50 lines
1.5 KiB
C
50 lines
1.5 KiB
C
#include "../../lv_examples.h"
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#if LV_USE_MSG && LV_USE_SLIDER && LV_USE_LABEL && LV_BUILD_EXAMPLES
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/*Define a message ID*/
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#define MSG_NEW_TEMPERATURE 1
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static void slider_event_cb(lv_event_t * e);
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static void label_event_cb(lv_event_t * e);
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/**
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* A slider sends a message on value change and a label display's that value
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*/
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void lv_example_msg_1(void)
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{
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/*Create a slider in the center of the display*/
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lv_obj_t * slider = lv_slider_create(lv_scr_act());
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lv_obj_center(slider);
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lv_obj_add_event_cb(slider, slider_event_cb, LV_EVENT_VALUE_CHANGED, NULL);
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/*Create a label below the slider*/
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lv_obj_t * label = lv_label_create(lv_scr_act());
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lv_obj_add_event_cb(label, label_event_cb, LV_EVENT_MSG_RECEIVED, NULL);
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lv_label_set_text(label, "0%");
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lv_obj_align(label, LV_ALIGN_CENTER, 0, 30);
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/*Subscribe the label to a message. Also use the user_data to set a format string here.*/
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lv_msg_subsribe_obj(MSG_NEW_TEMPERATURE, label, "%d °C");
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}
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static void slider_event_cb(lv_event_t * e)
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{
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/*Notify all subscribers (only the label now) that the slider value has been changed*/
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lv_obj_t * slider = lv_event_get_target(e);
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int32_t v = lv_slider_get_value(slider);
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lv_msg_send(MSG_NEW_TEMPERATURE, &v);
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}
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static void label_event_cb(lv_event_t * e)
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{
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lv_obj_t * label = lv_event_get_target(e);
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lv_msg_t * m = lv_event_get_msg(e);
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const char * fmt = lv_msg_get_user_data(m);
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const int32_t * v = lv_msg_get_payload(m);
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lv_label_set_text_fmt(label, fmt, *v);
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}
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#endif
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