Drawing API

Compounds
struct	gdm_point
Defines
#define	GDM_LINE   0
#define	GDM_POLYGON   1
#define	GDM_SEGMENT   2
Typedefs
typedef gdm_point	gdm_point
Functions
void	gdm_draw_point (gdm_display *dp, short x, short y)
void	gdm_draw_points (gdm_display *dp, gdm_point *pts, unsigned short npoints)
void	gdm_draw_line (gdm_display *dp, short x1, short y1, short x2, short y2)
void	gdm_draw_lines (gdm_display *dp, gdm_point *pts, unsigned short npoints, short mode)
void	gdm_fill_rectangle (gdm_display *dp, short x, short y, unsigned short width, unsigned short height)

Detailed Description

The drawing API allows to draw lines, circles, paint characters on the screen. The drawing operations are made in the display manager bitmap which is in memory. Once the drawing is finished, the bitmap must be synchronized with the LCD screen (see gdm_refresh in Management and Control API).

Each drawing operation is made using a graphical context. The graphical context defines the logical operation which is used when drawing the item (see gdm_set_gc in Management and Control API). The following operations are supported:

GDM_PLOT_OR

In the OR mode, a logical or is used to write the item in the bitmap. This mode can be used to force the item to appear on the screen.

GDM_PLOT_XOR

In the XOR mode, a logical xor is used thus providing an inversion of the dots corresponding to the item. This mode is in general used to provide reverse video effects and can be used to show a cursor.

GDM_PLOT_AND

In the AND mode, a logical and is used. It can be used to clear the screen.

All the drawing operation implement a clipping mechanism to restrict the drawing to the LCD screen and optionally a region that you specify. The coordinates can be outside of the LCD screen and outside of the clipping region. Drawing will take place only within the clipping region. For example, it is safe to do:

      static gdm_display display;
      ...
      / * Clear screen. * /
      gdm_set_gc (&display, GDM_PLOT_AND);
      gdm_fill_rectangle (&display, -100, -200, 1024, 2048);

      / * Draw a line crossing the screen. * /
      gdm_set_gc (&display, GDM_PLOT_OR);
      gdm_draw_line (&display, -100, -200, 1024, 2048);
    

Define Documentation

#define GDM_LINE   0

Draw a continuous line. Definition at line 443 of file display.h.

#define GDM_POLYGON   1

Draw a continuous closed line (polygon). Definition at line 446 of file display.h.

#define GDM_SEGMENT   2

Draw several segments. Definition at line 449 of file display.h.

Typedef Documentation

typedef struct gdm_point gdm_point

Representation of a point.

Function Documentation

void gdm_draw_line (  gdm_display *    dp, short    x1, short    y1, short    x2, short    y2 )

Draw a line between two points. Draw a line between x1, y1 and x2, y2. The line is clipped to the display window and using the current clipping region. The points of the line are drawn using the current graphical context (or, and, xor). Parameters: dp  Display Manager x1  X coordinate of first point y1  Y coordinate of first point x2  X coordinate of second point y2  Y coordinate of second point See also: gdm_draw_lines, gdm_refresh

void gdm_draw_lines (  gdm_display *    dp, gdm_point *    pts, unsigned short    npoints, short    mode )

Draw a continuous line, some segments or a polygon. Draw a continuous line, a set of segments or a polygon based on the list of points specified in pts. The mode parameter controls the drawing mode: GDM_LINE A continuous line is drawn between each point of the list. GDM_POLYGON The continous line is closed to form a polygon GDM_SEGMENT The list of points represents couples of points to define one or several segments. npoints / 2 segments are drawn. Parameters: dp  Display Manager pts  Table of points to display npoints  Number of points in the table mode  Mode to display the line See also: gdm_draw_line, gdm_refresh

void gdm_draw_point (  gdm_display *    dp, short    x, short    y )

Draw a point on the graphic display. The point at x, y is plotted using the current color and graphic operation. The point is clipped to the current display clipping region. The point is plotted in the bitmap only and a display refresh is necessary to make the change visible. Parameters: dp  Display manager x  X coordinate y  Y coordinate See also: gdm_draw_points, gdm_refresh

void gdm_draw_points (  gdm_display *    dp, gdm_point *    pts, unsigned short    npoints )

Draw a list of points on the graphic display. The points specified in the table pts are plotted using the current color and graphic operation. The points are clipped to the current display clipping region. The point is plotted in the bitmap only and a display refresh is necessary to make the change visible. Parameters: dp  Display manager pts  Table of points to display npoints  Number of points to print See also: gdm_draw_point, gdm_refresh

void gdm_fill_rectangle (  gdm_display *    dp, short    x, short    y, unsigned short    width, unsigned short    height )

Fill a rectangle with current gc mode. The rectangle defined by x, y, width, height is filled with the current graphical context. The rectangle is clipped to the display and to the optional clipping region. Parameters: dp  Display Manager x  X coordinate y  Y coordinate width  Width of rectangle height  Height of rectangle See also: gdm_refresh