1 对象 object
1.1 对象 lv_obj_t
对象object：构建用户界面的基本单位，也称之为控件widgets；对于button,label,image,list等组件都可称之为对象；
//lv_obj.h 对象结构体；
typedef struct _lv_obj_t {
const lv_obj_class_t *class_p;
struct _lv_obj_t *parent;
_lv_obj_spec_attr_t *spec_attr;
_lv_obj_style_t *styles;
#if LV_USE_USER_DATA
void *user_data;
#endif
lv_area_t coords;
lv_obj_flag_t flags;
lv_state_t state;
uint16_t layout_inv : 1;
uint16_t scr_layout_inv : 1;
uint16_t skip_trans : 1;
uint16_t style_cnt : 6;
uint16_t h_layout : 1;
uint16_t w_layout : 1;
} lv_obj_t;1.2 对象属性
1.2.1 基本属性 basic attributes
所有对象共享一些基本属性，如position,size,parent,styles,event handlers等等，可对其进行设置/获取，举例如下；
//obj的pos,class,style,draw,scroll属性等都有自己的xx.c和xx.h，可见obj的重要；
//lv_obj_pos.h
void lv_obj_set_pos(struct _lv_obj_t *obj, lv_coord_t x, lv_coord_t y);
void lv_obj_set_size(struct _lv_obj_t *obj, lv_coord_t w, lv_coord_t h);
lv_coord_t lv_obj_get_width(const struct _lv_obj_t *obj);
//lv_obj_styles.h
void lv_obj_add_style(struct _lv_obj_t *obj, lv_style_t *style, lv_style_selector_t selector);
void lv_obj_refresh_style(struct _lv_obj_t *obj, lv_part_t part, lv_style_prop_t prop);1.2.2 特定属性 specific attributes
一些对象拥有一些自己的特殊属性，所以一些对象也会拥有属于自己的特殊函数；
//lv_slider.h 位于widgets/下
static inline void lv_slider_set_range(lv_obj_t *obj, int32_t min, int32_t max);
static inline void lv_slider_set_value(lv_obj_t *obj, int32_t value, lv_anim_enable_t anim);
1.2.3 父对象
每个对象只允许有一个父对象，父对象可视为子对象的容器，但是父对象可以允许有多个子对象；
每个子对象只有在父对象范围内可见，超出部分不可见；子对象会随着父对象的移动而移动；
lv_obj_t * parent = lv_obj_create(lv_scr_act()); /*Create a parent object on the current screen*/
lv_obj_set_size(parent, 100, 80); /*Set the size of the parent*/
lv_obj_t * obj1 = lv_obj_create(parent); /*Create an object on the previously created parent object*/
lv_obj_set_pos(obj1, 10, 10); /*Set the position of the new object*/
//lv_obj.c lv_obj_create()1.3 创建/删除对象
/** //lv_obj.h
* Create a base object (a rectangle)
* @param parent pointer to a parent object. If NULL then a screen will be created.
* @return pointer to the new object
*/
lv_obj_t *lv_obj_create(lv_obj_t *parent);
/** //lv_obj_tree.h
* Delete an object and all of its children.
* Also remove the objects from their group and remove all animations (if any).
* Send `LV_EVENT_DELETED` to deleted objects.
* @param obj pointer to an object
*/
void lv_obj_del(struct _lv_obj_t *obj);
/** //lv_obj_tree.h
* Helper function for asynchronously deleting objects.
* Useful for cases where you can't delete an object directly in an `LV_EVENT_DELETE` handler (i.e. parent).
* @param obj object to delete
* @see lv_async_call cae在lv_timer周期性回调的时候来删除对象，通常是1ms之后删除，看tick;
*/
void lv_obj_del_async(struct _lv_obj_t *obj);
/** //lv_obj_tree.h
* Delete all children of an object.
* Also remove the objects from their group and remove all animations (if any).
* Send `LV_EVENT_DELETED` to deleted objects.
* @param obj pointer to an object
*/
void lv_obj_clean(struct _lv_obj_t *obj);2 屏幕 screen
屏幕属于没有parent的obj，屏幕本身也还是obj，可以用创建obj的方式来创建屏幕；
大约屏幕没啥内容，但是呢又很常见无处不在，屏幕本身也还是obj，所以lvgl把屏幕也概括在了obj章节里；
//对象在创建的时候如果还没有创建好屏幕，那么对象也可以作为屏幕；
lv_obj_t * scr1 = lv_obj_create(NULL);
/** //lv_disp.h
* Get the active screen of the default display
* @return pointer to the active screen
*/
static inline lv_obj_t * lv_scr_act(void)
{
return lv_disp_get_scr_act(lv_disp_get_default());
}
/** //lv_disp.h
* Make a screen active
* @param scr pointer to a screen
*/
static inline void lv_scr_load(lv_obj_t * scr)
{
lv_disp_load_scr(scr);
}2.1 层 layers
对于屏幕而言，每个屏幕上都有两层layer，分别是top layer和system layer；
top layer位于所有obj之上，top layer主要用来放置弹出窗口；
system layer位于top layer之上；system layer只能放置系统层控件，比如鼠标等；
/** //lv_disp.h
* Get the top layer of the default display
* @return pointer to the top layer
*/
static inline lv_obj_t *lv_layer_top(void)
{
return lv_disp_get_layer_top(lv_disp_get_default());
}
//example:
lv_obj_t *bg = lv_layer_top();
lv_obj_set_style_bg_color(bg, lv_color_hex(0x6f8af6), 0);/** //lv_disp.h
* Get the active screen of the default display
* @return pointer to the sys layer
*/
static inline lv_obj_t *lv_layer_sys(void)
{
return lv_disp_get_layer_sys(lv_disp_get_default());
}
//eg:
perf_label = lv_label_create(lv_layer_sys());
lv_obj_set_style_bg_opa(perf_label, LV_OPA_50, 0);2.2 动画加载屏幕
typedef enum {
LV_SCR_LOAD_ANIM_NONE, //cae无动画，就是直接加载;
LV_SCR_LOAD_ANIM_OVER_LEFT, //cae新屏幕以定向覆盖的方式来加载;
LV_SCR_LOAD_ANIM_OVER_RIGHT,
LV_SCR_LOAD_ANIM_OVER_TOP,
LV_SCR_LOAD_ANIM_OVER_BOTTOM,
LV_SCR_LOAD_ANIM_MOVE_LEFT, //cae新旧屏幕一起定向加载;
LV_SCR_LOAD_ANIM_MOVE_RIGHT,
LV_SCR_LOAD_ANIM_MOVE_TOP,
LV_SCR_LOAD_ANIM_MOVE_BOTTOM,
LV_SCR_LOAD_ANIM_FADE_IN, //cae在旧屏幕上淡入新屏幕;
LV_SCR_LOAD_ANIM_FADE_ON = LV_SCR_LOAD_ANIM_FADE_IN, /*For backward compatibility*/
LV_SCR_LOAD_ANIM_FADE_OUT,
LV_SCR_LOAD_ANIM_OUT_LEFT, //cae以旧屏幕定向滑出的方式来加载;
LV_SCR_LOAD_ANIM_OUT_RIGHT,
LV_SCR_LOAD_ANIM_OUT_TOP,
LV_SCR_LOAD_ANIM_OUT_BOTTOM,
} lv_scr_load_anim_t;
/** //lv_disp.h 以动画方式加载屏幕，本质还是屏幕，而不是动画;
* Switch screen with animation
* @param scr pointer to the new screen to load
* @param anim_type type of the animation from `lv_scr_load_anim_t`, e.g. `LV_SCR_LOAD_ANIM_MOVE_LEFT`
* @param time time of the animation
* @param delay delay before the transition
* @param auto_del true: automatically delete the old screen
*/
void lv_scr_load_anim(lv_obj_t * scr, lv_scr_load_anim_t anim_type, uint32_t time, uint32_t delay, bool auto_del);2.3 显示屏幕
每个screen都是创建在default display上的；default display是最后一个用lv_disp_drv_register( )注册的显示；
lv_scr_act( ), lv_src_load( ), lv_src_load_anim( )都是在default screen上操作的；
/** //lv_disp.h 每个屏幕加载之后会在tick时间后更新，也可能是屏幕会在调用lv_scr_act()之后tick时间更新，先放着；
* Get the active screen of the default display
* @return pointer to the active screen
*/
static inline lv_obj_t * lv_scr_act(void)
{
return lv_disp_get_scr_act(lv_disp_get_default());
}3 parts
对象或部件是由一种或多种parts构成的；
比如basic obj使用main part和scrollbar part，silider使用main part、indicator part、knob part组成；
如果想设置一个widgets部分parts的样式，那么这个parts用来区分出parts，可不是很方便嘛；
/** //lv_obj.h
* The possible parts of widgets.
* The parts can be considered as the internal building block of the widgets.
* E.g. slider = background + indicator + knob
* Not all parts are used by every widget
*/
enum {
LV_PART_MAIN = 0x000000, /**< A background like rectangle*/
LV_PART_SCROLLBAR = 0x010000, /**< The scrollbar(s)*/
LV_PART_INDICATOR = 0x020000, /**< Indicator, e.g. for slider, bar, switch, or the tick box of the checkbox*/
LV_PART_KNOB = 0x030000, /**< Like handle to grab to adjust the value*/
LV_PART_SELECTED = 0x040000, /**< Indicate the currently selected option or section*/
LV_PART_ITEMS = 0x050000, /**< Used if the widget has multiple similar elements (e.g. table cells)*/
LV_PART_TICKS = 0x060000, /**< Ticks on scale e.g. for a chart or meter*/
LV_PART_CURSOR = 0x070000, /**< Mark a specific place e.g. for text area's cursor or on a chart*/
LV_PART_CUSTOM_FIRST = 0x080000, /**< Extension point for custom widgets*/
LV_PART_ANY = 0x0F0000, /**< Special value can be used in some functions to target all parts*/
};
typedef uint32_t lv_part_t;4 状态 states
对象可以处于以下几种状态的组合，状态通常在用户操作时自动更改，但是也可以代码更改；
状态的作用是什么呢？在写回调函数的时候，通过设置对哪几个state来响应回调函数；
/** lv_obj.h
* Possible states of a widget.
* OR-ed values are possible
*/
enum {
LV_STATE_DEFAULT = 0x0000, //Normal, released state
LV_STATE_CHECKED = 0x0001, //Toggled or checked state
LV_STATE_FOCUSED = 0x0002, //Focused via keypad or encoder or clicked via touchpad/mouse
LV_STATE_FOCUS_KEY = 0x0004, //Focused via keypad or encoder but not via touchpad/mouse
LV_STATE_EDITED = 0x0008, //Edit by an encoder
LV_STATE_HOVERED = 0x0010, //Hovered by mouse (not supported now)
LV_STATE_PRESSED = 0x0020, //Being pressed
LV_STATE_SCROLLED = 0x0040, //Being scrolled
LV_STATE_DISABLED = 0x0080, //Disabled state
LV_STATE_USER_1 = 0x1000,
LV_STATE_USER_2 = 0x2000,
LV_STATE_USER_3 = 0x4000,
LV_STATE_USER_4 = 0x8000,
LV_STATE_ANY = 0xFFFF, /**< Special value can be used in some functions to target all states*/
};
typedef uint16_t lv_state_t;/** //lv_obj.h
* Add one or more states to the object. The other state bits will remain unchanged.
* If specified in the styles, transition animation will be started from the previous state to the current.
* @param obj pointer to an object
* @param state the states to add. E.g `LV_STATE_PRESSED | LV_STATE_FOCUSED`
*/
void lv_obj_add_state(lv_obj_t *obj, lv_state_t state);
/**
* Remove one or more states to the object. The other state bits will remain unchanged.
* If specified in the styles, transition animation will be started from the previous state to the current.
* @param obj pointer to an object
* @param state the states to add. E.g `LV_STATE_PRESSED | LV_STATE_FOCUSED`
*/
void lv_obj_clear_state(lv_obj_t *obj, lv_state_t state);5 坐标 coordinates
坐标方向：以父类左上角的坐标为原点，水平方向以x轴正方向为lvgl_obj正方向，垂直方向以y轴负方向为lvgl_obj正方向；
坐标单位：数值的单位都是像素点 pixels；
坐标存储：lvgl的坐标信息是存储在styles中的；所以可以单独设置坐标信息，也可以使用style对其进行设置；
5.1 位置 positions
5.1.1 位置 position
//lv_obj_pos.h
void lv_obj_set_pos(struct _lv_obj_t * obj, lv_coord_t x, lv_coord_t y);
void lv_obj_set_x(struct _lv_obj_t * obj, lv_coord_t x);
void lv_obj_set_y(struct _lv_obj_t * obj, lv_coord_t y);
void lv_obj_refr_pos(struct _lv_obj_t * obj); //用法保持怀疑，在tick范围内刷新一遍的话应该不调用也行;5.1.2 对齐 align
//lv_area.h
//child_obj向parent_obj对齐，使用LV_ALIGN_XX，在parent_obj内对齐，以child_obj顶点作为偏移坐标原点；
// 使用LV_ALIGN_OUT_XX，对齐无效，坐标原点始终是父对象坐标原点;所以不要这么用；
//align_obj向base_obj对齐， 使用LV_ALIGN_OUT_XX，偏移坐标原点为对齐后align_obj原点；
enum _lv_align_t {
LV_ALIGN_DEFAULT = 0,
LV_ALIGN_TOP_LEFT,
LV_ALIGN_TOP_MID,
LV_ALIGN_TOP_RIGHT,
LV_ALIGN_BOTTOM_LEFT,
LV_ALIGN_BOTTOM_MID,
LV_ALIGN_BOTTOM_RIGHT,
LV_ALIGN_LEFT_MID,
LV_ALIGN_RIGHT_MID,
LV_ALIGN_CENTER,
LV_ALIGN_OUT_TOP_LEFT,
LV_ALIGN_OUT_TOP_MID,
LV_ALIGN_OUT_TOP_RIGHT,
LV_ALIGN_OUT_BOTTOM_LEFT,
LV_ALIGN_OUT_BOTTOM_MID,
LV_ALIGN_OUT_BOTTOM_RIGHT,
LV_ALIGN_OUT_LEFT_TOP,
LV_ALIGN_OUT_LEFT_MID,
LV_ALIGN_OUT_LEFT_BOTTOM,
LV_ALIGN_OUT_RIGHT_TOP,
LV_ALIGN_OUT_RIGHT_MID,
LV_ALIGN_OUT_RIGHT_BOTTOM,
};
#ifdef DOXYGEN
typedef _lv_align_t lv_align_t;
#else
typedef uint8_t lv_align_t;
#endif /*DOXYGEN*///lv_obj_pos.h
//obj向parent对齐，所以不是设计用来配置LV_ALIGN_OUT_XX的;
void lv_obj_align(lv_obj_t * obj, lv_align_t align, lv_coord_t x_ofs, lv_coord_t y_ofs);
void lv_obj_set_align(lv_obj_t * obj, lv_align_t align);
//obj向base对齐，对齐之后以obj顶点作为坐标原点
//LV_ALIGN_OUT_XX：obj在base_obj外对齐;
//LV_ALIGN_XX: obj在base_obj内对齐;
void lv_obj_align_to(lv_obj_t * obj, const lv_obj_t * base, lv_align_t align, lv_coord_t x_ofs, lv_coord_t y_ofs)5.2 尺寸 size
//lv_obj_pos.h
void lv_obj_set_size(struct _lv_obj_t * obj, lv_coord_t w, lv_coord_t h);
void lv_obj_set_width(struct _lv_obj_t * obj, lv_coord_t w); //The actual width: padding left + w + padding right
void lv_obj_set_height(struct _lv_obj_t * obj, lv_coord_t h); //The actual width: padding top + h + padding bottom
bool lv_obj_refr_size(struct _lv_obj_t * obj);
/**
* Get the width reduced by the left and right padding and the border width.
* @param obj pointer to an object
* @note The position of the object is recalculated only on the next redraw. To force coordinate recalculation
* call `lv_obj_update_layout(obj)`.
* @return the width which still fits into its parent without causing overflow (making the parent scrollable)
*/
lv_coord_t lv_obj_get_content_width(const struct _lv_obj_t * obj);
/**
* Get the height reduced by the top and bottom padding and the border width.
* @param obj pointer to an object
* @note The position of the object is recalculated only on the next redraw. To force coordinate recalculation
* call `lv_obj_update_layout(obj)`.
* @return the height which still fits into the parent without causing overflow (making the parent scrollable)
*/
lv_coord_t lv_obj_get_content_height(const struct _lv_obj_t * obj);5.3 布局 layouts
用来更新当前对象子类的position和size，和flexbox、grid部件一起使用，对布局进行实时更新么？先放着；
//lv_obj_pos.h layout函数并不多，先放着;
extern uint16_t LV_LAYOUT_GRID; //lv_grid.h
extern uint16_t LV_LAYOUT_FLEX; //lv_flex.h
void lv_obj_set_layout(struct _lv_obj_t * obj, uint32_t layout);5.3.1 flags
用来配置子类对象 如何响应他的父类对象的layout局部；所以这个flag是layout给子类对象使用的；
//lv_obj.h
/**
* On/Off features controlling the object's behavior.
* OR-ed values are possible
*/
enum {
LV_OBJ_FLAG_HIDDEN = (1L << 0), /**< Make the object hidden. (Like it wasn't there at all)*/
LV_OBJ_FLAG_CLICKABLE = (1L << 1), /**< Make the object clickable by the input devices*/
LV_OBJ_FLAG_CLICK_FOCUSABLE = (1L << 2), /**< Add focused state to the object when clicked*/
LV_OBJ_FLAG_CHECKABLE = (1L << 3), /**< Toggle checked state when the object is clicked*/
LV_OBJ_FLAG_SCROLLABLE = (1L << 4), /**< Make the object scrollable*/
LV_OBJ_FLAG_SCROLL_ELASTIC = (1L << 5), /**< Allow scrolling inside but with slower speed*/
LV_OBJ_FLAG_SCROLL_MOMENTUM = (1L << 6), /**< Make the object scroll further when "thrown"*/
LV_OBJ_FLAG_SCROLL_ONE = (1L << 7), /**< Allow scrolling only one snappable children*/
LV_OBJ_FLAG_SCROLL_CHAIN_HOR = (1L << 8), /**< Allow propagating the horizontal scroll to a parent*/
LV_OBJ_FLAG_SCROLL_CHAIN_VER = (1L << 9), /**< Allow propagating the vertical scroll to a parent*/
LV_OBJ_FLAG_SCROLL_CHAIN = (LV_OBJ_FLAG_SCROLL_CHAIN_HOR | LV_OBJ_FLAG_SCROLL_CHAIN_VER),
LV_OBJ_FLAG_SCROLL_ON_FOCUS = (1L << 10), /**< Automatically scroll object to make it visible when focused*/
LV_OBJ_FLAG_SCROLL_WITH_ARROW = (1L << 11), /**< Allow scrolling the focused object with arrow keys*/
LV_OBJ_FLAG_SNAPPABLE = (1L << 12), /**< If scroll snap is enabled on the parent it can snap to this object*/
LV_OBJ_FLAG_PRESS_LOCK = (1L << 13), /**< Keep the object pressed even if the press slid from the object*/
LV_OBJ_FLAG_EVENT_BUBBLE = (1L << 14), /**< Propagate the events to the parent too*/
LV_OBJ_FLAG_GESTURE_BUBBLE = (1L << 15), /**< Propagate the gestures to the parent*/
LV_OBJ_FLAG_ADV_HITTEST = (1L << 16), /**< Allow performing more accurate hit (click) test. E.g. consider rounded corners.*/
LV_OBJ_FLAG_IGNORE_LAYOUT = (1L << 17), /**< Make the object ignored by layouts,so obj can be set as usual*/
LV_OBJ_FLAG_FLOATING = (1L << 18), /**< Do not scroll the object when the parent scrolls and ignore layout,这个等于上一行那个*/
LV_OBJ_FLAG_OVERFLOW_VISIBLE = (1L << 19), /**< Do not clip the children's content to the parent's boundary*/
LV_OBJ_FLAG_LAYOUT_1 = (1L << 23), /**< Custom flag, free to use by layouts*/
LV_OBJ_FLAG_LAYOUT_2 = (1L << 24), /**< Custom flag, free to use by layouts*/
LV_OBJ_FLAG_WIDGET_1 = (1L << 25), /**< Custom flag, free to use by widget*/
LV_OBJ_FLAG_WIDGET_2 = (1L << 26), /**< Custom flag, free to use by widget*/
LV_OBJ_FLAG_USER_1 = (1L << 27), /**< Custom flag, free to use by user*/
LV_OBJ_FLAG_USER_2 = (1L << 28), /**< Custom flag, free to use by user*/
LV_OBJ_FLAG_USER_3 = (1L << 29), /**< Custom flag, free to use by user*/
LV_OBJ_FLAG_USER_4 = (1L << 30), /**< Custom flag, free to use by user*/
};
typedef uint32_t lv_obj_flag_t;
/**
* Set one or more flags
* @param obj pointer to an object
* @param f R-ed values from `lv_obj_flag_t` to set.
*/
void lv_obj_add_flag(lv_obj_t * obj, lv_obj_flag_t f);
/**
* Clear one or more flags
* @param obj pointer to an object
* @param f OR-ed values from `lv_obj_flag_t` to set.
*/
void lv_obj_clear_flag(lv_obj_t * obj, lv_obj_flag_t f);6 小结
对象obj，以及对象一些基本的简单属性的概括；