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The Window Class (ifm::Wstream)

Definition

The class ifm::Wstream represents a window that can be used for IO-operations and an associated graphic context. The graphic context defines the drawing color (default: black), line width (default: 1) and drawing mode (default: GXcopy) and affects any output operation. There are a number of member functions to change the state of the graphic context. With the window comes a Cartesian coordinate system where the origin sits in the lower left corner, i.e., the window resides in the all-positive quadrant. All output is internally buffered, so in order to make it visible on the display, this buffer has to be flushed. Many functions handle expose-events, that means if parts of the window get obscured, their content is redrawn automatically, as soon as they get visible (exposed) again.

Creation

ifm::Wstream w ( string str = "ifm:: Wstream");
	Creates a window with dimensions (512 x 512) and name str and positions it with upper left corner (100, 100) on the X display (your screen).
ifm::Wstream w ( int xsize, int ysize, string str = "ifm:: Wstream");
	Precondition: 10 $$ xsize, ysize $$ 2048. Creates a window with dimensions (xsize x ysize) and name str and positions it with upper left corner (100, 100) on the X display (your screen).
ifm::Wstream w ( int xpos, int ypos, int xsize, int ysize, string str);
	Precondition: 10 $$ xsize, ysize $$ 2048. Creates a window with dimensions (xsize x ysize) and name str and positions it with upper left corner (xpos, ypos) on the X display (your screen).
ifm::Wstream w ( ifm::Wstream);
	copy constructor.

ifm::Wstream&

w = ifm::Wstream

copy assignment.

Operations

int	w.xmin ()	returns minimal x-xoordinate in w.
int	w.xmax ()	returns maximal x-xoordinate in w.
int	w.ymin ()	returns minimal y-xoordinate in w.
int	w.ymax ()	returns maximal y-xoordinate in w.
ifm::Wstream&	& w << ifm::Drawable d
		d is drawn into w.
ifm::Wstream&	& w >> ifm::Getable d
		d is set from w.
ifm::Wstream&	w.flush ()	Buffer is flushed and all output drawn onto the display. Returns w.
ifm::Wstream&	w.endl ()	same as flush.
ifm::Wstream&	w.sync ()	Buffer is flushed, all output is drawn onto the display and all pending X-requests have been processed. Returns w.
ifm::Wstream&	w.clear ()	Clears the window and flushes the buffer. Returns w.
ifm::Wstream&	w.wait ( unsigned long microsec)
		Flushes buffer and waits for microsec microseconds.
bool	w.check_key ()	Returns true, iff there is a KeyRelease event pending.
bool	w.check_mouse ()	Returns true, iff there is a MouseMotion event pending.
bool	w.check_mouse_click ()
		Returns true, iff there is a ButtonRelease event pending.
int	w.get_key ()	Flushes buffer, waits for a KeyRelease event and returns the pressed key's ASCII-code. (65 $$  A, 97 $$  a). Expose events during the waiting period are handled.
void	w.get_mouse ( int& x, int& y)
		Flushes buffer, waits for a MouseMotion event and sets (x, y) to the mouse position. Expose events during the waiting period are handled.
int	w.get_mouse_click ( int& x, int& y)
		Flushes buffer, waits for a ButtonRelease event, sets (x, y) to the mouse position and returns the number of the pressed mouse button. (1 $$  left, 2 $$  middle, 3 $$  right). Expose events during the waiting period are handled.
void	w.wait_for_mouse_click ( int button = 0)
		Precondition: 0 $$ button $$ 3. Flushes buffer and waits until specified (0 $$  any) mouse button gets released. Expose events during the waiting period are handled.
ifm::Wstream&	w.set_draw_mode ( int m)
		Drawing mode is set to m. (Possible values include GXcopy, GXxor, GXand, ....) Returns w.
ifm::Wstream&	w.set_line_width ( int w)
		Precondition: w $$> 0. Drawing line width is set to w. Returns w.
int	w.number_of_colors ()
		Returns the number of available colors.
ifm::Wstream&	w.set_color ( int c)
		Precondition: 0 $$ c $$ number_of_colors(). Drawing color is set to c. The last two colors are always black and white, i.e., set_color(number_of_colors()) selects black. The rest is evenly divided by interpolating the following colors in order: red, orange, yellow, green, blue, magenta and purple. Returns w.

Example

The following code reads in a Circle c, draws c and its bounding square and then tracks the mouse pointer by drawing line segments between consecutive positions until finally a mouse button is pressed.

#include <IFM/window>

int main()
{
    // define a 200 x 200 pixel window  
    ifm::Wstream w(200, 200, "LibWindow-Example");

    // read in a circle
    ifm::Circle c;
    w >> c;
    
    // print c and its bounding square
    w << ifm::yellow << c << ifm::red
      << ifm::Rectangle(c.x() - c.r(), c.y() - c.r(),
                        c.x() + c.r(), c.y() + c.r())
      << ifm::flush;

    // tracks mouse pointer
    ifm::Point p_last(c.x(), c.y());
    do {
        int x, y;
        w.get_mouse(x, y);
        w << ifm::blue << ifm::Line(p_last.x(), p_last.y(), x, y) 
          << ifm::flush;
        p_last = ifm::Point(x, y);
    } while (!w.check_mouse_click());
    
    return 0;
}

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Next: Class declaration of ifm::Point

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Michael Hoffmann. Wed, November 17, 2004.