Debug assertion failed in hairline_aa.rs:124

[danieldg]

Using tiny-skia-0.11.4:

use tiny_skia::*;

fn main() {
    let mut pixmap = Pixmap::new(100, 10).unwrap();
    let paint = Paint {
        shader: Shader::SolidColor(Color::BLACK),
        anti_alias: true,
        ..Default::default()
    };
    let rect = Rect::from_ltrb(88.1, 0., 89.6, 10.).unwrap();

    pixmap.fill_rect(rect, &paint, Default::default(), None);
}

Backtrace:

#14 0x00005555555602f3 in core::panicking::panic ()
#15 0x0000555555568b1c in tiny_skia::scan::hairline_aa::fill_dot8 (l=22554, t=<optimized out>, r=22938, b=2560, fill_inner=true, blitter=...) at src/scan/hairline_aa.rs:124
#16 tiny_skia::scan::hairline_aa::fill_fixed_rect (blitter=..., rect=<optimized out>) at src/scan/hairline_aa.rs:58
#17 tiny_skia::scan::hairline_aa::fill_rect (rect=<optimized out>, clip=<optimized out>, blitter=...) at src/scan/hairline_aa.rs:54
#18 0x0000555555561331 in tiny_skia::scan::fill_rect_aa (rect=0x7fffffffddd0, clip=0x7fffffffc8f0, blitter=...) at src/scan/mod.rs:38
#19 tiny_skia::pixmap::PixmapMut::fill_rect (self=0x7fffffffdd30, rect=..., paint=0x7fffffffdde8, transform=..., mask=...) at src/painter.rs:203
#20 0x000055555556113e in tiny_skia::pixmap::Pixmap::fill_rect (self=<optimized out>, rect=<error reading variable: Cannot access memory at address 0x555e>, paint=0x6, transform=..., mask=...) at src/painter.rs:114

[Yevhenii Reizner]

Thanks, will take a look.

[Nathan Whitehead]

I came across what I think is the same issue. I was drawing aa rects with width exactly 1 and non-integral horizontal positions.

I think the right fix is to let width be 0 in the inner part of hairline_aa.rs:fill_dot8 and just skip the blit_rect for that case with no error.

I put up a pull request with test and fix at #119.

[Yevhenii Reizner]

Thanks. Will take a look.
The correct fix would be to have exactly the same logic Skia does. So the main problem here is for me to find time to dive into Skia sources.