background object

[アーティクル]
05/31/2018

[The Windows Gadget Platform/Sidebar is available for use in the operating systems specified in the Requirements section. It may be altered or unavailable in subsequent versions. ]

Declares a gadget background with content and properties.

Members

The background object has these types of members:

Methods
Properties

Methods

The background object has these methods.

Method	Description
addGlow	Adds a glow effect to the g:background element.
addImageObject	Adds a g:image element to the g:background element.
addShadow	Adds a shadow effect to the g:background image.
addTextObject	Adds a g:text element to the g:background element.
removeObjects	Removes all g:text and g:image elements added to the gadget background using the addTextObject and addImageObject methods.

Properties

The background object has these properties.

Property	Access type	Description
blur	Read/write	Gets or sets the level of blur applied to the g:background element.
brightness	Read/write	Gets or sets the brightness of the g:background element.
opacity	Read/write	Gets or sets the opacity of the g:background element.
rotation	Read/write	Gets or sets the degree of rotation applied to the g:background element.
softEdge	Read/write	Gets or sets the amount of edge softening that is applied to the g:background element.
src	Read/write	Gets or sets the image file used by the g:background element.

Remarks

The Windows Sidebar supports JPEG, bitmap (BMP), Graphics Interchange Format (GIF), and Portable Network Graphics (PNG) image types. Only PNG supports alpha channel transparency.

This element is declared in the gadget HTML file through a non-standard tag.

An image can be assigned to the g:background element from a gadget script file by using the background property or src property.

Note

The Cascading Style Sheets (CSS) backgroundImage property can also be used to assign an image to the background.

Attributes of the g:background element can be accessed from the gadget script files if the element has an id tag.

This element is a $disp element.

This element requires a closing tag.

Examples

The following example shows how to declare a g:background element in HTML.

<g:background id="imgBackground" src="images/background.png" />

The following example shows how to use the src property to assign an image to the g:background element.

\\ imgBackground is the value of the 'id' attribute for the g:background element.
imgBackground.src = "../images/bg_undocked.jpg";

The following example shows how to access attributes of the g:background element.

\\ imgBackground is the value of the 'id' attribute for the g:background element.
imgBackground.opacity = 50;

The following example shows how to use the background property to assign an image to the g:background element.

[!Caution]
When using background images with alpha channel transparency the following two methods can result in unpredictable rendering, such as transparent pixels replaced with magenta, and limitations in functionality. As such, they are presented here for information purposes only and are not recommended.

[!Important]
For Windows 7, when the new <autoscaleDPI> element of the gadget manifest is set to true (for high-DPI support) and the following methods are used, rendering issues can increase significantly.

<html>
    <head>
        <title>Hello World</title>
        <script type="text/jscript" language="jscript">
        function init()
        {
            System.Gadget.background = "images\\background.png";
        }
        </script>
    </head>
    
    <body onload="init()">
        <g:background id="imgBackground">
            <span id="gadgetContent">Hello World!</span>
        </g:background>
    </body>
</html>

The following example shows how to use CSS to assign an image to the g:background element.

[!Important]
When using background images with alpha channel transparency the following method can result in unpredictable rendering (typically with magenta replacing transparent pixels) and limitations in functionality. As such, it is presented here for information purposes only and is not recommended.

[!Warning]
For Windows 7, when the <autoscaleDPI> element is set to true and the following method is used, rendering issues increase significantly.

<html>
    <head>
        <title>Hello World</title>
        <script type="text/jscript" language="jscript">
        function init()
        {
            with(document.body.style)
                backgroundImage = "images\\background.png"; 
        }
        </script>
    </head>
    
    <body onload="init()">
        <g:background id="imgBackground">
            <span id="gadgetContent">Hello World!</span>
        </g:background>
    </body>
</html>

Requirements


Minimum supported client	Windows Vista [desktop apps only]
Minimum supported server	Windows Server 2008 [desktop apps only]
End of client support	Windows 7
End of server support	Windows Server 2008
IDL	Sidebar.idl
DLL	Sidebar.Exe (version 1.00 or later)

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