examples/calculator: add an LVGL touchscreen calculator

Add a touchscreen calculator with cooperative shutdown and board initialization through BOARDIOC_FINALINIT.

Signed-off-by: aviralgarg05 <gargaviral99@gmail.com>

examples/calculator/CMakeLists.txt

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+# ##############################################################################
+# apps/examples/calculator/CMakeLists.txt
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more contributor
+# license agreements.  See the NOTICE file distributed with this work for
+# additional information regarding copyright ownership.  The ASF licenses this
+# file to you under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License.  You may obtain a copy of
+# the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations under
+# the License.
+#
+# ##############################################################################
+
+if(CONFIG_EXAMPLES_CALCULATOR)
+  nuttx_add_application(
+    NAME
+    calc
+    PRIORITY
+    ${CONFIG_EXAMPLES_CALCULATOR_PRIORITY}
+    STACKSIZE
+    ${CONFIG_EXAMPLES_CALCULATOR_STACKSIZE}
+    MODULE
+    ${CONFIG_EXAMPLES_CALCULATOR}
+    DEPENDS
+    lvgl
+    SRCS
+    calculator_main.c)
+endif()

examples/calculator/Kconfig

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+#
+# For a description of the syntax of this configuration file,
+# see the file kconfig-language.txt in the NuttX tools repository.
+#
+
+menuconfig EXAMPLES_CALCULATOR
+	tristate "Calculator"
+	default n
+	depends on GRAPHICS_LVGL && INPUT_TOUCHSCREEN
+	select LV_FONT_MONTSERRAT_20
+	---help---
+		Enable the simple LVGL touchscreen calculator example.
+
+if EXAMPLES_CALCULATOR
+
+config EXAMPLES_CALCULATOR_PRIORITY
+	int "calculator task priority"
+	default 100
+
+config EXAMPLES_CALCULATOR_STACKSIZE
+	int "calculator stack size"
+	default 16384
+
+config EXAMPLES_CALCULATOR_INPUT_DEVPATH
+	string "Touchscreen device path"
+	default "/dev/input0"
+	---help---
+		The path to the touchscreen device. Default: "/dev/input0"
+
+config EXAMPLES_CALCULATOR_FB_DEVPATH
+	string "Framebuffer device path"
+	default "/dev/fb0"
+	---help---
+		The path to the framebuffer device. Default: "/dev/fb0"
+
+config EXAMPLES_CALCULATOR_YOFFSET
+	int "Top screen offset"
+	default 0
+	---help---
+		Rows to leave unused at the top of the display. Set this to the
+		height of any supervisor bar shown above the calculator.
+
+endif # EXAMPLES_CALCULATOR

examples/calculator/Make.defs

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+############################################################################
+# apps/examples/calculator/Make.defs
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.  The
+# ASF licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the
+# License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+############################################################################
+
+ifneq ($(CONFIG_EXAMPLES_CALCULATOR),)
+CONFIGURED_APPS += $(APPDIR)/examples/calculator
+endif

examples/calculator/Makefile

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+############################################################################
+# apps/examples/calculator/Makefile
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.  The
+# ASF licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the
+# License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+############################################################################
+
+include $(APPDIR)/Make.defs
+
+PROGNAME = calc
+PRIORITY = $(CONFIG_EXAMPLES_CALCULATOR_PRIORITY)
+STACKSIZE = $(CONFIG_EXAMPLES_CALCULATOR_STACKSIZE)
+MODULE = $(CONFIG_EXAMPLES_CALCULATOR)
+
+MAINSRC = calculator_main.c
+
+include $(APPDIR)/Application.mk

examples/calculator/calculator_main.c

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+/****************************************************************************
+ * apps/examples/calculator/calculator_main.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/boardctl.h>
+
+#include <lvgl/lvgl.h>
+
+#define CALC_DISPLAY_MAX 16
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* Polled by the main loop for cooperative shutdown. */
+
+static volatile sig_atomic_t g_quit_requested;
+
+static lv_obj_t *g_display;
+static char g_display_buf[CALC_DISPLAY_MAX + 1] = "0";
+static double g_accumulator;
+static char g_pending_op;
+static bool g_start_new_entry = true;
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static void quit_signal_handler(int signo)
+{
+  (void)signo;
+  g_quit_requested = 1;
+}
+
+/* Let standalone launches exit without an external SIGTERM. */
+
+static void close_event_cb(lv_event_t *e)
+{
+  UNUSED(e);
+  g_quit_requested = 1;
+}
+
+static void calc_update_display(void)
+{
+  lv_label_set_text(g_display, g_display_buf);
+}
+
+static void calc_set_display_number(double value)
+{
+  snprintf(g_display_buf, sizeof(g_display_buf), "%.10g", value);
+  calc_update_display();
+}
+
+static double calc_apply(double a, double b, char op, bool *ok)
+{
+  *ok = true;
+
+  switch (op)
+    {
+      case '+':
+        return a + b;
+
+      case '-':
+        return a - b;
+
+      case '*':
+        return a * b;
+
+      case '/':
+        if (b == 0)
+          {
+            *ok = false;
+            return 0;
+          }
+
+        return a / b;
+
+      default:
+        return b;
+    }
+}
+
+static void calc_clear(void)
+{
+  g_accumulator = 0;
+  g_pending_op = 0;
+  g_start_new_entry = true;
+  snprintf(g_display_buf, sizeof(g_display_buf), "0");
+  calc_update_display();
+}
+
+static void calc_handle_digit(char digit)
+{
+  size_t len;
+
+  if (g_start_new_entry)
+    {
+      g_display_buf[0] = '\0';
+      g_start_new_entry = false;
+    }
+
+  if (strcmp(g_display_buf, "0") == 0)
+    {
+      g_display_buf[0] = '\0';
+    }
+
+  len = strlen(g_display_buf);
+  if (len + 1 >= sizeof(g_display_buf))
+    {
+      /* Ignore digits that do not fit. */
+
+      return;
+    }
+
+  g_display_buf[len] = digit;
+  g_display_buf[len + 1] = '\0';
+  calc_update_display();
+}
+
+static void calc_handle_point(void)
+{
+  size_t len;
+
+  if (g_start_new_entry)
+    {
+      snprintf(g_display_buf, sizeof(g_display_buf), "0");
+      g_start_new_entry = false;
+    }
+
+  if (strchr(g_display_buf, '.') != NULL)
+    {
+      return;
+    }
+
+  len = strlen(g_display_buf);
+  if (len + 1 >= sizeof(g_display_buf))
+    {
+      return;
+    }
+
+  g_display_buf[len] = '.';
+  g_display_buf[len + 1] = '\0';
+  calc_update_display();
+}
+
+static void calc_handle_op(char op)
+{
+  double current = atof(g_display_buf);
+  bool ok;
+
+  if (g_pending_op != 0)
+    {
+      g_accumulator = calc_apply(g_accumulator, current, g_pending_op, &ok);
+      if (!ok)
+        {
+          snprintf(g_display_buf, sizeof(g_display_buf), "Error");
+          calc_update_display();
+          g_pending_op = 0;
+          g_start_new_entry = true;
+          return;
+        }
+    }
+  else
+    {
+      g_accumulator = current;
+    }
+
+  g_pending_op = op;
+  g_start_new_entry = true;
+  calc_set_display_number(g_accumulator);
+}
+
+static void calc_handle_equals(void)
+{
+  double current = atof(g_display_buf);
+  bool ok;
+
+  if (g_pending_op == 0)
+    {
+      g_accumulator = current;
+    }
+  else
+    {
+      g_accumulator = calc_apply(g_accumulator, current, g_pending_op, &ok);
+      if (!ok)
+        {
+          snprintf(g_display_buf, sizeof(g_display_buf), "Error");
+          calc_update_display();
+          g_pending_op = 0;
+          g_start_new_entry = true;
+          return;
+        }
+    }
+
+  g_pending_op = 0;
+  g_start_new_entry = true;
+  calc_set_display_number(g_accumulator);
+}
+
+static void button_event_cb(lv_event_t *e)
+{
+  FAR const char *code = lv_event_get_user_data(e);
+
+  switch (code[0])
+    {
+      case 'C':
+        calc_clear();
+        break;
+
+      case '.':
+        calc_handle_point();
+        break;
+
+      case '=':
+        calc_handle_equals();
+        break;
+
+      case '+':
+      case '-':
+      case '*':
+      case '/':
+        calc_handle_op(code[0]);
+        break;
+
+      default:
+        calc_handle_digit(code[0]);
+        break;
+    }
+}
+
+static lv_obj_t *make_button(lv_obj_t *parent, FAR const char *label,
+                             FAR const char *code, uint32_t color)
+{
+  lv_obj_t *btn;
+  lv_obj_t *btn_label;
+
+  btn = lv_obj_create(parent);
+  lv_obj_set_style_radius(btn, 10, 0);
+  lv_obj_set_style_bg_color(btn, lv_color_hex(color), 0);
+  lv_obj_set_style_bg_color(btn, lv_color_hex(0xffffff),
+                            LV_STATE_PRESSED);
+  lv_obj_set_style_bg_opa(btn, LV_OPA_30, LV_STATE_PRESSED);
+  lv_obj_set_style_border_width(btn, 0, 0);
+  lv_obj_clear_flag(btn, LV_OBJ_FLAG_SCROLLABLE);
+  lv_obj_add_flag(btn, LV_OBJ_FLAG_CLICKABLE);
+
+  btn_label = lv_label_create(btn);
+  lv_label_set_text(btn_label, label);
+  lv_obj_set_style_text_color(btn_label, lv_color_hex(0xffffff), 0);
+  lv_obj_center(btn_label);
+
+  lv_obj_add_event_cb(btn, button_event_cb, LV_EVENT_CLICKED,
+                      (void *)code);
+
+  return btn;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+int main(int argc, FAR char *argv[])
+{
+  lv_nuttx_dsc_t info;
+  lv_nuttx_result_t result;
+  lv_obj_t *screen;
+  lv_obj_t *grid;
+  lv_obj_t *close_btn;
+  lv_obj_t *close_label;
+  struct sigaction sa;
+  int32_t display_height;
+  int32_t display_width;
+  static const char *const keys[5][4] =
+  {
+    { "7", "8", "9", "/" },
+    { "4", "5", "6", "*" },
+    { "1", "2", "3", "-" },
+    { "C", "0", ".", "+" },
+    { "=", "=", "=", "=" },
+  };
+
+  static const int32_t col_dsc[] =
+  {
+    LV_GRID_FR(1), LV_GRID_FR(1), LV_GRID_FR(1), LV_GRID_FR(1),
+    LV_GRID_TEMPLATE_LAST
+  };
+
+  static const int32_t row_dsc[] =
+  {
+    LV_GRID_FR(1), LV_GRID_FR(1), LV_GRID_FR(1), LV_GRID_FR(1),
+    LV_GRID_FR(1), LV_GRID_TEMPLATE_LAST
+  };
+
+  g_quit_requested = 0;
+  g_display_buf[0] = '0';
+  g_display_buf[1] = '\0';
+  g_accumulator = 0;
+  g_pending_op = 0;
+  g_start_new_entry = true;
+
+  memset(&sa, 0, sizeof(sa));
+  sa.sa_handler = quit_signal_handler;
+  sigemptyset(&sa.sa_mask);
+  if (sigaction(SIGTERM, &sa, NULL) < 0)
+    {
+      LV_LOG_ERROR("calculator: failed to install SIGTERM handler");
+      return 1;
+    }
+
+  if (lv_is_initialized())
+    {
+      LV_LOG_ERROR("LVGL already initialized! aborting.");
+      return -1;
+    }
+
+#ifdef CONFIG_BOARDCTL_FINALINIT
+  boardctl(BOARDIOC_FINALINIT, 0);
+#endif
+
+  lv_init();
+
+  lv_nuttx_dsc_init(&info);
+  info.fb_path = CONFIG_EXAMPLES_CALCULATOR_FB_DEVPATH;
+  info.input_path = CONFIG_EXAMPLES_CALCULATOR_INPUT_DEVPATH;
+
+  lv_nuttx_init(&info, &result);
+
+  if (result.disp == NULL)
+    {
+      LV_LOG_ERROR("calculator: LVGL display init failed!");
+      lv_nuttx_deinit(&result);
+      lv_deinit();
+      return 1;
+    }
+
+  if (result.indev == NULL)
+    {
+      LV_LOG_ERROR("calculator: touchscreen init failed!");
+      lv_nuttx_deinit(&result);
+      lv_deinit();
+      return 1;
+    }
+
+  display_width = lv_display_get_horizontal_resolution(result.disp);
+  display_height = lv_display_get_vertical_resolution(result.disp);
+  if (display_width <= 0 ||
+      display_height <= CONFIG_EXAMPLES_CALCULATOR_YOFFSET)
+    {
+      LV_LOG_ERROR("calculator: display is too small");
+      lv_nuttx_deinit(&result);
+      lv_deinit();
+      return 1;
+    }
+
+  screen = lv_obj_create(NULL);
+  lv_obj_set_size(screen, display_width,
+                  display_height - CONFIG_EXAMPLES_CALCULATOR_YOFFSET);
+  lv_obj_set_pos(screen, 0, CONFIG_EXAMPLES_CALCULATOR_YOFFSET);
+  lv_obj_set_style_bg_color(screen, lv_color_hex(0x101827), 0);
+  lv_obj_set_style_border_width(screen, 0, 0);
+  lv_obj_clear_flag(screen, LV_OBJ_FLAG_SCROLLABLE);
+
+  g_display = lv_label_create(screen);
+  lv_obj_set_width(g_display, LV_PCT(90));
+  lv_obj_set_style_text_font(g_display, &lv_font_montserrat_20, 0);
+  lv_obj_set_style_text_color(g_display, lv_color_hex(0xffffff), 0);
+  lv_obj_set_style_text_align(g_display, LV_TEXT_ALIGN_RIGHT, 0);
+  lv_label_set_text(g_display, g_display_buf);
+  lv_obj_align(g_display, LV_ALIGN_TOP_MID, 0, 48);
+
+  close_btn = lv_obj_create(screen);
+  lv_obj_set_size(close_btn, 36, 36);
+  lv_obj_align(close_btn, LV_ALIGN_TOP_RIGHT, -8, 8);
+  lv_obj_set_style_radius(close_btn, 8, 0);
+  lv_obj_set_style_bg_color(close_btn, lv_color_hex(0xf0554c), 0);
+  lv_obj_set_style_bg_color(close_btn, lv_color_hex(0xb03830),
+                            LV_STATE_PRESSED);
+  lv_obj_set_style_border_width(close_btn, 0, 0);
+  lv_obj_clear_flag(close_btn, LV_OBJ_FLAG_SCROLLABLE);
+  lv_obj_add_flag(close_btn, LV_OBJ_FLAG_CLICKABLE);
+
+  close_label = lv_label_create(close_btn);
+  lv_label_set_text(close_label, LV_SYMBOL_CLOSE);
+  lv_obj_set_style_text_color(close_label, lv_color_hex(0xffffff), 0);
+  lv_obj_clear_flag(close_label, LV_OBJ_FLAG_CLICKABLE);
+  lv_obj_center(close_label);
+
+  lv_obj_add_event_cb(close_btn, close_event_cb, LV_EVENT_CLICKED, NULL);
+
+  grid = lv_obj_create(screen);
+  lv_obj_set_size(grid, LV_PCT(90), LV_PCT(70));
+  lv_obj_align(grid, LV_ALIGN_BOTTOM_MID, 0, -16);
+  lv_obj_set_style_bg_opa(grid, LV_OPA_TRANSP, 0);
+  lv_obj_set_style_border_width(grid, 0, 0);
+  lv_obj_set_style_pad_all(grid, 4, 0);
+  lv_obj_set_style_pad_gap(grid, 8, 0);
+  lv_obj_clear_flag(grid, LV_OBJ_FLAG_SCROLLABLE);
+  lv_obj_set_grid_dsc_array(grid, col_dsc, row_dsc);
+  lv_obj_set_layout(grid, LV_LAYOUT_GRID);
+
+  for (int row = 0; row < 5; row++)
+    {
+      for (int col = 0; col < 4; col++)
+        {
+          FAR const char *code = keys[row][col];
+          uint32_t color = 0x2a3648;
+          lv_obj_t *btn;
+
+          if (row == 4)
+            {
+              /* Create the full-width button once. */
+
+              if (col > 0)
+                {
+                  continue;
+                }
+            }
+
+          if (strchr("+-*/=", code[0]) != NULL)
+            {
+              color = 0x3d8bff;
+            }
+          else if (code[0] == 'C')
+            {
+              color = 0xf0554c;
+            }
+
+          btn = make_button(grid, code, code, color);
+          if (row == 4)
+            {
+              lv_obj_set_grid_cell(btn, LV_GRID_ALIGN_STRETCH, 0, 4,
+                                   LV_GRID_ALIGN_STRETCH, row, 1);
+            }
+          else
+            {
+              lv_obj_set_grid_cell(btn, LV_GRID_ALIGN_STRETCH, col, 1,
+                                   LV_GRID_ALIGN_STRETCH, row, 1);
+            }
+        }
+    }
+
+  lv_screen_load(screen);
+
+  while (!g_quit_requested)
+    {
+      uint32_t idle;
+
+      idle = lv_timer_handler();
+
+      /* Minimum sleep of 1ms */
+
+      idle = idle ? idle : 1;
+      usleep(idle * 1000);
+    }
+
+  lv_nuttx_deinit(&result);
+  lv_deinit();
+
+  return 0;
+}