main : drawing a line series on a plot

plots/plot_draw_lines.py

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+import dearpygui.dearpygui as dpg
+dpg.create_context()
+
+def lock_axis(axis):
+    xmin, xmax = dpg.get_axis_limits(axis)
+    dpg.set_axis_limits(axis, xmin, xmax)
+
+def unlock_axis(axis):
+    dpg.set_axis_limits_auto(axis)
+
+def plot_mouse_click_callback():
+    lock_axis(xaxis), lock_axis(yaxis)
+    dpg.delete_item(xaxis, children_only=True) # delete the previous line series
+
+    x,y = dpg.get_plot_mouse_pos()
+    data_x, data_y, lines = [x],[y],[]
+    while dpg.is_mouse_button_down(button=0): #and dpg.is_key_down(dpg.mvKey_Control):
+        new_x,new_y  = dpg.get_plot_mouse_pos()
+        if new_x != x or new_y != y:
+            if new_x < x: # only if the mouse is dragged left
+                continue
+
+            data_x.append(new_x), data_y.append(new_y)
+            lines.append(dpg.draw_line([x,y], [new_x,new_y], parent=plot))
+            x,y = new_x, new_y
+
+    for line in lines: # delete the lines we just drew
+        dpg.delete_item(line)
+    # at this point you could do further processing on the data, e.g. smooth it.
+    dpg.add_line_series(data_x, data_y, parent=xaxis) # add the data as a line series
+
+    unlock_axis(yaxis), unlock_axis(xaxis)
+
+with dpg.window():
+    dpg.add_text("Left click and drag on the plot to add a line series.\nIt only works if you drag left to right.")
+    with dpg.plot(anti_aliased=True) as plot: 
+        xaxis = dpg.add_plot_axis(dpg.mvXAxis)
+        yaxis = dpg.add_plot_axis(dpg.mvYAxis)
+        dpg.set_axis_limits(xaxis, 0, 100)
+        dpg.set_axis_limits(yaxis, 0, 100)
+
+    with dpg.item_handler_registry() as registry:
+        dpg.add_item_clicked_handler(button=dpg.mvMouseButton_Left, callback=plot_mouse_click_callback)
+    dpg.bind_item_handler_registry(plot, registry)
+
+dpg.create_viewport(width=800, height=600, title="Plot with mouse click callback")
+dpg.setup_dearpygui()
+dpg.show_viewport()
+dpg.start_dearpygui()
+dpg.destroy_context()