lv_obj_get_scroll_right
时间: 2023-07-30 12:09:14 浏览: 63
`lv_obj_get_scroll_right` 是 LittlevGL(lvgl)中的一个函数,用于获取对象(obj)在水平方向上是否可以向右滚动。如果对象可以向右滚动,则该函数返回剩余可滚动像素数(像素),否则返回 0。
函数原型如下:
```c
lv_coord_t lv_obj_get_scroll_right(const lv_obj_t * obj);
```
参数说明:
- `obj`:要获取滚动信息的对象指针。
示例用法:
```c
// 获取对象在水平方向上是否可以向右滚动
lv_coord_t scroll_right = lv_obj_get_scroll_right(obj);
if (scroll_right > 0) {
// 对象可以向右滚动,剩余可滚动像素数为 scroll_right
} else {
// 对象不能向右滚动
}
```
这将获取对象在水平方向上是否可以向右滚动,并根据需要进行处理。
相关问题
void lv_example_scroll_2_dir(void) { #if 1 lv_obj_t* cont = lv_obj_create(lv_scr_act()); lv_obj_set_size(cont, 400, 300); lv_obj_add_flag(cont, LV_OBJ_FLAG_SCROLL_ONE); /*Allow max 1 page swipe*/ lv_obj_set_scroll_snap_x(cont, LV_SCROLL_SNAP_CENTER); /*Snap a page to the center*/ lv_obj_set_scrollbar_mode(cont, LV_SCROLLBAR_MODE_OFF); lv_obj_add_event_cb(cont, scroll_end_event, LV_EVENT_SCROLL_BEGIN/*LV_EVENT_ALL*//*LV_EVENT_SCROLL*//*LV_EVENT_SCROLL_END*/, NULL); lv_obj_add_event_cb(cont, scroll_end_event, LV_EVENT_SCROLL_END, NULL); lv_obj_center(cont); /*A grid for the left center and right pages*/ lv_coord_t col_dsc[] = { LV_GRID_CONTENT, LV_GRID_CONTENT, LV_GRID_CONTENT, LV_GRID_CONTENT, LV_GRID_CONTENT, LV_GRID_TEMPLATE_LAST }; lv_coord_t row_dsc[] = { LV_GRID_FR(1), LV_GRID_TEMPLATE_LAST }; lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc); /*Create 5 pages*/ for (int i = 0; i < 10; i++) { lv_obj_t* obj = lv_obj_create(cont); lv_obj_set_size(obj, lv_pct(33), lv_pct(100)); lv_obj_t* label = lv_label_create(obj); lv_label_set_text_fmt(label, "Page %d", i); lv_obj_set_style_border_width(obj, 0, 0); } /*Page 2, 3 hidden, page 4, 0, 1 are placed to the grid */ //lv_obj_add_flag(lv_obj_get_child(cont, 2), LV_OBJ_FLAG_HIDDEN); //lv_obj_add_flag(lv_obj_get_child(cont, 3), LV_OBJ_FLAG_HIDDEN); //lv_obj_set_grid_cell(lv_obj_get_child(cont, 4), LV_GRID_ALIGN_CENTER, 0, 1, LV_GRID_ALIGN_CENTER, 0, 1); //lv_obj_set_grid_cell(lv_obj_get_child(cont, 0), LV_GRID_ALIGN_CENTER, 1, 1, LV_GRID_ALIGN_CENTER, 0, 1); //lv_obj_set_grid_cell(lv_obj_get_child(cont, 1), LV_GRID_ALIGN_CENTER, 2, 1, LV_GRID_ALIGN_CENTER, 0, 1); lv_obj_set_grid_cell(lv_obj_get_child(cont, 0), LV_GRID_ALIGN_CENTER, 0, 1, LV_GRID_ALIGN_CENTER, 0, 1); lv_obj_set_grid_cell(lv_obj_get_child(cont, 1), LV_GRID_ALIGN_CENTER, 1, 1, LV_GRID_ALIGN_CENTER, 0, 1); lv_obj_set_grid_cell(lv_obj_get_child(cont, 2), LV_GRID_ALIGN_CENTER, 2, 1, LV_GRID_ALIGN_CENTER, 0, 1); lv_obj_set_grid_cell(lv_obj_get_child(cont, 3), LV_GRID_ALIGN_CENTER, 3, 1, LV_GRID_ALIGN_CENTER, 0, 1); lv_obj_set_grid_cell(lv_obj_get_child(cont, 4), LV_GRID_ALIGN_CENTER, 4, 1, LV_GRID_ALIGN_CENTER, 0, 1); /*Be sure page 0 is centered*/ lv_obj_scroll_to_view(lv_obj_get_child(cont, 0), LV_ANIM_OFF); }帮我注释一下这段代码
这段代码是 LittlevGL (LVGL)的示例代码,实现了一个可以左右滑动的页面(类似于轮播图),页面可以居中对齐。下面是代码注释:
```C
void lv_example_scroll_2_dir(void) {
/*创建一个容器,作为滑动页面的容器*/
lv_obj_t* cont = lv_obj_create(lv_scr_act());
lv_obj_set_size(cont, 400, 300);
/*设置容器只能左右滑动一页*/
lv_obj_add_flag(cont, LV_OBJ_FLAG_SCROLL_ONE);
/*设置容器滑动时,页面停留在中心*/
lv_obj_set_scroll_snap_x(cont, LV_SCROLL_SNAP_CENTER);
/*关闭滚动条*/
lv_obj_set_scrollbar_mode(cont, LV_SCROLLBAR_MODE_OFF);
/*容器添加滑动事件*/
lv_obj_add_event_cb(cont, scroll_end_event, LV_EVENT_SCROLL_BEGIN/*LV_EVENT_ALL*//*LV_EVENT_SCROLL*//*LV_EVENT_SCROLL_END*/, NULL);
lv_obj_add_event_cb(cont, scroll_end_event, LV_EVENT_SCROLL_END, NULL);
/*容器居中*/
lv_obj_center(cont);
/*创建一个网格,用于布局页面*/
lv_coord_t col_dsc[] = { LV_GRID_CONTENT, LV_GRID_CONTENT, LV_GRID_CONTENT, LV_GRID_CONTENT, LV_GRID_CONTENT, LV_GRID_TEMPLATE_LAST };
lv_coord_t row_dsc[] = { LV_GRID_FR(1), LV_GRID_TEMPLATE_LAST };
lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);
/*创建 10 个页面*/
for (int i = 0; i < 10; i++) {
lv_obj_t* obj = lv_obj_create(cont);
lv_obj_set_size(obj, lv_pct(33), lv_pct(100));
lv_obj_t* label = lv_label_create(obj);
lv_label_set_text_fmt(label, "Page %d", i);
lv_obj_set_style_border_width(obj, 0, 0);
}
/*将第 0、1、2、3、4 个页面放到网格中,使它们居中*/
lv_obj_set_grid_cell(lv_obj_get_child(cont, 0), LV_GRID_ALIGN_CENTER, 0, 1, LV_GRID_ALIGN_CENTER, 0, 1);
lv_obj_set_grid_cell(lv_obj_get_child(cont, 1), LV_GRID_ALIGN_CENTER, 1, 1, LV_GRID_ALIGN_CENTER, 0, 1);
lv_obj_set_grid_cell(lv_obj_get_child(cont, 2), LV_GRID_ALIGN_CENTER, 2, 1, LV_GRID_ALIGN_CENTER, 0, 1);
lv_obj_set_grid_cell(lv_obj_get_child(cont, 3), LV_GRID_ALIGN_CENTER, 3, 1, LV_GRID_ALIGN_CENTER, 0, 1);
lv_obj_set_grid_cell(lv_obj_get_child(cont, 4), LV_GRID_ALIGN_CENTER, 4, 1, LV_GRID_ALIGN_CENTER, 0, 1);
/*将第 2、3 个页面隐藏*/
//lv_obj_add_flag(lv_obj_get_child(cont, 2), LV_OBJ_FLAG_HIDDEN);
//lv_obj_add_flag(lv_obj_get_child(cont, 3), LV_OBJ_FLAG_HIDDEN);
/*将页面 0 居中显示*/
lv_obj_scroll_to_view(lv_obj_get_child(cont, 0), LV_ANIM_OFF);
}
```
注释中已经解释了每一行代码的作用,其中有些代码是被注释掉了的,这可能是作者在开发过程中的调试代码。
lvgl函数lv_indev_get_scroll_obj是干啥用的
lv_indev_get_scroll_obj函数是用于获取当前正在滚动的对象。在LVGL中,滚动对象是指可以在屏幕上滚动的对象,如文本框、列表、下拉列表等。当用户使用触摸屏或鼠标滚轮滚动这些对象时,LVGL会自动调用lv_indev_get_scroll_obj函数来获取当前正在滚动的对象。这个函数返回的是一个指向滚动对象的指针。开发者可以使用这个函数来检测用户正在滚动哪个对象,并根据需要进行相应的处理。
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