LVGL button 类型输入坐标

一、添加输入设备

1. lv_port_indev.c中间，增加button类型的代码
   注意点：

   • 必须加入到group中，否则不会有event传递
   • 按键返回值，对应btn_points的下标

   //    /*Register a button input device*/
       lv_indev_drv_init(&indev_drv);
       indev_drv.type = LV_INDEV_TYPE_BUTTON;
      indev_drv.read_cb = button_read;
       indev_button = lv_indev_drv_register(&indev_drv);
       lv_indev_set_group(indev_button, group);
   
   //    /*Assign buttons to points on the screen*/
       static const lv_point_t btn_points[2] = {   //对应按键 0 和 1
               {160/2, 80/2},   /*Button 0 -> x:10; y:10*/ //点屏幕中间
              {40, 100},  /*Button 1 -> x:40; y:100*/
       };
       lv_indev_set_button_points(indev_button, btn_points);//将按键和point 对应起来
   

2. 按键处理
   注意点：

   • 返回 - 1 ，代表REL，也就是 RELEASE 松手，所以要自己是适配一下这个返回值

   /*Will be called by the library to read the button*/
   static void button_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
   {
   
       static uint8_t last_btn = 0;
   
       /*Get the pressed button's ID*/
       int8_t btn_act = button_get_pressed_id();
       if(btn_act >= 0) {
           data->state = LV_INDEV_STATE_PR;
           last_btn = btn_act;
       } else {
           data->state = LV_INDEV_STATE_REL;
       }
       /*Save the last pressed button's ID*/
       data->btn_id = last_btn;
   }
   
   /*Get ID  (0, 1, 2 ..) of the pressed button*/
   static int8_t button_get_pressed_id(void)
   {
       uint8_t i;
   
       /*Check to buttons see which is being pressed (assume there are 2 buttons)*/
       #if 0
       for(i = 0; i < 2; i++) {
           /*Return the pressed button's ID*/
           if(button_is_pressed(i)) {
               return i;
           }
       }
       #else 
   
   	uint32_t btn = my_read_key();
   	//注意按键是从 0 开始，对应 btn_points 如果没按键就返回-1
   	switch(btn)
   	{
   		case 5: //我的boot按键
   		return 0;//当成0返回
   		break;
   		default:
   		break;
   	}
   
   	
       #endif
       /*No button pressed*/
       return -1;//没按键直接返回 -1
   }
   

二、创建obj

1. 创建obj和设置回调，监听所有EVENT

   static void my_lvgl_test(void)
   {
   	lv_obj_t * btn = lv_btn_create( lv_scr_act());
   	LV_LOG_USER("lv_scr_act: %x \r\n",lv_scr_act());
   	LV_LOG_USER("btn addr: %x \r\n",btn);
   	lv_obj_set_size( btn, 40, 20 );
   	lv_obj_add_event_cb( btn, event_handler, LV_EVENT_ALL, NULL );	// 设置事件句柄
   	lv_group_add_obj( group, btn );	// 添加进group 如果用触摸屏就不用
   	lv_obj_align( btn, LV_ALIGN_CENTER, 0, 0);
   	lv_obj_add_flag(btn, LV_OBJ_FLAG_CHECKABLE);
   	
       lv_obj_t * label1 = lv_label_create(btn);
       lv_label_set_recolor(label1, true);
       lv_label_set_text(label1, "#ffffff release#");
       //lv_obj_align(label1, btn, 0, 0);
   	//lv_label_set_text(label1, "#ff0000 red#,#00ff00 green#,#0000ff blue#");//使用了 3 次重绘色
   	lv_obj_center(label1);	
   //    lv_obj_t * label;
   //
   //    lv_obj_t * btn1 = lv_btn_create(lv_scr_act());
   //    lv_obj_add_event_cb(btn1, event_handler, LV_EVENT_ALL, NULL);
   //	lv_group_add_obj( group, btn1 );	// 添加进group 如果用触摸屏就不用
   //    lv_obj_align(btn1, LV_ALIGN_CENTER, 0, -10);
   //
   //    label = lv_label_create(btn1);
   //    lv_label_set_text(label, "Button");
   //    lv_obj_center(label);	
   }
   

2. 回调

   /* 引入之前创建的group */
   extern lv_group_t * group;	// 如果用触摸屏就不用
   
   static void event_handler(lv_obj_t * obj, lv_event_t event)
   {
   	
       switch (event.code) {
       case LV_EVENT_CLICKED:
          
           //lv_obj_del( obj ); // 点击就消失
   		LV_LOG_USER( "btn Clicked\n" );
           break;
       default:
           break;
       }
   
   	
   	lv_event_code_t code = lv_event_get_code(obj);
       lv_obj_t * btn = lv_event_get_target(obj);
       lv_obj_t * label = lv_obj_get_child(btn, 0);
   	
   	
       LV_LOG_USER("code: %d\n",event.code);	
   	
   	
       if(code == LV_EVENT_CLICKED) {
           LV_LOG_USER("Clicked");
       }
       else if(code == LV_EVENT_VALUE_CHANGED) {
   //		lv_label_set_text(obj, "press");
           //lv_label_set_text_fmt(label, "%s", "press");
           //LV_LOG_USER("Toggled");
       }
   	
   }
   

三、调用的大致流程

1. 注册了button类型的输入后（注意要添加到group内）lv_indev_drv_register，button的回调就会周期性调用判断是否有按键输入
2. 所有输入设备的轮训，在lv_indev.c中
3. 当判断到按键PRESS，就会发送EVENT过去，这样应用层就能拿到了
4. indev_proc_press中，通过button 返回的坐标，查找对应现在的obj，这样就会发送对应的EVENT了