        /// Include Mexico flag
        /// </summary>
        private bool _IncludeMexico;

That helps us within the class, but we are going to want those properties to be exposed at design-time via the Visual Studio properties window. Let’s add some public accessors to expose the private members:


        /// <summary>
        /// Gets or sets a value indicating if US states should be included in the ComboBoxEdit
        /// </summary>
        [Browsable(true)]
        [PropertyTab("Geography", PropertyTabScope.Component)]
        [Description("Gets or sets a value indicating if US states should be included in the ComboBoxEdit")]
        public bool IncludeUSA
        {
            get { return _IncludeUSA; }
            set { _IncludeUSA = value; }
        }

        /// <summary>
        /// Gets or sets a value indicating if Canadian provinces should be included in the ComboBoxEdit
        /// </summary>
        [Browsable(true)]
        [PropertyTab("Geography", PropertyTabScope.Component)]
        [Description("Gets or sets a value indicating if Canadian provinces should be included in the ComboBoxEdit")]
        public bool IncludeCanada
        {
            get { return _IncludeCanada; }
            set { _IncludeCanada = value; }
        }

        /// <summary>
        /// Gets or sets a value indicating if Mexican states should be included in the ComboBoxEdit
        /// </summary>
        [Browsable(true)]
        [PropertyTab("Geography", PropertyTabScope.Component)]
        [Description("Gets or sets a value indicating if Mexican states should be included in the ComboBoxEdit")]
        public bool IncludeMexico
        {
            get { return _IncludeMexico; }
            set { _IncludeMexico = value; }
        }

The important take-away from the above snippet is to decorate your properties with the [Browsable(true)] attribute. Without this, Visual Studio will not display these properties in the designer.

If you want to pre-populate a list editor, do so within the OnLoaded event:

        /// <summary>
        /// On loaded event handler
        /// </summary>
        protected override void OnLoaded()
        {
            Properties.TextEditStyle = DevExpress.XtraEditors.Controls.TextEditStyles.DisableTextEditor;
            LoadStates(_IncludeUSA, _IncludeCanada, _IncludeMexico);

            base.OnLoaded();

        }   //End the OnLoaded() method

Here you’ll see that we’re disabling the ability for end-users to enter their own text within the drop-down by default. We certainly don’t want them inventing their own state/province abbreviations! From there, we invoke the LoadStates method and pass in our Boolean flags that indicate what should be contained within the drop-down. I chose to NOT populate the list within this event because I’d like to be able to reload the list at runtime; for instance, if we have another drop down called “Country”, it doesn’t make sense to show Canadian provinces if the user selects “United States”. At runtime, I can call the StateComboBoxEdit’s LoadStates method to change what is visible in the list.

The LoadStates method just builds a basic object array to be assigned to the control’s Items collection:

        /// <summary>
        /// Populates the State ComboBoxEdit with states/provinces
        /// </summary>
        /// <param name="includeCanada">True to include Canadian provinces</param>
        public void LoadStates(bool includeUSA, bool includeCanada, bool includeMexico)
        {
            //Clear existing items
            if (DesignMode == true || Properties.Items.Count > 0)
                Properties.Items.Clear();

            //Add states/provinces
            if (includeUSA == true)
            {
                Properties.Items.AddRange(new object[] 
                { 
                    "AK",
                    "AL",
                    "AP",
                    "AR",
                    "AS",
                    "AZ",
                    "CA",
                    "CO",
                    "CT",
                    "DC",
                    "DE",
                    "FL",
                    "FM",
                    "GA",
                    "GU",
                    "HI",
                    "IA",
                    "ID",
                    "IL",
                    "IN",
                    "KS",
                    "KY",
                    "LA",
                    "MA",
                    "MD",
                    "ME",
                    "MH",
                    "MI",
                    "MN",
                    "MO",
                    "MP",
                    "MS",
                    "MT",
                    "NB",
                    "NC",
                    "ND",
                    "NE",
                    "NF",
                    "NH",
                    "NJ",
                    "NM",
                    "NT",
                    "NU",
                    "NV",
                    "NY",
                    "OH",
                    "OK",
                    "OR",
                    "PA",
                    "PR",
                    "PW",                
                    "RI",
                    "SC",
                    "SD",                
                    "TN",
                    "TX",
                    "UT",
                    "VA",
                    "VI",
                    "VT",
                    "WA",
                    "WI",
                    "WV",
                    "WY"                
                });
            }

            if (includeCanada == true)
            {
                Properties.Items.AddRange(new object[]
                {
                    "AA",
                    "AB",
                    "AE",
                    "BC",
                    "MB",
                    "NS",
                    "ON",
                    "PE",
                    "PQ",
                    "QC",
                    "SK",
                    "YT"
                });
            }

        }   //End the LoadStates() method

The only thing of note in this method is that I first check if we’re in design-mode or if the list already has items in it. If you don’t do this you’ll find that every time the list is opened (or created as you switch from design view to code view and back-and-forth) your items will be added again. This is obviously not ideal, so take care to always perform this check with list editors!

Take some time and look at your application to see what editors are duplicated to perform common tasks and you may find that it’s worthwhile to create your own control assembly. Personally, I’ve built some useful editors such as:

  • CountryComboBoxEdit – a basic drop down with a list of countries
  • DataLayoutControlEx – an extension of the DataLayoutControl which disables end-user manipulation by default, is automatically set to DockStyle.Fill, focuses an editor when its corresponding caption is clicked (similar to a <label> tag in Html) and overrides the default behavior to use my UpperCaseTextEdit in lieu of the TextEdit when an item is bound to a string type.
  • EmailAddressEdit and UrlEdit :¬† ButtonEdit descendants which have a default button that opens the user’s email editor with the control’s text set as the mail to, or opens a browser with the provided Url.
  • PhoneNumberEdit: a TextEdit control which has a default RegEx mask set for North American phone numbers.

Download the full source code for our examples here and experiment! CustomEditors

Extending XtraEditors for fun and profit

Overriding XtraReport or print preview toolbar commands

I happened upon a cool question on the Support Center the other day, asking how to override the default functionality in the Print Preview window to email a document via Gmail. If you look at the default Print Preview (in either ribbon or standard toolbar configuration), you’ll see that you’re given the option to email the document in various formats (Pdf, Xls, RTF etc…): Print Preview window Doing so will typically open a dialog window which prompts you to save the file to your computer before your default email program is opened and the file is attached. This is all done via MAPI, which may not be the method you want to take. It opens the user’s default email client and constructs a blank message with the file attached. Historically, DevExpress used the 32-bit version of MAPI which causes issues if you were to build your application to 64 bit. Additionally, you may not want to save the file to your computer before sending it because then you’ll need to delete it afterwards. And if your end user doesn’t have a default email program set up on their PC, they’ll be prompted with the Windows email wizard which attempts to walk them through the process of setting up an email account. So what if you’d prefer the document to be emailed through your server or a third-party server like Gmail? At first glance you have a couple of options:

  • Create a form, place a DocumentViewer component on the form and then create your own toolbar. You’ll have to provide your own implementation for each of the various commands that are offered by the built-in Document Viewer toolbar.
  • Do the same as above, but create the default Document Viewer toolbar (or ribbon control) via the smart tag. Then, assign an ItemClick event handler to the functions you’d like to control. The problem is that your code will run first and then the default button command will run afterwards. Hardly ideal.
  • Again, create a form with a Document Viewer but remove the BarButtomItems that you want to override. Insert your own BarButtonItems for the commands that you’d like to control. There’s nothing inherently wrong with this approach unless you want to use the built-in print-preview methods offered by controls like the XtraGrid or the XtraTreeList. In this case, they’ll use the default print preview window rather than your custom one.

So it can be done, but I’m not sure if any of these options are really optimal. Fortunately for us, all of the BarButtomItems in the Document Viewer window implement an ICommandHandler interface which, when implemented, tells the Document Viewer window two important things:

  1. Can I handle this command? (done by implementing the CanHandleCommand method)
  2. How should I handle this command? (done by implementing the HandleCommand method)

All of this is detailed in the documentation topic for How to: Execute and Modify Commands in a Print Preview. So how can we apply this to the topic that was originally presented?

Assuming we have a simple project containing an XtraReport and we want to send a Pdf copy via Gmail through the standard toolbar, we’ll need to first create our own CommandHandler.

To create your own CommandHandler, create a new class in Visual Studio and name it “MyCommandHandler”. Your class will need to implement ICommandHandler. You can then tell Visual Studio to implement the interface, which will automatically insert a CanHandleCommand and a HandleCommand method.

Let’s start with the CanHandleCommand method:

public virtual bool CanHandleCommand(PrintingSystemCommand command, IPrintControl control)
{
    //This handler overrides the Send Pdf command.
    return command == PrintingSystemCommand.SendPdf;
}

This crux of this method is to tell the Document Viewer (or printing system) if this handler can process the provided command. The PrintingSystemCommand enum contains all of the commands that are available by the default toolbar/ribbon control. In this case, we’re telling the printing system that we can handle the SendPdf command ourselves and no default action is necessary.

That being said, we now have to do the heavy lifting ourselves and actually do something when the button is clicked. To do that, we provide an implementation for the HandleCommand method.

public virtual void HandleCommand(PrintingSystemCommand command, object[] args, IPrintControl control, ref bool handled)
{

    const string Username = &quot;YOUR_GMAIL_USERNAME_HERE&quot;;   //your username here
    const string Password = &quot;YOUR_GMAIL_PASSWORD_HERE&quot;; ///your password here

    if (CanHandleCommand(command, control) == false)
        return;

    using (MailMessage mailMessage = new MailMessage())
    {
        //Set to/from
        mailMessage.From = new MailAddress(&quot;email address here&quot;);
        mailMessage.To.Add(new MailAddress(&quot;email address here&quot;));
        mailMessage.Subject = &quot;Test message&quot;;
        mailMessage.Body = &quot;This is my test email!&quot;;

        //Create an attachment
        using (MemoryStream ms = new MemoryStream())
        {
            control.PrintingSystem.ExportToPdf(ms);
            ms.Position = 0;
            mailMessage.Attachments.Add(new Attachment(ms, &quot;MyFile.pdf&quot;, &quot;application/pdf&quot;));

            using (SmtpClient client = new SmtpClient())
            {
                client.Host = &quot;smtp.gmail.com&quot;;
                client.Port = 587;
                client.EnableSsl = true;
                client.DeliveryMethod = SmtpDeliveryMethod.Network;
                client.UseDefaultCredentials = false;
                client.Credentials = new NetworkCredential(Username, Password);

                client.Send(mailMessage);
            }
        }
    }

    //Ensure the default action isn't fired by setting Handled to True
    handled = true;
}

So here we’ve created a nice implementation that sends a Pdf copy of the document via email.

Note that I’ve decided to user a MemoryStream here instead of saving the Pdf file to the user’s PC first. This alleviates the need to save a file to the disk, but it does remove the ability to customize the Pdf. If you want to change some of the Pdf properties upon export, you can use the PdfExportOptions class offered by the ExportToPdf overload.

The only thing left to do is tell our PrintPreview window to actually use this CommandHandler. We do that via the PrintingSystem.AddCommandHandler method:

// Create a report instance, assigned to a Print Tool.
ReportPrintTool pt = new ReportPrintTool(new XtraReport1());

// Generate the report's document. This step is required
// to activate its PrintingSystem and access it later.
pt.Report.CreateDocument(false);

// Override the Send Pdf command.
pt.PrintingSystem.AddCommandHandler(new SendToGmailCommandHandler());

// Show the report's print preview.
pt.ShowPreview();

And just like that, we’ve overrided the default behavior and created our own implementation.

Going forward, we can also use this CommandHandler for print previewing other DevExpress controls such as the GridControl. By handling the GridView’s PrintInitialize event, we can insert our CommandHandler and reuse the same implementation:

private void gridView1_PrintInitialize(object sender, DevExpress.XtraGrid.Views.Base.PrintInitializeEventArgs e)
{
    (e.PrintingSystem as PrintingSystemBase).AddCommandHandler(new MyCommandHandler());
}

The full source code is available here: CustomCommandHandler

Overriding XtraReport or print preview toolbar commands