feat(bar): reverse drawing direction of lv_bar if min > max (#4654)

Signed-off-by: wangxuedong <wangxuedong@xiaomi.com>

examples/widgets/bar/index.rst

@@ -34,3 +34,9 @@ Custom drawer to show the current value
 .. lv_example:: widgets/bar/lv_example_bar_6
   :language: c
 
+Bar with opposite direction
+---------------------------
+
+.. lv_example:: widgets/bar/lv_example_bar_7
+  :language: c
+

examples/widgets/bar/lv_example_bar_7.c

@@ -0,0 +1,23 @@
+#include "../../lv_examples.h"
+#if LV_USE_BAR && LV_BUILD_EXAMPLES
+
+/**
+ * Bar with opposite direction
+ */
+void lv_example_bar_7(void)
+{
+    lv_obj_t * label;
+
+
+    lv_obj_t * bar_tob = lv_bar_create(lv_scr_act());
+    lv_obj_set_size(bar_tob, 20, 200);
+    lv_bar_set_range(bar_tob, 100, 0);
+    lv_bar_set_value(bar_tob, 70, LV_ANIM_OFF);
+    lv_obj_align(bar_tob, LV_ALIGN_CENTER, 0, -30);
+
+    label = lv_label_create(lv_scr_act());
+    lv_label_set_text(label, "From top to bottom");
+    lv_obj_align_to(label, bar_tob, LV_ALIGN_OUT_TOP_MID, 0, -5);
+}
+
+#endif

examples/widgets/bar/lv_example_bar_7.py

@@ -0,0 +1 @@
+pass

examples/widgets/lv_example_widgets.h

@@ -36,6 +36,7 @@ void lv_example_bar_3(void);
 void lv_example_bar_4(void);
 void lv_example_bar_5(void);
 void lv_example_bar_6(void);
+void lv_example_bar_7(void);
 
 void lv_example_button_1(void);
 void lv_example_button_2(void);
@@ -118,6 +119,7 @@ void lv_example_scale_5(void);
 void lv_example_slider_1(void);
 void lv_example_slider_2(void);
 void lv_example_slider_3(void);
+void lv_example_slider_4(void);
 
 void lv_example_span_1(void);
 

examples/widgets/slider/index.rst

@@ -17,4 +17,8 @@ Slider with extended drawer
 .. lv_example:: widgets/slider/lv_example_slider_3
   :language: c
 
+Slider with opposite direction
+------------------------------
 
+.. lv_example:: widgets/slider/lv_example_slider_4
+  :language: c

examples/widgets/slider/lv_example_slider_4.c

@@ -0,0 +1,34 @@
+#include "../../lv_examples.h"
+#if LV_USE_SLIDER && LV_BUILD_EXAMPLES
+
+static void slider_event_cb(lv_event_t * e);
+static lv_obj_t * slider_label;
+
+/**
+ * Slider with opposite direction
+ */
+void lv_example_slider_4(void)
+{
+    /*Create a slider in the center of the display*/
+    lv_obj_t * slider = lv_slider_create(lv_scr_act());
+    lv_obj_center(slider);
+    lv_obj_add_event(slider, slider_event_cb, LV_EVENT_VALUE_CHANGED, NULL);
+    /*Reverse the direction of the slider*/
+    lv_slider_set_range(slider, 100, 0);
+    /*Create a label below the slider*/
+    slider_label = lv_label_create(lv_scr_act());
+    lv_label_set_text(slider_label, "0%");
+
+    lv_obj_align_to(slider_label, slider, LV_ALIGN_OUT_BOTTOM_MID, 0, 10);
+}
+
+static void slider_event_cb(lv_event_t * e)
+{
+    lv_obj_t * slider = lv_event_get_target(e);
+    char buf[8];
+    lv_snprintf(buf, sizeof(buf), "%d%%", (int)lv_slider_get_value(slider));
+    lv_label_set_text(slider_label, buf);
+    lv_obj_align_to(slider_label, slider, LV_ALIGN_OUT_BOTTOM_MID, 0, 10);
+}
+
+#endif

examples/widgets/slider/lv_example_slider_4.py

@@ -0,0 +1,21 @@
+#
+# Slider with opposite direction
+#
+def slider_event_cb(e):
+
+    slider = e.get_target_obj()
+    slider_label.set_text("{:d}%".format(slider.get_value()))
+    slider_label.align_to(slider, lv.ALIGN.OUT_BOTTOM_MID, 0, 10)
+
+# Create a slider in the center of the display
+slider = lv.slider(lv.screen_active())
+slider.center()
+slider.add_event(slider_event_cb, lv.EVENT.VALUE_CHANGED, None)
+slider.set_range(100, 0)
+
+# Create a label below the slider
+slider_label = lv.label(lv.screen_active())
+slider_label.set_text("0%")
+
+slider_label.align_to(slider, lv.ALIGN.OUT_BOTTOM_MID, 0, 10)
+