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-rw-r--r--src/lib.rs207
1 files changed, 178 insertions, 29 deletions
diff --git a/src/lib.rs b/src/lib.rs
index 0e32ee9..5679f60 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -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)
+ /// ![kill_eol_before](https://crates.microjoe.org/charlcd/media/docs/kill_eol_before.jpg)
+ /// ![kill_eol](https://crates.microjoe.org/charlcd/media/docs/kill_eol.jpg)
+ ///
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)
+ /// ![full](https://crates.microjoe.org/charlcd/media/docs/full.jpg)
+ /// ![clear](https://crates.microjoe.org/charlcd/media/docs/clear.jpg)
+ ///
+ /// 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)
+ /// ![full](https://crates.microjoe.org/charlcd/media/docs/full.jpg)
+ /// ![display_off](https://crates.microjoe.org/charlcd/media/docs/display_off.jpg)
+ ///
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)
+ /// ![display_off](https://crates.microjoe.org/charlcd/media/docs/display_off.jpg)
+ /// ![full](https://crates.microjoe.org/charlcd/media/docs/full.jpg)
+ ///
+ 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)
+ /// ![test_clear](https://crates.microjoe.org/charlcd/media/docs/test_clear.jpg)
+ /// ![cursor_on](https://crates.microjoe.org/charlcd/media/docs/cursor_on.jpg)
+ ///
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)
+ /// ![test](https://crates.microjoe.org/charlcd/media/docs/test.jpg)
+ /// ![cursor_off](https://crates.microjoe.org/charlcd/media/docs/blink_on.jpg)
+ ///
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)
+ /// ![test_clear](https://crates.microjoe.org/charlcd/media/docs/test_clear.jpg)
+ /// ![blink_on](https://crates.microjoe.org/charlcd/media/docs/blink_on.jpg)
+ ///
+ /// 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)
+ /// ![test](https://crates.microjoe.org/charlcd/media/docs/test.jpg)
+ /// ![blink_off](https://crates.microjoe.org/charlcd/media/docs/cursor_on.jpg)
+ ///
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)
+ /// ![test](https://crates.microjoe.org/charlcd/media/docs/test.jpg)
+ /// ![clear](https://crates.microjoe.org/charlcd/media/docs/clear.jpg)
+ ///
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)
+ /// ![test](https://crates.microjoe.org/charlcd/media/docs/test.jpg)
+ /// ![back](https://crates.microjoe.org/charlcd/media/docs/back.jpg)
+ ///
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)
+ /// ![test](https://crates.microjoe.org/charlcd/media/docs/test.jpg)
+ /// ![shift_cursor_left](https://crates.microjoe.org/charlcd/media/docs/shift_cursor_left.jpg)
+ ///
pub fn shift_cursor_left(&mut self) -> std::io::Result<()> {
write_simple_code!(self, SpecialCode::ShiftCursorLeft)
}
/// Shift cursor right.
+ ///
+ /// # Live footage (before and after)
+ /// ![test](https://crates.microjoe.org/charlcd/media/docs/test.jpg)
+ /// ![shift_cursor_right](https://crates.microjoe.org/charlcd/media/docs/shift_cursor_right.jpg)
+ ///
pub fn shift_cursor_right(&mut self) -> std::io::Result<()> {
write_simple_code!(self, SpecialCode::ShiftCursorRight)
}
/// Shift display left.
+ ///
+ /// # Live footage (before and after)
+ /// ![shift](https://crates.microjoe.org/charlcd/media/docs/shift.jpg)
+ /// ![shift_display_left](https://crates.microjoe.org/charlcd/media/docs/shift_display_left.jpg)
+ ///
+ /// 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)
+ /// ![shift](https://crates.microjoe.org/charlcd/media/docs/shift.jpg)
+ /// ![shift_display_right](https://crates.microjoe.org/charlcd/media/docs/shift_display_right.jpg)
+ ///
+ /// 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.
///
- /// ![test](https://blog.microjoe.org/images/hd44780-lcd-i2c-screen-using-linux-mainline-charlcd-driver/linux_419.medium.jpg)
+ /// # Live footage (before and after)
+ /// ![full](https://crates.microjoe.org/charlcd/media/docs/full.jpg)
+ /// ![one_line](https://crates.microjoe.org/charlcd/media/docs/one_line.jpg)
+ ///
+ /// 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)
+ /// ![one_line](https://crates.microjoe.org/charlcd/media/docs/one_line.jpg)
+ /// ![two_lines](https://crates.microjoe.org/charlcd/media/docs/two_lines.jpg)
+ ///
+ /// 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()