Module embedded_graphics::mock_display

Mock display for use in tests.

MockDisplay can be used to replace a real display in tests. The internal framebuffer wraps the color values in Option to be able to test which pixels were modified by drawing operations.

The from_pattern method provides a convenient way of creating expected test results. The same patterns are used by the implementation of Debug and will be shown in failing tests.

The display is internally capped at 64x64px.

Characters used in BinaryColor patterns

Character	Color	Description
' '	None	No drawing operation changed the pixel
'.'	Some(BinaryColor::Off)	Pixel was changed to BinaryColor::Off
'#'	Some(BinaryColor::On)	Pixel was changed to BinaryColor::On

Characters used in Gray8 patterns

Character	Color	Description
' '	None	No drawing operation changed the pixel
'0'	Some(Gray8::new(0x00))	Pixel was changed to Gray8::new(0x00)
'1'	Some(Gray8::new(0x11))	Pixel was changed to Gray8::new(0x11)
⋮	⋮	⋮
'E'	Some(Gray8::new(0xEE))	Pixel was changed to Gray8::new(0xEE)
'F'	Some(Gray8::new(0xFF))	Pixel was changed to Gray8::new(0xFF)

Characters used in Rgb888 patterns

Character	Color	Description
' '	None	No drawing operation changed the pixel
'K'	Some(Rgb888::BLACK)	Pixel was changed to Rgb888::BLACK
'R'	Some(Rgb888::RED)	Pixel was changed to Rgb888::RED
'G'	Some(Rgb888::GREEN)	Pixel was changed to Rgb888::GREEN
'B'	Some(Rgb888::BLUE)	Pixel was changed to Rgb888::BLUE
'Y'	Some(Rgb888::YELLOW)	Pixel was changed to Rgb888::YELLOW
'M'	Some(Rgb888::MAGENTA)	Pixel was changed to Rgb888::MAGENTA
'C'	Some(Rgb888::CYAN)	Pixel was changed to Rgb888::CYAN
'W'	Some(Rgb888::WHITE)	Pixel was changed to Rgb888::WHITE

Examples

Assert that a modified display matches the expected value

This example sets three pixels on the display and checks that they’re turned on.

use embedded_graphics::{mock_display::MockDisplay, pixelcolor::BinaryColor, prelude::*};

let mut display = MockDisplay::new();

Pixel(Point::new(0, 0), BinaryColor::On).draw(&mut display);
Pixel(Point::new(2, 1), BinaryColor::On).draw(&mut display);
Pixel(Point::new(1, 2), BinaryColor::On).draw(&mut display);

#[rustfmt::skip]
assert_eq!(
    display,
    MockDisplay::from_pattern(&[
        "#  ",
        "  #",
        " # ",
    ])
);

Load and validate a 24BPP TGA image

This example loads the following test image (scaled 10x to make it visible) and tests the returned pixels against an expected pattern.

use embedded_graphics::{
    image::Image,
    mock_display::MockDisplay,
    pixelcolor::{Rgb888, RgbColor},
    prelude::*,
};
use tinytga::Tga;

let data = include_bytes!("../../tinytga/tests/type1_tl.tga");

let tga = Tga::from_slice(data).unwrap();

let image: Image<Tga, Rgb888> = Image::new(&tga, Point::zero());

let mut display: MockDisplay<Rgb888> = MockDisplay::new();

image.draw(&mut display);

assert_eq!(
    display,
    MockDisplay::from_pattern(&[
        "WKRGBYMCW",
        "KKRGBYMCW",
        "WKRGBYMCW",
        "KKKKKKKKK",
        "WKWCMYBGR",
    ])
);

Structs

MockDisplay

Mock display struct

Traits

ColorMapping

Mapping between chars and colors.