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Layer

Corresponds to a layer in an HTML page and provides a means for manipulating that layer.

Client-side object

Implemented in

JavaScript 1.2

Created by

The HTML LAYER or ILAYER tag, or using cascading style sheet syntax. The JavaScript runtime engine creates a Layer object corresponding to each layer in your document. It puts these objects in an array in the document.layers property. You access a Layer object by indexing this array.

To define a layer, use standard HTML syntax. If you specify the ID attribute, you can use the value of that attribute to index into the layers array.

For a complete description of layers, see Dynamic HTML in Netscape Communicator.

Some layer properties can be directly modified by assignment; for example, "mylayer.visibility = hide". A layer object also has methods that can affect these properties.

Event handlers

Property Summary

Property Description
above

The layer object above this one in z-order, among all layers in the document or the enclosing window object if this layer is topmost.

background

The image to use as the background for the layer's canvas.

bgColor

The color to use as a solid background color for the layer's canvas.

below

The layer object below this one in z-order, among all layers in the document or null if this layer is at the bottom.

clip.bottom

The bottom edge of the clipping rectangle (the part of the layer that is visible.)

clip.height

The height of the clipping rectangle (the part of the layer that is visible.)

clip.left

The left edge of the clipping rectangle (the part of the layer that is visible.)

clip.right

The right edge of the clipping rectangle (the part of the layer that is visible.)

clip.top

The top edge of the clipping rectangle (the part of the layer that is visible.)

clip.width

The width of the clipping rectangle (the part of the layer that is visible.)

document

The layer's associated document.

left

The horizontal position of the layer's left edge, in pixels, relative to the origin of its parent layer.

name

A string specifying the name assigned to the layer through the ID attribute in the LAYER tag.

pageX

The horizontal position of the layer, in pixels, relative to the page.

pageY

The vertical position of the layer, in pixels, relative to the page.

parentLayer

The layer object that contains this layer, or the enclosing window object if this layer is not nested in another layer.

siblingAbove

The layer object above this one in z-order, among all layers that share the same parent layer, or null if the layer has no sibling above.

siblingBelow

The layer object below this one in z-order, among all layers that share the same parent layer, or null if layer is at the bottom.

src

A string specifying the URL of the layer's content.

top

The vertical position of the layer's top edge, in pixels, relative to the origin of its parent layer.

visibility

Whether or not the layer is visible.

zIndex

The relative z-order of this layer with respect to its siblings.

Method Summary

Method Description
captureEvents

Sets the window or document to capture all events of the specified type.

handleEvent

Invokes the handler for the specified event.

load

Changes the source of a layer to the contents of the specified file, and simultaneously changes the width at which the layer's HTML contents will be wrapped.

moveAbove

Stacks this layer above the layer specified in the argument, without changing either layer's horizontal or vertical position.

moveBelow

Stacks this layer below the specified layer, without changing either layer's horizontal or vertical position.

moveBy

Changes the layer position by applying the specified deltas, measured in pixels.

moveTo

Moves the top-left corner of the window to the specified screen coordinates.

moveToAbsolute

Changes the layer position to the specified pixel coordinates within the page (instead of the containing layer.)

releaseEvents

Sets the layer to release captured events of the specified type, sending the event to objects further along the event hierarchy.

resizeBy

Resizes the layer by the specified height and width values (in pixels).

resizeTo

Resizes the layer to have the specified height and width values (in pixels).

routeEvent

Passes a captured event along the normal event hierarchy.

In addition, this object inherits the watch and unwatch methods from Object.

NOTE: Just as in the case of a document, if you want to define mouse click response for a layer, you must capture onMouseDown and onMouseUp events at the level of the layer and process them as you want.
For details about capturing events, see the Client-Side JavaScript Guide.

If an event occurs in a point where multiple layers overlap, the topmost layer gets the event, even if it is transparent. However, if a layer is hidden, it does not get events.


above

The layer object above this one in z-order, among all layers in the document or the enclosing window object if this layer is topmost.

Property of

Layer

Read-only

Implemented in

JavaScript 1.2


background

The image to use as the background for the layer's canvas (which is the part of the layer within the clip rectangle).

Property of

Layer

Implemented in

JavaScript 1.2

Description

Each layer has a background property, whose value is an image object, whose src attribute is a URL that indicates the image to use to provide a tiled backdrop. The value is null if the layer has no backdrop. For example:

layer.background.src = "fishbg.gif";

below

The layer object below this one in z-order, among all layers in the document or null if this layer is at the bottom.

Property of

Layer

Read-only

Implemented in

JavaScript 1.2


bgColor

A string specifying the color to use as a solid background color for the layer's canvas (the part of the layer within the clip rectangle).

Property of

Layer

Implemented in

JavaScript 1.2

Description

The bgColor property is expressed as a hexadecimal RGB triplet or as a string literal (see the Client-Side JavaScript Guide). This property is the JavaScript reflection of the BGCOLOR attribute of the BODY tag.

You can set the bgColor property at any time.

If you express the color as a hexadecimal RGB triplet, you must use the format rrggbb. For example, the hexadecimal RGB values for salmon are red=FA, green=80, and blue=72, so the RGB triplet for salmon is "FA8072".

Examples

The following example sets the background color of the myLayer layer's canvas to aqua using a string literal:

myLayer.bgColor="aqua"
The following example sets the background color of the myLayer layer's canvas to aqua using a hexadecimal triplet:

myLayer.bgColor="00FFFF"

See also

Layer.bgColor


captureEvents

Sets the window or document to capture all events of the specified type.

Method of

Layer

Implemented in

JavaScript 1.2

Syntax

captureEvents(eventType)

Parameters

eventType

Type of event to be captured. Available event types are listed in the Client-Side JavaScript Guide.

Description

When a window with frames wants to capture events in pages loaded from different locations (servers), you need to use captureEvents in a signed script and precede it with enableExternalCapture. For more information and an example, see enableExternalCapture.

captureEvents works in tandem with releaseEvents, routeEvent, and handleEvent. For information on handling events, see the Client-Side JavaScript Guide.


clip.bottom

The bottom edge of the clipping rectangle (the part of the layer that is visible.) Any part of a layer that is outside the clipping rectangle is not displayed.

Property of

Layer

Implemented in

JavaScript 1.2


clip.height

The height of the clipping rectangle (the part of the layer that is visible.) Any part of a layer that is outside the clipping rectangle is not displayed.

Property of

Layer

Implemented in

JavaScript 1.2


clip.left

The left edge of the clipping rectangle (the part of the layer that is visible.) Any part of a layer that is outside the clipping rectangle is not displayed.

Property of

Layer

Implemented in

JavaScript 1.2


clip.right

The right edge of the clipping rectangle (the part of the layer that is visible.) Any part of a layer that is outside the clipping rectangle is not displayed.

Property of

Layer

Implemented in

JavaScript 1.2


clip.top

The top edge of the clipping rectangle (the part of the layer that is visible.) Any part of a layer that is outside the clipping rectangle is not displayed.

Property of

Layer

Implemented in

JavaScript 1.2


clip.width

The width of the clipping rectangle (the part of the layer that is visible.) Any part of a layer that is outside the clipping rectangle is not displayed.

Property of

Layer

Implemented in

JavaScript 1.2


document

The layer's associated document.

Property of

Layer

Read-only

Implemented in

JavaScript 1.2

Description

Each layer object contains its own document object. This object can be used to access the images, applets, embeds, links, anchors and layers that are contained within the layer. Methods of the document object can also be invoked to change the contents of the layer.


handleEvent

Invokes the handler for the specified event.

Method of

Layer

Implemented in

JavaScript 1.2

Syntax

handleEvent(event)

Parameters

event

Name of an event for which the specified object has an event handler.

Description

handleEvent works in tandem with captureEvents, releaseEvents, and routeEvent. For information on handling events, see the Client-Side JavaScript Guide.


left

The horizontal position of the layer's left edge, in pixels, relative to the origin of its parent layer.

Property of

Layer

Implemented in

JavaScript 1.2


load

Changes the source of a layer to the contents of the specified file and simultaneously changes the width at which the layer's HTML contents are wrapped.

Method of

Layer

Implemented in

JavaScript 1.2

Syntax

load(sourcestring, width)

Parameters

sourcestring

A string indicating the external file name.

width

The width of the layer as a pixel value.


moveAbove

Stacks this layer above the layer specified in the argument, without changing either layer's horizontal or vertical position. After re-stacking, both layers will share the same parent layer.

Method of

Layer

Implemented in

JavaScript 1.2

Syntax

moveAbove(aLayer)

Parameters

aLayer

The layer above which to move the current layer.


moveBelow

Stacks this layer below the specified layer, without changing either layer's horizontal or vertical position. After re-stacking, both layers will share the same parent layer.

Method of

Layer

Implemented in

JavaScript 1.2

Syntax

moveBelow(aLayer)

Parameters

aLayer

The layer below which to move the current layer.


moveBy

Changes the layer position by applying the specified deltas, measured in pixels.

Method of

Layer

Implemented in

JavaScript 1.2

Syntax

moveBy(horizontal, vertical)

Parameters

horizontal

The number of pixels by which to move the layer horizontally.

vertical

The number of pixels by which to move the layer vertically.


moveTo

Moves the top-left corner of the window to the specified screen coordinates.

Method of

Layer

Implemented in

JavaScript 1.2

Syntax

moveTo(x-coordinate, y-coordinate)

Parameters

x-coordinate

An integer representing the top edge of the window in screen coordinates.

y-coordinate

An integer representing the left edge of the window in screen coordinates.

Security

To move a window offscreen, call the moveTo method in a signed script. For information on security, see the Client-Side JavaScript Guide.

Description

Changes the layer position to the specified pixel coordinates within the containing layer. For ILayers, moves the layer relative to the natural inflow position of the layer.

See also

Layer.moveBy


moveToAbsolute

Changes the layer position to the specified pixel coordinates within the page (instead of the containing layer.)

Method of

Layer

Implemented in

JavaScript 1.2

Syntax

moveToAbsolute(x, y)

Parameters

x

An integer representing the top edge of the window in pixel coordinates.

y

An integer representing the left edge of the window in pixel coordinates.

Description

This method is equivalent to setting both the pageX and pageY properties of the layer object.


name

A string specifying the name assigned to the layer through the ID attribute in the LAYER tag.

Property of

Layer

Read-only

Implemented in

JavaScript 1.2


pageX

The horizontal position of the layer, in pixels, relative to the page.

Property of

Layer

Implemented in

JavaScript 1.2


pageY

The vertical position of the layer, in pixels, relative to the page.

Property of

Layer

Implemented in

JavaScript 1.2


parentLayer

The layer object that contains this layer, or the enclosing window object if this layer is not nested in another layer.

Property of

Layer

Read-only

Implemented in

JavaScript 1.2


releaseEvents

Sets the window or document to release captured events of the specified type, sending the event to objects further along the event hierarchy.

Method of

Layer

Implemented in

JavaScript 1.2

Syntax

releaseEvents(eventType)

Parameters

eventType

Type of event to be captured.

Description

If the original target of the event is a window, the window receives the event even if it is set to release that type of event. releaseEvents works in tandem with captureEvents, routeEvent, and handleEvent. For more information, see the Client-Side JavaScript Guide.


resizeBy

Resizes the layer by the specified height and width values (in pixels).

Method of

Layer

Implemented in

JavaScript 1.2

Syntax

resizeBy(width, height)

Parameters

width

The number of pixels by which to resize the layer horizontally.

height

The number of pixels by which to resize the layer vertically.

Description

This does not layout any HTML contained in the layer again. Instead, the layer contents may be clipped by the new boundaries of the layer. This method has the same effect as adding width and height to clip.width and clip.height.


resizeTo

Resizes the layer to have the specified height and width values (in pixels).

Method of

Layer

Implemented in

JavaScript 1.2

Description

This does not layout any HTML contained in the layer again. Instead, the layer contents may be clipped by the new boundaries of the layer.

Syntax

resizeTo(width, height)

Parameters

width

An integer representing the layer's width in pixels.

height

An integer representing the layer's height in pixels.

Description

This method has the same effect setting clip.width and clip.height.


routeEvent

Passes a captured event along the normal event hierarchy.

Method of

Layer

Implemented in

JavaScript 1.2

Syntax

routeEvent(event)

Parameters

event

The event to route.

Description

If a sub-object (document or layer) is also capturing the event, the event is sent to that object. Otherwise, it is sent to its original target.

routeEvent works in tandem with captureEvents, releaseEvents, and handleEvent. For more information, see the Client-Side JavaScript Guide.


siblingAbove

The layer object above this one in z-order, among all layers that share the same parent layer or null if the layer has no sibling above.

Property of

Layer

Read-only

Implemented in

JavaScript 1.2


siblingBelow

The layer object below this one in z-order, among all layers that share the same parent layer or null if layer is at the bottom.

Property of

Layer

Read-only

Implemented in

JavaScript 1.2


src

A URL string specifying the source of the layer's content. Corresponds to the SRC attribute.

Property of

Layer

Implemented in

JavaScript 1.2


top

The top property is a synonym for the topmost Navigator window, which is a document window or web browser window.

Property of

Layer

Read-only

Implemented in

JavaScript 1.2

Description

The top property refers to the topmost window that contains frames or nested framesets. Use the top property to refer to this ancestor window.

The value of the top property is

<object objectReference>
where objectReference is an internal reference.

Examples

The statement top.close() closes the topmost ancestor window.

The statement top.length specifies the number of frames contained within the topmost ancestor window. When the topmost ancestor is defined as follows, top.length returns three:

<FRAMESET COLS="30%,40%,30%">
<FRAME SRC=child1.htm NAME="childFrame1">
<FRAME SRC=child2.htm NAME="childFrame2">
<FRAME SRC=child3.htm NAME="childFrame3">
</FRAMESET>

visibility

Whether or not the layer is visible.

Property of

Layer

Implemented in

JavaScript 1.2

Description

A value of show means show the layer; hide means hide the layer; inherit means inherit the visibility of the parent layer.


zIndex

The relative z-order of this layer with respect to its siblings.

Method of

Layer

Implemented in

JavaScript 1.2

Description

Sibling layers with lower numbered z-indexes are stacked underneath this layer. The value of zIndex must be 0 or a positive integer.


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Last Updated: 11/16/98 12:56:36

Copyright (c) 1998 Netscape Communications Corporation