Hi，大家好，欢迎来到STM32之littlevGL课堂，我们在上节课中学习了容器控件(lv_cont)，本节课带大家来学习一下下拉列表控件，相信大家对下拉列表肯定很熟悉了，比如我们想让用户选择几个固定的选项的时候，下拉列表就很合适了！那么废话少说！ 一 有图有真相
这里给大家展示一下下拉列表和上拉列表，其实就是列表内容的展示方向不同而已，当下拉列表的下面还有很多可展示区域时，就可以选择往下弹出选择界面，但是当没有足够的展示区域时，我们可以选择往上弹出选择界面。 二 代码分析 1. 下拉 static void ddlist_event_handler(lv_obj_t * obj, lv_event_t event)
{
if(event == LV_EVENT_VALUE_CHANGED) {
char buf[32];
lv_ddlist_get_selected_str(obj, buf, sizeof(buf));
printf("Option: %s\n", buf);
}
}
static void ddlist_test1(void)
{
/*Create a drop down list*/
lv_obj_t * ddlist = lv_ddlist_create(lv_scr_act(), NULL);
lv_ddlist_set_options(ddlist, "Apple\n"
"Banana\n"
"Orange\n"
"Melon\n"
"Grape\n"
"Raspberry");
lv_ddlist_set_fix_width(ddlist, 150);
lv_ddlist_set_draw_arrow(ddlist, true);
lv_obj_align(ddlist, NULL, LV_ALIGN_IN_TOP_MID, 0, 20);
lv_obj_set_event_cb(ddlist, ddlist_event_handler);
}2.上拉 static void ddlist_test2(void)
{
/*Create a drop down list*/
lv_obj_t * ddlist = lv_ddlist_create(lv_scr_act(), NULL);
lv_ddlist_set_options(ddlist, "Apple\n"
"Banana\n"
"Orange\n"
"Melon\n"
"Grape\n"
"Raspberry");
lv_ddlist_set_fix_width(ddlist, 150);
lv_ddlist_set_fix_height(ddlist, 150);
lv_ddlist_set_draw_arrow(ddlist, true);
/* Enable auto-realign when the size changes.
* It will keep the bottom of the ddlist fixed*/
lv_obj_set_auto_realign(ddlist, true);
/*It will be called automatically when the size changes*/
lv_obj_align(ddlist, NULL, LV_ALIGN_IN_BOTTOM_MID, 0, -20);
}OK，那么本节课先到这里，那么我们下节课学习仪表控件，我们下节课再见！ |
