Source Code

'~ This is file example_simplecurve.bas
'~ Example source code for GooData graphic library.
'
'~ Licence: GPLv3
'~ (C) 2012 Thomas[ dot ]Freiherr[ at ]gmx[ dot ]net


'~ create the data
RANDOMIZE TIMER
CONST cols = 1, az = 69, l = 3, line_group = 1.0
DIM AS GooType datas(az, cols)
FOR i AS INTEGER = 0 TO az
  VAR a = i / az * l
  datas(i, 0) = a
  a *= a
  datas(i, 1) = a + RND() * COS(a * a) - .5
NEXT
VAR Dat = goo_data_points_new(az + 1, cols + 1, @datas(0, 0))
VAR wdth = 422.0, hght = 240.0

'~ the group for all items
VAR group = goo_canvas_group_new(Glob, _
            "line_width", line_group, _
            "font", "Arial", _
            NULL)

'~ the header line
VAR title = goo_canvas_text_new(group, _
            "<span size=""xx-large"">" _
            "Simple Curve (" & az + 1 & " Points)" _
           !"</span>\n", _
            0.0, 0.0, wdth, GOO_CANVAS_ANCHOR_SW, _
            "use_markup", TRUE, _
            "alignment", PANGO_ALIGN_CENTER, _
            NULL)

'~ the background item
VAR back = goo_canvas_rect_new(group, _
            0.0, 0.0, wdth, hght, _
            NULL)

'~ X-axis
VAR xaxis = goo_axis_new(group, back, GOO_AXIS_SOUTH, _
            "X-Value", _
            "range", "-0.15 3.15", _
            "ticks", "0.5", _
            NULL)

'~ gray grid lines for X-axis
goo_axis_set_grid_properties(xaxis, _
            "stroke_color", "lightgray", _
            NULL)

'~ Y-axis
VAR yaxis = goo_axis_new(group, back, GOO_AXIS_WEST, _
           !"𝘺 ≃ 𝘹²", _
            "offset_label", 7., _
            "range", "-0.75 9.75", _
            "ticks", "1", _
            NULL)

'~ gray grid lines for Y-axis
goo_axis_set_grid_properties(yaxis, _
            "stroke_color", "lightgray", _
            NULL)

'~ a line dash with 0.0 and a big gap to draw points only
VAR dash = goo_canvas_line_dash_new(2, 0.0, wdth * hght)

'~ round points
VAR c1 = goo_simplecurve2d_new(group, xaxis, yaxis, Dat, 0, 1, _
            "stroke_color", "gray", _
            "line_width", line_group * 7, _
            "line_cap", CAIRO_LINE_CAP_ROUND, _
            "line_dash", dash, _
            NULL)

'~ a second line on top
VAR c2 = goo_simplecurve2d_new(group, xaxis, yaxis, Dat, 0, 1, _
            "stroke_color", "red", _
            "line_width", line_group, _
            "line_join", CAIRO_LINE_JOIN_ROUND, _
            NULL)