flxzt/rnote · error

Asserting image validity failed, invalid size or data.

Error message

Asserting image validity failed, invalid size or data.

What it means

Image::assert_valid failed because the image has zero width/height or its data buffer length does not equal 4 * pixel_width * pixel_height (RGBA8 bytes per pixel). Called before any consumer (into_imgbuf, into_encoded_bytes, to_memtexture, to_rendernode) touches the data.

Solutions

1. Fix the producer of the Image so pixel_width/pixel_height match data.len()/4 and are > 0.
2. Check where dimensions are computed (e.g. width_scaled as u32) and guard against 0 via max(1).
3. Re-encode/re-download the source image if data arrived truncated.
4. Call assert_valid() right after constructing Image to fail fast near the real bug.

Example fix

// before
let image = Image { pixel_width: w, pixel_height: h, data };
// after
assert!(w > 0 && h > 0 && data.len() as u32 == 4 * w * h, "image size/data mismatch");
let image = Image { pixel_width: w, pixel_height: h, data };

// rust
fn image_dims_match(img: &Image) -> bool {
    img.pixel_width > 0 && img.pixel_height > 0
        && img.data.len() as u32 == 4 * img.pixel_width * img.pixel_height
}

fn is_valid_image(img: &Image) -> bool {
    img.pixel_width.checked_mul(img.pixel_height)
        .map(|px| px > 0 && img.data.len() as u32 == 4 * px)
        .unwrap_or(false)
}

if let Err(e) = image.assert_valid() {
    eprintln!("discarding invalid image: {e}");
    return Ok(None); // or rebuild the image
}

When it happens

Trigger: Creating an Image with pixel_width or pixel_height == 0, or with a `data` byte buffer whose length mismatches width*height*4; then calling any of the into_*/to_* accessors.

Common situations: Off-by-one scaling math when generating surfaces (integer truncation to 0); clipboard/paste handlers storing partial data; serialization bugs where the byte count drifted from the declared dimensions.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Creating RgbaImage from data failed for image with…
• on-conflict behaviour is still
• Expected directory, found file
• Expected file, found directory
• Expected file with extension

AI-assisted analysis of flxzt/rnote@bbc5354502 (2026-09-08). Data as JSON: /api/errors/470241bedc77eff3. Report an issue: GitHub.

Appendix: source

Thrown at crates/rnote-engine/src/image.rs:190

    fn rotate(&mut self, angle: f64, center: Vector2) {
        self.rectangle.rotate(angle, center)
    }

    fn scale(&mut self, scale: Vector2) {
        self.rectangle.scale(scale)
    }
}

impl Image {
    pub fn assert_valid(&self) -> anyhow::Result<()> {
        self.rectangle.bounds().assert_valid()?;

        if self.pixel_width == 0
            || self.pixel_height == 0
            || self.data.len() as u32 != 4 * self.pixel_width * self.pixel_height
        {
            Err(anyhow::anyhow!(
                "Asserting image validity failed, invalid size or data."
            ))
        } else {
            Ok(())
        }
    }

    pub fn try_from_encoded_bytes(bytes: &[u8]) -> Result<Self, anyhow::Error> {
        let reader = ImageReader::new(io::Cursor::new(bytes)).with_guessed_format()?;
        Ok(Image::from(reader.decode()?))
    }

    pub fn try_from_cairo_surface(
        mut surface: cairo::ImageSurface,
        bounds: Aabb,
    ) -> anyhow::Result<Self> {
        let width = surface.width() as u32;
        let height = surface.height() as u32;

View on GitHub (pinned to bbc5354502)