ImageLoader.CustomGetImageInfo Event

Occurs before image metadata is loaded.

Namespace: DevExpress.ExpressApp.Utils

Assembly: DevExpress.ExpressApp.v24.1.dll

NuGet Package: DevExpress.ExpressApp

Declaration

C#

public static event EventHandler<CustomGetImageInfoEventArgs> CustomGetImageInfo

VB.NET

Public Shared Event CustomGetImageInfo As EventHandler(Of CustomGetImageInfoEventArgs)

Event Data

The CustomGetImageInfo event's data class is DevExpress.ExpressApp.Utils.CustomGetImageInfoEventArgs.

Remarks

Handle this event to manually provide an ImageInfo object via the CustomizeImageInfoEventArgs.ImageName parameter. The example below demonstrates how to load images from a database.

• Implement the following MyImageObject business class:

  C# (EF Core)

  using DevExpress.Persistent.Base;
  using DevExpress.Persistent.BaseImpl.EF;
  // ...
  [DefaultClassOptions]
  public class MyImageObject : BaseObject {
      public virtual string Name { get; set; }
      [ImageEditorAttribute(ImageEditorMode.PictureEdit, ImageEditorMode.PictureEdit, 
          DetailViewImageEditorFixedHeight = 32, DetailViewImageEditorFixedWidth = 32)]
      [VisibleInListView(true)]
      public virtual byte[] Image { get; set; }
  }
  
  // Make sure that you use options.UseChangeTrackingProxies() in your DbContext settings.
  

  C# (XPO)

  using DevExpress.ExpressApp.DC;
  using DevExpress.ExpressApp.Model;
  using DevExpress.ExpressApp.Security;
  using DevExpress.Persistent.Base;
  using DevExpress.Persistent.BaseImpl;
  using DevExpress.Xpo;
  using System.ComponentModel;
  //...
  [DefaultClassOptions]
  
  public class MyImageObject : XPObject {
  public MyImageObject(Session session) : base(session) { }
  
  string name;
  
  [Size(SizeAttribute.DefaultStringMappingFieldSize)]
  public string Name {
      get => name;
      set => SetPropertyValue(nameof(Name), ref name, value);
  }
  byte[] image;
  [ImageEditorAttribute(ImageEditorMode.PictureEdit, ImageEditorMode.PictureEdit,
          DetailViewImageEditorFixedHeight = 32, DetailViewImageEditorFixedWidth = 32)]
  [VisibleInListView(true)]
  [Size(SizeAttribute.Unlimited)]
  public byte[] Image { get => image; set => SetPropertyValue(nameof(Image), ref image, value); }
  }
  

• Create several predefined MyImageObject instances on the overridden ModuleUpdater.UpdateDatabaseAfterUpdateSchema method.

  C#

  public override void UpdateDatabaseAfterUpdateSchema() {
      base.UpdateDatabaseAfterUpdateSchema();
      MyImageObject image1 = ObjectSpace.CreateObject<MyImageObject>();
      image1.Name = "Image 1";
      var stream = new System.IO.MemoryStream();
      ImageLoader.Instance.GetSmallImageInfo("Action_Save").Image.Save(stream, ImageFormat.Png);
      image1.Image = stream.ToArray();
  
      MyImageObject image2 = ObjectSpace.CreateObject<MyImageObject>();
      image2.Name = "Image 2";
      stream = new System.IO.MemoryStream();
      ImageLoader.Instance.GetSmallImageInfo("Action_Delete").Image.Save(stream, ImageFormat.Png);
      image2.Image = stream.ToArray();
      ObjectSpace.CommitChanges();
   }
  

  VB.NET

  Public Overrides Sub UpdateDatabaseAfterUpdateSchema()
      MyBase.UpdateDatabaseAfterUpdateSchema()
      Dim image1 As MyImageObject = ObjectSpace.CreateObject(Of MyImageObject)()
      image1.Name = "Image 1"
      Dim stream = New System.IO.MemoryStream()
      ImageLoader.Instance.GetSmallImageInfo("Action_Save").Image.Save(stream, ImageFormat.Png)
      image1.Image = stream.ToArray()
  
      Dim image2 As MyImageObject = ObjectSpace.CreateObject(Of MyImageObject)()
      image2.Name = "Image 2"
      stream = New System.IO.MemoryStream()
      ImageLoader.Instance.GetSmallImageInfo("Action_Delete").Image.Save(stream, ImageFormat.Png)
      image2.Image = stream.ToArray()
      ObjectSpace.CommitChanges()
  End Sub
  

• In the WinForms application project, edit the Program.cs (Program.vb) file and handle the static CustomGetImageInfo event before the XafApplication.Setup method is called.

  C#

  using System.IO;
  using System.Drawing;
  using System.Drawing.Imaging;
  // ...
  ImageLoader.CustomGetImageInfo += (sender, e) => {
      if(e.ImageName.StartsWith(MyWindowController.MyImagePrefix)) {
          int key;
          string key_string = e.ImageName.Split('_')[1];
          if(int.TryParse(key_string, out key)) {
              using(IObjectSpace objectSpace = winApplication.CreateObjectSpace(typeof(MyImageObject))) {
                  MyImageObject imageObject = objectSpace.GetObjectByKey<MyImageObject>(key);
                  if(imageObject != null) {
                      e.ImageInfo = new ImageInfo(e.ImageName, Image.FromStream(new MemoryStream(imageObject.Image)), null);
                      e.Handled = true;
                  }
              }
          }
      }
  };
  

  VB.NET

  Imports System.IO
  Imports System.Drawing
  Imports System.Drawing.Imaging
  ' ...
  Private ImageLoader.CustomGetImageInfo += Sub(sender, e)
      If e.ImageName.StartsWith(MyWindowController.MyImagePrefix) Then
          Dim key As Integer
          Dim key_string As String = e.ImageName.Split("_"c)(1)
          If Integer.TryParse(key_string, key) Then
              Using objectSpace As IObjectSpace = winApplication.CreateObjectSpace(GetType(MyImageObject))
                  Dim imageObject As MyImageObject = objectSpace.GetObjectByKey(Of MyImageObject)(key)
                  If imageObject IsNot Nothing Then
                      e.ImageInfo = New ImageInfo(e.ImageName, Image.FromStream(New MemoryStream(imageObject.Image)), Nothing)
                      e.Handled = True
                  End If
              End Using
          End If
      End If
  End Sub
  

• Handle the static CustomGetImageInfo event in the Application_Start method located in the Global.asax.cs (Global.asax.vb) file. In contrast to the WinForms application, pass an URL that will be included into the page markup as the imageUrl parameter of the ImageInfo constructor. The browser will query the content by this URL in a separate request that will be processed by the BinaryDataHttpHandler.

  C#

  using System.IO;
  using System.Drawing;
  using System.Drawing.Imaging;
  using DevExpress.ExpressApp.Web.Editors.ASPx;
  // ...
  ImageLoader.CustomGetImageInfo += (s, args) => {
      if (args.ImageName.StartsWith(MyWindowController.MyImagePrefix)) {
          int key;
          string key_string = args.ImageName.Split('_')[1];
          if (int.TryParse(key_string, out key)) {
              using (IObjectSpace objectSpace = WebApplication.Instance.CreateObjectSpace(typeof(MyImageObject))) {
                  MyImageObject imageObject = objectSpace.GetObjectByKey<MyImageObject>(key);
                  if (imageObject != null) {
                      args.ImageInfo = new ImageInfo(
                              args.ImageName, Image.FromStream(new MemoryStream(imageObject.Image)),
                              ImageProcessorsHelper.GetImageUrl(objectSpace, imageObject, "Image"));
                      args.Handled = true;
                  }
              }
          }
      }
  };
  

  VB.NET

  Imports System.IO
  Imports System.Drawing
  Imports System.Drawing.Imaging
  Imports DevExpress.ExpressApp.Web.Editors.ASPx
  ' ...
  Private ImageLoader.CustomGetImageInfo += Sub(s, args)
      If args.ImageName.StartsWith(MyWindowController.MyImagePrefix) Then
          Dim key As Integer
          Dim key_string As String = args.ImageName.Split("_"c)(1)
          If Integer.TryParse(key_string, key) Then
              Using objectSpace As IObjectSpace = WebApplication.Instance.CreateObjectSpace(GetType(MyImageObject))
                  Dim imageObject As MyImageObject = objectSpace.GetObjectByKey(Of MyImageObject)(key)
                  If imageObject IsNot Nothing Then
                      args.ImageInfo = New ImageInfo(args.ImageName, Image.FromStream(New MemoryStream(imageObject.Image)), _
                      ImageProcessorsHelper.GetImageUrl(objectSpace, imageObject, "Image"))
                      args.Handled = True
                  End If
              End Using
          End If
      End If
  End Sub
  

• Now, you can specify images as follows:

  C#

  using DevExpress.ExpressApp;
  using DevExpress.ExpressApp.Actions;
  // ...
  public class MyWindowController : WindowController {
      public const string MyImagePrefix = "MyImageObject_";
      SingleChoiceAction action;
      public MyWindowController() : base() {
          this.TargetWindowType = WindowType.Main;
          action = new SingleChoiceAction(this, "My Action", DevExpress.Persistent.Base.PredefinedCategory.Edit);
          action.ImageMode = ImageMode.UseItemImage;
          action.ItemType = SingleChoiceActionItemType.ItemIsOperation;
      }
      protected override void OnActivated() {
          base.OnActivated();
          action.Items.Clear();
          using(IObjectSpace objectSpace = Application.CreateObjectSpace(typeof(MyImageObject))) {
              foreach(MyImageObject imageObject in objectSpace.GetObjects<MyImageObject>()) {
                  ChoiceActionItem item = new ChoiceActionItem();
                  item.Caption = imageObject.Name;
                  item.ImageName = MyImagePrefix + imageObject.ID;
                  action.Items.Add(item);
              }
          }
      }
  }
  

  VB.NET

  Imports DevExpress.ExpressApp
  Imports DevExpress.ExpressApp.Actions
  ' ...
  Public Class MyWindowController
      Inherits WindowController
      Public Const MyImagePrefix As String = "MyImageObject_"
      Private action As SingleChoiceAction
      Public Sub New()
          MyBase.New()
          Me.TargetWindowType = WindowType.Main
          action = New SingleChoiceAction(Me, "My Action", DevExpress.Persistent.Base.PredefinedCategory.Edit)
          action.ImageMode = ImageMode.UseItemImage
          action.ItemType = SingleChoiceActionItemType.ItemIsOperation
      End Sub
      Protected Overrides Sub OnActivated()
          MyBase.OnActivated()
          action.Items.Clear()
          Using objectSpace As IObjectSpace = Application.CreateObjectSpace(GetType(MyImageObject))
              For Each imageObject As MyImageObject In objectSpace.GetObjects(Of MyImageObject)()
                  Dim item As New ChoiceActionItem()
                  item.Caption = imageObject.Name
                  item.ImageName = MyImagePrefix & imageObject.ID
                  action.Items.Add(item)
              Next imageObject
          End Using
      End Sub
  End Class