close all
clear h

h.ax = axes ("position", [0.05 0.42 0.5 0.5]);
h.fcn = @(x) polyval([-0.1 0.5 3 0], x);

function update_plot (obj, init = false)

  ## gcbo holds the handle of the control
  h = guidata (obj);
  replot = false;
  recalc = false;
  switch (gcbo)
    case {h.print_pushbutton}
      fn =  uiputfile ("*.png");
      print (fn);
    case {h.grid_checkbox}
      v = get (gcbo, "value");
      grid (merge (v, "on", "off"));
    case {h.minor_grid_toggle}
      v = get (gcbo, "value");
      grid ("minor", merge (v, "on", "off"));
    case {h.plot_title_edit}
      v = get (gcbo, "string");
      set (get (h.ax, "title"), "string", v);
    case {h.linecolor_radio_blue}
      set (h.linecolor_radio_red, "value", 0);
      replot = true;
    case {h.linecolor_radio_red}
      set (h.linecolor_radio_blue, "value", 0);
      replot = true;
    case {h.linestyle_popup, h.markerstyle_list}
      replot = true;
    case {h.noise_slider}
      recalc = true;
  endswitch

  if (recalc || init)
    x = linspace (-4, 9);
    noise = get (h.noise_slider, "value");
    set (h.noise_label, "string", sprintf ("Noise: %.1f%%", noise * 100));
    y = h.fcn (x) + 5 * noise * randn (size (x));
    if (init)
      h.plot = plot (x, y, "b");
      guidata (obj, h);
    else
      set (h.plot, "ydata", y);
    endif
  endif

  if (replot)
    cb_red = get (h.linecolor_radio_red, "value");
    lstyle = get (h.linestyle_popup, "string"){get (h.linestyle_popup, "value")};
    lstyle = strtrim (lstyle(1:2));

    mstyle = get (h.markerstyle_list, "string"){get (h.markerstyle_list, "value")};
    if (strfind (mstyle, "none"))
      mstyle = "none";
    else
      mstyle = mstyle(2);
    endif
  
    set (h.plot, "color", merge (cb_red, [1 0 0 ], [0 0 1]),
                 "linestyle", lstyle,
                 "marker", mstyle);
  endif
  
endfunction


## plot title
h.plot_title_label = uicontrol ("style", "text",
                                "units", "normalized",
                                "string", "plot title: (text)",
                                "horizontalalignment", "left",
                                "position", [0.6 0.85 0.35 0.08]);

h.plot_title_edit = uicontrol ("style", "edit",
                               "units", "normalized",
                               "string", "Please fill me! (edit)",
                               "callback", @update_plot,
                               "position", [0.6 0.80 0.35 0.06]);

## grid
h.grid_checkbox = uicontrol ("style", "checkbox",
                             "units", "normalized",
                             "string", "show grid\n(checkbox)",
                             "value", 0,
                             "callback", @update_plot,
                             "position", [0.6 0.65 0.35 0.09]);

h.minor_grid_toggle = uicontrol ("style", "togglebutton",
                                 "units", "normalized",
                                 "string", "minor\n(togglebutton)",
                                 "callback", @update_plot,
                                 "value", 0,
                                 "position", [0.77 0.65 0.18 0.09]);

## print figure
h.print_pushbutton = uicontrol ("style", "pushbutton",
                                "units", "normalized",
                                "string", "print plot\n(pushbutton)",
                                "callback", @update_plot,
                                "position", [0.6 0.45 0.35 0.09]);
## noise
h.noise_label = uicontrol ("style", "text",
                           "units", "normalized",
                           "string", "Noise:",
                           "horizontalalignment", "left",
                           "position", [0.05 0.3 0.35 0.08]);

h.noise_slider = uicontrol ("style", "slider",
                            "units", "normalized",
                            "string", "slider",
                            "callback", @update_plot,
                            "value", 0.4,
                            "position", [0.05 0.25 0.35 0.06]);

## linecolor
h.linecolor_label = uicontrol ("style", "text",
                               "units", "normalized",
                               "string", "Linecolor:",
                               "horizontalalignment", "left",
                               "position", [0.05 0.12 0.35 0.08]);

h.linecolor_radio_blue = uicontrol ("style", "radiobutton",
                                    "units", "normalized",
                                    "string", "blue",
                                    "callback", @update_plot,
                                    "position", [0.05 0.08 0.15 0.04]);

h.linecolor_radio_red = uicontrol ("style", "radiobutton",
                                   "units", "normalized",
                                   "string", "red",
                                   "callback", @update_plot,
                                   "value", 0,
                                   "position", [0.05 0.02 0.15 0.04]);

## linestyle
h.linestyle_label = uicontrol ("style", "text",
                               "units", "normalized",
                               "string", "Linestyle:",
                               "horizontalalignment", "left",
                               "position", [0.25 0.12 0.35 0.08]);

h.linestyle_popup = uicontrol ("style", "popupmenu",
                               "units", "normalized",
                               "string", {"-  solid lines",
                                          "-- dashed lines",
                                          ":  dotted lines",
                                          "-. dash-dotted lines"},
                               "callback", @update_plot,
                               "position", [0.25 0.05 0.3 0.06]);

## markerstyle
h.markerstyle_label = uicontrol ("style", "text",
                                 "units", "normalized",
                                 "string", "Marker style:",
                                 "horizontalalignment", "left",
                                 "position", [0.58 0.3 0.35 0.08]);

h.markerstyle_list = uicontrol ("style", "listbox",
                                "units", "normalized",
                                "string", {"none",
                                           "'+' crosshair",
                                           "'o'  circle",
                                           "'*'  star",
                                           "'.'  point",
                                           "'x'  cross",
                                           "'s'  square",
                                           "'d'  diamond",
                                           "'^'  upward-facing triangle",
                                           "'v'  downward-facing triangle",
                                           "'>'  right-facing triangle",
                                           "'<'  left-facing triangle",
                                           "'p'  pentagram",
                                           "'h'  hexagram"},
                                "callback", @update_plot,
                                "position", [0.58 0.04 0.38 0.26]);

set (gcf, "color", get(0, "defaultuicontrolbackgroundcolor"))
guidata (gcf, h)
update_plot (gcf, true);