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use std::collections::HashMap;
use pdf_writer::Ref;
use typst::diag::SourceResult;
use crate::{PdfChunk, WithGlobalRefs};
/// A PDF external graphics state.
#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
pub struct ExtGState {
// In the range 0-255, needs to be divided before being written into the graphics state!
pub stroke_opacity: u8,
// In the range 0-255, needs to be divided before being written into the graphics state!
pub fill_opacity: u8,
}
impl Default for ExtGState {
fn default() -> Self {
Self { stroke_opacity: 255, fill_opacity: 255 }
}
}
impl ExtGState {
pub fn uses_opacities(&self) -> bool {
self.stroke_opacity != 255 || self.fill_opacity != 255
}
}
/// Embed all used external graphics states into the PDF.
pub fn write_graphic_states(
context: &WithGlobalRefs,
) -> SourceResult<(PdfChunk, HashMap<ExtGState, Ref>)> {
let mut chunk = PdfChunk::new();
let mut out = HashMap::new();
context.resources.traverse(&mut |resources| {
for external_gs in resources.ext_gs.items() {
if out.contains_key(external_gs) {
continue;
}
let id = chunk.alloc();
out.insert(*external_gs, id);
chunk
.ext_graphics(id)
.non_stroking_alpha(external_gs.fill_opacity as f32 / 255.0)
.stroking_alpha(external_gs.stroke_opacity as f32 / 255.0);
}
Ok(())
})?;
Ok((chunk, out))
}
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