example obj_usage: begin

lv_examples/1_2_obj_usage/obj_usage.c

@@ -0,0 +1,129 @@
+/**
+ * @file lv_hello_world.c
+ *
+ */
+
+/*
+ * The basic building blocks in LittlevGL are the graphical objects.
+ * For example:
+ *  - Buttons
+ *  - Labels
+ *  - Charts
+ *  - Sliders etc
+ *
+ * Regardless to the object type the 'lv_obj_t' is used stores objects
+ * and you can refer to an object with an lv_obj_t pointer (lv_obj_t *)
+ *
+ *
+ * INHERITANCE
+ * -------------
+ * Similarly to object oriented languages some kind of inheritance is used
+ * among the object types.
+ *
+ * Every object is derived from the 'Basic object'. (lv_obj)
+ *
+ * The types are backward compatible which means a type can use all the ancestor
+ * attributes/functions too.
+ *
+ * For example a 'Button' is derived from 'Container'  which is derived from 'Basic objects'.
+ * Therefore a button can use container attributes like automatically fit size to the content.
+ *
+ * PARENT-CHILD
+ * -------------
+ * A parent can be considered as the container of its children.
+ * Every object has exactly one parent object (except screens) but
+ * a parent can have unlimited number of children.
+ * There is no limitation for the type of the parent.
+ *
+ * The children are visible only on their parent. The parts outside will be cropped (not displayed)
+ *
+ * If the parent is moved the children move with it.
+ *
+ * The earlier created object (and its children) will drawn earlier.
+ * Using this layers can be built.
+ *
+ * LEARN MORE
+ * -------------
+ * - General overview: http://www.gl.littlev.hu/objects
+ * - Detailed description of types: http://www.gl.littlev.hu/object-types
+ */
+
+/*********************
+ *      INCLUDES
+ *********************/
+#include "obj_usage.h"
+#if USE_LV_EXAMPLE != 0
+
+#include "lvgl/lvgl.h"
+
+/*********************
+ *      DEFINES
+ *********************/
+
+/**********************
+ *      TYPEDEFS
+ **********************/
+
+/**********************
+ *  STATIC PROTOTYPES
+ **********************/
+static  lv_action_res_t btn_rel_action(lv_obj_t * btn, lv_dispi_t * dispi);
+
+/**********************
+ *  STATIC VARIABLES
+ **********************/
+
+/**********************
+ *      MACROS
+ **********************/
+
+/**********************
+ *   GLOBAL FUNCTIONS
+ **********************/
+
+/**
+ *
+ */
+void lv_obj_usage_init(void)
+{
+
+    /* Create a new screen and load it
+     * Screen can be created from any type object
+     * Now a Page is used which is an objects with scrollable content*/
+    lv_obj_t * scr = lv_page_create(NULL, NULL);
+    lv_scr_load(scr);
+
+    /*Add a title*/
+    lv_obj_t * label = lv_label_create(scr, NULL);  /*First parameters (scr) is the parent*/
+    lv_label_set_text(label, "Object usage demo");  /*Set the text*/
+    lv_obj_set_x(label, 50);       /*Labels are inherited from Basic object so 'lv_obj_...' functions can be used*/
+
+    /*Create a button*/
+    lv_obj_t * btn1 = lv_btn_create(lv_scr_act(), NULL);    /*Create a button the currently loaded screen*/
+    lv_btn_set_rel_action(btn1, btn_rel_action);            /*Set function to call when the button is released*/
+    lv_obj_align(btn1, label, LV_ALIGN_OUT_BOTTOM_LEFT, 0, 20); /*Align below the label*/
+    label = lv_label_create(btn1, NULL);            /*Create a label on the button (the 'label' variable can be reused)*/
+    lv_label_set_text(label, "Button 1");
+
+    /*Copy the previous button*/
+    lv_obj_t * btn2 = lv_btn_create(lv_scr_act(), btn1);    /*Second parameter is an object to copy*/
+    lv_obj_align(btn2, btn1, LV_ALIGN_OUT_RIGHT_MID, 50, 0);/*Align next to the prev. button.*/
+    label = lv_label_create(btn2, NULL);                     /*Create a label on the button*/
+    lv_label_set_text(label, "Button 2");
+
+    /*Add a slider (inheritance: lv_obj -> lv_bar -> lv_slider)*/
+    lv_obj_t * slider = lv_slider_create(scr, NULL);
+}
+
+/**********************
+ *   STATIC FUNCTIONS
+ **********************/
+static  lv_action_res_t btn_rel_action(lv_obj_t * btn, lv_dispi_t * dispi)
+{
+    cord_t width = lv_obj_get_width(btn);
+    lv_obj_set_width(btn, width + 20);
+
+    return LV_ACTION_RES_OK;
+}
+
+#endif /*USE_LV_EXAMPLE != 0*/

lv_examples/1_2_obj_usage/obj_usage.h

@@ -0,0 +1,42 @@
+/**
+ * @file lv_hello_world.h
+ *
+ */
+
+#ifndef LV_OBJ_USAGE_H
+#define LV_OBJ_USAGE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*********************
+ *      INCLUDES
+ *********************/
+#include "lv_conf.h"
+#if USE_LV_EXAMPLE != 0
+
+/*********************
+ *      DEFINES
+ *********************/
+
+/**********************
+ *      TYPEDEFS
+ **********************/
+
+/**********************
+ * GLOBAL PROTOTYPES
+ **********************/
+void lv_obj_usage_init(void);
+
+/**********************
+ *      MACROS
+ **********************/
+
+#endif /*USE_LV_EXAMPLE != 0*/
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /*LV_OBJ_USAGE_H*/