Method write_remapped_image_rows_internal

src/quant.rs:83–117

(&mut self, image: &mut Image, mut output_pixels: RowBitmapMut<'_, MaybeUninit<PalIndexRemap>>)

    #[inline(never)]
    pub(crate) fn write_remapped_image_rows_internal(&mut self, image: &mut Image, mut output_pixels: RowBitmapMut<'_, MaybeUninit<PalIndexRemap>>) -> Result<(), Error> {
        let progress_stage1 = if self.use_dither_map != DitherMapMode::None { 20 } else { 0 };
        if self.remap_progress(progress_stage1 as f32 * 0.25) {
            return Err(Error::Aborted);
        }

        image.free_histogram_inputs();

        let mut palette = self.palette.clone();
        let mut remapped = Box::new(Remapped {
            int_palette: Palette { count: 0, entries: [RGBA::default(); MAX_COLORS] },
            palette_error: None,
        });
        if self.dither_level == 0. {
            palette.init_int_palette(&mut remapped.int_palette, self.gamma, self.min_posterization_output);
            remapped.palette_error = Some(remap_to_palette(&mut image.px, image.background.as_deref_mut(), image.importance_map.as_deref(), &mut output_pixels, &mut palette)?.0);
        } else {
            let uses_background = image.background.is_some();
            let dither_map_error = Self::optionally_generate_dither_map(self.use_dither_map, image, uses_background, &mut output_pixels, &mut palette)?;
            if self.remap_progress(progress_stage1 as f32 * 0.5) {
                return Err(Error::Aborted);
            }

            let output_image_is_remapped = dither_map_error.is_some();
            let palette_error = dither_map_error.or(self.palette_error);

            // remapping above was the last chance to do K-Means iteration, hence the final palette is set after remapping
            palette.init_int_palette(&mut remapped.int_palette, self.gamma, self.min_posterization_output);
            remapped.palette_error = palette_error;
            let max_dither_error = (palette_error.unwrap_or(quality_to_mse(80)) * 2.4).max(quality_to_mse(35)) as f32;
            remap_to_palette_floyd(image, output_pixels, &palette, self, max_dither_error, output_image_is_remapped)?;
        }
        self.remapped = Some(remapped);
        Ok(())
    }

    fn optionally_generate_dither_map(use_dither_map: DitherMapMode, image: &mut Image<'_>, uses_background: bool, output_pixels: &mut RowBitmapMut<'_, MaybeUninit<PalIndexRemap>>, palette: &mut PalF) -> Result<Option<f64>, Error> {
        let is_image_huge = (image.px.width * image.px.height) > 2000 * 2000;