The Most Useful of the Graphics Functions.
MakeWindow(w, h);
Create a new graphics window, w pixels wide and h pixels tall.
MakeWindow(w, h, x, y);
Same as above, but also specifying x,y co-ordinates of the top left corner.
CloseWindow();
Make the graphics window go away permanently.
SetCaption(string s);
Set the caption in the graphics window’s title bar.
MoveTo(x, y);
Move the imaginary pen to co-ordinates x,y without drawing a line.
DrawLineTo(x, y);
Draw a line from the pen’s current position to co-ordinates x,y, and leave the pen there ready for
the next operation.
DrawPointAt(x, y);
Draw a single point at co-ordinates x,y. Remember that a single point isn’t necessarily a single
pixel; the current pen width determines the diameter.
DrawPointHere();
Draw a single point at the pen’s current position.
DrawRectangleXYWH(x, y, w, h);
Draw the outline of a rectangle, x,y are the co-ordinates of the top left corner, it is w pixles wide
and h pixels tall.
DrawRectangleXYXY(x1, y1, x2, y2);
Draw the outline of a rectangle, x1,y1 are the co-ordinates of the top left corner, and x2,y2 are
the co-ordinates of the bottom right corner.
FillRectangleXYWH(x, y, w, h);
FillRectangleXYXY(x1, y1, x2, y2);
The same as the draw-rectangle functions, except that a solid coloured-in rectangle is drawn, not
just the outline.
PenWidth(w);
Set the pen’s width (tip diameter).
PenColor(c);
PenColor(r1, g1, b1);
PenColor0255(r2, g2, b2);
Set the pen’s colour: c is a colour code; r1, g1, b1 are the red, green, blue components of the
colour in the range 0.0 to 1.0; r2, g2, b2 are the same but as integers in the range 0 to 255.
There are ten predefined colour codes: PEN_BLACK, PEN_RED, PEN_GREEN, PEN_BLUE,
PEN_YELLOW, PEN_MAGENTA, PEN_CYAN, PEN_ORANGE, PEN_PINK, and PEN_WHITE. For
anything else, the functions EncodeColor(r1, g1, b1) and EncodeColor0255(r2, g2,
b2) return a single representative int value.
WriteText(string s);
Draw the text string s in the graphics window, starting from the pen’s current position.
WriteTextf(string format, ...other parameters...);
For C programmers, this is identical to printf, except of course that it produces text in the
graphics window. For non-C programmers, learn how printf works.
SetFontSize(int sz);
Changes the font to be used by WriteText and WriteTextf. The size parameter corresponds
exactly to the sizes in standard windows applications, it is approximately the height in pixels of a
capital letter.
SetFontAttributes(int at);
Changes the font to be used by WriteText and WriteTextf. The attribute parameter may be any
combination of FONT_NORMAL, FONT_BOLD, FONT_ITALIC, FONT_UNDERLINE, and
FONT_STRIKEOUT. These values are integers that may be added together to produce combined
results, but not all options will be available for all fonts.
SetFontFace(int fa);
Changes the font to be used by WriteText and WriteTextf. The face parameter may be any one of
FONT_ROMAN, FONT_FIXED, FONT_SANS_SERIF. These correspond to the default
Times/Roman, Fixed-Width, and Dialogue fonts for the system.
SetFontFace(string fn);
Changes the font to be used by WriteText and WriteTextf. This gives more control if you know
the exact name of the desired font. The fontname parameter should be the exact name of any font
that is installed on the system, for example “Times New Roman”, “Comic Sans MS”, or
“Symbol”.
SetFontFaceAttributesSize(string fn, int at, int sz);
Sets all three font parameters at once. Much more efficient, because the intermediate unused
fonts do not have to be loaded.
GetNumberOfFonts()
Returns an int, being the number of fonts currently installed.
GetFontName(int n);
Returns a string, being the name of the nth of the currently installed fonts. N ranges from 0 to
number_of_fonts-1.
MeasureText(String s, int w, int h);
Works out how much space would be required to draw the text in the currently selected font, and
sets the w and h parameters (which must be int variables) to the width and height respectively, in
pixels.
CaptureEvents(int codes);
Notifies the system that you would like to be informed whenever an event of the indicated kind
occurs. The codes parameter may be any combination (formed by adding) of the following items:
MOUSE_CLICK_L, MOUSE_CLICK_R, KEY_TYPED, WINDOW_RESIZED, TIMER_SIGNAL. There
are many other kinds of events, see the full documentation for details. In particular, mouse events
with CLICK replaced by PRESS or RELEASE also exist. When a requested event occurs, your
program is not interrupted; it must explicitly ask for the next notification.
GetNextEvent(e, x, y, t, c);
All parameters must be int variables. If no event of a requested type has occurred since the last
call of this function, the function returns zero. If a requested event has occurred, its details are
stored in the five variable parameters, and 1 is returned. The notified event is deleted from the
event queue. E is set to the event kind (e.g. MOUSE_CLICK_L), X and Y are set to eventdependent values. T is the time at which the event occurred, measured in milliseconds since the
program started, and C is the Cause of the event: 0 means the user, 1 means it was program
generated.
For mouse-related events, x and y are the relevant co-ordinates. For size related events, x and y
are the width and height. For keyboard related events, x is the extended-ascii code for the
character. See the full documentation for the extended ascii codes.
Pause(t);
Suspends program execution for t seconds (t is a floating point number, so it does not have to be
a whole number of seconds). Typically, if GetNextEvent returns 0, a Pause of 1mS before
calling it again gives the system a chance to do other things and continue to run smoothly.
StartSingleTimer(t);
Requests that a TIMER_SIGNAL event should be generated automatically t seconds into the
future. T does not have to be a whole number.
StartRegularTimer(t);
Requests that a TIMER_SIGNAL event should be generated automatically t seconds into the
future, and again every t seconds thereafter. T does not have to be a whole number.
The complete documentation also contains information on many other
functions not listed here. In particular, the system gives support for
Dialogues (pop-up informative windows) of various kinds, Menus, Creating,
Reading, and Displaying image (.BMP) files, and multi-threaded processing.