WindowManager Icons (changes)

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WindowManager

» Technical Details

» Icons

Overview

An icon is a rectangular area of a window’s workspace. It can be used to display either text, or a sprite, or both text and sprite, automatically. It needs the help of the application if it is to display something else to the user; for example, a graph displaying share prices.

Icons can also be writable. That is, the Wimp will deal with user input, and also handle certain editing functions such as Delete and left and right cursor movements.

Icon Definition

Icons are defined by 32 bytes of data and 12 bytes of data named [[Icon Data]. The icon’s dimensions must also be provided in OS units. A full detailed description of an icon can be found in theIcon Data. The icon’s dimensions must also be provided in OS units. A full detailed description of an icon can be found in the Icon Block page. A quick overview can be found below.

Icons have handles that are unique within the window they reside in. Thus, an icon can be uniquely defined by it’s window/icon handles.

Note: User icon handles begin from zero, whereas system area icons (close, title bar, etc) have negative icon numbers.

Dimensions

Two sets of x and y co-ordinates define the size of the icon within a window.

Icon Flags

Thirty two bytes of data are used to specify numerous settings for the icon, such as Border type, horizontal and vertical alignment, colour, font data, how the button responds to button clicks and whether the icon needs help from the application to be redrawn correctly.

The full detailed description is available in the Icon Flags page.

Icon Data

The Icon Data are divided into three three words (4 bytes each). Icons can be configured to use either Direct or Indirect data for the following attributes of an icon:

If the data is set as Direct, a 12 character limit is imposed.

If the data is set as Indirect, then there is no limit as to how many character can be used to define the above attributes.

Icon Creating and Deleting

There are three ways that an icon can be created. They are:

Wimp_CreateIcon and Wimp_DeleteIcon are used to create and delete an icon. Two important side effects of using these calls are:

Another method of deleting an icon is to use Wimp_SetIconState. Bit 23 of the window flags when using this call must be set, to ensure that the icon is deleted and not simply redrawn on top of itself.

Icon Selection

Icons can be defined to be part of an Exclusive Selection Group(ESG) group. That is, only one icon per ESG can be selected at a given time. The default is for an icon not to be part of any ESG. Note: These are often referred to as Radio Buttons.

When an icon has been selected using the Wimp, the icon colours are inverted, and any other icons in the ESG will be deselected.

Mouse Button Differences

An icon can be disabled so it cannot be selected. In this instance, the Wimp shades the icon to denote that it cannot be selected.

Icon Sprites

Sprites used in an icon can come from the following sources:

However, the use of system-sprites is not recommended as certain operations cannot be performed on them; for example, scaling and colour translation.

Wimp sprites are useful because one copy can be used by many applications.

User-sprites are used when sprites unique to the application are required.

The Wimp-sprite area is divided in two parts: a permanent part held in ROM and a transient expandable part held in the RMA.

The Wimp_SpriteOp allows automatic access to Wimp Sprites by name. This is a read-only access call, and the only operation allowed on Wimp sprites that can change them is the MergeSpriteFile (reason code 11) or the equivalent *IconSprites command.

See also

• Wimp_CreateIcon
• Icon Block
• Icon Flag
• Icon Data
• Wimp_GetPointerInfo
• Wimp_PlotIcon
• Wimp_SpriteOp
• *IconSprites

For a detailed description on defining the appearance and size of sprites, see the Sprites and Icons? section in the RISC OS Style Guide.