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The TreeViewWrapper.exe file contains the following files:
Collapse this tableExpand this table
| File name | Size |
|---|
| Images.xml | 1 KB |
| picture.bmp | 406 bytes |
| picture2.bmp | 406 bytes |
| picture3.bmp | 406 bytes |
| TreeViewWrapper.CAB | 16 KB |
| TreeViewWrapper.exp | 2 KB |
| TreeViewWrapper.HTM | 2 KB |
| TreeViewWrapper.lib | 3 KB |
| TreeViewWrapper.ocx | 32 KB |
| TreeViewWrapper.PDM | 4 KB |
| TreeViewWrapper.vbp | 1 KB |
| TreeViewWrapper.vbw | 1 KB |
| TreeViewWrapperCtl.ctl | 7 KB |
Q313675 Security Patch turns off a feature in Internet Explorer known as
Inline Data, which permits base64-encoded binary data to be assigned to an ActiveX control. However, you may have written Web pages that use the
TreeView control and the
ImageList control as directed by the following article:
BUG: Setting TreeView1.ImageList Causes Err in Internet Explorer
184975�
BUG: Setting TreeView1.ImageList Causes Err in Internet Explorer
In the sample, you can load the images of the
ImageList control if you encode all images in base64, and then assign the string after that to the
DATA attribute of the
OBJECT tag of the
ImageList. This procedure is the feature that is turned off by Q313675 Security Patch.
You can develop a control that encapsulates both the
TreeView control and the
ImageList control, and then loads the
ImageList from an XML-based list of Uniform Resource Locator (URL) image references. The object requires that any script that is written against the raw
TreeView control must be rewritten, but the required functionality of the
TreeView is preserved, while the object also adheres to the new provisions that are introduced by the security patch.
Populate the ImageList from a List of URLs
While the
DATA attribute permits the
ImageList to be used in a Web page, the technique is cumbersome. You can populate the control if you use URL references instead of the base64-encoded image data. TreeViewWrapperProj.exe gives this capability. The
LoadImages public method takes a reference to a simple XML document of the following format:
<Images>
<Image Name="ImgH" Url="http://localhost/TreeViewWrapper/picture.bmp" />
<Image Name="ImgG" Url="http://localhost/TreeViewWrapper/picture2.bmp" />
<Image Name="ImgI" Url="http://localhost/TreeViewWrapper/picture3.bmp" />
</Images>
iterates through these nodes, grabs each of the URLs, and then uses the built-in
AsyncRead method of the
UserControl to download each of the URLs one-by-one from the Web. The
UserControl_AsyncReadComplete event handler responds to each completed download by adding the images to your encapsulated
ImageList control. The
UserControl_AsyncReadComplete event handler uses the
Name attribute in the XML file as the image key:
Private Sub UserControl_AsyncReadComplete(AsyncProp As AsyncProperty)
On Error GoTo ErrHandler
ImageList1.ListImages.Add ImageList1.ListImages.Count + 1, _
AsyncProp.PropertyName, AsyncProp.Value
Exit Sub
' Report errors during dev. There is little end users can do with
' a failure here.
ErrHandler:
Debug.Assert "AsyncReadComplete: Could not add image " & _
AsyncProp.PropertyName & "; error is " & Err.Description
End Sub
Notice that, although the method that is used to download images in
LoadImages is called
AsyncRead, you use the
AsyncReadOptions parameter to force synchronous image downloads:
UserControl.AsyncRead imgUrl, vbAsyncTypePicture, imgName, _
AsyncReadConstants.vbAsyncReadSynchronousDownload
You do this because the
ImageList cannot be assigned to the
TreeView until the
TreeView has been populated with images. You can force a synchronous read, which is less cumbersome than if you use flags to test for the final
AsyncReadComplete event.
Use TreeViewWrapper in a Web Page
After you build your control, you can host your control by using a simple object tag. Code in the
onload event handler of the HTML file is used to load the
ImageList from the XML file and to add nodes to the tree:
<HTML>
<HEAD>
<TITLE>TreeViewWrapper.CAB</TITLE>
<script language="jscript">
function LoadTreeView()
{
tv1.LoadImages("http://localhost/TreeViewWrapper/images.xml");
tv1.tvStyle = "TreelinesPictureText";
tv1.AddNode("", 1, "Node1", "Top Node", "ImgH");
tv1.AddNode("Node1", 4, "Node2", "Subnode 1", "ImgH");
tv1.AddNode("Node1", 4, "Node3", "Subnode 2", "ImgI");
tv1.AddNode("Node1", 4, "Node4", "Subnode 3", "ImgG");
}
</script>
</HEAD>
<BODY onload="LoadTreeView();">
<OBJECT ID="tv1"
CLASSID="CLSID:6DFF1758-3C5B-4DAD-B6A9-E36654D17CBE"
CODEBASE="TreeViewWrapper.CAB#version=1,0,0,2" VIEWASTEXT>
</OBJECT>
</BODY>
</HTML>
Deploy TreeViewWrapper to Client Machines
The sample page that is included in this project works on a development computer or a computer where TreeViewWrapper.ocx is manually registered by using Regsrv32.exe. To deploy the sample page to arbitrary clients, you must use the Visual Basic Package and Deployment Wizard (PDW) to create a .cab file. You can then reference that .cab file in your
CODEBASE attribute of the
OBJECT tag. Note that you must modify both the Images.xml file and the
tv1.LoadImages(...) method to point to the appropriate file path.