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The Window Manager provides what is commonly known as theWIMP environment. Programs that run under the control of the Wimp can also be referred to as Applications or Tasks. Within the Window Manager section, the words Program, Application and Task should be treated as synonyms.
Like As in most modern Operating System Systems with window environments, the use of windows are used to contain and display information to the user. The display and updating of windows is shared between the application and the Window Manager.
The Window Manager and the application communicates communicate by way of a message-passing scheme. The Window Manager sends messages when something needs updating. Applications must be able to respond to these messages so that they can update the necessary windows.
Depending on the complexity of the application, much of the work required to keep windows windows’ contents up to date can be delegated to the Wimp.
Another Icons constitute another important feature of the Window Manager Manager. are Icons. An Icon is a rectangular area within a window whose contents can be one of the following: text, a sprite1, text & a sprite or User-drawn graphic.
The table below details which type of icon can be updated automatically.
Icon Type | Responsible for Update |
---|---|
Text | Wimp (Automatic) |
Sprite | Wimp (Automatic) |
Text & Sprite | Wimp (Automatic) |
User-Drawn Graphic | Application |
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It will come as no surprise that Menus are an integral part of wholeRISC OS Window Manager experience. Unlike many other Operating Systems, Menus under RISC OS are pop-up rather than pull-down. Menus are also opened by pressing the dedicated menu menu-button button on the mouse.
In Menus addition are to context-sensitive: this, they menus depend can upon be context-sensitive. i.e. the menu that appears is appropriate to the position of the mouse when the menu was is opened.
Nested Menus Windows may are be also nested. available, That that is, where a one menu entry can lead to another menu, recursively to any desired ‘depth’. depth. A ‘cute’ useful feature is that each menu (or leaf as it’s it is also known) is a window in its own right and thus can be moved while it is open.
RISC OS uses the co-operative method multi-tasking. of By Multi-tasking. calling the Wimp’s polling routine a task hands over control to the Wimp, which may pass on control to other tasks. Each application gains regains control on return from the call to the Wimp’s polling routine.
To ensure a smooth running Window Environment experience, each application must not consume too much time between Polling, otherwise other tasks will be prevented from running.
However, it is possible to enforce pre-emption pre-emptive2 multi-tasking for non-Wimp applications by running them within a task window.
Each application application, when it has control control, has is given the perception illusion that it alone has access to the application workspace. For this to occur, some memory management must be accomplished in advance of switching between Applications.
Application workspace starts at &8000.
The amount of workspace that an application has, has is set before its starts up.
As described above, each application must be able to respond to the messages from the Window Manager to ensure it can update its windows and their contents correctly (if applicable). it has any).
In addition to this, applications can communicate with each other. Again, this is provided by a powerful message-passing scheme.
fn1. A Sprite is the name given to the default nativeRISC OS pixel graphics file. It can be thought of as the RISC OS equivalent of a BitMap File(BMP) on Windows.
2 Pre-emption is a method of multi-tasking whereby the the OS switches takes control to from each applications. An application at will arbitrary in times, general without not its know prior in knowledge. advance when this will happen.