vectorcraft/crates/render/src/encode.rs

//! Raster export: render a document region with [`RasterExportOptions`] (resolution, background,
//! anti-aliasing) and encode it as PNG ([`png`]: resolution in `pHYs`, Adam7 interlacing), JPEG
//! ([`jpeg`]: RGB, CMYK or grey, progressive, resolution and colour profile), lossless WebP, or
//! a palette image ([`quantize`]) as PNG-8 or [`gif`], [`tiff`] (RGB, CMYK or grey, LZW, either byte
//! order, the profile), [`bmp`] (1–32 bits, RLE) or [`tga`]; [`web`] adds what Save for Web optimises
//! further (web snap, colour table edits, lossy GIF, comments); [`psd`] writes layered bitmaps.

pub mod bmp;
pub mod gif;
pub mod jpeg;
pub mod png;
pub mod psd;
pub mod quantize;
pub mod tga;
pub mod tiff;
pub mod web;

use std::sync::Arc;

use vectorcraft_doc::{Document, Node, NodeKind, SymbolBoxes};
use vectorcraft_geom::Rect;

use crate::{AntiAlias, RenderOptions, Rendered, Renderer, fx};

/// A raster file format.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum RasterFormat {
    Png,
    Jpeg,
    WebP,
    /// Indexed PNG: a palette of up to 256 colours.
    Png8,
    Gif,
    Tiff,
    Bmp,
    Tga,
    /// Layered bitmap (.psd).
    Psd,
}

/// How a raster export renders and encodes.
#[derive(Clone, Debug, PartialEq)]
pub struct RasterExportOptions {
    /// Resolution in pixels per inch: 72 renders one pixel per point. Stored in the file.
    pub ppi: f64,
    /// Opaque background colour (RGB); `None` = transparent (JPEG has no alpha: white).
    pub background: Option<[u8; 3]>,
    pub anti_alias: AntiAlias,
    /// PNG, PNG-8: Adam7 interlacing; GIF: interlaced rows.
    pub interlaced: bool,
    /// JPEG quality 0–100.
    pub quality: u8,
    /// JPEG colour model, coding and profile.
    pub jpeg: jpeg::JpegOptions,
    /// PNG-8 and GIF: the colour reduction (also BMP's at 1, 4 and 8 bits).
    pub palette: quantize::PaletteOptions,
    /// TIFF colour model, compression, byte order and profile.
    pub tiff: tiff::TiffOptions,
    /// BMP layout, depth, compression and row order.
    pub bmp: bmp::BmpOptions,
    /// Targa depth.
    pub tga: tga::TgaOptions,
    /// PSD colour model, layers and profile.
    pub psd: psd::PsdOptions,
    /// Appearance of Black › Printing / Exporting › Output All Blacks as Rich Black: pure CMYK
    /// black (K alone at 100%) becomes RGB black in RGB raster exports (document values unchanged).
    pub rich_black: bool,
}

impl Default for RasterExportOptions {
    fn default() -> Self {
        Self {
            ppi: 72.0,
            background: None,
            anti_alias: AntiAlias::Art,
            interlaced: false,
            quality: 90,
            jpeg: jpeg::JpegOptions::default(),
            palette: quantize::PaletteOptions::default(),
            tiff: tiff::TiffOptions::default(),
            bmp: bmp::BmpOptions::default(),
            tga: tga::TgaOptions::default(),
            psd: psd::PsdOptions::default(),
            rich_black: false,
        }
    }
}

impl RasterExportOptions {
    /// Pixels per point.
    pub fn scale(&self) -> f64 {
        self.ppi / 72.0
    }

    /// What the renderer draws for `format`: template layers and guides left out, over the background
    /// (white for a JPEG or a flat PSD without one), composited in floating point.
    pub fn render_options(&self, format: RasterFormat) -> RenderOptions {
        let flat = format == RasterFormat::Jpeg || (format == RasterFormat::Psd && !self.psd.layers);
        let background = self.background.or(flat.then_some([255; 3]));
        RenderOptions {
            background: background.map(|[r, g, b]| [r, g, b, 255]),
            skip_templates: true,
            anti_alias: self.anti_alias,
            // Opaque art stays exactly opaque where translucent edges cross it (#787).
            precise: true,
            // Shapes meeting edge to edge leave no seam (#983).
            supersample: true,
            rich_black: self.rich_black,
            ..Default::default()
        }
    }

    /// Encode a rendered image as `format`. A CMYK JPEG separates the screen colours, and a PSD is
    /// flat; [`Renderer::export_region`] draws the inks and the layers instead.
    pub fn encode(&self, img: &Rendered, format: RasterFormat) -> Result<Vec<u8>, String> {
        match format {
            RasterFormat::Png => {
                png::encode(&img.to_straight(), img.width, img.height, &png::PngOptions { ppi: Some(self.ppi), interlaced: self.interlaced })
            }
            RasterFormat::Jpeg => {
                let px = match self.jpeg.color_model {
                    jpeg::ColorModel::Cmyk => jpeg::separated(img),
                    model => jpeg::screen_pixels(img, model == jpeg::ColorModel::Gray),
                };
                jpeg::encode(&px, img.width, img.height, self.quality, Some(self.ppi), &self.jpeg)
            }
            RasterFormat::WebP => webp(img),
            RasterFormat::Png8 | RasterFormat::Gif => {
                let ix = quantize::quantize(&img.to_straight(), img.width, img.height, &self.palette);
                match format {
                    RasterFormat::Gif => gif::encode(&ix, self.interlaced),
                    _ => png::encode_indexed(&ix, &png::PngOptions { ppi: Some(self.ppi), interlaced: self.interlaced }),
                }
            }
            RasterFormat::Tiff => tiff::encode(img, self.ppi, &self.tiff),
            RasterFormat::Bmp => bmp::encode(&img.to_straight(), img.width, img.height, self.ppi, &self.bmp, &self.palette),
            RasterFormat::Tga => tga::encode(&img.to_straight(), img.width, img.height, &self.tga),
            RasterFormat::Psd => psd::encode(img, self.ppi, &self.psd),
        }
    }

    /// Does `format` write ink amounts (a CMYK JPEG or TIFF)?
    fn cmyk(&self, format: RasterFormat) -> bool {
        match format {
            RasterFormat::Jpeg => self.jpeg.color_model == jpeg::ColorModel::Cmyk,
            RasterFormat::Tiff => self.tiff.color_model == jpeg::ColorModel::Cmyk,
            _ => false,
        }
    }
}

impl Renderer {
    /// Render `region` of `doc` (an artboard or any rect) as exported and encode it as `format`.
    /// Callers check the size first ([`crate::raster_size`]). A CMYK JPEG or TIFF is drawn as ink
    /// amounts ([`Renderer::render_region_inks`]); a PSD with its layers ([`psd::export`]).
    pub fn export_region(&mut self, doc: &Document, region: Rect, format: RasterFormat, opts: &RasterExportOptions) -> Result<Vec<u8>, String> {
        if format == RasterFormat::Psd {
            return psd::export(self, doc, region, opts);
        }
        if opts.cmyk(format) {
            let (w, h) = crate::region_pixels(region, opts.scale());
            let inks = self.render_region_inks(doc, region, opts.scale(), &opts.render_options(format));
            return match format {
                RasterFormat::Tiff => tiff::encode_samples(&inks, w, h, opts.ppi, &opts.tiff),
                _ => jpeg::encode(&inks, w, h, opts.quality, Some(opts.ppi), &opts.jpeg),
            };
        }
        let img = self.render_region_with(doc, region, opts.scale(), &opts.render_options(format));
        opts.encode(&img, format)
    }
}

/// Baseline RGB JPEG at `quality` 1–100, partly transparent pixels flattened on white, with the
/// resolution `ppi` (if any) in the JFIF header and no colour profile.
pub(crate) fn jpeg(img: &Rendered, quality: u8, ppi: Option<f64>) -> Result<Vec<u8>, String> {
    let o = jpeg::JpegOptions { embed_icc: false, ..Default::default() };
    jpeg::encode(&jpeg::screen_pixels(img, false), img.width, img.height, quality, ppi, &o)
}

/// A straight-alpha pixel composited over white.
pub fn on_white(p: &[u8; 4]) -> [u8; 3] {
    let a = u32::from(p[3]);
    [0, 1, 2].map(|i| ((u32::from(p[i]) * a + 255 * (255 - a) + 127) / 255) as u8)
}

/// Lossless WebP.
pub(crate) fn webp(img: &Rendered) -> Result<Vec<u8>, String> {
    let mut buf = Vec::new();
    let enc = image::codecs::webp::WebPEncoder::new_lossless(&mut buf);
    image::ImageEncoder::write_image(enc, &img.to_straight(), img.width, img.height, image::ExtendedColorType::Rgba8)
        .map_err(|e| format!("WebP encoding failed: {e}"))?;
    Ok(buf)
}

/// Bounds of the art an export draws: visible objects off template layers (guides left out),
/// each measured by [`crate::effect_bounds`]: with its strokes and its effects (the effects of
/// groups, layers, type and images included), symbol instances by their art, and a Shaper group
/// without effects of its own by the art it shows. `None` when nothing would be drawn.
pub fn art_bounds(doc: &Document) -> Option<Rect> {
    let symbols = doc.symbol_boxes();
    doc.layers.iter().fold(None, |acc, l| vectorcraft_geom::union_opt(acc, drawn_bounds(&symbols, l)))
}

/// Bounds of the art an export draws ([`art_bounds`]) that is on artboard rectangle `rect`: each
/// object of a layer or sublayer whose drawn bounds overlap `rect`, with all of its bounds; a group
/// or a clipping layer counts as one object. `None` when no object overlaps `rect`.
pub fn art_bounds_on(doc: &Document, rect: Rect) -> Option<Rect> {
    art_bounds_on_with(doc, rect, None)
}

impl crate::Renderer {
    /// [`art_bounds_on`], its 3D art measured as this renderer draws and keeps it
    /// (`Renderer::bounds_of`): a pass over each artboard builds each solid once. What it
    /// keeps is measured with the document's symbol boxes as it first measured them, and found by
    /// the objects' addresses: give each document its own renderer.
    pub fn art_bounds_on(&mut self, doc: &Document, rect: Rect) -> Option<Rect> {
        art_bounds_on_with(doc, rect, Some(self))
    }
}

fn art_bounds_on_with(doc: &Document, rect: Rect, mut renderer: Option<&mut crate::Renderer>) -> Option<Rect> {
    // Art flush with an edge from outside can overlap it by a rounding error (#1295).
    let rect = rect.inflate(-1e-6, -1e-6);
    fn on(symbols: &SymbolBoxes, n: &Arc<Node>, rect: Rect, mut renderer: Option<&mut crate::Renderer>) -> Option<Rect> {
        match &n.kind {
            NodeKind::Layer { template: false, clip: false, children, .. } if n.visible => {
                children.iter().fold(None, |acc, c| vectorcraft_geom::union_opt(acc, on(symbols, c, rect, renderer.as_deref_mut())))
            }
            _ => drawn_bounds_with(symbols, n, Some(n), renderer).filter(|b| b.x0 < rect.x1 && b.x1 > rect.x0 && b.y0 < rect.y1 && b.y1 > rect.y0),
        }
    }
    let symbols = doc.symbol_boxes();
    doc.layers.iter().fold(None, |acc, l| vectorcraft_geom::union_opt(acc, on(&symbols, l, rect, renderer.as_deref_mut())))
}

/// Bounds of what an export draws of object `n` ([`art_bounds`]): `None` when `n` is hidden, a
/// guide or a template layer. The hidden objects, guides and template layers in it are left out,
/// except in a group or layer with effects of its own that keep all its members (`without_undrawn`
/// lists them). Symbol instances are measured by their art in `symbols`.
pub fn drawn_bounds(symbols: &SymbolBoxes, n: &Node) -> Option<Rect> {
    drawn_bounds_with(symbols, n, None, None)
}

/// [`drawn_bounds`] of `n` (`held`: `n` as held in its document, which `renderer` keeps what it
/// measures by).
fn drawn_bounds_with(symbols: &SymbolBoxes, n: &Node, held: Option<&Arc<Node>>, mut renderer: Option<&mut crate::Renderer>) -> Option<Rect> {
    if !n.visible {
        return None;
    }
    match &n.kind {
        NodeKind::Layer { template: true, .. } | NodeKind::Path { guide: true, .. } => None,
        NodeKind::Layer { children, clip: false, .. } | NodeKind::Group { children, clip: false } if !fx::has_object_fx(n) => children
            .iter()
            .skip(usize::from(n.extras().shaper.is_some()))
            .fold(None, |acc, c| vectorcraft_geom::union_opt(acc, drawn_bounds_with(symbols, c, Some(c), renderer.as_deref_mut()))),
        _ => match (without_undrawn(n), held, renderer) {
            // A new object, measured once a pass by the one it was made from.
            (Some(kept), Some(a), Some(r)) => {
                let key = Arc::as_ptr(a) as usize;
                if let Some((node, b)) = r.pass_bounds.get(&key)
                    && Arc::ptr_eq(node, a)
                {
                    return *b;
                }
                let b = crate::bounds::effect_bounds_with(symbols, &kept, None, Some(r));
                r.pass_bounds.insert(key, (a.clone(), b));
                b
            }
            (Some(kept), _, renderer) => crate::bounds::effect_bounds_with(symbols, &kept, None, renderer),
            (None, held, renderer) => crate::bounds::effect_bounds_with(symbols, n, held, renderer),
        },
    }
}

/// `n`, a group or layer that doesn't clip, without the hidden objects, guides and template layers
/// in it and in the groups and layers in it that don't clip, or `None` when it holds none of them
/// or is anything else. A Shaper group keeps all its members, and so does a group or layer with a
/// visible geometry, Pathfinder, Crop Marks or 3D effect, or with a visible effect on one of its
/// own visible fills or strokes.
fn without_undrawn(n: &Node) -> Option<Node> {
    use crate::effects;
    let keeps_all = n.extras().shaper.is_some()
        || effects::has_geometry(&n.appearance.effects)
        || effects::has_pathfinder(n)
        || effects::has_crop_marks(n)
        || effects::has_revolve(n)
        || effects::has_solid(n)
        || n.appearance.items.iter().any(|i| i.visible() && i.effects().iter().any(|e| e.visible));
    if keeps_all || !matches!(n.kind, NodeKind::Layer { clip: false, .. } | NodeKind::Group { clip: false, .. }) {
        return None;
    }
    let undrawn = |c: &Node| !c.visible || matches!(c.kind, NodeKind::Layer { template: true, .. } | NodeKind::Path { guide: true, .. });
    let mut changed = false;
    let kept: Vec<Arc<Node>> = n
        .children()?
        .iter()
        .filter_map(|c| {
            if undrawn(c) {
                changed = true;
                return None;
            }
            let part = without_undrawn(c);
            changed |= part.is_some();
            Some(part.map_or_else(|| c.clone(), Arc::new))
        })
        .collect();
    if !changed {
        return None;
    }
    let mut out = n.clone();
    *out.children_mut()? = kept;
    Some(out)
}

#[cfg(test)]
mod tests;
#[cfg(test)]
mod tests_bmp;
#[cfg(test)]
mod tests_jpeg;
#[cfg(test)]
mod tests_palette;
#[cfg(test)]
mod tests_psd;
#[cfg(test)]
mod tests_tga;
#[cfg(test)]
mod tests_tiff;
#[cfg(test)]
mod tests_web;