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//! A module for generic representation of image.
// from rust
use std::collections::HashMap;
// from external crate
// from local crate
use error::{RasterError, RasterResult};
use color::Color;
/// A struct for easily representing a raster image.
#[derive(Debug, Clone)]
pub struct Image {
/// Width of image in pixels.
pub width: i32, // i32 type is used as computation with negative integers is common.
/// Height of image in pixels.
pub height: i32,
/// Vector containing sequence of bytes in RGBA format.
pub bytes: Vec<u8>,
}
impl<'a> Image {
/// Create a blank image. Default color is black.
///
/// # Examples
///
/// ```
/// use raster::Image;
///
/// let image = Image::blank(2, 2);
///
/// println!("{:?}", image.bytes);
///
/// assert_eq!(image.width, 2);
/// assert_eq!(image.height, 2);
/// ```
pub fn blank(w:i32, h:i32) -> Image {
let mut bytes = Vec::with_capacity((w * h) as usize * 4);
for _ in 0..h {
for _ in 0..w {
bytes.extend_from_slice(&[0, 0, 0, 255]);
}
}
Image {
width: w,
height: h,
bytes: bytes
}
}
/// Check if there is a pixel at this location given by x and y.
///
/// # Examples
///
/// ```
/// use raster::Image;
///
/// let image = Image::blank(2, 2);
///
/// assert_eq!(image.check_pixel(0, 0), true);
/// assert_eq!(image.check_pixel(3, 3), false);
/// ```
pub fn check_pixel(&self, x: i32, y:i32) -> bool {
if y < 0 || y > self.height { // TODO: check on actual vectors and not just width and height?
false
} else {
!(x < 0 || x > self.width)
}
}
/// Get the histogram of the image.
///
/// # Examples
///
/// Visualizing the histogram of the red channel of this image:
///
/// Image:
///
/// 
///
/// Code:
///
/// ```
/// use raster::Image;
/// use raster::Color;
///
/// let image = raster::open("tests/in/sample.png").unwrap();
///
/// let (r_bin, _, _, _) = image.histogram().unwrap();
///
/// let mut max_r_bin = 0;
/// for (_, count) in &r_bin {
/// if *count > max_r_bin {
/// max_r_bin = *count;
/// }
/// }
///
/// let canvas_w = 256;
/// let canvas_h: i32 = 100;
/// let mut image = Image::blank(canvas_w, canvas_h);
/// raster::editor::fill(&mut image, Color::rgb(214, 214, 214)).unwrap();
///
/// for x in 0..256 as i32 { // 0-255
/// let key = x as u8;
/// match r_bin.get(&key) {
/// Some(count) => {
///
/// let height = (canvas_h as f32 * (*count as f32 / max_r_bin as f32)).round() as i32;
///
/// for y in canvas_h-height..canvas_h {
///
/// image.set_pixel(x, y, Color::hex("#e22d11").unwrap()).unwrap();
///
/// }
/// },
/// None => {}
/// }
/// }
///
/// raster::save(&image, "tests/out/histogram.png").unwrap();
/// ```
///
/// Histogram:
///
/// 
///
/// Photoshop's result:
///
/// 
///
pub fn histogram(&self) -> RasterResult<Histogram> {
let w = self.width;
let h = self.height;
let mut r_bin: HashMap<u8, u32> = HashMap::new();
let mut g_bin: HashMap<u8, u32> = HashMap::new();
let mut b_bin: HashMap<u8, u32> = HashMap::new();
let mut a_bin: HashMap<u8, u32> = HashMap::new();
for y in 0..h {
for x in 0..w {
let pixel = try!(self.get_pixel(x, y));
let r_bin_c = r_bin.entry(pixel.r).or_insert(0); // Insert the key with a value of 0 if key does not exist yet. Then return the count (which is zero).
*r_bin_c += 1; // +1 to the count.
let g_bin_c = g_bin.entry(pixel.g).or_insert(0);
*g_bin_c += 1;
let b_bin_c = b_bin.entry(pixel.b).or_insert(0);
*b_bin_c += 1;
let a_bin_c = a_bin.entry(pixel.a).or_insert(0);
*a_bin_c += 1;
}
}
Ok((r_bin, g_bin, b_bin, a_bin))
}
/// Get pixel in a given x and y location of an image.
///
/// # Errors
///
/// If either the x or y coordinate falls out of bounds, this will fail with
/// `RasterError::PixelOutOfBounds`.
///
/// # Examples
///
/// ```
/// use raster::Image;
/// use raster::Color;
///
/// let mut image = Image::blank(2, 2); // Creates a 2x2 black image.
///
/// let pixel = image.get_pixel(0, 0).unwrap();
///
/// assert_eq!(0, pixel.r);
/// assert_eq!(0, pixel.g);
/// assert_eq!(0, pixel.b);
/// assert_eq!(255, pixel.a);
/// ```
pub fn get_pixel(&self, x: i32, y:i32) -> RasterResult<Color> {
let rgba = 4;
let start = (y * self.width) + x;
let start = start * rgba;
let end = start + rgba;
let len = self.bytes.len();
if start as usize > len || end as usize > len {
Err(RasterError::PixelOutOfBounds(x, y))
} else {
let slice = &self.bytes[start as usize..end as usize];
Ok(Color {
r: slice[0],
g: slice[1],
b: slice[2],
a: slice[3],
})
}
}
/// Set pixel in a given x and y location of an image.
///
/// # Errors
///
/// If either the x or y coordinate falls out of bounds, this will fail with
/// `RasterError::PixelOutOfBounds`.
///
/// If the calculated byte start index is less than 0, this will fail with
/// `RasterError::InvalidStartIndex`.
///
/// # Examples
///
/// ```
/// use raster::Image;
/// use raster::Color;
///
/// let mut image = Image::blank(2, 2); // Creates a 2x2 black image.
///
/// let _ = image.set_pixel(0, 0, Color::rgba(255, 0, 0, 255)); // Set first pixel to red
///
/// let pixel = image.get_pixel(0, 0).unwrap();
///
/// assert_eq!(255, pixel.r);
/// assert_eq!(0, pixel.g);
/// assert_eq!(0, pixel.b);
/// assert_eq!(255, pixel.a);
/// ```
pub fn set_pixel(&mut self, x: i32, y:i32, color: Color ) -> RasterResult<()> {
let rgba = 4; // length
let start = (y * &self.width) + x;
let start = start * rgba;
if x >= self.width || y >= self.height {
Err(RasterError::PixelOutOfBounds(x, y))
} else if start < 0 {
Err(RasterError::InvalidStartIndex(start))
} else {
self.bytes[start as usize] = color.r;
self.bytes[start as usize + 1] = color.g;
self.bytes[start as usize + 2] = color.b;
self.bytes[start as usize + 3] = color.a;
Ok(())
}
}
}
/// Holds histogram information.
pub type Histogram = (HashMap<u8, u32>, HashMap<u8, u32>, HashMap<u8, u32>, HashMap<u8, u32>);
/// Enumeration of supported raster formats.
#[derive(Debug)]
pub enum ImageFormat {
Gif,
Jpeg,
Png,
}