User interface

18 User interface

Contents

18.1 Cursors: the 'cursor' property

Value:	[ [<uri> ,]* [ auto \| crosshair \| default \| pointer \| move \| e-resize \| ne-resize \| nw-resize \| n-resize \| se-resize \| sw-resize \| s-resize \| w-resize\| text \| wait \| help ] ] \| inherit
Initial:	auto
Applies to:	all elements
Inherited:	yes
Percentages:	N/A
Media:	visual, interactive

This property specifies the type of cursor to be displayed for the pointing device. Values have the following meanings:

auto: The UA determines the cursor to display based on the current context.
crosshair: A simple crosshair (e.g., short line segments resembling a "+" sign).
default: The platform-dependent default cursor. Often rendered as an arrow.
pointer: The cursor is a pointer that indicates a link.
move: Indicates something is to be moved.
e-resize, ne-resize, nw-resize, n-resize, se-resize, sw-resize, s-resize, w-resize: Indicate that some edge is to be moved. For example, the 'se-resize' cursor is used when the movement starts from the south-east corner of the box.
text: Indicates text that may be selected. Often rendered as an I-bar.
wait: Indicates that the program is busy and the user should wait. Often rendered as a watch or hourglass.
help: Help is available for the object under the cursor. Often rendered as a question mark or a balloon.
<uri>: The user agent retrieves the cursor from the resource designated by the URI. If the user agent cannot handle the first cursor of a list of cursors, it should attempt to handle the second, etc. If the user agent cannot handle any user-defined cursor, it must use the generic cursor at the end of the list.

P { cursor : url("mything.cur"), url("second.csr"), text; }

18.2 User preferences for colors

In addition to being able to assign pre-defined color values to text, backgrounds, etc., CSS2 allows authors to specify colors in a manner that integrates them into the user's graphic environment. Style rules that take into account user preferences thus offer the following advantages:

They produce pages that fit the user's defined look and feel.
They produce pages that may be more accessible as the current user settings may be related to a disability.

The set of values defined for system colors is intended to be exhaustive. For systems that do not have a corresponding value, the specified value should be mapped to the nearest system attribute, or to a default color.

The following lists additional values for color-related CSS attributes and their general meaning. Any color property (e.g., 'color' or 'background-color') can take one of the following names. Although these are case-insensitive, it is recommended that the mixed capitalization shown below be used, to make the names more legible.

ActiveBorder: Active window border.
ActiveCaption: Active window caption.
AppWorkspace: Background color of multiple document interface.
Background: Desktop background.
ButtonFace: Face color for three-dimensional display elements.
ButtonHighlight: Dark shadow for three-dimensional display elements (for edges facing away from the light source).
ButtonShadow: Shadow color for three-dimensional display elements.
ButtonText: Text on push buttons.
CaptionText: Text in caption, size box, and scrollbar arrow box.
GrayText: Grayed (disabled) text. This color is set to #000 if the current display driver does not support a solid gray color.
Highlight: Item(s) selected in a control.
HighlightText: Text of item(s) selected in a control.
InactiveBorder: Inactive window border.
InactiveCaption: Inactive window caption.
InactiveCaptionText: Color of text in an inactive caption.
InfoBackground: Background color for tooltip controls.
InfoText: Text color for tooltip controls.
Menu: Menu background.
MenuText: Text in menus.
Scrollbar: Scroll bar gray area.
ThreeDDarkShadow: Dark shadow for three-dimensional display elements.
ThreeDFace: Face color for three-dimensional display elements.
ThreeDHighlight: Highlight color for three-dimensional display elements.
ThreeDLightShadow: Light color for three-dimensional display elements (for edges facing the light source).
ThreeDShadow: Dark shadow for three-dimensional display elements.
Window: Window background.
WindowFrame: Window frame.
WindowText: Text in windows.

For example, to set the foreground and background colors of a paragraph to the same foreground and background colors of the user's window, write the following:

P { color: WindowText; background-color: Window }

18.3 User preferences for fonts

As for colors, authors may specify fonts in a way that makes use of a user's system resources. Please consult the 'font' property for details.

18.4 Dynamic outlines: the 'outline' property

At times, style sheet authors may want to create outlines around visual objects such as buttons, active form fields, image maps, etc., to make them stand out. CSS2 outlines differ from borders in the following ways:

Outlines do not take up space.
Outlines may be non-rectangular.

The outline properties control the style of these dynamic outlines.

'outline'

Value:	[ <'outline-color'> \|\| <'outline-style'> \|\| <'outline-width'> ] \| inherit
Initial:	see individual properties
Applies to:	all elements
Inherited:	no
Percentages:	N/A
Media:	visual, interactive

'outline-width'

Value:	<border-width> \| inherit
Initial:	medium
Applies to:	all elements
Inherited:	no
Percentages:	N/A
Media:	visual, interactive

'outline-style'

Value:	<border-style> \| inherit
Initial:	none
Applies to:	all elements
Inherited:	no
Percentages:	N/A
Media:	visual, interactive

'outline-color'

Value:	<color> \| invert \| inherit
Initial:	invert
Applies to:	all elements
Inherited:	no
Percentages:	N/A
Media:	visual, interactive

The outline created with the outline properties is drawn "over" a box, i.e., the outline is always on top, and doesn't influence the position or size of the box, or of any other boxes. Therefore, displaying or suppressing outlines does not cause reflow.

The outline is drawn starting just outside the border edge.

Outlines may be non-rectangular. For example, if the element is broken across several lines, the outline is the minimum outline that encloses all the element's boxes. In contrast to borders, the outline is not open at the line box's end or start, but is always fully connected.

The 'outline-width' property accepts the same values as 'border-width'.

The 'outline-style' property accepts the same values as 'border-style', except that 'hidden' is not a legal outline style.

The 'outline-color' accepts all colors, as well as the keyword 'invert'. 'Invert' is expected to perform a color inversion on the pixels on the screen. This is a common trick to ensure the focus border is visible, regardless of color background.

The 'outline' property is a shorthand property, and sets all three of 'outline-style', 'outline-width', and 'outline-color'.

Note that the outline is the same on all sides. In contrast to borders, there is no 'outline-top' or 'outline-left' property.

This specification does not define how multiple overlapping outlines are drawn, or how outlines are drawn for boxes that are partially obscured behind other elements.

Note. Since the focus outline does not affect formatting (i.e., no space is left for it in the box model), it may well overlap other elements on the page.

Here's an example of drawing a thick outline around a BUTTON element:

BUTTON { outline-width : thick }

Scripts may be used to dynamically change the width of the outline, without provoking reflow.

18.4.1 Outlines and the focus

Graphical user interfaces may use outlines around elements to tell the user which element on the page has the focus. These outlines are in addition to any borders, and switching outlines on and off should not cause the document to reflow. The focus is the subject of user interaction in a document (e.g., for entering text, selecting a button, etc.). User agents supporting the interactive media group must keep track of where the focus lies and must also represent the focus. This may be done by using dynamic outlines in conjunction with the :focus pseudo-class.

For example, to draw a thick black line around an element when it has the focus, and a thick red line when it is active, the following rules can be used:

:focus  { outline: thick solid black }
:active { outline: thick solid red }

18.5 Magnification

The CSS working group considers that the magnification of a document or portions of a document should not be specified through style sheets. User agents may support such magnification in different ways (e.g., larger images, louder sounds, etc.)

When magnifying a page, UAs should preserve the relationships between positioned elements. For example, a comic strip may be composed of images with overlaid text elements. When magnifying this page, a user agent should keep the text within the comic strip balloon.

Document created the 04/02/2006, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/css-rf-ui.html

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References

CSS specifications : https://www.w3.org

These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.

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