arch add small 3rd party libs to lvgl (#2569)

* move png, sjpg, bmp, gif, fs_if to extra/libs

* reorganize the examples

* update lv_conf_internal.h

* fix warnings

* add freetype

* remove unused assets

* add the new libs to build tests

* update the docs

examples/libs/freetype/index.rst

@@ -0,0 +1,6 @@
+Open a front with FreeTpye
+"""""""""""""""""""""""""""""""""""""""""""""""
+
+.. lv_example:: libs/freetype/lv_example_freetype_1
+  :language: c
+

examples/libs/freetype/lv_example_freetype.h

@@ -0,0 +1,38 @@
+/**
+ * @file lv_example_freetype.h
+ *
+ */
+
+#ifndef LV_EXAMPLE_FREETYPE_H
+#define LV_EXAMPLE_FREETYPE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*********************
+ *      INCLUDES
+ *********************/
+
+/*********************
+ *      DEFINES
+ *********************/
+
+/**********************
+ *      TYPEDEFS
+ **********************/
+
+/**********************
+ * GLOBAL PROTOTYPES
+ **********************/
+void lv_example_freetype_1(void);
+
+/**********************
+ *      MACROS
+ **********************/
+
+#ifdef __cplusplus
+} /*extern "C"*/
+#endif
+
+#endif /*LV_EXAMPLE_FREETYPE_H*/

examples/libs/freetype/lv_example_freetype_1.c

@@ -0,0 +1,30 @@
+#include "../../lv_examples.h"
+#if LV_USE_FREETYPE && LV_BUILD_EXAMPLES
+
+/**
+ * Load a font with FreeType
+ */
+void lv_example_freetype_1(void)
+{
+    /*Create a font*/
+    static lv_ft_info_t info;
+    /*FreeType uses C standard file system, so no driver letter is required.*/
+    info.name = "./lvgl/examples/libs/freetype/arial.ttf";
+    info.weight = 24;
+    info.style = FT_FONT_STYLE_NORMAL;
+    lv_ft_font_init(&info);
+
+    /*Create style with the new font*/
+    static lv_style_t style;
+    lv_style_init(&style);
+    lv_style_set_text_font(&style, info.font);
+    lv_style_set_text_align(&style, LV_TEXT_ALIGN_CENTER);
+
+    /*Create a label with the new style*/
+    lv_obj_t * label = lv_label_create(lv_scr_act());
+    lv_obj_add_style(label, &style, 0);
+    lv_label_set_text(label, "Hello world\nI'm a font created with FreeType");
+    lv_obj_center(label);
+}
+
+#endif