Merge pull request #448 from tock/u8g2-increment

U8G2: Add increment/decrement example app

examples/tests/u8g2-demos/increment/Makefile

@@ -0,0 +1,13 @@
+# Makefile for user application
+
+# Specify this directory relative to the current application.
+TOCK_USERLAND_BASE_DIR = ../../../..
+
+# Which files to compile.
+C_SRCS := $(wildcard *.c)
+
+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/increment/README.md

@@ -0,0 +1,7 @@
+U8G2 Demo: Increment
+====================
+
+Draw a counter with up and down arrows. Pressing the buttons will increase or
+decrease the count.
+
+![Increment](increment.gif)

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

@@ -0,0 +1,69 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <libtock/interface/button.h>
+
+#include <u8g2-tock.h>
+#include <u8g2.h>
+
+u8g2_t u8g2;
+
+#define BTN_NUM_UP 0
+#define BTN_NUM_DOWN 2
+
+const char* UP_ARROW   = "\x93";
+const char* DOWN_ARROW = "\x8b";
+
+int counter = 10;
+
+static void button_callback(__attribute__ ((unused)) returncode_t ret, int btn_num, bool pressed) {
+  if (pressed) {
+    if (btn_num == BTN_NUM_UP) {
+      counter += 1;
+    } else if (btn_num == BTN_NUM_DOWN) {
+      counter -= 1;
+    }
+  }
+}
+
+int main(void) {
+  int ret = u8g2_tock_init(&u8g2);
+  if (ret != 0) return -100;
+
+  // Setup increment and decrement buttons.
+  libtock_button_notify_on_press(BTN_NUM_UP, button_callback);
+  libtock_button_notify_on_press(BTN_NUM_DOWN, button_callback);
+
+  // Loop, displaying the updated counter.
+  while (1) {
+    u8g2_ClearBuffer(&u8g2);
+
+    int width  = u8g2_GetDisplayWidth(&u8g2);
+    int height = u8g2_GetDisplayHeight(&u8g2);
+
+    u8g2_SetFont(&u8g2, u8g2_font_cursor_tf);
+
+    // UP ARROW
+    u8g2_SetFontPosTop(&u8g2);
+    u8g2_DrawStr(&u8g2, width / 2, -7, UP_ARROW);
+
+    // DOWN ARROW
+    u8g2_SetFontPosBottom(&u8g2);
+    u8g2_DrawStr(&u8g2, width / 2, height + 6, DOWN_ARROW);
+
+    // COUNTER
+    u8g2_SetFont(&u8g2, u8g2_font_helvB14_tr);
+    u8g2_SetFontPosCenter(&u8g2);
+
+    char buf[100];
+    snprintf(buf, 100, "%i", counter);
+    int str_width = u8g2_GetStrWidth(&u8g2, buf);
+    u8g2_DrawStr(&u8g2, (width - str_width) / 2, height / 2, buf);
+
+    u8g2_SendBuffer(&u8g2);
+
+    // The only pending upcall we have at this point is the button, so this will
+    // only return when a button is pressed.
+    yield();
+  }
+}