Add support for drawing anti-aliased lines and thick lines. about imageproc

[ArtemGr]

And then maybe answer this question:
http://stackoverflow.com/questions/34440429/draw-a-line-in-a-bitmap-possibly-with-piston
; )

[dbrgn]

I added a simple Rust implementation of the Bresenham algorithm to the StackOverflow question: http://stackoverflow.com/a/34722500/284318

I'd be interested in giving this issue a stab. @theotherphil can you give me some starting point on where in the library I'd add something like that, and what stucts the function would operate on? Or in other words, what should the API look like?

[dbrgn]

Also, drawing a line with a thickness is probably just a specialization of filled rectangle drawing, right?

[dbrgn]

Sorry for the triple post, but I dug deeper in the docs and found some functions that are already present. Aren't these already covering the issue?

Drawing a line: imageproc::drawing::draw_line_segment
Drawing a thick line: imageproc::drawing::draw_filled_rect

[dbrgn]

Can't get it to work though:

extern crate image;
extern crate imageproc;

use image::RgbImage;
use imageproc::rect::Rect;
use imageproc::drawing::draw_filled_rect;

fn main() {
    let mut img = RgbImage::new(256, 256);
    let thickness = 10;
    draw_filled_rect(&img, Rect::at(128, 10).of_size(118, thickness), [240, 240, 255]);
    img.save("output.png").unwrap();
}

Results in:

src/main.rs:16:5: 16:21 error: the trait image::image::GenericImage is not implemented for the type image::buffer::ImageBuffer<image::color::Rgb<u8>, collections::vec::Vec<u8>> [E0277]
src/main.rs:16 draw_filled_rect(&img, Rect::at(128, 10).of_size(118, thickness), [240, 240, 255]);
^~~~~~~~~~~~~~~~

I'm not sure how I can use an RgbImage as a GenericImage.

If I find out, maybe I can contribute some docs with examples.

[theotherphil]

There's only support for axis-aligned rectangles, so we still need to add code for slanted wide lines.

Your compiler error might just be because you're missing a "use image::GenericImage". If that doesn't work I'll check when I get home (about five hours from now).

More examples in the docs would be great, even if this approach doesn't end up solving the original problem.

[dbrgn]

Your compiler error might just be because you're missing a "use image::GenericImage".

No, that didn't help.

[theotherphil]

Ah, the last parameter to draw_filled_rect should be Rgb([240, 240, 255]), instead of just the array.

[dbrgn]

That didn't solve the problem either :(

use image::{Rgb, RgbImage};
// ...

fn main() {
    // ...
    draw_filled_rect(&img, Rect::at(128, 10).of_size(118, thickness),
                     Rgb([240, 240, 255]));
    // ...
}

Same output as above.

[theotherphil]

Ok, I'll have a look when I get home.

[theotherphil]

Very odd. The following code works fine for me:

extern crate image;
extern crate imageproc;

use image::{
    Rgb,
    RgbImage
};

use imageproc::rect::Rect;
use imageproc::drawing::draw_filled_rect_mut;

fn main() {
    let mut img = RgbImage::new(256, 256);
    let thickness = 10;
    draw_filled_rect_mut(&mut img, Rect::at(128, 10).of_size(118, thickness), Rgb([240, 240, 255]));
    img.save("output.png").unwrap();
}

(Your code compiled too, but didn't do anything useful - I've replaced the use of draw_filled_rect with draw_filled_rect_mut so that we update the image in place.)

[theotherphil]

Are you trying this in a new project? If so, what does your Cargo.toml file look like?

[dbrgn]

I copy-pasted your code and still get the same errors :(

I'm using latest versions of both image and imageproc. Used * version specifiers for quick testing:

[package]
name = "img"
version = "0.1.0"
authors = ["..."]

[dependencies]
image = "*"
imageproc = "*"

Maybe you're on a different version?

[theotherphil]

For some reason

image = "*" 

resulted in cargo producing a gigantic wall of complaints around not being able to find packages. However, with

image = "0.3.15"
imageproc = "*"

I can compile and run successfully on latest stable, latest nightly, and nightly from the end of last year.

[dbrgn]

You're right, it works with image 0.3.15. The current verision of image is 0.6.1 though. Could imageproc maybe be updated to support that version? And/or could/should important imports from image be re-exported?

[theotherphil]

Yes, it's pretty embarrassing that this doesn't work with more recent versions of image. I'd not noticed as I was using a fixed version of image. The breaking change looks to happen between 0.3.15 and 0.4.1.

[theotherphil]

This works with latest image:

extern crate image;
extern crate imageproc;

use image::{
    Rgb,
    RgbImage,
    GenericImage
};

fn constraints<I>(image: &I, color: I::Pixel)
    where I: GenericImage,
    I::Pixel: 'static
{
    let x = image.height();
    println!("{}", x);
}

fn main() {
    let img = RgbImage::new(256, 256);
    constraints(&img, Rgb([0, 0, 0]));
}

Where where I'm using the same bounds as the draw_filled_rect function. So I'm none the wiser as to what's going on.

[theotherphil]

@bvssvni @tafia Am I missing something obvious here?

[tafia]

When I do a cargo clean then cargo build --verbose it apparently compiles 2 versions of several crates

• png (0.4.1 and 0.3.1)
• image (0.6.1 and 0.3.15)
• byteorder (0.4.2 and 0.3.13)
• bitflags (0.3.3 and 0.4.0)

If I force using image 0.6.1 (via .cargo/config file) the code works fine.
I suppose there is some conflict somewhere.

I also noted that there is a commit in image:

e7fd748 Fixed `NotEnoughData(..)` => `NotEnoughData`

which corresponds to the first warning messages I have.

EDIT: Looking at Cargo.lock is actually much simpler than using --verbose ...

[tafia]

@theotherphil I think the issue is in your Cargo.toml / Cargo.lock => you should probably upgrade to higher version.

It specifically mentions it uses image 0.3.15. You should update the dependencies it and push it to crates.io.

[[package]]
name = "imageproc"
version = "0.1.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
 "conv 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "image 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
 "itertools 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
 "nalgebra 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "num 0.1.30 (registry+https://github.com/rust-lang/crates.io-index)",
 "quickcheck 0.2.24 (registry+https://github.com/rust-lang/crates.io-index)",
 "rand 0.3.13 (registry+https://github.com/rust-lang/crates.io-index)",
]

[korczis]

Any news? Any plans to fix/implement this?

I am looking for functionality similar to http://chunkypng.com/

Any plans to implement such functions/interface?

[theotherphil]

I had a quick look at the documentation for that library and couldn't see anything about drawing anti-aliased lines. Which functions specifically did you have in mind?

If you're just after PNG loading and saving then this is already supported by the image library (whose image types and traits this library uses).

[korczis]

For example this method - http://www.rubydoc.info/github/wvanbergen/chunky_png/ChunkyPNG/Canvas/Drawing#line_xiaolin_wu-instance_method

[theotherphil]

Aha, thanks. I'll add that and the polygon function this weekend.

[korczis]

Wow. That will be really great. Thanks a lot.

[theotherphil]

I've made a start in #140. Take a look and let me know what you think. It's not as fast as it should be at the moment, but is hopefully correct. Is this good enough for your current use case? The initial aim of all the drawing functions was just to show points of interest on an image when debugging or verifying results of some vision algorithms, so none of them are particularly well written. This can certainly be improved though.

I'm afraid I won't get time to implement the polygon algorithm this weekend after all.

[theotherphil]

Fixed by 142 and 144

[korczis]

Works for me. Thanks.