Partilhar via

Alpha Filter

  • Artigo

This topic documents a feature of Visual Filters and Transitions, which is deprecated as of Windows Internet Explorer 9.

Adjusts the opacity of the content of the object.

Syntax

HTML
<ELEMENT STYLE="filter:progid:DXImageTransform.Microsoft.Alpha(sProperties)" ... >
Internet Explorer 5.5 or later
Scripting
object.style.filter ="progid:DXImageTransform.Microsoft.Alpha(sProperties)"
Internet Explorer 5.5 or later

Possible Values

sProperties String that specifies one or more properties exposed by the filter.

Members Table

The following table lists the members exposed by the Alpha object.

Attribute Property Description
enabled Enabled

Sets or retrieves a value that indicates whether the filter is enabled.
finishOpacity FinishOpacity

Sets or retrieves the opacity level at the end of the gradient applied with the Alpha filter.
finishX FinishX

Sets or retrieves the horizontal position at which the opacity gradient ends.
finishY FinishY

Sets or retrieves the vertical position at which the opacity gradient ends.
opacity Opacity

Sets or retrieves the opacity level at the beginning of the gradient applied with the Alpha filter.
startX StartX

Sets or retrieves the horizontal position at which the opacity gradient starts.
startY StartY

Sets or retrieves the vertical position at which the opacity gradient starts.
style Style

Sets or retrieves the shape characteristics of the opacity gradient.

Remarks

You can set the opacity as uniform or graded, in a linear or radial fashion. The following list of allowable Style property values provides more information on how the Alpha filter properties support each style of filtered output.

  • 0—Uniform—Applies Opacity value evenly across the object.
  • 1—Linear—Applies an even opacity gradient, beginning with the Opacity value on a line from StartX to StartY and ending with the FinishOpacity value on a line from FinishX to FinishY.
  • 2—Radial—Applies an even opacity gradient, beginning in the center with the Opacity value and ending at the middle of the sides of the object with the FinishOpacity value. The corners of the object are not affected by the opacity gradient.
  • 3—Rectangular—Applies an even opacity gradient, beginning at the sides of the object with the Opacity value and ending at the center of the object with the FinishOpacity value.

This effect is supported in Microsoft Internet Explorer 4.0. For more information about Internet Explorer 4.0 filter behavior, see Downlevel Support and Internet Explorer 4.0 Filters.

The object that the filter is applied to must have layout before the filter effect displays. You can give the object layout by setting the height or width property, setting the position property to absolute, setting the writingMode property to tb-rl, or setting the contentEditable property to true.

You can assign multiple filters or transitions to an object by declaring each in the filter property of the object. The following div declaration assigns two filters and a Wheel transition to a div element.

<DIV STYLE="width:100%; filter:
    progid:DXImageTransform.Microsoft.MotionBlur(strength=13, direction=310)
    progid:DXImageTransform.Microsoft.Blur(pixelradius=2)
    progid:DXImageTransform.Microsoft.Wheel(duration=3);">
        Blurry text with smudge of gray.</div>

When multiple filters are applied to an object, each filter is processed in source order, with the exception of procedural surfaces, which are computed first. To emphasize a filter's effect, place it last in source order or on the object's parent. Always place transitions last in source order.

Note  As of Internet Explorer 9, the visual effect of this filter is only applied when content is displayed on a screen; the effect is not applied when content is printed.

Examples

The following example shows the effects of this filter when its properties are modified.

Code example: http://samples.msdn.microsoft.com/workshop/samples/author/filter/Alpha.htm

This example uses the Alpha filter and the Opacity property to change the appearance of a button.

<STYLE>
   INPUT.aFilter {filter:progid:DXImageTransform.Microsoft.Alpha(opacity=50);}
</STYLE>

<INPUT TYPE="button" VALUE="Button" CLASS="aFilter">

Code example: http://samples.msdn.microsoft.com/workshop/samples/author/filter/shortSamples/alphaEX1.htm

Applies To

A, ABBR, ACRONYM, ADDRESS, B, BDO, BIG, BLOCKQUOTE, BODY, BUTTON, CAPTION, CENTER, CITE, CODE, CUSTOM, DD, DEL, DFN, DIR, DIV, DL, DT, EM, FIELDSET, FONT, FORM, FRAME, hn, I, IFRAME, IMG, INPUT type=button, INPUT type=checkbox, INPUT type=file, INPUT type=image, INPUT type=password, INPUT type=radio, INPUT type=reset, INPUT type=submit, INPUT type=text, INS, KBD, LABEL, LEGEND, LI, MARQUEE, MENU, NOBR, OL, OBJECT, P, PLAINTEXT, PRE, Q, RT, RUBY, runtimeStyle, S, SAMP, SMALL, SPAN, STRIKE, STRONG, style, SUB, SUP, TABLE, TD, TEXTAREA, TH, TT, U, UL, VAR, XMP

See Also

Scripting Filters, Filter Design Considerations