Liren Large Software Subsidy 7/07.iso/c/c100/3.ddi/BGICLA.ZIP/ARC.CPP

C/C++ Source or Header | 1990-06-24 | 5.9 KB | 205 lines

/**************************************************************************
    Listing 13  -   ARC.CPP

    Written by Kevin D. Weeks, April 1990
    Released to the Public Domain
*/

#include "arc.hpp"

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
    Constructor - creates an empty instance.
*/
Arc::Arc(void)
{
    struct linesettingstype line_type;

    // set attributes to 0 or current BGI defaults
    start_angle = 0;
    end_angle = 0;
    radius = 0;
    getlinesettings(&line_type);
    width = (line_widths)line_type.thickness;
    color = (COLORS)getcolor();
    visible = FALSE;
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
    Constructor - since the "copy constructor", Arc(const Arc &source),
    won't accept a pointer easily so we define a separate pointer
    constructor for convenience' sake.
*/
Arc::Arc(const Arc *source)
{
    start_angle = source->start_angle;
    end_angle = source->end_angle;
    radius = source->radius;
    center = source->center;
    width = source->width;
    color = source->color;
    visible = FALSE;
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
    Constructor - primary constructor. Copies of all attributes are
    accepted although init_color and init_width may be defaults.
*/
Arc::Arc(const int starting_angle, const int ending_angle,
         const int init_radius, const Point &init_center,
         const COLORS init_color, const line_widths init_width)
{
    struct linesettingstype line_type;

    if (init_width == DEFAULT)
    {
        getlinesettings(&line_type);
        width = (line_widths)line_type.thickness;
    }
    else
        width = init_width;

    if (init_color == DEFAULT)
        color = (COLORS)getcolor();
    else
        color = init_color;

    start_angle = starting_angle;
    end_angle = ending_angle;
    radius = init_radius;
    center = init_center;
    visible = FALSE;
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
    color can be set whether the line is visible or not
*/
void    Arc::set_color(const COLORS new_color)
{
    if (new_color == DEFAULT)
        color = (COLORS)getcolor();
    else
        color = new_color;
    if (visible)
    {
        erase();
        draw();
    }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
    width can be set whether the line is visible or not
*/
void    Arc::set_width(line_widths new_width)
{
    struct linesettingstype line_type;

    if (new_width == DEFAULT)
    {
        getlinesettings(&line_type);
        new_width = (line_widths)line_type.thickness;
    }
    if (visible)
    {
        erase();                            // erase using old width
        width = new_width;                  // change style
        draw();                             // draw using new width
    }
    else
        width = new_width;
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
    the draw() method first preserves the current BGI settings, then
    resets the BGI defaults for this particular object, and finally
    restores the original settings. had we written the graphics routines
    from scratch the step of preserving and then restoring the settings
    wouldn't be neccessary.
*/
void    Arc::draw(void)
{
    struct linesettingstype hold_current;
    int    default_color;

    // don't draw it twice
    if (visible)
        return;

    // preserve current settings
    getlinesettings(&hold_current);
    default_color = getcolor();

    // select color and line style for this object and draw it
    setcolor(color);
    setlinestyle(hold_current.linestyle,0,width);
    arc(center.get_x(),center.get_y(),start_angle,end_angle,radius);

    // restore original settings
    setlinestyle(hold_current.linestyle,hold_current.upattern,
                 hold_current.thickness);
    setcolor(default_color);
    visible = TRUE;
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
    the erase method draws over the existing arc using the background
    color. as with the draw method, the current BGI settings must be
    preserved and then restored.
*/
void    Arc::erase(void)
{
    struct linesettingstype hold_current;
    int    default_color;

    // don't erase it if it isn't visible
    if (!visible)
        return;

    // preserve current settings
    getlinesettings(&hold_current);
    default_color = getcolor();

    // set the foreground current color to the background color and set the
    // BGI defaults for this object and draw over it
    setcolor(getbkcolor());
    setlinestyle(hold_current.linestyle,0,width);
    arc(center.get_x(),center.get_y(),start_angle,end_angle,radius);

    // restore the defaults
    setlinestyle(hold_current.linestyle,hold_current.upattern,
                 hold_current.thickness);
    setcolor(default_color);
    visible = FALSE;
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
void    Arc::move_relative(Point &distance)
{
    erase();
    center += distance;
    draw();
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
void    Arc::move_absolute(Point &new_location, Point &reference)
{
    erase();
    center += new_location - reference;
    draw();
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
    this is the private method used by the copy constructor and the =
    operator. Note that the visible attribute is forced to FALSE.
*/
Arc    &Arc::copy(const Arc &source)
{
    start_angle = source.start_angle;
    end_angle = source.end_angle;
    radius = source.radius;
    center = source.center;
    width = source.width;
    color = source.color;
    visible = FALSE;
    return *this;
}