Demo program that breaks text. Move it left and right with the up and down keys.

gistfile1.c

#include "pebble_os.h"
#include "pebble_app.h"
#include "pebble_fonts.h"


#define MY_UUID { 0xFC, 0xF3, 0xC3, 0xF1, 0xBC, 0xE4, 0x48, 0x3D, 0x92, 0x48, 0x79, 0x97, 0xAC, 0xC7, 0x2F, 0x7F }
PBL_APP_INFO_SIMPLE(MY_UUID, "Text Rendering Error", "Demo Corp", 1 /* App version */);


Window window;
Layer layer;
int8_t offset;


// Modify these common button handlers

void up_single_click_handler(ClickRecognizerRef recognizer, Window *window) {
    ++offset;
	layer_mark_dirty(&layer);
}


void down_single_click_handler(ClickRecognizerRef recognizer, Window *window) {
	--offset;
	layer_mark_dirty(&layer);
}

void click_config_provider(ClickConfig **config, Window *window) {
	config[BUTTON_ID_UP]->click.handler = (ClickHandler) up_single_click_handler;
	config[BUTTON_ID_UP]->click.repeat_interval_ms = 100;

	config[BUTTON_ID_DOWN]->click.handler = (ClickHandler) down_single_click_handler;
	config[BUTTON_ID_DOWN]->click.repeat_interval_ms = 100;
}

void update_proc(Layer* layer, GContext* context) {
	static char str[] = "Test";
	GFont font = fonts_get_system_font(FONT_KEY_GOTHAM_30_BLACK);
	graphics_context_set_text_color(context, GColorBlack);
	graphics_text_draw(context, str, font, GRect(offset, 0, 100, 40), GTextOverflowModeTrailingEllipsis, GTextAlignmentLeft, NULL);
}

void handle_init(AppContextRef ctx) {
	window_init(&window, "Debug");
	window_stack_push(&window, true /* Animated */);

	layer_init(&layer, GRect(10,10,124,40));
	layer.update_proc = update_proc;
	layer_add_child(&window.layer, &layer);

	// Attach our desired button functionality
	window_set_click_config_provider(&window, (ClickConfigProvider) click_config_provider);
}

void pbl_main(void *params) {
	PebbleAppHandlers handlers = {
		.init_handler = &handle_init
	};
	app_event_loop(params, &handlers);
}