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use anyhow::Context;
use super::Image;
pub fn convolution2x2<F>(bitmap: &Image, callback: F) -> anyhow::Result<Image>
where F: Fn(&Image) -> anyhow::Result<u8>
{
let width: u8 = bitmap.width();
let height: u8 = bitmap.height();
if width < 2 || height < 2 {
return Err(anyhow::anyhow!("too small bitmap, must be 2x2 or bigger"));
}
let mut computed_bitmap = Image::zero(width - 1, height - 1);
let mut conv_bitmap = Image::zero(2, 2);
for self_y in 0..height-1 {
for self_x in 0..width-1 {
for conv_y in 0..2u8 {
for conv_x in 0..2u8 {
let get_x: i32 = (self_x as i32) + (conv_x as i32);
let get_y: i32 = (self_y as i32) + (conv_y as i32);
let pixel_value: u8 = bitmap.get(get_x, get_y)
.ok_or_else(|| anyhow::anyhow!("self.get({},{}) returned None", get_x, get_y))?;
conv_bitmap.set(conv_x as i32, conv_y as i32, pixel_value)
.ok_or_else(|| anyhow::anyhow!("conv_bitmap.set({},{}) returned None", conv_x, conv_y))?;
}
}
let computed_value: u8 = callback(&conv_bitmap)
.with_context(|| format!("error in callback when computing ({},{})", self_x, self_y))?;
computed_bitmap.set(self_x as i32, self_y as i32, computed_value)
.ok_or_else(|| anyhow::anyhow!("computed_bitmap.set({},{}) returned None", self_x, self_y))?;
}
}
Ok(computed_bitmap)
}
#[allow(dead_code)]
fn conv2x2_max(bm: &Image) -> anyhow::Result<u8> {
let mut value: u8 = 0;
for pixel in bm.pixels() {
value = u8::max(value, *pixel);
}
Ok(value)
}
#[allow(dead_code)]
fn conv2x2_min(bm: &Image) -> anyhow::Result<u8> {
let mut value: u8 = 255;
for pixel in bm.pixels() {
value = u8::min(value, *pixel);
}
Ok(value)
}
#[cfg(test)]
mod tests {
use super::*;
use crate::arc::ImageTryCreate;
#[test]
fn test_10000_callback() {
// Arrange
let pixels: Vec<u8> = vec![
1, 2, 3,
4, 5, 6,
7, 8, 9,
];
let input: Image = Image::try_create(3, 3, pixels).expect("image");
// Act
let output: Image = convolution2x2(&input, |bm| {
let mut sum: u64 = 0;
for pixel in bm.pixels() {
sum += *pixel as u64;
}
let value = (sum & 255) as u8;
Ok(value)
}).expect("image");
// Assert
assert_eq!(output.width(), 2);
assert_eq!(output.height(), 2);
assert_eq!(output.get(0, 0), Some(1+2+4+5));
assert_eq!(output.get(1, 0), Some(2+3+5+6));
assert_eq!(output.get(0, 1), Some(4+5+7+8));
assert_eq!(output.get(1, 1), Some(5+6+8+9));
}
#[test]
fn test_20000_max() {
// Arrange
let pixels: Vec<u8> = vec![
1,2,3,4,
5,6,7,8,
9,10,11,12,
13,14,15,16,
];
let input: Image = Image::try_create(4, 4, pixels).expect("image");
// Act
let output: Image = convolution2x2(&input, conv2x2_max).expect("image");
// Assert
let expected_pixels: Vec<u8> = vec![
6,7,8,
10,11,12,
14,15,16,
];
let expected: Image = Image::try_create(3, 3, expected_pixels).expect("image");
assert_eq!(output, expected);
}
#[test]
fn test_20001_min() {
// Arrange
let pixels: Vec<u8> = vec![
1,2,3,4,
5,6,7,8,
9,10,11,12,
13,14,15,16,
];
let input: Image = Image::try_create(4, 4, pixels).expect("image");
// Act
let output: Image = convolution2x2(&input, conv2x2_min).expect("image");
// Assert
let expected_pixels: Vec<u8> = vec![
1,2,3,
5,6,7,
9,10,11,
];
let expected: Image = Image::try_create(3, 3, expected_pixels).expect("image");
assert_eq!(output, expected);
}
}
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