102
Chapter 11: Creating the User Interface
TI
-
89 / TI
-
92 Plus Developer Guide
Not for Distribution
Beta Version January 26, 2001
SCR_RECTs are defined as a union since the four bytes that define the
coordinates can also be represented by an unsigned long value. There is a
global SCR_RECT called
ScrRect
that defines the entire writeable region of the
screen. This includes the area normally reserved for an app’s menu but does
NOT include the status line. This area can be changed by interrupt routines in
response to keystrokes, and is not available to write to under normal
circumstances.
11.1.2. BITMAP
BITMAPs are used to store or retrieve rectangular regions on a window. They
can also be used for cursors (text or graphic), to do animation, to highlight areas
on the screen, and as images in menus (along with ICONs). A BITMAP is defined
as follows:
typedef struct {
WORD NumRows;
WORD NumCols;
BYTE Data[1];
} BITMAP;
A BITMAP must always have one or more rows and one or more columns so its
size is always at least 5 bytes long. The macro BITMAP_HDR_SIZE defines the
size of the BITMAP header (4 bytes). The
CalcBitmapSize
routine calculates the
size given a pointer to a BITMAP structure.
11.1.3. ICON
An ICON can be thought of as a fixed 16x16 bitmap. Since ICONs do not have
the BITMAP header, they cannot be used interchangeably with BITMAPs. They
are stored as an array of 16 unsigned shorts (WORD). ICONs are normally only
used in MENUs.
11.2. Windows
The Window routines provide a method to write to the screen of the calculator.
Each active window must have an associated WINDOW structure. The Window
routines use the WIN_RECT structure (defined in section
11.1.1. Screen/Window
Regions and Coordinates
) to define regions. Coordinates are all specified by the
WIN_COORDS type.
All screen IO must go through an opened window. Windows are opened with the
WinOpen
function. The windows in the system are linked together so that when
a window is closed, the system can walk the list of windows to determine which
windows are dirty and therefore need to be repainted. Hence, it is important for
an app to close its window when done to remove it from the linked-list of
To Next Page
Loading...
Need help?
General
