diff options
Diffstat (limited to 'src/lib.rs')
| -rw-r--r-- | src/lib.rs | 207 |
1 files changed, 178 insertions, 29 deletions
@@ -11,10 +11,14 @@ use std::io::Write; use codes::SpecialCode; use codes::WriteInto; +// Increment this number when appropriate: +// +// NUMBER_OF_LCD_SCREENS_DESTROYED_DURING_TESTING: 1 + /// A screen that allows you to send commands to a charlcd driver (or whatever -/// that implements the `Write` trait). +/// that implements the [`Write`] trait). /// -/// Nominal usage: +/// # Simple example /// /// ```rust /// use charlcd::Screen; @@ -43,48 +47,104 @@ impl<T> Screen<T> where T: Write, { - /// Create a new display instance that will use the provided Writer under - /// the hood to send commands. + /// Create a new [`Screen`] instance that will use the provided [`Write`] + /// under the hood to send commands. pub fn new(writer: T) -> Screen<T> { Screen { writer } } - /// Clean the rest of the current line, from cursor's position. + /// Clean the rest of the current line, from current cursor position. + /// + /// # Live footage (before and after) + ///  + ///  + /// pub fn kill_eol(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::KillEndOfLine) } - /// Reinitialize the display to its default values. + /// Reinitialize the display to its default hardware values. + /// + /// # Live footage (before and after) + ///  + ///  + /// + /// Note: we observe that the cursor *and* blink are activated after a call + /// to [`Screen::reinit()`], although the [`Screen::blink_on()`] and + /// [`Screen::cursor_on()`] methods are *not* called in this function. We + /// can deduce it is a hardware default to put back the blink and cursor on + /// at initialization. + /// + /// You may want to disable them after a call to this function by using the + /// [`Screen::blink_off()`] and [`Screen::cursor_off()`] functions. pub fn reinit(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::ReinitializeDisplay) } - /// Enable the display text output. - pub fn display_on(&mut self) -> std::io::Result<()> { - write_simple_code!(self, SpecialCode::DisplayOn) - } - - /// Disable the display text output. + /// Disable the display. + /// + /// The displayed content is not lost and kept into the screen buffer. Call + /// [`Screen::display_on()`] to display back what was printed to the screen. + /// + /// # Live footage (before and after) + ///  + ///  + /// pub fn display_off(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::DisplayOff) } + /// Enable the display. + /// + /// The content of the screen buffer will be displayed back with no change. + /// + /// # Live footage (before and after) + ///  + ///  + /// + pub fn display_on(&mut self) -> std::io::Result<()> { + write_simple_code!(self, SpecialCode::DisplayOn) + } + /// Enable the underscore cursor (independent of blinking cursor). + /// + /// # Live footage (before and after) + ///  + ///  + /// pub fn cursor_on(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::CursorOn) } /// Disable the underscore cursor (independent of blinking cursor). + /// + /// # Live footage (before and after) + ///  + ///  + /// pub fn cursor_off(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::CursorOff) } /// Enable the blinking cursor (independent of underscore cursor). + /// + /// # Live footage (before and after) + ///  + ///  + /// + /// Note: due to long exposure duration of the camera (1 second), the + /// blinking cursor appears dim in the footage. + /// pub fn blink_on(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::BlinkOn) } /// Disable the blinking cursor (independent of underscore cursor). + /// + /// # Live footage (before and after) + ///  + ///  + /// pub fn blink_off(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::BlinkOff) } @@ -100,17 +160,35 @@ where } /// Flash the backlight during a small duration. + /// + /// The exact duration is specified in the driver. As of today, the default + /// value is set to 4 seconds (`LCD_BL_TEMPO_PERIOD` define in `charlcd.c`). pub fn flash_backlight(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::FlashBacklight) } /// Clear the screen and return the cursor at original (0, 0) XY position. + /// + /// # Live footage (before and after) + ///  + ///  + /// pub fn clear(&mut self) -> std::io::Result<()> { self.write(&[0x0c])?; // '\f' escape not defined in Rust Ok(()) } - /// Move the cursor back one character. + /// Move the cursor back one character, and delete the character at this + /// position. + /// + /// This is an utility function that will send the raw byte value for the + /// `'\b'` escape sequence. This sequence is valid in C, but is not + /// available in Rust. + /// + /// # Live footage (before and after) + ///  + ///  + /// pub fn back(&mut self) -> std::io::Result<()> { self.write(&[0x08])?; // '\b' escape not defined in Rust Ok(()) @@ -119,49 +197,93 @@ where // Less-used (and some non-working?) methods below /// Shift cursor left. + /// + /// # Live footage (before and after) + ///  + ///  + /// pub fn shift_cursor_left(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::ShiftCursorLeft) } /// Shift cursor right. + /// + /// # Live footage (before and after) + ///  + ///  + /// pub fn shift_cursor_right(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::ShiftCursorRight) } /// Shift display left. + /// + /// # Live footage (before and after) + ///  + ///  + /// + /// Note: we can observe that the shift will create an artefact on the n+2 + /// line, as the extra characters will be shifted there. pub fn shift_display_left(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::ShiftDisplayLeft) } /// Shift display right. + /// + /// # Live footage (before and after) + ///  + ///  + /// + /// Note: we can observe that the shift will create an artefact on the n+2 + /// line, as the extra characters will be shifted there. pub fn shift_display_right(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::ShiftDisplayRight) } /// Enable one line mode. /// - ///  + /// # Live footage (before and after) + ///  + ///  + /// + /// We can see that the screen seems to disable power for the second and + /// fourth line of the display (in case of a 4 lines one). Cutting the + /// power for half the screen means that the contrast adjustment will not + /// be correct anymore, as the screen uses less power by managing only half + /// of the characters. + /// + /// A manual recalibration of the contrast will be necessary if you change + /// between [`Screen::one_line()`] and [`Screen::two_lines()`] modes. pub fn one_line(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::OneLine) } /// Enable two lines mode. + /// + /// # Live footage (before and after) + ///  + ///  + /// + /// This will mess up the screen if coming from [`Screen::one_line()`] mode. + /// + /// A manual recalibration of the contrast will be necessary if you change + /// between [`Screen::one_line()`] and [`Screen::two_lines()`] modes. pub fn two_lines(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::TwoLines) } /// Enable small font mode. /// - /// Seems to have no effect on the screen given the tests with multiple - /// screen variants. + /// Note: this function seems to have no effect on the screen after tests + /// with multiple screen variants. No relevant footage available. pub fn small_font(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::SmallFont) } /// Enable big font mode. /// - /// Seems to have no effect on the screen given the tests with multiple - /// screen variants. + /// Note: this function seems to have no effect on the screen after tests + /// with multiple screen variants. No relevant footage available. pub fn large_font(&mut self) -> std::io::Result<()> { write_simple_code!(self, SpecialCode::LargeFont) } @@ -195,19 +317,33 @@ impl FileScreen { Ok(Screen::new(buf)) } - /// Create a default Screen instance based on `"/dev/lcd"` path. + /// Create a default Screen instance based on `/dev/lcd` device driver + /// path. pub fn default() -> std::io::Result<FileScreen> { Screen::from_dev_path(&Path::new(DEFAULT_SCREEN_DEV_PATH)) } /// Get the width of the screen, in number of characters it can display. /// - /// **Important note:** The implementation behind this function is - /// currently a hack that will go find the value in the `auxdisplay` - /// platform device tree node in + /// # Example + /// + /// ```rust + /// let screen = Screen::default()?; // the screen is 20x4 in this test + /// let width = screen.width()?; + /// assert_eq!(width, 20); + /// ``` + /// + /// # Important note + /// + /// The implementation behind this function is currently a hack that will + /// go find the value in the `auxdisplay` platform device tree node in /// `/sys/devices/platform/auxdisplay/of_node/*`. This is because the - /// `charlcd` driver does not export the screen width nor height to - /// userspace (could be using `ioctl` or `read` syscalls). + /// `charlcd` driver does not export the `width` nor `height` fields to + /// userspace. + /// + /// In the future, this function may be able to read the value directly + /// from the `/dev/lcd` device if a proper `ioctl` or `read` call is + /// implemented for this purpose. /// pub fn width(&self) -> std::io::Result<u32> { of_node::display_width_chars() @@ -215,12 +351,25 @@ impl FileScreen { /// Get the height of the screen, in number of characters it can display. /// - /// **Important note:** The implementation behind this function is - /// currently a hack that will go find the value in the `auxdisplay` - /// platform device tree node in + /// # Example + /// + /// ```rust + /// let screen = Screen::default()?; // the screen is 20x4 in this test + /// let width = screen.height()?; + /// assert_eq!(width, 4); + /// ``` + /// + /// # Important note + /// + /// The implementation behind this function is currently a hack that will + /// go find the value in the `auxdisplay` platform device tree node in /// `/sys/devices/platform/auxdisplay/of_node/*`. This is because the - /// `charlcd` driver does not export the screen width nor height to - /// userspace (could be using `ioctl` or `read` syscalls). + /// `charlcd` driver does not export the `width` nor `height` fields to + /// userspace. + /// + /// In the future, this function may be able to read the value directly + /// from the `/dev/lcd` device if a proper `ioctl` or `read` call is + /// implemented for this purpose. /// pub fn height(&self) -> std::io::Result<u32> { of_node::display_height_chars() |