add lv_i18n support

Makefile

@@ -0,0 +1,5 @@
+extract:
+	lv_i18n extract -s 'src/**/*.+(c|cpp|h|hpp)' -t 'translations/*.yml'
+
+compile:
+	lv_i18n compile -t 'translations/*.yml' -o 'src/lv_i18n'

src/lv_i18n/lv_i18n.c

@@ -0,0 +1,221 @@
+#include "./lv_i18n.h"
+
+
+////////////////////////////////////////////////////////////////////////////////
+// Define plural operands
+// http://unicode.org/reports/tr35/tr35-numbers.html#Operands
+
+// Integer version, simplified
+
+#define UNUSED(x) (void)(x)
+
+static inline uint32_t op_n(int32_t val) { return (uint32_t)(val < 0 ? -val : val); }
+static inline uint32_t op_i(uint32_t val) { return val; }
+// always zero, when decimal part not exists.
+static inline uint32_t op_v(uint32_t val) { UNUSED(val); return 0;}
+static inline uint32_t op_w(uint32_t val) { UNUSED(val); return 0; }
+static inline uint32_t op_f(uint32_t val) { UNUSED(val); return 0; }
+static inline uint32_t op_t(uint32_t val) { UNUSED(val); return 0; }
+
+static lv_i18n_phrase_t en_gb_singulars[] = {
+    {"appName", "OS-Railway EN"},
+    {NULL, NULL} // End mark
+};
+
+
+
+static uint8_t en_gb_plural_fn(int32_t num)
+{
+    uint32_t n = op_n(num); UNUSED(n);
+    uint32_t i = op_i(n); UNUSED(i);
+    uint32_t v = op_v(n); UNUSED(v);
+
+    if ((i == 1 && v == 0)) return LV_I18N_PLURAL_TYPE_ONE;
+    return LV_I18N_PLURAL_TYPE_OTHER;
+}
+
+static const lv_i18n_lang_t en_gb_lang = {
+    .locale_name = "en-GB",
+    .singulars = en_gb_singulars,
+
+    .locale_plural_fn = en_gb_plural_fn
+};
+
+static lv_i18n_phrase_t de_de_singulars[] = {
+    {"appName", "OS-Railway DE"},
+    {NULL, NULL} // End mark
+};
+
+
+
+static uint8_t de_de_plural_fn(int32_t num)
+{
+    uint32_t n = op_n(num); UNUSED(n);
+    uint32_t i = op_i(n); UNUSED(i);
+    uint32_t v = op_v(n); UNUSED(v);
+
+    if ((i == 1 && v == 0)) return LV_I18N_PLURAL_TYPE_ONE;
+    return LV_I18N_PLURAL_TYPE_OTHER;
+}
+
+static const lv_i18n_lang_t de_de_lang = {
+    .locale_name = "de-DE",
+    .singulars = de_de_singulars,
+
+    .locale_plural_fn = de_de_plural_fn
+};
+
+const lv_i18n_language_pack_t lv_i18n_language_pack[] = {
+    &en_gb_lang,
+    &de_de_lang,
+    NULL // End mark
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+
+// Internal state
+static const lv_i18n_language_pack_t * current_lang_pack;
+static const lv_i18n_lang_t * current_lang;
+
+
+/**
+ * Reset internal state. For testing.
+ */
+void __lv_i18n_reset(void)
+{
+    current_lang_pack = NULL;
+    current_lang = NULL;
+}
+
+/**
+ * Set the languages for internationalization
+ * @param langs pointer to the array of languages. (Last element has to be `NULL`)
+ */
+int lv_i18n_init(const lv_i18n_language_pack_t * langs)
+{
+    if(langs == NULL) return -1;
+    if(langs[0] == NULL) return -1;
+
+    current_lang_pack = langs;
+    current_lang = langs[0];     /*Automatically select the first language*/
+    return 0;
+}
+
+/**
+ * Change the localization (language)
+ * @param l_name name of the translation locale to use. E.g. "en-GB"
+ */
+int lv_i18n_set_locale(const char * l_name)
+{
+    if(current_lang_pack == NULL) return -1;
+
+    uint16_t i;
+
+    for(i = 0; current_lang_pack[i] != NULL; i++) {
+        // Found -> finish
+        if(strcmp(current_lang_pack[i]->locale_name, l_name) == 0) {
+            current_lang = current_lang_pack[i];
+            return 0;
+        }
+    }
+
+    return -1;
+}
+
+
+static const char * __lv_i18n_get_text_core(lv_i18n_phrase_t * trans, const char * msg_id)
+{
+    uint16_t i;
+    for(i = 0; trans[i].msg_id != NULL; i++) {
+        if(strcmp(trans[i].msg_id, msg_id) == 0) {
+            /*The msg_id has found. Check the translation*/
+            if(trans[i].translation) return trans[i].translation;
+        }
+    }
+
+    return NULL;
+}
+
+
+/**
+ * Get the translation from a message ID
+ * @param msg_id message ID
+ * @return the translation of `msg_id` on the set local
+ */
+const char * lv_i18n_get_text(const char * msg_id)
+{
+    if(current_lang == NULL) return msg_id;
+
+    const lv_i18n_lang_t * lang = current_lang;
+    const void * txt;
+
+    // Search in current locale
+    if(lang->singulars != NULL) {
+        txt = __lv_i18n_get_text_core(lang->singulars, msg_id);
+        if (txt != NULL) return txt;
+    }
+
+    // Try to fallback
+    if(lang == current_lang_pack[0]) return msg_id;
+    lang = current_lang_pack[0];
+
+    // Repeat search for default locale
+    if(lang->singulars != NULL) {
+        txt = __lv_i18n_get_text_core(lang->singulars, msg_id);
+        if (txt != NULL) return txt;
+    }
+
+    return msg_id;
+}
+
+/**
+ * Get the translation from a message ID and apply the language's plural rule to get correct form
+ * @param msg_id message ID
+ * @param num an integer to select the correct plural form
+ * @return the translation of `msg_id` on the set local
+ */
+const char * lv_i18n_get_text_plural(const char * msg_id, int32_t num)
+{
+    if(current_lang == NULL) return msg_id;
+
+    const lv_i18n_lang_t * lang = current_lang;
+    const void * txt;
+    lv_i18n_plural_type_t ptype;
+
+    // Search in current locale
+    if(lang->locale_plural_fn != NULL) {
+        ptype = lang->locale_plural_fn(num);
+
+        if(lang->plurals[ptype] != NULL) {
+            txt = __lv_i18n_get_text_core(lang->plurals[ptype], msg_id);
+            if (txt != NULL) return txt;
+        }
+    }
+
+    // Try to fallback
+    if(lang == current_lang_pack[0]) return msg_id;
+    lang = current_lang_pack[0];
+
+    // Repeat search for default locale
+    if(lang->locale_plural_fn != NULL) {
+        ptype = lang->locale_plural_fn(num);
+
+        if(lang->plurals[ptype] != NULL) {
+            txt = __lv_i18n_get_text_core(lang->plurals[ptype], msg_id);
+            if (txt != NULL) return txt;
+        }
+    }
+
+    return msg_id;
+}
+
+/**
+ * Get the name of the currently used locale.
+ * @return name of the currently used locale. E.g. "en-GB"
+ */
+const char * lv_i18n_get_current_locale(void)
+{
+    if(!current_lang) return NULL;
+    return current_lang->locale_name;
+}

src/lv_i18n/lv_i18n.h

@@ -0,0 +1,85 @@
+#ifndef LV_I18N_H
+#define LV_I18N_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+#include <string.h>
+
+typedef enum {
+    LV_I18N_PLURAL_TYPE_ZERO,
+    LV_I18N_PLURAL_TYPE_ONE,
+    LV_I18N_PLURAL_TYPE_TWO,
+    LV_I18N_PLURAL_TYPE_FEW,
+    LV_I18N_PLURAL_TYPE_MANY,
+    LV_I18N_PLURAL_TYPE_OTHER,
+    _LV_I18N_PLURAL_TYPE_NUM,
+} lv_i18n_plural_type_t;
+
+typedef struct {
+    const char * msg_id;
+    const char * translation;
+} lv_i18n_phrase_t;
+
+typedef struct {
+    const char * locale_name;
+    lv_i18n_phrase_t * singulars;
+    lv_i18n_phrase_t * plurals[_LV_I18N_PLURAL_TYPE_NUM];
+    uint8_t (*locale_plural_fn)(int32_t num);
+} lv_i18n_lang_t;
+
+// Null-terminated list of languages. First one used as default.
+typedef const lv_i18n_lang_t * lv_i18n_language_pack_t;
+
+
+extern const lv_i18n_language_pack_t lv_i18n_language_pack[];
+
+
+/**
+ * Set the languages for internationalization
+ * @param langs pointer to the array of languages. (Last element has to be `NULL`)
+ */
+int lv_i18n_init(const lv_i18n_language_pack_t * langs);
+
+/**
+ * Change the localization (language)
+ * @param l_name name of the translation locale to use. E.g. "en_GB"
+ */
+int lv_i18n_set_locale(const char * l_name);
+
+/**
+ * Get the translation from a message ID
+ * @param msg_id message ID
+ * @return the translation of `msg_id` on the set local
+ */
+const char * lv_i18n_get_text(const char * msg_id);
+
+/**
+ * Get the translation from a message ID and apply the language's plural rule to get correct form
+ * @param msg_id message ID
+ * @param num an integer to select the correct plural form
+ * @return the translation of `msg_id` on the set local
+ */
+const char * lv_i18n_get_text_plural(const char * msg_id, int32_t num);
+
+/**
+ * Get the name of the currently used localization.
+ * @return name of the currently used localization. E.g. "en_GB"
+ */
+const char * lv_i18n_get_current_locale(void);
+
+
+void __lv_i18n_reset(void);
+
+
+#define _(text) lv_i18n_get_text(text)
+#define _p(text, num) lv_i18n_get_text_plural(text, num)
+
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /*LV_LANG_H*/

src/main.cpp

@@ -19,10 +19,14 @@
 #include <Arduino.h>
 
 #include "gfx/lv_setup.h"
+#include "lv_i18n/lv_i18n.h"
 #include "ui/launch_screen.h"
 
 void setup()
 {
+  lv_i18n_init(lv_i18n_language_pack);
+  lv_i18n_set_locale("de-DE");
+
   lv_begin();
   ui_LaunchScreen_open();
 }

src/ui/launch_screen.cpp

@@ -1,6 +1,7 @@
 #include "ui/launch_screen.h"
 
 #include <lvgl.h>
+#include "lv_i18n/lv_i18n.h"
 
 void ui_LaunchScreen_open()
 {
@@ -14,7 +15,7 @@ void ui_LaunchScreen_open()
     lv_obj_align(img, LV_ALIGN_CENTER, 0, 0);
 
     auto *label = lv_label_create(ui_SplashScreen);
-    lv_label_set_text(label, "OS-Railway");
+    lv_label_set_text(label, _("appName"));
     lv_obj_align(label, LV_ALIGN_BOTTOM_MID, 0, -25);
 
     lv_disp_load_scr(ui_SplashScreen);

translations/de-DE.yml

@@ -0,0 +1,2 @@
+de-DE:
+  appName: OS-Railway DE

translations/en-GB.yml

@@ -0,0 +1,2 @@
+en-GB:
+  appName: OS-Railway EN