Using the WebImageViewer control on the server side

Perform the following steps to create a project that uses the features of the LEADTOOLS WebImageViewer Control from the server side:

  1. Start Visual Studio 2005.

  2. Choose File->New->Web Site… from the menu.

  3. In the New Web Site dialog box, choose "ASP.NET Web Site" in the Templates List, and choose either "Visual C#" or "VB" in the Language drop-down list box.

  4. In the Location drop-down list box choose "File System". Enter “C:\Inetpub\wwwroot\UsingImageViewer_Server” into the Project Name field, and then click OK.

    If desired, type a new location for your project or select a directory by clicking Browse, and then click OK.

  5. In the Solution Explorer pane, right-click on the project node, and select "Add Reference…" from the context menu. In the Add Reference dialog box, click the .NET tab and select "System.Windows.Forms". Click OK to close the Add Reference dialog box.

  6. Repeat the previous step but this time in the Add Reference dialog box select the Browse tab. Browse to the "<LEADTOOLS_INSTALLDIR>\Bin\Dotnet\Win32" folder and select the following DLL:

    • Leadtools.Web.dll.

    Now click OK to close the Add Reference dialog box.

  7. In the Solution Explorer pane right-click on the "Default.aspx" file and choose the View Designer from the context menu.

  8. Go to the toolbox (View->Toolbox) and drag and drop an instance of the WebImageImageViewer onto the web form. If you do not have the WebImageViewer in your toolbox, select "Tools->Choose Toolbox Items..." from the menu. Click Browse and then select "Leadtools.Web.dll" from the "<LEADTOOLS_INSTALLDIR>\Bin\Dotnet\Win32" folder and then click Open and then click OK.

  9. Go to the toolbox (View-Toolbox) and from the Standard tab drag and drop 7 Labels, 4 Text Boxes, 4 drop-down list boxes, and 3 Buttons onto the web form.

  10. Change the properties of the dropped controls as follows:

Control Property New Value
Label1 IDText _lblImageUrlImage Url
TextBox1 ID _tbImageUrl
Label2 IDText _lblImageWidthImage Width
TextBox2 ID _tbImageWidth
Label3 IDText _lblImageHeightImage Height
TextBox3 ID _tbImageHeight
Button1 IDText _btnGetImageSizeGet Image Size
Button2 IDText _btnViewImageView Image
Label4 IDText _lblSizeModeSizeMode
DropDownList1 IDAutoPostBack _ddlSizeModeTrue
Label5 IDText _lblScaleFactorScaleFactor
DropDownList2 IDAutoPostBack _ddlScaleFactorTrue
Label6 IDText _lblHorizontalAlignModeHorizontalAlignMode
DropDownList3 IDAutoPostBack _ddlHorizontalAlignModeTrue
Label7 IDText _lblVerticalAlignModeVerticalAlignMode
DropDownList4 IDAutoPostBack _ddlVerticalAlignModeTrue
Button3 IDText _btnGetRealScaleFactorsGet Real Scale Factors
TextBox4 ID _tbRealScaleFactors
  1. Switch to the "Default.aspx" code view (right-click default.aspx in the Solution Explorer, then select View Code), and add the following lines at the beginning of the file:

    VB

    Imports System.Windows.Forms 
    Imports System.Web.Hosting 
    Imports System.Xml 
    Imports System.Drawing 
                     
    Imports System.IO 
    Imports Leadtools.Web.Controls 
    Imports Leadtools.Web.Handlers 

    C#

    using System.Windows.Forms; 
    using System.Web.Hosting; 
    using System.Xml; 
    using System.IO; 
    using System.Drawing; 
                     
    using Leadtools.Web.Controls; 
    using Leadtools.Web.Handlers; 

  2. Update the Page_Load event handler to be as follows:

    VB

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load 
       If (Not IsPostBack) Then 
          ' Initialize the WebImageViewer control. 
          ImageViewer1.ResourcesPath = "Resources" 
          ImageViewer1.ScrollBarSize = SystemInformation.VerticalScrollBarWidth 
          ' Fill in the Combo Boxes 
          BindDropDownListToEnum(_ddlSizeMode, GetType(ImageViewerSizeMode), ImageViewer1.SizeMode) 
          BindDropDownListToEnum(_ddlHorizontalAlignMode, GetType(ImageViewerAlignMode), ImageViewer1.HorizontalAlignMode) 
          BindDropDownListToEnum(_ddlVerticalAlignMode, GetType(ImageViewerAlignMode), ImageViewer1.VerticalAlignMode) 
          Dim scaleFactors() As Integer = {1000, 800, 600, 400, 200, 100, 75, 50, 25, 10} 
          Dim factor1 As Integer = CInt(ImageViewer1.ScaleFactor) 
          For i As Integer = 0 To scaleFactors.Length - 1 
             _ddlScaleFactor.Items.Add(scaleFactors(i).ToString()) 
             If (factor1 = scaleFactors(i)) Then 
                _ddlScaleFactor.SelectedIndex = i 
             End If 
          Next 
       End If 
    End Sub 

    C#

    protected void Page_Load(object sender, EventArgs e) 
    { 
       if(!IsPostBack) 
       { 
          // Initialize the WebImageViewer control. 
          ImageViewer1.ResourcesPath = "Resources"; 
          ImageViewer1.ScrollBarSize = SystemInformation.VerticalScrollBarWidth; 
                        
          // Fill in the Drop-down list boxes 
          BindDropDownListToEnum(_ddlSizeMode, typeof(ImageViewerSizeMode), ImageViewer1.SizeMode); 
          BindDropDownListToEnum(_ddlHorizontalAlignMode, typeof(ImageViewerAlignMode), ImageViewer1.HorizontalAlignMode); 
          BindDropDownListToEnum(_ddlVerticalAlignMode, typeof(ImageViewerAlignMode), ImageViewer1.VerticalAlignMode); 
                        
          int[] scaleFactors = { 1000, 800, 600, 400, 200, 100, 75, 50, 25, 10 }; 
          int factor1 = (int)(ImageViewer1.ScaleFactor); 
          for(int i = 0; i < scaleFactors.Length; i++) 
          { 
             _ddlScaleFactor.Items.Add(scaleFactors[i].ToString()); 
             if(factor1 == scaleFactors[i]) 
                _ddlScaleFactor.SelectedIndex = i; 
          } 
       } 
    } 

  3. double-click on the _btnGetImageSize, _btnViewImage, _ddlSizeMode, _ddlScaleFactor, _ddlHorizontalAlignMode _ddlVerticalAlignMode, and _btnGetRealScaleFactors controls and update the event handlers as follows:

    VB

    Protected Sub _btnGetImageSize_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles _btnGetImageSize.Click 
       Dim queryString As String = String.Format("url={0}", _tbImageUrl.Text) 
       Dim sbResponse As StringWriter = New StringWriter() 
       Dim wr As HttpWorkerRequest = New SimpleWorkerRequest("", queryString, sbResponse) 
       Dim context As HttpContext = New HttpContext(wr) 
       Dim ii As ImageInformation = New ImageInformation() 
       ii.ProcessRequest(context) 
       Dim xmlInfo As XmlDocument = New XmlDocument() 
       If (sbResponse.ToString().Length > 0) Then 
          xmlInfo.LoadXml(sbResponse.ToString()) 
          Dim width As XmlNode = xmlInfo.SelectSingleNode("descendant::Width") 
          Dim height As XmlNode = xmlInfo.SelectSingleNode("descendant::Height") 
          If (Not width Is Nothing) Then 
             _tbImageWidth.Text = width.InnerXml 
          End If 
          If (Not height Is Nothing) Then 
             _tbImageHeight.Text = height.InnerXml 
          End If 
       End If 
    End Sub 
    Protected Sub _btnViewImage_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles _btnViewImage.Click 
       ImageViewer1.ImageSize = New Size(Convert.ToInt32(_tbImageWidth.Text), Convert.ToInt32(_tbImageHeight.Text)) 
       ImageViewer1.ImageUrl = _tbImageUrl.Text 
    End Sub 
    Protected Sub _ddlSizeMode_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles _ddlSizeMode.SelectedIndexChanged 
       ImageViewer1.SizeMode = GetDropDownListSelectedItem(_ddlSizeMode, GetType(ImageViewerSizeMode)) 
    End Sub 
    Protected Sub _ddlScaleFactor_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles _ddlScaleFactor.SelectedIndexChanged 
       ImageViewer1.ScaleFactor = Convert.ToInt32(_ddlScaleFactor.SelectedItem.Value) 
    End Sub 
    Protected Sub _ddlHorizontalAlignMode_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles _ddlHorizontalAlignMode.SelectedIndexChanged 
       ImageViewer1.HorizontalAlignMode = GetDropDownListSelectedItem(_ddlHorizontalAlignMode, GetType(ImageViewerAlignMode)) 
    End Sub 
    Protected Sub _ddlVerticalAlignMode_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles _ddlVerticalAlignMode.SelectedIndexChanged 
       ImageViewer1.VerticalAlignMode = GetDropDownListSelectedItem(_ddlVerticalAlignMode, GetType(ImageViewerAlignMode)) 
    End Sub 
    Protected Sub _btnGetRealScaleFactors_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles _btnGetRealScaleFactors.Click 
       _tbRealScaleFactors.Text = String.Format("Horizontal:{0}, Vertical:{1}", ImageViewer1.HorizontalRealScaleFactor, ImageViewer1.VerticalRealScaleFactor) 
    End Sub 

    C#

    protected void _btnGetImageSize_Click(object sender, EventArgs e) 
    { 
       string queryString = string.Format("url={0}", _tbImageUrl.Text); 
       StringWriter sbResponse = new StringWriter(); 
       HttpWorkerRequest wr = new SimpleWorkerRequest("", queryString, sbResponse); 
       HttpContext context = new HttpContext(wr); 
       ImageInformation ii = new ImageInformation(); 
       ii.ProcessRequest(context); 
       XmlDocument xmlInfo = new XmlDocument(); 
       if(sbResponse.ToString().Length > 0) 
       { 
          xmlInfo.LoadXml(sbResponse.ToString()); 
          XmlNode width = xmlInfo.SelectSingleNode("descendant::Width"); 
          XmlNode height = xmlInfo.SelectSingleNode("descendant::Height"); 
          if(width != null) 
          { 
             _tbImageWidth.Text = width.InnerXml; 
          } 
                        
          if(height != null) 
          { 
             _tbImageHeight.Text = height.InnerXml; 
           } 
       } 
    } 
    protected void _btnViewImage_Click(object sender, EventArgs e) 
    { 
       ImageViewer1.ImageSize = new Size(Convert.ToInt32(_tbImageWidth.Text), Convert.ToInt32(_tbImageHeight.Text)); 
       ImageViewer1.ImageUrl = _tbImageUrl.Text; 
    } 
    protected void _ddlSizeMode_SelectedIndexChanged(object sender, EventArgs e) 
    { 
      ImageViewer1.SizeMode = (ImageViewerSizeMode)GetDropDownListSelectedItem(_ddlSizeMode, typeof(ImageViewerSizeMode)); 
    } 
    protected void _ddlScaleFactor_SelectedIndexChanged(object sender, EventArgs e) 
    { 
      ImageViewer1.ScaleFactor = Convert.ToInt32(_ddlScaleFactor.SelectedItem.Value); 
    } 
    protected void _ddlHorizontalAlignMode_SelectedIndexChanged(object sender, EventArgs e) 
    { 
      ImageViewer1.HorizontalAlignMode = (ImageViewerAlignMode)GetDropDownListSelectedItem(_ddlHorizontalAlignMode, typeof(ImageViewerAlignMode)); 
    } 
    protected void _ddlVerticalAlignMode_SelectedIndexChanged(object sender, EventArgs e) 
    { 
      ImageViewer1.VerticalAlignMode = (ImageViewerAlignMode)GetDropDownListSelectedItem(_ddlVerticalAlignMode, typeof(ImageViewerAlignMode)); 
    } 
                     
    protected void _btnGetRealScaleFactors_Click(object sender, EventArgs e) 
    { 
       _tbRealScaleFactors.Text = string.Format("Horizontal:{0}, Vertical:{1}", ImageViewer1.HorizontalRealScaleFactor, ImageViewer1.VerticalRealScaleFactor); 
    } 

  4. Add the following functions to the end of the "Default.aspx.cs" file (for C#) or before the "End Class" statement (for VB):

    VB

    Private Sub BindDropDownListToEnum(ByVal ddl As DropDownList, ByVal t As Type, ByVal selected As Object) 
       Dim a As Array = [Enum].GetValues(t) 
       ddl.DataSource = a 
       ddl.DataBind() 
       Dim selectedValue As String = selected.ToString() 
       For i As Integer = 0 To ddl.Items.Count - 1 
          If (ddl.Items(i).Value = selectedValue) Then 
             ddl.SelectedIndex = i 
             Return 
          End If 
       Next 
    End Sub 
    Private Function GetDropDownListSelectedItem(ByVal ddl As DropDownList, ByVal t As Type) As Object 
       Return [Enum].Parse(t, ddl.SelectedItem.Value) 
    End Function 

    C#

    private void BindDropDownListToEnum(DropDownList ddl, Type t, object selected) 
    { 
       Array a = Enum.GetValues(t); 
       ddl.DataSource = a; 
       ddl.DataBind(); 
       string selectedValue = selected.ToString(); 
       for(int i = 0; i < ddl.Items.Count; i++) 
       { 
          if(ddl.Items[i].Value == selectedValue) 
          { 
             ddl.SelectedIndex = i; 
             return; 
          } 
       } 
    } 
    private object GetDropDownListSelectedItem(DropDownList ddl, Type t) 
    { 
       return Enum.Parse(t, ddl.SelectedItem.Value); 
    } 

  5. From the path "<LEADTOOLS_INSTALLDIR>\Bin\Dotnet\Win32", copy the Leadtools.Codecs.Bmp, Leadtools.Codecs.Gif, Leadtools.Codecs.Png and Leadtools.Codecs.Cmp DLLs to the project's Bin folder.

  6. Inside the project folder create a folder named "Resources" and copy all of the java script files and images found in the "<LEADTOOLS_INSTALLDIR>\Examples\DotNet\Resources\Web" folder to it.

  7. Run the project and play with it as follows:

    • Type a path to one of the Internet Browser supported formats (gif, bmp, png or jpeg) in the ImageUrl TextBox.

    • Click GetImageSize to update the ImageWidth and ImageHeight Text Boxes by the image width and height.

    • Click ViewImage to load the image into the WebImageViewer control.

    • Change the selected items in the drop-down list boxes and notice the differences in the displayed image.
Help Version 20.0.2018.3.2
Products | Support | Contact Us | Copyright Notices
© 1991-2018 LEAD Technologies, Inc. All Rights Reserved.
LEADTOOLS Imaging, Medical, and Document