adding micropython examples (#2286)

* adding micropython examples

* adding micropython examples

examples/widgets/dropdown/lv_example_dropdown_1.py

@@ -1,21 +1,26 @@
-def event_handler(obj, event):
-    if event == lv.EVENT.VALUE_CHANGED:
+def event_handler(e):
+    code = e.get_code()
+    obj = lv.dropdown.__cast__(e.get_target())
+    if code == lv.EVENT.VALUE_CHANGED: 
         option = " "*10 # should be large enough to store the option
         obj.get_selected_str(option, len(option))
         # .strip() removes trailing spaces
         print("Option: \"%s\"" % option.strip())
 
-# Create a drop down list
-ddlist = lv.ddlist(lv.scr_act())
-ddlist.set_options("\n".join([
-                    "Apple",
-                    "Banana",
-                    "Orange",
-                    "Melon",
-                    "Grape",
-                    "Raspberry"]))
+# Create a normal drop down list
+dd = lv.dropdown(lv.scr_act())
+dd.set_options("\n".join([
+    "Apple\n"
+    "Banana\n"
+    "Orange\n"
+    "Cherry\n"
+    "Grape\n"
+    "Raspberry\n"
+    "Melon\n"
+    "Orange\n"
+    "Lemon\n"
+    "Nuts\n"]))
+
+dd.align(lv.ALIGN.TOP_MID, 0, 20)
+dd.add_event_cb(event_handler, lv.EVENT.ALL, None)
 
-ddlist.set_fix_width(150)
-ddlist.set_draw_arrow(True)
-ddlist.align(None, lv.ALIGN.IN_TOP_MID, 0, 20)
-ddlist.set_event_cb(event_handler)

examples/widgets/dropdown/lv_example_dropdown_2.py

@@ -1,23 +1,34 @@
-# Create a drop UP list by applying auto realign
+#
+# Create a drop down, up, left and right menus
+#
 
-# Create a drop down list
-ddlist = lv.ddlist(lv.scr_act())
-ddlist.set_options("\n".join([
-                    "Apple",
-                    "Banana",
-                    "Orange",
-                    "Melon",
-                    "Grape",
-                    "Raspberry"]))
+opts = "\n".join([
+    "Apple\n"
+    "Banana\n"
+    "Orange\n"
+    "Melon\n"
+    "Grape\n"
+    "Raspberry"])
+
+dd = lv.dropdown(lv.scr_act())
+dd.set_options_static(opts)
+dd.align(lv.ALIGN.TOP_MID, 0, 10)
+dd = lv.dropdown(lv.scr_act())
+dd.set_options_static(opts)
+dd.set_dir(lv.DIR.BOTTOM)
+dd.set_symbol(lv.SYMBOL.UP)
+dd.align(lv.ALIGN.BOTTOM_MID, 0, -10)
+
+dd = lv.dropdown(lv.scr_act())
+dd.set_options_static(opts)
+dd.set_dir(lv.DIR.RIGHT)
+dd.set_symbol(lv.SYMBOL.RIGHT)
+dd.align(lv.ALIGN.LEFT_MID, 10, 0)
+
+dd = lv.dropdown(lv.scr_act())
+dd.set_options_static(opts)
+dd.set_dir(lv.DIR.LEFT)
+dd.set_symbol(lv.SYMBOL.LEFT)
+dd.align(lv.ALIGN.RIGHT_MID, -10, 0)
 
 
-ddlist.set_fix_width(150)
-ddlist.set_fix_height(150)
-ddlist.set_draw_arrow(True)
-
-# Enable auto-realign when the size changes.
-# It will keep the bottom of the ddlist fixed
-ddlist.set_auto_realign(True)
-
-# It will be called automatically when the size changes
-ddlist.align(None, lv.ALIGN.IN_BOTTOM_MID, 0, -20)

examples/widgets/dropdown/lv_example_dropdown_3.py

@@ -0,0 +1,53 @@
+from imagetools import get_png_info, open_png
+
+# Register PNG image decoder
+decoder = lv.img.decoder_create()
+decoder.info_cb = get_png_info
+decoder.open_cb = open_png
+
+# Create an image from the png file
+try:
+    with open('../../assets/img_caret_down.png','rb') as f:
+        png_data = f.read()
+except:
+    print("Could not find img_caret_down.png")
+    sys.exit()
+    
+img_caret_down_argb = lv.img_dsc_t({
+  'data_size': len(png_data),
+  'data': png_data 
+})
+
+def event_cb(e):
+    dropdown = lv.dropdown.__cast__(e.get_target())
+    option = " "*64 # should be large enough to store the option
+    dropdown.get_selected_str(option, len(option))
+    print(option.strip() +" is selected")
+#
+# Create a menu from a drop-down list and show some drop-down list features and styling
+#
+
+# Create a drop down list
+dropdown = lv.dropdown(lv.scr_act())
+dropdown.align(lv.ALIGN.TOP_LEFT, 10, 10)
+dropdown.set_options("".join([
+    "New project\n",
+    "New file\n",
+    "Open project\n",
+    "Recent projects\n",
+    "Preferences\n",
+    "Exit"]))
+
+# Set a fixed text to display on the button of the drop-down list
+dropdown.set_text("Menu")
+
+# Use a custom image as down icon and flip it when the list is opened
+# LV_IMG_DECLARE(img_caret_down)
+dropdown.set_symbol(img_caret_down_argb)
+dropdown.set_style_transform_angle(1800, lv.STATE.CHECKED)
+
+# In a menu we don't need to show the last clicked item
+dropdown.set_selected_highlight(False)
+
+dropdown.add_event_cb(event_cb, lv.EVENT.VALUE_CHANGED, None)
+