view_clipaddoval

#View.ClipAddOval

##Syntax View.ClipAddOval (x, y, xradius, yradius : int)

##Description The View.ClipAddOval procedure adds another oval specified by (x, y) and xradius and yradius) to the clipping region. If no clipping region has been specified, then the oval becomes the complete clipping region.

A clipping region is the region that the output will appear in. If the rectangle is specified as the clipping region, any drawing done outside the oval will not appear.

To set the initial clipping, or remove the old region and replace it with a new rectangle, use View.ClipSet. To set the clipping region back to the entire screen or window, use View.ClipOff.

These commands only work in "graphics" mode.

##Example This program sets the clipping region to five circles and then draws random squares. The squares will only appear (or partially appear) in the ovals.

    const c1 : int := maxy div 4
    const c2 : int := 3* maxy div 4
    const radius : int := maxy div 4
    View.ClipAddOval (c1, c1, radius, radius)
    View.ClipAddOval (c1, c2, radius, radius)
    View.ClipAddOval (c2, c1, radius, radius)
    View.ClipAddOval (c2, c2, radius, radius)

    % Draw the random squares in the box
    var x, y, clr : int
    loop
        x := Rand.Int (0, maxx - 30)     % Random x
        y := Rand.Int (0, maxy - 30)     % Random y
        clr := Rand.Int (0, maxcolor)    % Random color
        Draw.FillBox (x, y, x + 30, y + 30, clr)
    end loop

##Execute

##Execute By combining animation using View.Update and View.ClipAddOval, you can achieve a moving spotlight effect.

##Status Exported qualified.

This means that you can only call the function by calling View.ClipAddOval, not by calling ClipAddOval.

##See also view_clipset-2.html, view_clipadd-2.html and view_clipoff-2.html functions.