PyChart Reference Manual

Node:Clipping, Next:Redirecting output, Previous:canvas, Up:Tricks

### Clipping

A rectangle, polygon, or ellipsis can be used to define a clipping region. Any drawing commands (see canvas) issued afterwards are confined in the region. You can even nest multiple clipping regions, in which case, drawings will be clipped to the intersection of the regions. `canvas.endclip()` ends the clipping. Clipping commands and `endclip()` must nest properly.

    from pychart import *

    data = [(10, 20), (20, 65), (30, 55), (40, 45)]

    # tic_angle is the angle X values are displayed below the axis.
    xaxis = axis.X(label="Stuff")
    yaxis = axis.Y(label="Value")

    ar = area.T(x_axis=xaxis, y_axis=yaxis)

    plot = line_plot.T(label="foo", data=data, xcol=0, ycol=1,
                       tick_mark=tick_mark.star)

    ar.add_plot(plot)
    canvas.ellipsis(line_style.T(width=1.5,dash=(4,4)), None, 30, 20, 80, 0.8)
    canvas.clip_ellipsis(30, 20, 80, 0.8)
    ar.draw()
    canvas.endclip()

canvas.clip X1, Y1, X2, Y2, | Function

Activate a rectangular clip region, (X1, Y1) - (X2, Y2). You must call endclip() after you completed drawing.
    canvas.clip(x,y,x2,y2)
    draw something ...
    canvas.endclip()

canvas.clip_ellipsis X, Y, RADIUS, Y_ELONGATION | Function

Draw an ellipsis with line_style and fill PATTERN. The center is (X, Y), X radius is RADIUS, and Y radius is RADIUS*RATIO, whose default value is 1.0. SHADOW is either None or a tuple (XDELTA, YDELTA, fillstyle). If non-null, a shadow of FILLSTYLE is drawn beneath the polygon at the offset of (XDELTA, YDELTA).

canvas.clip_polygon [(X1,Y2),(X2,Y2), ..., (Xn, Yn)] | Function

Create a polygon clip region. You must call endclip() after you completed drawing. See also the polygon method.