Class

WebHTMLViewer


Description

WebHTMLViewer is used to display HTML in your web applications. The HTML can be supplied as a string or can come from an external URL to display pages that are not part of the web application.

Methods

Name

Parameters

Returns

Shared

Close

ExecuteJavaScript

Script As String

GotoURL

Url As String, inNewWindow As Boolean = False

LoadHTML

HTML As String

LoadURL

URL As String

Print

SetFocus

UpdateBrowser

Events

Name

Parameters

Returns

Closed

ContextualMenuSelected

hitItem As WebMenuItem

Hidden

Opening

Shown

Property descriptions


WebHTMLViewer.ContextualMenu

ContextualMenu As WebMenuItem

If you assign a WebMenuItem to the control, it will be displayed when the user right-clicks the control.

On a WebPage, you can disable/remove the default contextual menu by an empty WebMenuItem class object to this property.

This code populates a contextual menu in the Shown event of the control.

Var menu As New WebMenuItem

menu.AddMenuItem("One")
menu.AddMenuItem("Two")
menu.AddMenuItem("Three")
Me.ContextualMenu = menu

The menu selection is then handled by the ContextualMenuSelected event when the user right-clicks on the control. For example, it can be of the form:

Select case hitItem.Value
Case "One"
  MessageBox("One")
Case "Two"
  MessageBox("Two")
Case "Three"
  MessageBox("Three")
End Select

WebHTMLViewer.ControlID

ControlID As String

Identifies the control on a per session basis.

This property is read-only.


WebHTMLViewer.Enabled

Enabled As Boolean

When True the WebControl is drawn enabled and responds to user action. When False, the control appears as disabled and does not respond to user actions.

In the case of WebTimer, when set to False this disables and stops the WebTimer. When set to True, it starts the WebTimer.

Disable a button when a check box value changes:

If AllowSaveCheckBox.Value Then
  SaveButton.Enabled = True
Else
  AllowSaveButton.Enabled = False
End If

WebHTMLViewer.Height

Height As Integer

The height (in pixels) of the control.


WebHTMLViewer.HTML

HTML As String

HTML to be rendered in the WebHTMLViewer.


WebHTMLViewer.Indicator

Indicator As Indicators

The color scheme for the control.

When a WebButton's Default or Cancel properties are True, the Indictor property is ignored as Default and Cancel buttons have a default indicator.


WebHTMLViewer.Left

Left As Integer

The position of the left side of the WebUIControl in pixels, relative to the web page.


WebHTMLViewer.LockBottom

LockBottom As Boolean

Determines whether the bottom edge of the control should stay at a set distance from the bottom edge of the parent control, if there is one, or the owning web page.

This property is read-only.


WebHTMLViewer.LockHorizontal

LockHorizontal As Boolean

LockHorizontal overrides LockLeft and LockRight. It allows you to proportionally lock a control's position to the center of its parent control (or web page).

This property is read-only.

For example, if you place a control in the center of the page and sets both LockHorizontal and LockVertical, the control will stay in the center of the page.


WebHTMLViewer.LockLeft

LockLeft As Boolean

Determines whether the left edge of the control should stay at a set distance from the left edge of the parent control, if there is one, or the owning web page.

This property is read-only.


WebHTMLViewer.LockRight

LockRight As Boolean

Determines whether the right edge of the control should stay at a set distance from the right edge of the parent control, if there is one, or the owning web page.

This property is read-only.


WebHTMLViewer.LockVertical

LockVertical As Boolean

LockVertical overrides LockTop and LockBottom. It allows you to proportionally lock a control's position to keep it centered within the parent control or web page.

This property is read-only.

For example, if you place a control in the center of the page, and sets both LockHorizontal and LockVertical, the control will stay in the center of the page.


WebHTMLViewer.Name

Name As String

The name of the control.

This property is read-only.


WebHTMLViewer.Page

Page As WebPage

Identifies the web page that contains the control.

This property is read-only.


WebHTMLViewer.Parent

Parent As WebControl

Used to get the control's parent control or page. If the parent control is a WebContainer, then it returns the WebContainer. If it is on a WebPage, it returns the WebPage.

This property is read-only.


WebHTMLViewer.Style

Style As WebStyle

The WebStyle for the control.

In the Pressed event of a WebButton, set the text to bold:

Var style As New WebStyle
style.Bold = True
Me.Style = style

WebHTMLViewer.TabIndex

TabIndex As Integer

The WebUIControl's control's position in the Tab Order. The control with a TabIndex of 0 is the first WebUIControl to get the focus when the page opens in the browser.

This example sets the control's TabIndex.

Me.TabIndex = 2

WebHTMLViewer.Tooltip

Tooltip As String

Text of a message displayed as a tooltip.

The tip is displayed when the user places the mouse on the control and leaves it there.

This code in the Shown event of a Button sets the tooltip:

Me.Tooltip = "Save changes"

WebHTMLViewer.Top

Top As Integer

The top of the control in local coordinates relative to the web page.


WebHTMLViewer.URL

URL As String

The URL of the web page to display. Defaults to "http://www.xojo.com".

Changing the URL property immediately causes the page to be displayed.

This example displays the URL that a user enters in a WebTextField when the user clicks a button:

Var url As String
url = URLField.Text
HTMLViewer1.URL = url

WebHTMLViewer.UseSandbox

UseSandbox As Boolean

If True, sandboxes the page in the WebHTMLViewer from being able to access the web application in which it is used.


WebHTMLViewer.Visible

Visible As Boolean

If True, the control is drawn. If False, it's not.

Hide a control based on a checkbox setting:

If ShowEmailCheckbox.Value Then
  EmailField.Visible = True
Else
  EmailField.Visible = False
End If

WebHTMLViewer.Width

Width As Integer

The width (in pixels) of the web control.

This code in the Shown event handler increases the size of the control:

Me.Width = Me.Width + 50

Method descriptions


WebHTMLViewer.Close

Close

Removes the control from the page.


WebHTMLViewer.ExecuteJavaScript

ExecuteJavaScript(Script As String)

Executes the JavaScript passed. The JavaScript passed can call a JavaScript function in a WebPageSource control.

The Xojo web framework uses EcmaScript 6 which is more strict than previous versions of JavaScript. For more details, see the EcmaScript 6 documentation.

This code in the Pressed event of a Button displays an alert using JavaScript:

Me.ExecuteJavaScript("alert('Hello!');")

This code will select the text in a WebTextField (or WebTextArea):

WebTextField1.ExecuteJavascript("document.getElementById('" + _
  WebTextField1.ControlID + "_inner').select();")

WebHTMLViewer.GotoURL

GotoURL(Url As String, inNewWindow As Boolean = False)

Opens the passed URL in place of the current web page or downloads a file. If InNewWindow is True, the browser is asked to open the URL in a new window.

If the browser has popup windows disabled and InNewWindow is True, the method silently fails and the page is not shown.

If InNewWindow is False, the running web app is replaced with the specified URL. If you want to display an external web site within your web app, use the WebHTMLViewer control.

Display a web site in a new popup window:

Me.GotoURL("http://www.wikipedia.org", True)

WebHTMLViewer.LoadHTML

LoadHTML(HTML As String)

Loads the specified HTML into the WebHTMLViewer.

If HTML is loaded via https, all links instead the HTML must also be https.

You can load HTML directly from a string like so:

HTMLViewer1.LoadHTML("<body><h1>Hello World!</h1></body>")

To display HTML from a file, first load the file into a String:

Var htmlFile As New FolderItem("test.html")
If htmlFile <> Nil And htmlFile.Exists Then
  Var html As String
  Var htmlInput As TextInputStream
  Try
    htmlInput = TextInputStream.Open(htmlFile)
    html = htmlInput.ReadAll
    htmlInput.Close
  Catch e As IOException
    html = "<body><h1>Error loading file on server.</h1></body>"
  End Try
  HTMLViewer1.LoadHTML(html)
End If

This code executes JavaScript within the HTML:

Var js As String = "<script type=""text/javascript"">document.write(""Hello World!"")</script>"
Var html As String = "<body>" + js + "</body>"
HTMLViewer1.LoadHTML(html)

WebHTMLViewer.LoadURL

LoadURL(URL As String)

Loads the page at the specified URL into the WebHTMLViewer.


WebHTMLViewer.Print

Print

Prints the contents of the WebHTMLViewer (or web page with some browsers).

Firefox and Internet Explorer print the contents of the entire web page, not just the WebHTMLViewer.

The contents will not print if the domain and port of the WebPage do not match the domain and port of the WebHTMLViewer contents. This means content from other web sites cannot be printed.

This example first loads some HTML into the viewer in the Open event. A WebButton then calls the Print method. Print displays the Print dialog for the platform on which the client is running and then prints the content.

This code is in the Open event of the WebHTMLViewer:

Me.LoadHTML("<body><h1>This is a test</h1></body>")

This code is in the Action event of a WebButton:

HTMLViewer1.Print

WebHTMLViewer.SetFocus

SetFocus

Sets the focus to the Control.

This code checks for a required value when a button is pressed:

If UserNameField.Value = "" Then
  MessageBox("Please enter your UserName.")
  UserNameField.SetFocus
  Return
End If

WebHTMLViewer.UpdateBrowser

UpdateBrowser

Forces the current values of the control to be sent to the browser.

This method is useful when you are computing values in a loop and wish to update the browser immediately rather than wait until the current method ends.

This code iterates through a RowSet of database rows, updates a ProgressBar and then forces the updated ProgressBar to be sent to the browser via UpdateBrowser.

ProgressBar1.Maximum = SalesData.RowCount
For Each row As DatabaseRow in SalesData
 AnalyzeSales(row)
 ProgressBar1.Value = ProgressBar1.Value + 1
 ProgressBar1.UpdateBrowser
Next

Event descriptions


WebHTMLViewer.Closed

Closed

The control has been removed from the browser either because the page has closed or the control's Close method was called.


WebHTMLViewer.ContextualMenuSelected

ContextualMenuSelected(hitItem As WebMenuItem)

Called when a contextual menu item is selected. This selected item is contained in hitItem.

This code populates a contextual menu in the Opening event of a WebToolbar:

Var menu As New WebMenuItem

menu.AddMenuItem("One")
menu.AddMenuItem("Two")
menu.AddMenuItem("Three")
Me.ContextualMenu = menu

The menu selection is then handled by the ContextualMenuSelected event when the user right-clicks on the control. For example, it can be of the form:

Select case hitItem.Value
Case "One"
  MessageBox("One")
Case "Two"
  MessageBox("Two")
Case "Three"
  MessageBox("Three")
End Select

WebHTMLViewer.Hidden

Hidden

The control is about to become no longer visible. This could be because the page is being closed, is being replaced as the foreground page by another page or because the control or a parent control's Visible property has been set to False.

Note

This event is equivalent to the DesktopWindow.Deactivated event in a desktop app.


WebHTMLViewer.Opening

Opening

The control has been created and the page is opening but has not been sent to the browser yet.

The Opening event handler can be used to initialize non-visual properties and settings for controls.

In most cases, you should use the Shown event to initialize controls.


WebHTMLViewer.Shown

Shown

The control has appeared on the currently displayed page. This could be because its parent page just finished loading, its parent page has come to the foreground or the control is now visible having been previously invisible because it or its parent control's Visible property has been set to True.

Use the Shown event for initializing your controls or doing anything that would interact with other controls or user interface elements on the web page instead of the Opening event.

Note

This event is the web equivalent to the DesktopWindow.Activated event.

This code in the Shown event of a WebListBox adds 2 rows with 3 columns:

Me.RemoveAllRows
Me.AddRow("Row 1", "Bob", "Roberts")
Me.AddRow("Row 2", "Barb", "Reynolds")

This example sets the text of a label:

If Session.LoggedIn Then
  Me.Value = "Welcome!"
Else
  Me.Value = "Welcome, " + Session.UserName
End If

Notes

The WebHTMLViewer appears in the Web Page Layout Editor as a large rectangular area.

Compatibility

Web projects on all supported operating systems.

See also

WebUIControl parent class; HTMLViewer, WebFile, WebImageViewer