Add examples to Nextion page (#548)

* Update nextion.h

* Added more examples

* Update nextion.h

* Update nextion.h

* Update nextion.h

esphome/components/nextion/nextion.h

@@ -23,6 +23,13 @@ class Nextion : public PollingComponent, public uart::UARTDevice {
    * Set the text of a component to a static string.
    * @param component The component name.
    * @param text The static text to set.
+   *
+   * Example:
+   * ```cpp
+   * it.set_component_text("textview", "Hello World!");
+   * ```
+   *
+   * This will set the `txt` property of the component `textview` to `Hello World`.
    */
   void set_component_text(const char *component, const char *text);
   /**
@@ -30,18 +37,41 @@ class Nextion : public PollingComponent, public uart::UARTDevice {
    * @param component The component name.
    * @param format The printf-style format string.
    * @param ... The arguments to the format.
+   *
+   * Example:
+   * ```cpp
+   * it.set_component_text_printf("textview", "The uptime is: %.0f", id(uptime_sensor).state);
+   * ```
+   *
+   * This will change the text on the component named `textview` to `The uptime is:` Then the value of `uptime_sensor`.
+   * with zero decimals of accuracy (whole number).
+   * For example when `uptime_sensor` = 506, then, `The uptime is: 506` will be displayed.
    */
   void set_component_text_printf(const char *component, const char *format, ...) __attribute__((format(printf, 3, 4)));
   /**
    * Set the integer value of a component
    * @param component The component name.
    * @param value The value to set.
+   *
+   * Example:
+   * ```cpp
+   * it.set_component_value("gauge", 50);
+   * ```
+   *
+   * This will change the property `value` of the component `gauge` to 50.
    */
   void set_component_value(const char *component, int value);
   /**
    * Set the picture of an image component.
    * @param component The component name.
    * @param value The picture name.
+   *
+   * Example:
+   * ```cpp
+   * it.set_component_picture("pic", "4");
+   * ```
+   *
+   * This will change the image of the component `pic` to the image with ID `4`.
    */
   void set_component_picture(const char *component, const char *picture) {
     this->send_command_printf("%s.val=%s", component, picture);
@@ -50,24 +80,61 @@ class Nextion : public PollingComponent, public uart::UARTDevice {
    * Set the background color of a component.
    * @param component The component name.
    * @param color The color (as a string).
+   *
+   * Example:
+   * ```cpp
+   * it.set_component_background_color("button", "17013");
+   * ```
+   *
+   * This will change the background color of the component `button` to blue.
+   * Use this [color picker](https://nodtem66.github.io/nextion-hmi-color-convert/index.html) to convert color codes to
+   * Nextion HMI colors.
    */
   void set_component_background_color(const char *component, const char *color);
   /**
    * Set the pressed background color of a component.
    * @param component The component name.
    * @param color The color (as a string).
+   *
+   * Example:
+   * ```cpp
+   * it.set_component_pressed_background_color("button", "17013");
+   * ```
+   *
+   * This will change the pressed background color of the component `button` to blue. This is the background color that
+   * is shown when the component is pressed. Use this [color
+   * picker](https://nodtem66.github.io/nextion-hmi-color-convert/index.html) to convert color codes to Nextion HMI
+   * colors.
    */
   void set_component_pressed_background_color(const char *component, const char *color);
   /**
    * Set the font color of a component.
    * @param component The component name.
    * @param color The color (as a string).
+   *
+   * Example:
+   * ```cpp
+   * it.set_component_font_color("textview", "17013");
+   * ```
+   *
+   * This will change the font color of the component `textview` to a blue color.
+   * Use this [color picker](https://nodtem66.github.io/nextion-hmi-color-convert/index.html) to convert color codes to
+   * Nextion HMI colors.
    */
   void set_component_font_color(const char *component, const char *color);
   /**
    * Set the pressed font color of a component.
    * @param component The component name.
    * @param color The color (as a string).
+   *
+   * Example:
+   * ```cpp
+   * it.set_component_pressed_font_color("button", "17013");
+   * ```
+   *
+   * This will change the pressed font color of the component `button` to a blue color.
+   * Use this [color picker](https://nodtem66.github.io/nextion-hmi-color-convert/index.html) to convert color codes to
+   * Nextion HMI colors.
    */
   void set_component_pressed_font_color(const char *component, const char *color);
   /**
@@ -75,12 +142,26 @@ class Nextion : public PollingComponent, public uart::UARTDevice {
    * @param component The component name.
    * @param x The x coordinate.
    * @param y The y coordinate.
+   *
+   * Example:
+   * ```cpp
+   * it.set_component_coordinates("pic", 55, 100);
+   * ```
+   *
+   * This will move the position of the component `pic` to the x coordinate `55` and y coordinate `100`.
    */
   void set_component_coordinates(const char *component, int x, int y);
   /**
    * Set the font id for a component.
    * @param component The component name.
    * @param font_id The ID of the font (number).
+   *
+   * Example:
+   * ```cpp
+   * it.set_component_font("textview", "3");
+   * ```
+   *
+   * Changes the font of the component named `textveiw`. Font IDs are set in the Nextion Editor.
    */
   void set_component_font(const char *component, uint8_t font_id);
 #ifdef USE_TIME
@@ -94,26 +175,61 @@ class Nextion : public PollingComponent, public uart::UARTDevice {
   /**
    * Show the page with a given name.
    * @param page The name of the page.
+   *
+   * Example:
+   * ```cpp
+   * it.goto_page("main");
+   * ```
+   *
+   * Switches to the page named `main`. Pages are named in the Nextion Editor.
    */
   void goto_page(const char *page);
   /**
    * Hide a component.
    * @param component The component name.
+   *
+   * Example:
+   * ```cpp
+   * hide_component("button");
+   * ```
+   *
+   * Hides the component named `button`.
    */
   void hide_component(const char *component);
   /**
    * Show a component.
    * @param component The component name.
+   *
+   * Example:
+   * ```cpp
+   * show_component("button");
+   * ```
+   *
+   * Shows the component named `button`.
    */
   void show_component(const char *component);
   /**
    * Enable touch for a component.
    * @param component The component name.
+   *
+   * Example:
+   * ```cpp
+   * enable_component_touch("button");
+   * ```
+   *
+   * Enables touch for component named `button`.
    */
   void enable_component_touch(const char *component);
   /**
    * Disable touch for a component.
    * @param component The component name.
+   *
+   * Example:
+   * ```cpp
+   * disable_component_touch("button");
+   * ```
+   *
+   * Disables touch for component named `button`.
    */
   void disable_component_touch(const char *component);
   /**
@@ -128,6 +244,13 @@ class Nextion : public PollingComponent, public uart::UARTDevice {
    * @param picture_id The picture id.
    * @param x1 The x coordinate.
    * @param y1 The y coordniate.
+   *
+   * Example:
+   * ```cpp
+   * display_picture(2, 15, 25);
+   * ```
+   *
+   * Displays the picture who has the id `2` at the x coordinates `15` and y coordinates `25`.
    */
   void display_picture(int picture_id, int x_start, int y_start);
   /**
@@ -137,6 +260,15 @@ class Nextion : public PollingComponent, public uart::UARTDevice {
    * @param width The width to draw.
    * @param height The height to draw.
    * @param color The color to draw with (as a string).
+   *
+   * Example:
+   * ```cpp
+   * fill_area(50, 50, 100, 100, "17013");
+   * ```
+   *
+   * Fills an area that starts at x coordiante `50` and y coordinate `50` with a height of `100` and width of `100` with
+   * the color of blue. Use this [color picker](https://nodtem66.github.io/nextion-hmi-color-convert/index.html) to
+   * convert color codes to Nextion HMI colors
    */
   void fill_area(int x1, int y1, int width, int height, const char *color);
   /**
@@ -146,6 +278,16 @@ class Nextion : public PollingComponent, public uart::UARTDevice {
    * @param x2 The ending x coordinate.
    * @param y2 The ending y coordinate.
    * @param color The color to draw with (as a string).
+   *
+   * Example:
+   * ```cpp
+   * it.line(50, 50, 75, 75, "17013");
+   * ```
+   *
+   * Makes a line that starts at x coordinate `50` and y coordinate `50` and ends at x coordinate `75` and y coordinate
+   * `75` with the color of blue. Use this [color
+   * picker](https://nodtem66.github.io/nextion-hmi-color-convert/index.html) to convert color codes to Nextion HMI
+   * colors.
    */
   void line(int x1, int y1, int x2, int y2, const char *color);
   /**
@@ -155,6 +297,16 @@ class Nextion : public PollingComponent, public uart::UARTDevice {
    * @param width The width of the rectangle.
    * @param height The height of the rectangle.
    * @param color The color to draw with (as a string).
+   *
+   * Example:
+   * ```cpp
+   * it.rectangle(25, 35, 40, 50, "17013");
+   * ```
+   *
+   * Makes a outline of a rectangle that starts at x coordinate `25` and y coordinate `35` and has a width of `40` and a
+   * length of `50` with color of blue. Use this [color
+   * picker](https://nodtem66.github.io/nextion-hmi-color-convert/index.html) to convert color codes to Nextion HMI
+   * colors.
    */
   void rectangle(int x1, int y1, int width, int height, const char *color);
   /**
@@ -171,17 +323,41 @@ class Nextion : public PollingComponent, public uart::UARTDevice {
    * @param center_y The center y coordinate.
    * @param radius The circle radius.
    * @param color The color to draw with (as a string).
+   *
+   * Example:
+   * ```cpp
+   * it.filled_cricle(25, 25, 10, "17013");
+   * ```
+   *
+   * Makes a filled circle at the x cordinates `25` and y coordinate `25` with a radius of `10` with a color of blue.
+   * Use this [color picker](https://nodtem66.github.io/nextion-hmi-color-convert/index.html) to convert color codes to
+   * Nextion HMI colors.
    */
   void filled_circle(int center_x, int center_y, int radius, const char *color);
 
   /** Set the brightness of the backlight.
    *
    * @param brightness The brightness, from 0 to 100.
+   *
+   * Example:
+   * ```cpp
+   * it.set_backlight_brightness(30);
+   * ```
+   *
+   * Changes the brightness of the display to 30%.
    */
   void set_backlight_brightness(uint8_t brightness);
   /**
    * Set the touch sleep timeout of the display.
    * @param timeout Timeout in seconds.
+   *
+   * Example:
+   * ```cpp
+   * it.set_touch_sleep_timeout(30);
+   * ```
+   *
+   * After 30 seconds the display will go to sleep. Note: the display will only wakeup by a restart or by setting up
+   * `thup`.
    */
   void set_touch_sleep_timeout(uint16_t timeout);