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Biromedic
1726c600d2
The canvas built its peniko gradients premultiplied (peniko's default), while Gradient::sample, the PDF export (shading plus SMask) and SVG viewers blend colour and opacity separately: a transparent white stop into black drew grey 127 halfway instead of 191. Opaque gradients are unchanged.
87 lines
3.8 KiB
Rust
87 lines
3.8 KiB
Rust
//! Paint conversion (solid, gradients, patterns) and image decoding.
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use vectorcraft_color::{GradientKind, Paint};
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use vectorcraft_geom::{Rect, Vec2};
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use vello_cpu::RenderContext;
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use vello_cpu::peniko::{self, ColorStop};
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use crate::Frame;
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/// Set the context paint (colours as frame `f` paints them). Returns false if nothing should be
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/// drawn.
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pub(crate) fn set_paint(ctx: &mut RenderContext, p: &Paint, bounds: Rect, f: &Frame) -> bool {
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match p {
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Paint::None => false,
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Paint::Solid { color: c, .. } => {
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ctx.set_paint(f.ink.color(c, 1.0));
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true
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}
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Paint::Gradient(g) if g.gradient.kind == GradientKind::Freeform => crate::freeform::set_freeform_paint(ctx, g, bounds, f.ink),
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Paint::Gradient(g) => {
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let geom = g.resolve(bounds);
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let stops: Vec<ColorStop> = g.gradient.expanded_stops().iter().map(|(o, c, a)| ColorStop::from((*o, f.ink.color(c, *a)))).collect();
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if stops.is_empty() {
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return false;
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}
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let grad = match g.gradient.kind {
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GradientKind::Radial => {
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let r = geom.length().max(1e-6) as f32;
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// The aspect ratio squashes the circle across the gradient vector.
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let squash = geom.radial_squash();
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ctx.set_paint_transform(squash);
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let g = match geom.focal {
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// An off-centre focal point: a two-point radial from it to the extent circle.
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Some(f) => peniko::Gradient::new_two_point_radial(squash.inverse() * f, 0.0, geom.start, r),
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None => peniko::Gradient::new_radial(geom.start, r),
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};
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g.with_stops(stops.as_slice())
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}
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_ => {
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ctx.reset_paint_transform();
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let (s, e) =
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if geom.start.distance(geom.end) < 1e-9 { (geom.start, geom.start + Vec2::new(1.0, 0.0)) } else { (geom.start, geom.end) };
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peniko::Gradient::new_linear(s, e).with_stops(stops.as_slice())
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}
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};
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// Colour and opacity blend each on its own, as the model samples them and as the PDF
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// and SVG exports draw them (peniko's default premultiplies).
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ctx.set_paint(grad.with_interpolation_alpha_space(peniko::InterpolationAlphaSpace::Unpremultiplied));
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true
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}
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Paint::Pattern { pattern, xf } => crate::pattern::set_pattern_paint(ctx, pattern, *xf, f),
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}
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}
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/// Decode encoded image bytes into a premultiplied pixmap.
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pub fn decode_pixmap(bytes: &[u8]) -> Option<vello_cpu::Pixmap> {
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pixmap_of(image::load_from_memory(bytes).ok()?.to_rgba8())
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}
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/// [`decode_pixmap`] shrunk to `w`×`h` pixels when the image is larger (never enlarged).
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pub fn decode_pixmap_fit(bytes: &[u8], w: u16, h: u16) -> Option<vello_cpu::Pixmap> {
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let img = image::load_from_memory(bytes).ok()?;
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let img = if img.width() > w as u32 || img.height() > h as u32 {
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img.resize_exact(w as u32, h as u32, image::imageops::FilterType::Triangle)
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} else {
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img
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};
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pixmap_of(img.to_rgba8())
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}
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/// An RGBA image as a premultiplied pixmap.
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fn pixmap_of(img: image::RgbaImage) -> Option<vello_cpu::Pixmap> {
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let (w, h) = img.dimensions();
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if w == 0 || h == 0 || w > u16::MAX as u32 || h > u16::MAX as u32 {
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return None;
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}
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let data: Vec<vello_cpu::color::PremulRgba8> = img
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.pixels()
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.map(|p| {
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let a = p[3] as u16;
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let m = |c: u8| ((c as u16 * a + 127) / 255) as u8;
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vello_cpu::color::PremulRgba8 { r: m(p[0]), g: m(p[1]), b: m(p[2]), a: p[3] }
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})
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.collect();
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Some(vello_cpu::Pixmap::from_parts(data, w as u16, h as u16))
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}
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