WinExplorerViewOptionsImageLoad Class

Provides access to the set of properties that manage image loading for this WinExplorerView.

Namespace: DevExpress.XtraGrid.WinExplorer

Assembly: DevExpress.XtraGrid.v23.2.dll

NuGet Packages: DevExpress.Win.Grid, DevExpress.Win.Navigation

Declaration

C#

public class WinExplorerViewOptionsImageLoad :
    BaseOptions

VB.NET

Public Class WinExplorerViewOptionsImageLoad
    Inherits BaseOptions

Related API Members

The following members return WinExplorerViewOptionsImageLoad objects:

• WinExplorerView.OptionsImageLoad

Remarks

The WinExplorerViewOptionsImageLoad object can be accessed through the WinExplorerView.OptionsImageLoad property and stores settings that maintain [Asynchronous Image Loading].

The example below illustrates how to use the OptionsImageLoad properties in TileView. In WinExplorer View these settings are identical.

Example

This example shows how to manually generate custom tile background images (thumbnails) in Tile View and display them asynchronously. The TileView is bound to a list that contains texture names. We need to create custom background thumbnails for all tiles based on corresponding texture names, and display these images asynchronously.Thumbnails are generated using the GetThumbnailImage event. The async image load is enabled with the AsyncLoad setting.

View Example

Form1.cs

using DevExpress.XtraGrid.Views.Tile;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace TileView_ManualThumbs {
    public partial class Form1 : Form {
        public Form1() {
            InitializeComponent();
        }

        List<Texture> textures;

        private void Form1_Load(object sender, EventArgs e) {
            InitData();

            gridControl1.DataSource = textures;
            tileView1.OptionsTiles.ItemSize = new Size(90, 40);
            tileView1.GetThumbnailImage += TileView1_GetThumbnailImage;
            // Specify a column that provides information on images to render.
            tileView1.ColumnSet.BackgroundImageColumn = colName;
            tileView1.OptionsImageLoad.RandomShow = true;
            tileView1.OptionsImageLoad.LoadThumbnailImagesFromDataSource = false;
            // Enable async image load.
            tileView1.OptionsImageLoad.AsyncLoad = true;
        }

        private void TileView1_GetThumbnailImage(object sender, DevExpress.Utils.ThumbnailImageEventArgs e) {
            string colorName = textures[e.DataSourceIndex].Name;
            //Generate a thumbnail for the current record.
            Bitmap image = new Bitmap(e.DesiredThumbnailSize.Width, e.DesiredThumbnailSize.Height);
            Graphics graphics = Graphics.FromImage(image);
            Color tileColor = Color.FromName(colorName);
            GraphicsUnit grUnit = GraphicsUnit.Pixel;
            RectangleF imageRect = image.GetBounds(ref grUnit);
            LinearGradientBrush brush =   new LinearGradientBrush(imageRect, Color.White, Color.White, 45, false);
            ColorBlend cblend = new ColorBlend(4);
            cblend.Colors = new Color[4] { Color.White, tileColor, tileColor, Color.White};
            cblend.Positions = new float[4] { 0f, 0.5f, 0.7f, 1f };
            brush.InterpolationColors = cblend;
            graphics.FillRectangle(brush, imageRect);
            e.ThumbnailImage = image;
            brush.Dispose();
        }

        private void InitData() {
            textures = new List<Texture>();
            System.Array colorsArray = Enum.GetNames(typeof(KnownColor));
            foreach(var colorName in colorsArray ) {
                textures.Add(new Texture(colorName.ToString()));
            }
        }
    }

    public class Texture { 
        public Texture(string name) {
            this.Name = name;
        }
        public string Name { get; set; }
    }
}

Form1.vb

Imports DevExpress.XtraGrid.Views.Tile
Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Linq
Imports System.Text
Imports System.Threading.Tasks
Imports System.Windows.Forms

Namespace TileView_ManualThumbs
    Partial Public Class Form1
        Inherits Form

        Public Sub New()
            InitializeComponent()
        End Sub

        Private textures As List(Of Texture)

        Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
            InitData()

            gridControl1.DataSource = textures
            tileView1.OptionsTiles.ItemSize = New Size(90, 40)
            AddHandler tileView1.GetThumbnailImage, AddressOf TileView1_GetThumbnailImage
            ' Specify a column that provides information on images to render.
            tileView1.ColumnSet.BackgroundImageColumn = colName
            tileView1.OptionsImageLoad.RandomShow = True
            tileView1.OptionsImageLoad.LoadThumbnailImagesFromDataSource = False
            ' Enable async image load.
            tileView1.OptionsImageLoad.AsyncLoad = True
        End Sub

        Private Sub TileView1_GetThumbnailImage(ByVal sender As Object, ByVal e As DevExpress.Utils.ThumbnailImageEventArgs)
            Dim colorName As String = textures(e.DataSourceIndex).Name
            'Generate a thumbnail for the current record.
            Dim image As New Bitmap(e.DesiredThumbnailSize.Width, e.DesiredThumbnailSize.Height)
            Dim graphics As Graphics = System.Drawing.Graphics.FromImage(image)
            Dim tileColor As Color = Color.FromName(colorName)
            Dim grUnit As GraphicsUnit = GraphicsUnit.Pixel
            Dim imageRect As RectangleF = image.GetBounds(grUnit)
            Dim brush As New LinearGradientBrush(imageRect, Color.White, Color.White, 45, False)
            Dim cblend As New ColorBlend(4)
            cblend.Colors = New Color(3) { Color.White, tileColor, tileColor, Color.White}
            cblend.Positions = New Single(3) { 0F, 0.5F, 0.7F, 1F }
            brush.InterpolationColors = cblend
            graphics.FillRectangle(brush, imageRect)
            e.ThumbnailImage = image
            brush.Dispose()
        End Sub

        Private Sub InitData()
            textures = New List(Of Texture)()
            Dim colorsArray As System.Array = System.Enum.GetNames(GetType(KnownColor))
            For Each colorName In colorsArray
                textures.Add(New Texture(colorName.ToString()))
            Next colorName
        End Sub
    End Class

    Public Class Texture
        Public Sub New(ByVal name As String)
            Me.Name = name
        End Sub
        Public Property Name() As String
    End Class
End Namespace

Inheritance

Object

ViewStatePersisterCore

BaseOptions

WinExplorerViewOptionsImageLoad