Documentation

Text file

Bitmap file

No input

Generated every refresh of the eventhandler

Keyboard key x is pressed down; ' ' for space, \t for tab, \n for enter

Left mouse button is pressed at location (x,y)

Left mouse button is released at location (x,y)

Mouse pointer is moved to location (x,y)

Mouse is double-clicked at location (x,y)

Prompt (windowname,textbox content)

Content returned from textbox in promptwindow with windowname

Panel buttonId [(controlId, value)]

Event indicating that in the panel, the button with buttonId is pressed and that at the time the controls had the given value

Note: the list is ordered by controlId

• For checkboxes a value "Y" indicates that they are checked and a value of "N" indicates they are unchecked
• Buttons have no controlstate

File name content

The found file with given name, and found content

Indicates if saving of file at filepath succeeded

Response to GetTime

The time from midnight, 0 <= t < 86401s (because of leap-seconds) It has a precision of 10^-12 s. Leap second is only added if day has leap seconds

Invalid / Unknown input

Command to change the drawing mode

Pictures returned from the eventhandler will normally be drawn on the screen and in a buffer, so that the window can be quickly redrawn.

A DrawOnBuffer command can change this default behavior, If the parameter is False, pictures are only drawn on the screen. If the parameter is True, drawing will be down on both the buffer and the screen. This can be useful in response to MouseMotion Events.

Example of rubber banding in line drawing program:

 handler (p1:ps) (MouseDown p2)
   = (p1:ps, [DrawOnBuffer False, DrawPicture (Color black $ Line [p1,p2])])
 handler (p1:ps) (MouseMotion p2)
   = (p1:ps, [DrawOnBuffer False, DrawPicture (Color black $ Line [p1,p2])])
 handler (p1:ps) (MouseUp p2)
   = (p2:p1:ps, [DrawOnBuffer True, DrawPicture (Color black $ Line [p1,p2])])

Draw the picture

GraphPrompt (windowName,info)

Create a graphical prompt window which asks the user to enter a string in a textbox. The user can be informed about valid entries through the info field.

Note: the entered string is recorded as the following input event: 'Prompt (windowName,enteredText)'

Command to create a panel with the given panel content, must be actived with the PanelUpdate command

PanelUpdate visible [(identifier, value)]

Command to change visibility and the content of a panel.

Note: not all controls need to be listed, the order can be arbitrary

• For checkboxes, a value "Y" checks them, a value "N" unchecks them
• Buttons can not be altered

Clear the screen and buffer

ReadFile fileName default

Read the file of the given filetype at the filename, if it fails The default content is returned

Note: the read file command generates following input event: 'File fileName content'

SaveFile fileName content

Save the file of the given filetype at the filename location

Note: the save file command generates following input event: Save fileName success (True/False)

Request the current time of day in seconds

Note: the gettime command generates the following input event: 'Time timeOfDay'