Difference between revisions of "GTRANS"
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| − | The GTRANS module allows to manage language translations. The language of an application can be changed dynamically during run-time using the GTRANS module. | + | The GTRANS module allows you to manage language translations. The language of an application can be changed dynamically during run-time using the GTRANS module. |
== API reference == | == API reference == | ||
Revision as of 02:13, 29 February 2016
The GTRANS module allows you to manage language translations. The language of an application can be changed dynamically during run-time using the GTRANS module.
Contents
API reference
The API reference of the GTRANS module can be found here.
Intended usage
Each translation is specified by a transTable struct which is essentially a table of strings:
typedef struct transTable { unsigned numEntries; // The number of strings that this table contains const char** strings; // The translated strings } transTable;
A translatable application needs to have a base language. All translations happen relative to that base language. The base language is specified using gtransSetBaseLanguage(). The current language of the application is set using gtransSetLanguage().
The actual translations take place by calling gtransString(). A string contained in the translation table of the base language is passed to gtransString(). The function returns the corresponding string of the current language that was set using gtransSetLanguage() or the passed string if none was found.
A wrapper macro named gt() around gtransString() is available to make writing and reading translatable applications easier:
#define gt(str) gtransString(str)Optimization
Calling gt() (or gtransString() directly) uses the strcmp() function of the standard C library to compare strings. This operation can take a lot of time. For performance critical applications or low-resource systems the application translation speed can be optimized by using gtransIndex() (instead of gtransString()) which directly takes the index of the string in the translation table. However, this introduces the limitation that each string in each of the translation tables need to be at the same position (the same index). Using gtransString() allows to have translation tables of unequal sizes due to the nature of the translation being based on string comparison rather than index accessing of the table.
Example
Complete examples can be found under /demos/modules/gtrans/ in the uGFX library directory.
Basic Example
The following code is a very simple usage example showing how the GTRANS module is used. This is a very minimalistic example with no dependencies other than the GDISP module to interface a display.
#include <stdio.h> #include "gfx.h" #define COLOR_BACKGROUND Silver #define COLOR_TEXT Black font_t font; // English Translation static const char* EnglishStrings[] = { "Welcome", "The temperature is %d degrees", "Goodbye", "This is a translated uGFX application" }; static const transTable EnglishTranslation = { sizeof(EnglishStrings)/sizeof(EnglishStrings[0]), EnglishStrings }; // German translation static const char* GermanStrings[] = { "Herzlich Willkommen", "Die Temperatur beträgt %d Grad", "Auf Wiedersehen", "Das ist eine übersetzte uGFX Anwendung" }; static const transTable GermanTranslation = { sizeof(GermanStrings)/sizeof(GermanStrings[0]), GermanStrings }; // French translation static const char* FrenchStrings[] = { "Bienvenue", "La température est de %d degrés", "Au revoir", "Ceci est une application traduit uGFX" }; static const transTable FrenchTranslation = { sizeof(FrenchStrings)/sizeof(FrenchStrings[0]), FrenchStrings }; void updateText() { coord_t width = 400; coord_t height = 30; // Translate some basic strings gdispFillStringBox(20, 20, width, height, gt("Welcome"), font, COLOR_TEXT, COLOR_BACKGROUND, justifyLeft); gdispFillStringBox(20, 60, width, height, gt("This is a translated uGFX application"), font, COLOR_TEXT, COLOR_BACKGROUND, justifyLeft); gdispFillStringBox(20, 100, width, height, gt("Goodbye"), font, COLOR_TEXT, COLOR_BACKGROUND, justifyLeft); // A more complex example using string formatting char buffer[128]; sprintf(buffer, gt("The temperature is %d degrees"), 18); gdispFillStringBox(20, 140, width, height, buffer, font, COLOR_TEXT, COLOR_BACKGROUND, justifyLeft); } int main(void) { // Initialize the uGFX library gfxInit(); gdispClear(COLOR_BACKGROUND); // Take the first font we find font = gdispOpenFont("*"); // Set the base language of the application gtransSetBaseLanguage(&EnglishTranslation); // Loop through the languages while (TRUE) { // English gtransSetLanguage(&EnglishTranslation); updateText(); gfxSleepMilliseconds(3000); // German gtransSetLanguage(&GermanTranslation); updateText(); gfxSleepMilliseconds(3000); // French gtransSetLanguage(&FrenchTranslation); updateText(); gfxSleepMilliseconds(3000); } return 0; }
Example with widgets
The following example demonstrates how the language of an application using widgets can be translated using GTRANS. The user can select the language using buttons.
ToDo
