Copyright	(c) Sebastiaan la Fleur, 2014
License	BSD3
Maintainer	sebastiaan.la.fleur@gmail.com
Stability	experimental
Portability	All
Safe Haskell	None
Language	Haskell98

EventLoop

Description

Complete import of all the exposed features of this library. The Eventloop package is used to express the communication between a Haskell server and a program modelling an 'IO Device'. This package contains an example implementation of how such a server would like when a browser is used as a graphical IO device also containing a mouse and keyboard. The InputEvent models the possible mouse and keyboard events. The OutputEvent models the possible graphical output events. There are also input and output systemmessages to communicate metadata between the Haskell server and the graphical IO browser. The starting point for this example implementation is start.

Synopsis

Documentation

start Source

Arguments

:: (a -> InputEvent -> ([OutputEvent], a))	Eventhandler from `InputEvent` to a list of `OutputEvent`. Also takes a variable of type a that holds the current state of information. Returns a changed variable of type a that will be called with next handler call.
-> a	The begin state of variable a.
-> IO ()

High-level function to start an eventloop. The eventloop takes an InputEvent and outputs an OutputEvent. Starting place for the example implementation of the eventloop. It takes a variable of type a to hold information in between handler calls.

type Pos = (Float, Float) Source

Type to express a position on the screen. It uses the format (x,y). As Canvas is used in the example implementation, remember that the lefttop corner is (0,0) and the leftbottom corner is (0, height of screen).

type Dimension = (Float, Float) Source

Type to express the dimension of an element. It uses the format (w,h).

type Element = [Char] Source

The name of a graphical element. It is used for Mouse to express the name of which element is clicked on.

data InputEvent Source

The central InputEvent type.

Constructors

InMouse Mouse	A `Mouse` event.
InKeyboard Keyboard	A `Keyboard` event.
InSysMessage SystemMessageIn	A `SystemMessage` event.

data Keyboard Source

Datatype to express the different Keyboard events.

Constructors

KeyPress KeyboardButton

type KeyboardButton = [Char] Source

Type to express how a KeyboardButton is modelled.

data Mouse Source

Datatype to express the different Mouse events. The Pos expresses where on the screen the event happened. The Element expresses on which top element on screen the event happened. The Element value is the name of the GObject.

Constructors

MouseClick MouseButton Pos Element	Expresses a complete `MouseClick` consisting of a `MouseUp` and a `MouseDown`.
MouseUp MouseButton Pos Element	Expresses when a `MouseButton` moves upward.
MouseDown MouseButton Pos Element	Expresses when a `MouseButton` is pushed down.

Instances

Show Mouse

data MouseButton Source

The MouseButton on the mouse.

Constructors

MLeft
MRight
MMiddle

Instances

Show MouseButton

data SystemMessageIn Source

The different possible SystemMessageIns.

Constructors

Setup	A request for the `Setup`. This should be generated when the connection to a client is made. The answer should be a `CanvasSetup` message.
Background	A request for the `Background`. This should be generated when the connection to a client is made. The answer could be the background of the graphical application.
Time	When a timer has been spawn, each 'tick' a `Time` is generated by the client to let the server know it is time.

data OutputEvent Source

The central OutputEvent type.

Constructors

OutGraphical Graphical
OutSysMessage [SystemMessageOut]

data SystemMessageOut Source

The different possible SystemMessageOuts.

Constructors

CanvasSetup Dimension	Answer to the `Setup` containing the dimensions of the canvas that will be used.
Timer Bool	Request to create a timer at the clientside that will generate a `Time` message each 'tick'.
Close	A request for the client to completely close the connection to the server.

data Graphical Source

Graphical Responses Out

Constructors

Draw GObject Groupname	Draw the graphical object with the given groupname.
MoveGroup Groupname Pos Relative	Move an entire group to a new position possibly relative to the old position.
MoveElement Name Pos Relative	Move a single element to a new position possibly relative to the old position.
RemoveGroup Groupname	Remove a group
RemoveElement Name	Remove an element.

data GObject Source

A general graphical object containing the common attributes of each Primitive.

Constructors

GObject	Graphical Object
Fields name :: Name Name of the graphical object/element prim :: Primitive The graphical primitive that should be drawn children :: [GObject] Children of the graphical primitive. Can be used to create composited graphical components containing multiple `GObject`s.
Container	A container for Graphical Objects
Fields children :: [GObject] Children of the graphical primitive. Can be used to create composited graphical components containing multiple `GObject`s.

Instances

Show GObject

data Primitive Source

Primitive graphical structures

Constructors

Text	The text graphical primitive
Fields edgeColor :: Color `Color` of the edges of the text edgeThickness :: Float The edge thickness of the text (Should be 1 most of the time) color :: Color The `Color` of the fill of the text position :: Pos The position on the screen of the text size :: Float The height of the text in pixels font :: Font Which font to be used text :: [Char] The actual text to be displayed fromCenter :: Bool Is the position the topleft corner of the text or the center of the text
Line	The line graphical primitive
Fields edgeColor :: Color `Color` of the edges of the text edgeThickness :: Float The edge thickness of the text (Should be 1 most of the time) positions :: [Pos] The list of positions the line should go through. A line will be drawn from point 1 to point 2 to point...
Rect	The rectangle graphical primitive
Fields edgeColor :: Color `Color` of the edges of the text edgeThickness :: Float The edge thickness of the text (Should be 1 most of the time) color :: Color The `Color` of the fill of the text position :: Pos The position on the screen of the text dimensions :: Dimension The dimensions of the rectangle
Arc	The arc graphical primitive. This is the part of a circle. When startAng=0 and endAng=360 you get a full circle.
Fields edgeColor :: Color `Color` of the edges of the text edgeThickness :: Float The edge thickness of the text (Should be 1 most of the time) color :: Color The `Color` of the fill of the text position :: Pos The position on the screen of the text radius :: Float The radius of the arc startAng :: Float The starting angle of the arc in degrees. endAng :: Float The ending angle of the arc in degrees.

Instances

Eq Primitive
Show Primitive

type Name = [Char] Source

The name of a graphical object. Another synonym in the package used for this is Element.

type Groupname = [Char] Source

The groupname of a set of graphical objects.

type Color = (Float, Float, Float) Source

The color expressed in (red, green, blue) code where each value is between 0 <= 255.

type Font = [Char] Source

The font associated with a Text primitive.

type Relative = Bool Source

A boolean expressing if an event should be carried out relative to the old situation or to the absolute situation Example of this is when moving an element. Should the move be relative to the old Pos or to the absolute Pos on the screen.

outSingle :: OutputEvent -> IO () Source

Outputs a single OutputEvent. Right now only Draw events are implemented. The server automatically determines the maximum Dimensions of the picture and sends a Setup containing those Dimensions.