ImageLoader.CustomGetImageInfo Event

Occurs before image metadata is loaded.

Namespace: DevExpress.ExpressApp.Utils

Assembly: DevExpress.ExpressApp.v25.2.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 the CustomGetImageInfo event to supply an ImageInfo object for a requested image. Use the ImageName value to identify the image to load. The following example loads 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 predefined **MyImageObject instances in 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();
   }
  

• Edit the Program.cs 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;
                  }
              }
          }
      }
  };
  

• 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);
              }
          }
      }
  }