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Version Q2 2011 released 07/12/2011
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ImageEditor / Change Transparency

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  • Change Opacity

    This example demonstrates how to change the transparency of a given image using the ImageEditor control. Creating an ImageEditorTool with command name Opacity will render a tool on the RadImageEditor's ToolBar that will enable you to modify the picture using the built-in Opacity dialog.
    It is, however, not necessary for this tool to be present, for the user to be able to set opacity on her image. The RadImageEditor's changeImageOpacity(opacity) client-side method can be used for this purpose, where the opacity parameter is an integer between 0-100 (percents).

    RadImageEditor sets the transparency directly on the client, so the changes are not actually applied to the image until a postback occurs.

Source Code

C# VB.NET
Show code in new window Demo isolation steps
  • <%@ Page Language="C#" AutoEventWireup="true" %>

    <%@ Register TagPrefix="telerik" Namespace="Telerik.Web.UI" Assembly="Telerik.Web.UI" %>
    <%@ Register TagPrefix="qsf" Namespace="Telerik.QuickStart" %>
    <%@ Register TagPrefix="qsf" TagName="Header" Src="~/Common/Header.ascx" %>
    <%@ Register TagPrefix="qsf" TagName="HeadTag" Src="~/Common/HeadTag.ascx" %>
    <%@ Register TagPrefix="qsf" TagName="Footer" Src="~/Common/Footer.ascx" %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
        <meta http-equiv="X-UA-Compatible" content="IE=Edge" />
        <qsf:HeadTag ID="Headtag1" runat="server" />
    </head>
    <body class="BODY">
        <form id="form1" runat="server">
        <qsf:Header ID="Header1" runat="server" NavigationLanguage="c#" />
        <telerik:RadScriptManager ID="ScriptManager1" runat="server" EnableScriptCombine="false" />
        <telerik:RadImageEditor ID="RadImageEditor1" runat="server" Width="585px" Height="300px"
            ImageUrl="~/ImageEditor/images/logo.png">
            <Tools>
                <telerik:ImageEditorToolGroup>
                    <telerik:ImageEditorTool CommandName="Save" IsToggleButton="true" />
                    <telerik:ImageEditorTool CommandName="Opacity" IsToggleButton="true" />
                </telerik:ImageEditorToolGroup>
            </Tools>
        </telerik:RadImageEditor>
        <qsf:Footer runat="server" ID="Footer1" />
        </form>
    </body>
    </html>

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