Slide 9.6: Line-by-line anatomy of Menu.c (cont.)

Line-by-line Anatomy of Menu.c (Cont.)


  case  menuEvent:

The menu routine MenuHandleEvent( ) sends this event:

when the user selects an item from a pull-down menu,
when the user selects a menu command using the command stroke followed by an available command; for example, Command-C for copy, or
when the user taps one of the buttons on the command toolbar and the button is set up to generate a menuEvent.

For this event, the data field contains the following structure:

  struct  menu {
    UInt16  itemID;        // Item ID of the selected menu command
  }  menu;


  MenuEraseStatus( NULL );

This function void MenuEraseStatus( MenuBarType *menuP ) erases the menu command status.

menuP

MenuBarType

NULL

When the user selects a menu command using the command keystroke, the command toolbar or status message is displayed at the bottom of the screen. MenuEraseStatus erases the toolbar or status message.


  FldDelete( fld, 0, FldGetTextLength( fld ) );

This function void FldDelete( FieldType *fldP, UInt16 start, UInt16 end ) deletes the specified range of characters from the field and redraws the field.

fldP: Pointer to the field object (FieldType structure) to delete from.
start: The beginning of the range of characters to delete given as a valid byte offset into the field's text string.
end: The end of the range of characters to delete given as a valid byte offset into the field's text string. If you pass a value that is greater than the number of bytes in the field, all characters in the field are deleted.