1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425
//! A target for embedded-graphics drawing operations.
use crate::{
geometry::Dimensions,
pixelcolor::PixelColor,
primitives::{PointsIter, Rectangle},
Pixel,
};
/// A target for embedded-graphics drawing operations.
///
/// The `DrawTarget` trait is used to add embedded-graphics support to a display
/// driver or similar targets like framebuffers or image files.
/// Targets are required to at least implement the [`draw_iter`] method and the [`Dimensions`]
/// trait. All other methods provide default implementations which use these methods internally.
///
/// Because the default implementations cannot use features specific to the target hardware they
/// can be overridden to improve performance. These target specific implementations might, for
/// example, use hardware accelerated drawing operations provided by a display controller or
/// specialized hardware modules in a microcontroller.
///
/// Note that some displays require a "flush" operation to write changes from a framebuffer to the
/// display. See docs associated with the chosen display driver for details on how to update the
/// display.
///
/// # Examples
///
/// ## Minimum implementation
///
/// In this example `DrawTarget` is implemented for an an imaginary 64px x 64px 8-bit grayscale display
/// that is connected using a simplified SPI interface. Because the hardware doesn't support any
/// acceleration only the [`draw_iter`] method and [`OriginDimensions`] trait need to be implemented.
///
/// To reduce the overhead caused by communicating with the display for each drawing operation
/// the display driver uses and framebuffer to store the pixel data in memory. This way all drawing
/// operations can be executed in local memory and the actual display is only updated on demand
/// by calling the `flush` method.
///
/// Because all drawing operations are using a local framebuffer no communication error can occur
/// while they are executed and the [`Error` type] can be set to `core::convert::Infallible`.
///
/// ```rust
/// use core::convert::TryInto;
/// use embedded_graphics::{
/// pixelcolor::{Gray8, GrayColor},
/// prelude::*,
/// primitives::{Circle, PrimitiveStyle},
/// };
/// #
/// # struct SPI1;
/// #
/// # impl SPI1 {
/// # pub fn send_bytes(&self, buf: &[u8]) -> Result<(), CommError> {
/// # Ok(())
/// # }
/// # }
/// #
///
/// /// SPI communication error
/// #[derive(Debug)]
/// struct CommError;
///
/// /// A fake 64px x 64px display.
/// struct ExampleDisplay {
/// /// The framebuffer with one `u8` value per pixel.
/// framebuffer: [u8; 64 * 64],
///
/// /// The interface to the display controller.
/// iface: SPI1,
/// }
///
/// impl ExampleDisplay {
/// /// Updates the display from the framebuffer.
/// pub fn flush(&self) -> Result<(), CommError> {
/// self.iface.send_bytes(&self.framebuffer)
/// }
/// }
///
/// impl DrawTarget for ExampleDisplay {
/// type Color = Gray8;
/// // `ExampleDisplay` uses a framebuffer and doesn't need to communicate with the display
/// // controller to draw pixel, which means that drawing operations can never fail. To reflect
/// // this the type `Infallible` was chosen as the `Error` type.
/// type Error = core::convert::Infallible;
///
/// fn draw_iter<I>(&mut self, pixels: I) -> Result<(), Self::Error>
/// where
/// I: IntoIterator<Item = Pixel<Self::Color>>,
/// {
/// for Pixel(coord, color) in pixels.into_iter() {
/// // Check if the pixel coordinates are out of bounds (negative or greater than
/// // (63,63)). `DrawTarget` implementation are required to discard any out of bounds
/// // pixels without returning an error or causing a panic.
/// if let Ok((x @ 0..=63, y @ 0..=63)) = coord.try_into() {
/// // Calculate the index in the framebuffer.
/// let index: u32 = x + y * 64;
/// self.framebuffer[index as usize] = color.luma();
/// }
/// }
///
/// Ok(())
/// }
/// }
///
/// impl OriginDimensions for ExampleDisplay {
/// fn size(&self) -> Size {
/// Size::new(64, 64)
/// }
/// }
///
/// let mut display = ExampleDisplay {
/// framebuffer: [0; 4096],
/// iface: SPI1,
/// };
///
/// // Draw a circle with top-left at `(22, 22)` with a diameter of `20` and a white stroke
/// let circle = Circle::new(Point::new(22, 22), 20)
/// .into_styled(PrimitiveStyle::with_stroke(Gray8::WHITE, 1));
///
/// circle.draw(&mut display)?;
///
/// // Update the display
/// display.flush().unwrap();
/// # Ok::<(), core::convert::Infallible>(())
/// ```
///
/// # Hardware acceleration - solid rectangular fill
///
/// This example uses an imaginary display with 16bpp RGB565 colors and hardware support for
/// filling of rectangular areas with a solid color. A real display controller that supports this
/// operation is the SSD1331 with it's "Draw Rectangle" (`22h`) command which this example
/// is loosely based on.
///
/// To leverage this feature in a `DrawTarget`, the default implementation of [`fill_solid`] can be
/// overridden by a custom implementation. Instead of drawing individual pixels, this target
/// specific version will only send a single command to the display controller in one transaction.
/// Because the command size is independent of the filled area, all [`fill_solid`] calls will only
/// transmit 8 bytes to the display, which is far less then what is required to transmit each pixel
/// color inside the filled area.
/// ```rust
/// use core::convert::TryInto;
/// use embedded_graphics::{
/// pixelcolor::{raw::RawU16, Rgb565, RgbColor},
/// prelude::*,
/// primitives::{Circle, Rectangle, PrimitiveStyle, PrimitiveStyleBuilder},
/// };
/// #
/// # struct SPI1;
/// #
/// # impl SPI1 {
/// # pub fn send_bytes(&self, buf: &[u16]) -> Result<(), ()> {
/// # Ok(())
/// # }
/// # }
/// #
///
/// /// SPI communication error
/// #[derive(Debug)]
/// struct CommError;
///
/// /// An example display connected over SPI.
/// struct ExampleDisplay {
/// iface: SPI1,
/// }
///
/// impl ExampleDisplay {
/// /// Send a single pixel to the display
/// pub fn set_pixel(&self, x: u32, y: u32, color: u16) -> Result<(), CommError> {
/// // ...
///
/// Ok(())
/// }
///
/// /// Send commands to the display
/// pub fn send_commands(&self, commands: &[u8]) -> Result<(), CommError> {
/// // Send data marked as commands to the display.
///
/// Ok(())
/// }
/// }
///
/// impl DrawTarget for ExampleDisplay {
/// type Color = Rgb565;
/// type Error = CommError;
///
/// fn draw_iter<I>(&mut self, pixels: I) -> Result<(), Self::Error>
/// where
/// I: IntoIterator<Item = Pixel<Self::Color>>,
/// {
/// for Pixel(coord, color) in pixels.into_iter() {
/// // Check if the pixel coordinates are out of bounds (negative or greater than
/// // (63,63)). `DrawTarget` implementation are required to discard any out of bounds
/// // pixels without returning an error or causing a panic.
/// if let Ok((x @ 0..=63, y @ 0..=63)) = coord.try_into() {
/// self.set_pixel(x, y, RawU16::from(color).into_inner())?;
/// }
/// }
///
/// Ok(())
/// }
///
/// fn fill_solid(&mut self, area: &Rectangle, color: Self::Color) -> Result<(), Self::Error> {
/// // Clamp the rectangle coordinates to the valid range by determining
/// // the intersection of the fill area and the visible display area
/// // by using Rectangle::intersection.
/// let area = area.intersection(&self.bounding_box());
///
/// // Do not send a draw rectangle command if the intersection size if zero.
/// // The size is checked by using `Rectangle::bottom_right`, which returns `None`
/// // if the size is zero.
/// let bottom_right = if let Some(bottom_right) = area.bottom_right() {
/// bottom_right
/// } else {
/// return Ok(());
/// };
///
/// self.send_commands(&[
/// // Draw rectangle command
/// 0x22,
/// // Top left X coordinate
/// area.top_left.x as u8,
/// // Top left Y coordinate
/// area.top_left.y as u8,
/// // Bottom right X coordinate
/// bottom_right.x as u8,
/// // Bottom right Y coordinate
/// bottom_right.y as u8,
/// // Fill color red channel
/// color.r(),
/// // Fill color green channel
/// color.g(),
/// // Fill color blue channel
/// color.b(),
/// ])
/// }
/// }
///
/// impl OriginDimensions for ExampleDisplay {
/// fn size(&self) -> Size {
/// Size::new(64, 64)
/// }
/// }
///
/// let mut display = ExampleDisplay { iface: SPI1 };
///
/// // Draw a rectangle with 5px red stroke and green fill.
/// // The stroke and fill can be broken down into multiple individual rectangles,
/// // so this uses `fill_solid` internally.
/// Rectangle::new(Point::new(20, 20), Size::new(50, 40))
/// .into_styled(
/// PrimitiveStyleBuilder::new()
/// .stroke_color(Rgb565::RED)
/// .stroke_width(5)
/// .fill_color(Rgb565::GREEN)
/// .build(),
/// )
/// .draw(&mut display)?;
///
/// // Draw a circle with top-left at `(5, 5)` with a diameter of `10` and a magenta stroke with
/// // cyan fill. This shape cannot be optimized by calls to `fill_solid` as it contains transparent
/// // pixels as well as pixels of different colors. It will instead delegate to `draw_iter`
/// // internally.
/// Circle::new(Point::new(5, 5), 10)
/// .into_styled(
/// PrimitiveStyleBuilder::new()
/// .stroke_color(Rgb565::MAGENTA)
/// .stroke_width(1)
/// .fill_color(Rgb565::CYAN)
/// .build(),
/// )
/// .draw(&mut display)?;
///
/// # Ok::<(), CommError>(())
/// ```
///
/// [`fill_solid`]: #method.fill_solid
/// [`draw_iter`]: #tymethod.draw_iter
/// [`Dimensions`]: ../geometry/trait.Dimensions.html
/// [`OriginDimensions`]: ../geometry/trait.OriginDimensions.html
/// [`Error` type]: #associatedtype.Error
pub trait DrawTarget: Dimensions {
/// The pixel color type the targetted display supports.
type Color: PixelColor;
/// Error type to return when a drawing operation fails.
///
/// This error is returned if an error occurred during a drawing operation. This mainly applies
/// to drivers that need to communicate with the display for each drawing operation, where a
/// communication error can occur. For drivers that use an internal framebuffer where drawing
/// operations can never fail, [`core::convert::Infallible`] can instead be used as the `Error`
/// type.
///
/// [`core::convert::Infallible`]: https://doc.rust-lang.org/stable/core/convert/enum.Infallible.html
type Error;
/// Draw individual pixels to the display without a defined order.
///
/// Due to the unordered nature of the pixel iterator, this method is likely to be the slowest
/// drawing method for a display that writes data to the hardware immediately. If possible, the
/// other methods in this trait should be implemented to improve performance when rendering
/// more contiguous pixel patterns.
fn draw_iter<I>(&mut self, pixels: I) -> Result<(), Self::Error>
where
I: IntoIterator<Item = Pixel<Self::Color>>;
/// Fill a given area with an iterator providing a contiguous stream of pixel colors.
///
/// Use this method to fill an area with contiguous, non-transparent pixel colors. Pixel
/// coordinates are iterated over from the top left to the bottom right corner of the area in
/// row-first order. The provided iterator must provide pixel color values based on this
/// ordering to produce correct output.
///
/// As seen in the example below, the [`PointsIter::points`] method can be used to get an
/// iterator over all points in the provided area.
///
/// The provided iterator is not required to provide `width * height` pixels to completely fill
/// the area. In this case, `fill_contiguous` should return without error.
///
/// This method should not attempt to draw any pixels that fall outside the drawable area of the
/// target display. The `area` argument can be clipped to the drawable area using the
/// [`Rectangle::intersection`] method.
///
/// The default implementation of this method delegates to [`draw_iter`](#tymethod.draw_iter).
///
/// # Examples
///
/// This is an example implementation of `fill_contiguous` that delegates to [`draw_iter`]. This
/// delegation behaviour is undesirable in a real application as it will be as slow as the
/// default trait implementation, however is shown here for demonstration purposes.
///
/// The example demonstrates the usage of [`Rectangle::intersection`] on the passed `area`
/// argument to only draw visible pixels. If there is no intersection between `area` and the
/// display area, no pixels will be drawn.
///
/// ```rust
/// use embedded_graphics::{
/// pixelcolor::{Gray8, GrayColor},
/// prelude::*,
/// primitives::{ContainsPoint, Rectangle},
/// };
///
/// struct ExampleDisplay;
///
/// impl DrawTarget for ExampleDisplay {
/// type Color = Gray8;
/// type Error = core::convert::Infallible;
///
/// fn draw_iter<I>(&mut self, pixels: I) -> Result<(), Self::Error>
/// where
/// I: IntoIterator<Item = Pixel<Self::Color>>,
/// {
/// // Draw pixels to the display
///
/// Ok(())
/// }
///
/// fn fill_contiguous<I>(&mut self, area: &Rectangle, colors: I) -> Result<(), Self::Error>
/// where
/// I: IntoIterator<Item = Self::Color>,
/// {
/// // Clamp area to drawable part of the display target
/// let drawable_area = area.intersection(&self.bounding_box());
///
/// // Check that there are visible pixels to be drawn
/// if drawable_area.size != Size::zero() {
/// self.draw_iter(
/// area.points()
/// .zip(colors)
/// .filter(|(pos, _color)| drawable_area.contains(*pos))
/// .map(|(pos, color)| Pixel(pos, color)),
/// )
/// } else {
/// Ok(())
/// }
/// }
/// }
///
/// impl OriginDimensions for ExampleDisplay {
/// fn size(&self) -> Size {
/// Size::new(64, 64)
/// }
/// }
/// ```
///
/// [`draw_iter`]: #tymethod.draw_iter
/// [`Rectangle::intersection`]: ../primitives/rectangle/struct.Rectangle.html#method.intersection
/// [`PointsIter::points`]: ../primitives/trait.PointsIter.html#tymethod.points
fn fill_contiguous<I>(&mut self, area: &Rectangle, colors: I) -> Result<(), Self::Error>
where
I: IntoIterator<Item = Self::Color>,
{
self.draw_iter(
area.points()
.zip(colors)
.map(|(pos, color)| Pixel(pos, color)),
)
}
/// Fill a given area with a solid color.
///
/// If the target display provides optimized hardware commands for filling a rectangular area of
/// the display with a solid color, this method should be overridden to use those commands to
/// improve performance.
///
/// The default implementation of this method calls [`fill_contiguous`](#method.fill_contiguous)
/// with an iterator that repeats the given `color` for every point in `area`.
fn fill_solid(&mut self, area: &Rectangle, color: Self::Color) -> Result<(), Self::Error> {
self.fill_contiguous(area, core::iter::repeat(color))
}
/// Fill the entire display with a solid color.
///
/// If the target hardware supports a more optimized way of filling the entire display with a
/// solid color, this method should be overridden to use those commands.
///
/// The default implementation of this method delegates to [`fill_solid`] to fill the
/// [`bounding_box`] returned by the [`Dimensions`] implementation.
///
/// [`Dimensions`]: ../geometry/trait.Dimensions.html
/// [`bounding_box`]: ../geometry/trait.Dimensions.html#tymethod.bounding_box
/// [`fill_solid`]: #method.fill_solid
fn clear(&mut self, color: Self::Color) -> Result<(), Self::Error> {
self.fill_solid(&self.bounding_box(), color)
}
}