<LAYER>...</LAYER>
Description
This description is taken from the Netscape description of the element.
With this element you can create several layers of content on a page. These
layers can be stacked on top of each other, showing parts of underlying layers
through non-occupied space. You can control the order of the layers, the
position on the page and if a layer is visible or not.
The difference between the LAYER element and the
ILAYER element is that a layer defined with the
LAYER element is positioned relative to the containing layer, or the document
if it is the top layer. The position of a layer defined by an ILAYER element is
the natural position in the flow of the text, just like an image.
Attributes
ABOVE
This attribute controls the stacking of the layers, in relation to other
layers. With it you specify which layer is positioned immediately above the
layer being defined. The value supplied must be the NAME of that layer.
The attributes ABOVE, BELOW and Z-INDEX are mutually exclusive, so if you use
this attribute, the attributes BELOW and Z-INDEX cannot be used.
BACKGROUND
Supply an image that is used as the background of the layer. If the space that
the layer occupies is larger than the image, the image is tiled to fill up the
used space. You can use images in the GIF and JPEG format.
If you use an transparent image the transparent parts will be shown in the
background color, or the HTML elements of underlying layers.
BELOW
This attribute controls the stacking of the layers, in relation to other
layers. With it you specify which layer is positioned immediately below the
layer being defined. The value supplied must be the NAME of that layer.
The attributes ABOVE, BELOW and Z-INDEX are mutually exclusive, so if you use
this attribute, the attributes ABOVE and Z-INDEX cannot be used.
BGCOLOR
Set the background color of the layer, hiding all elements of layers below it.
See the page Using colors for a description on
specifying colors.
CLIP
This attribute determines the clipping rectangle of the layer, that is, it
defines the boundaries of the visible area of the layer.
The value is a set of 4 numbers, indicating in order, the left value, the top
value, the right value, and the bottom value. The left and right values are
specified as pixels in from the left, while the top and bottom values are
specified as pixels down from the top of the containing document or layer.
Each of the 4 values are numbers of pixels. You can also specify the value as a
set of 2 numbers, in which case the left and top values default to 0. For
example:
clip="10,20"
is equivalent to
clip="0,0,10,20"
If you do not supply this attribute, the clipping rectangle of a layer is
determined by the values of WIDTH and HEIGHT. By default, a layer expands to
contain all of its content.
HEIGHT
The HEIGHT parameter determines the initial height of the clipping region of
the layer. The height can be expressed as an integer pixel value, or as a
percentage of the height of the containing layer (or the window for a top-level
layer.)
Note however that if the contents of the layer do not fit inside the specified
height, the layer will expand its height to include all its contents.
The main purpose of the HEIGHT attribute is to act as the reference height for
attribute values in its children layers that are specified using percentages.
This attribute is optional; by default, the layer height is the minimum height
that contains all the layer contents.
ID
Description of the ID attribute
LEFT
The LEFT parameter specifies the horizontal position of the top left corner of
the layer within its containing layer, or within the document if it is at the
top level. The attribute is optional. The default value is the horizontal
position of the element's contents as if they were not enclosed in a layer.
For positioned layers the origin is the upper-left-hand corner of the document
or containing layer, with coordinates increasing downwards and to the right.
NAME
The NAME parameter is an identification element for the layer. The NAME must
begin with an alphabetic character. (The NAME parameter is the same as the ID
parameter.)
You can use the layer's name to refer to the layer from within HTML and
external scripting languages such as JavaScript.
This attribute is optional; by default, layers are unnamed.
ONBLUR
This is an event handler. The value must be a function or inline Javascript
code. The onBlur handler is invoked when the layer loses keyboard focus.
ONFOCUS
This is an event handler. The value must be a function or inline Javascript
code. The onFocus handler is invoked the layer gets keyboard focus.
ONLOAD
This is an event handler. The value must be a function or inline Javascript
code. The onLoad handler is invoked when the layer is loaded, regardless of
whether the layer is visible or not.
ONMOUSEOUT
This is an event handler. The value must be a function or inline Javascript
code. The onMouseOut handler is invoked when the mouse leaves the layer.
ONMOUSEOVER
This is an event handler. The value must be a functions or inline Javascript
code. The onMouseOver handler is invoked when the mouse enters the layer.
PAGEX
The PAGEX parameter specifies the horizontal position of the top left corner of
the layer relative to the enclosing document (rather than the enclosing layer.)
PAGEY
The PAGEY parameter specifies the vertical position of the top left corner of
the layer relative to the enclosing document (rather than the enclosing layer.)
SRC
The SRC parameter specifies an external file that contains HTML-formatted text
to be displayed in this layer.
The file specified by SRC can contain an arbitrary HTML document.
The source file can include JavaScript code. Any LAYER elements in the source
file will be treated as child layers of the layer for which the source file is
providing content.
The SRC parameter is particularly useful if you want to dynamically change the
content of the layer. For example, a restaurant might have a web page that uses
a layer to describe the special meal of the day. Each morning, after the chef
has decided what the special is going to be for the day, he or she quickly
edits the file "special.htm" to describe the meal.
The chef doesn't have to re-write the entire page just to update the
information about the special of the day.
TOP
The TOP parameter specifies the vertical position of the top left corner of the
layer within its containing layer, or within the document if it is at the top
level. This attribute is optional. The default value is the vertical position
of the element's contents as if they were not enclosed in a layer.
For positioned layers the origin is the upper-left-hand corner of the document
or containing layer, with coordinates increasing downwards and to the right.
VISIBILITY
The VISIBILITY parameter determines whether the layer is visible or not. A
value of HIDE hides the layer; SHOW shows the layer; INHERIT causes the layer
to have the same visibility as its parent layer. For top level layers (that is,
layers that are not nested inside other layers, a value of INHERIT has the same
effect as SHOW since the body document is always visible.)
This attribute is optional. By default, a layer has the same visibility as its
parent layer, that is, the value of the VISIBILITY attribute is INHERIT.
Remember that even if the visibility of a layer is set to SHOW, you will
only be able to see the layer if there are no other visible, opaque layers
stacked on top of it.
WIDTH
The WIDTH parameter determines the width of the layer. The width can be
expressed as an integer pixel value, or as a percentage of the width of the
containing layer.
Note however that if the elements that cannot be wrapped, such as images,
extend beyond the width specified, the actual width of the contents of the
layer will expand accordingly.
This attribute is optional; by default, the layer contents wrap at the right
boundary of the enclosing layer.
Z-INDEX
This attribute controls the stacking of the layers, in relation to other
layers. With it you specify at which position in the stack of layers you want
to put the layer that you are creating. The number you supply is relative to
the parent layer, that is, the layer in which this layer is defined. A positive
value stacks the layer above the parent layer, a negative value below it.
The attributes ABOVE, BELOW and Z-INDEX are mutually exclusive, so if you use
this attribute, the attributes ABOVE and BELOW cannot be used.
Examples