add count demo

examples/tests/u8g2-demos/count/Makefile

@@ -0,0 +1,15 @@
+# Makefile for user application
+
+# Specify this directory relative to the current application.
+TOCK_USERLAND_BASE_DIR = ../../../..
+
+# Which files to compile.
+C_SRCS := $(wildcard *.c)
+
+APP_HEAP_SIZE := 20000
+
+EXTERN_LIBS += $(TOCK_USERLAND_BASE_DIR)/u8g2
+
+# Include userland master makefile. Contains rules and flags for actually
+# building the application.
+include $(TOCK_USERLAND_BASE_DIR)/AppMakefile.mk

examples/tests/u8g2-demos/count/main.c

@@ -0,0 +1,45 @@
+#include <screen.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <timer.h>
+
+#include <u8g2-tock.h>
+#include <u8g2.h>
+
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+u8g2_t u8g2;
+
+char buf[20];
+
+int main(void) {
+
+  u8g2_tock_init(&u8g2);
+
+  int width  = u8g2_GetDisplayWidth(&u8g2);
+  int height = u8g2_GetDisplayHeight(&u8g2);
+
+  u8g2_SetFont(&u8g2, u8g2_font_timB18_tn);
+  u8g2_SetFontPosCenter(&u8g2);
+
+  int count = 0;
+
+  while (1) {
+    u8g2_ClearBuffer(&u8g2);
+
+    snprintf(buf, 20, "%i", count);
+
+    int strwidth = u8g2_GetUTF8Width(&u8g2, buf);
+
+    int y_center = height / 2;
+    int x        = max((width / 2) - (strwidth / 2), 0);
+
+    u8g2_DrawStr(&u8g2, x, y_center, buf);
+    u8g2_SendBuffer(&u8g2);
+
+    count += 1;
+    delay_ms(1000);
+  }
+}