2023-08-05 12:03:26 +02:00

634 lines
20 KiB
Rust

use ecow::eco_format;
use pdf_writer::types::{
ActionType, AnnotationType, ColorSpaceOperand, LineCapStyle, LineJoinStyle,
};
use pdf_writer::writers::ColorSpace;
use pdf_writer::{Content, Filter, Finish, Name, Rect, Ref, Str};
use super::external_graphics_state::ExternalGraphicsState;
use super::{deflate, AbsExt, EmExt, PdfContext, RefExt, D65_GRAY, SRGB};
use crate::doc::{Destination, Frame, FrameItem, GroupItem, Meta, TextItem};
use crate::font::Font;
use crate::geom::{
self, Abs, Color, Em, Geometry, LineCap, LineJoin, Numeric, Paint, Point, Ratio,
Shape, Size, Stroke, Transform,
};
use crate::image::Image;
/// Construct page objects.
#[tracing::instrument(skip_all)]
pub fn construct_pages(ctx: &mut PdfContext, frames: &[Frame]) {
for frame in frames {
construct_page(ctx, frame);
}
}
/// Construct a page object.
#[tracing::instrument(skip_all)]
pub fn construct_page(ctx: &mut PdfContext, frame: &Frame) {
let page_ref = ctx.alloc.bump();
ctx.page_refs.push(page_ref);
ctx.page_heights.push(frame.height().to_f32());
let mut ctx = PageContext {
parent: ctx,
page_ref,
uses_opacities: false,
content: Content::new(),
state: State::default(),
saves: vec![],
bottom: 0.0,
links: vec![],
};
let size = frame.size();
// Make the coordinate system start at the top-left.
ctx.bottom = size.y.to_f32();
ctx.transform(Transform {
sx: Ratio::one(),
ky: Ratio::zero(),
kx: Ratio::zero(),
sy: Ratio::new(-1.0),
tx: Abs::zero(),
ty: size.y,
});
// Encode the page into the content stream.
write_frame(&mut ctx, frame);
let page = Page {
size,
content: ctx.content,
id: ctx.page_ref,
uses_opacities: ctx.uses_opacities,
links: ctx.links,
};
ctx.parent.pages.push(page);
}
/// Write the page tree.
#[tracing::instrument(skip_all)]
pub fn write_page_tree(ctx: &mut PdfContext) {
for page in std::mem::take(&mut ctx.pages).into_iter() {
write_page(ctx, page);
}
let mut pages = ctx.writer.pages(ctx.page_tree_ref);
pages
.count(ctx.page_refs.len() as i32)
.kids(ctx.page_refs.iter().copied());
let mut resources = pages.resources();
let mut spaces = resources.color_spaces();
spaces.insert(SRGB).start::<ColorSpace>().srgb();
spaces.insert(D65_GRAY).start::<ColorSpace>().d65_gray();
spaces.finish();
let mut fonts = resources.fonts();
for (font_ref, f) in ctx.font_map.pdf_indices(&ctx.font_refs) {
let name = eco_format!("F{}", f);
fonts.pair(Name(name.as_bytes()), font_ref);
}
fonts.finish();
let mut images = resources.x_objects();
for (image_ref, im) in ctx.image_map.pdf_indices(&ctx.image_refs) {
let name = eco_format!("Im{}", im);
images.pair(Name(name.as_bytes()), image_ref);
}
images.finish();
let mut ext_gs_states = resources.ext_g_states();
for (gs_ref, gs) in ctx.ext_gs_map.pdf_indices(&ctx.ext_gs_refs) {
let name = eco_format!("Gs{}", gs);
ext_gs_states.pair(Name(name.as_bytes()), gs_ref);
}
ext_gs_states.finish();
resources.finish();
pages.finish();
}
/// Write a page tree node.
#[tracing::instrument(skip_all)]
fn write_page(ctx: &mut PdfContext, page: Page) {
let content_id = ctx.alloc.bump();
let mut page_writer = ctx.writer.page(page.id);
page_writer.parent(ctx.page_tree_ref);
let w = page.size.x.to_f32();
let h = page.size.y.to_f32();
page_writer.media_box(Rect::new(0.0, 0.0, w, h));
page_writer.contents(content_id);
if page.uses_opacities {
page_writer
.group()
.transparency()
.isolated(false)
.knockout(false)
.color_space()
.srgb();
}
let mut annotations = page_writer.annotations();
for (dest, rect) in page.links {
let mut annotation = annotations.push();
annotation.subtype(AnnotationType::Link).rect(rect);
annotation.border(0.0, 0.0, 0.0, None);
let pos = match dest {
Destination::Url(uri) => {
annotation
.action()
.action_type(ActionType::Uri)
.uri(Str(uri.as_bytes()));
continue;
}
Destination::Position(pos) => pos,
Destination::Location(loc) => ctx.introspector.position(loc),
};
let index = pos.page.get() - 1;
let y = (pos.point.y - Abs::pt(10.0)).max(Abs::zero());
if let Some(&height) = ctx.page_heights.get(index) {
annotation
.action()
.action_type(ActionType::GoTo)
.destination()
.page(ctx.page_refs[index])
.xyz(pos.point.x.to_f32(), height - y.to_f32(), None);
}
}
annotations.finish();
page_writer.finish();
let data = page.content.finish();
let data = deflate(&data);
ctx.writer.stream(content_id, &data).filter(Filter::FlateDecode);
}
/// Data for an exported page.
pub struct Page {
/// The indirect object id of the page.
pub id: Ref,
/// The page's dimensions.
pub size: Size,
/// The page's content stream.
pub content: Content,
/// Whether the page uses opacities.
pub uses_opacities: bool,
/// Links in the PDF coordinate system.
pub links: Vec<(Destination, Rect)>,
}
/// An exporter for the contents of a single PDF page.
struct PageContext<'a, 'b> {
parent: &'a mut PdfContext<'b>,
page_ref: Ref,
content: Content,
state: State,
saves: Vec<State>,
bottom: f32,
uses_opacities: bool,
links: Vec<(Destination, Rect)>,
}
/// A simulated graphics state used to deduplicate graphics state changes and
/// keep track of the current transformation matrix for link annotations.
#[derive(Debug, Default, Clone)]
struct State {
transform: Transform,
font: Option<(Font, Abs)>,
fill: Option<Paint>,
fill_space: Option<Name<'static>>,
external_graphics_state: Option<ExternalGraphicsState>,
stroke: Option<Stroke>,
stroke_space: Option<Name<'static>>,
}
impl PageContext<'_, '_> {
fn save_state(&mut self) {
self.saves.push(self.state.clone());
self.content.save_state();
}
fn restore_state(&mut self) {
self.content.restore_state();
self.state = self.saves.pop().expect("missing state save");
}
fn set_external_graphics_state(&mut self, graphics_state: &ExternalGraphicsState) {
let current_state = self.state.external_graphics_state.as_ref();
if current_state != Some(graphics_state) {
self.parent.ext_gs_map.insert(*graphics_state);
let name = eco_format!("Gs{}", self.parent.ext_gs_map.map(*graphics_state));
self.content.set_parameters(Name(name.as_bytes()));
if graphics_state.uses_opacities() {
self.uses_opacities = true;
}
}
}
fn set_opacities(&mut self, stroke: Option<&Stroke>, fill: Option<&Paint>) {
let stroke_opacity = stroke
.map(|stroke| {
let Paint::Solid(color) = stroke.paint;
if let Color::Rgba(rgba_color) = color {
rgba_color.a
} else {
255
}
})
.unwrap_or(255);
let fill_opacity = fill
.map(|paint| {
let Paint::Solid(color) = paint;
if let Color::Rgba(rgba_color) = color {
rgba_color.a
} else {
255
}
})
.unwrap_or(255);
self.set_external_graphics_state(&ExternalGraphicsState {
stroke_opacity,
fill_opacity,
});
}
fn transform(&mut self, transform: Transform) {
let Transform { sx, ky, kx, sy, tx, ty } = transform;
self.state.transform = self.state.transform.pre_concat(transform);
self.content.transform([
sx.get() as _,
ky.get() as _,
kx.get() as _,
sy.get() as _,
tx.to_f32(),
ty.to_f32(),
]);
}
fn set_font(&mut self, font: &Font, size: Abs) {
if self.state.font.as_ref().map(|(f, s)| (f, *s)) != Some((font, size)) {
self.parent.font_map.insert(font.clone());
let name = eco_format!("F{}", self.parent.font_map.map(font.clone()));
self.content.set_font(Name(name.as_bytes()), size.to_f32());
self.state.font = Some((font.clone(), size));
}
}
fn set_fill(&mut self, fill: &Paint) {
if self.state.fill.as_ref() != Some(fill) {
let f = |c| c as f32 / 255.0;
let Paint::Solid(color) = fill;
match color {
Color::Luma(c) => {
self.set_fill_color_space(D65_GRAY);
self.content.set_fill_gray(f(c.0));
}
Color::Rgba(c) => {
self.set_fill_color_space(SRGB);
self.content.set_fill_color([f(c.r), f(c.g), f(c.b)]);
}
Color::Cmyk(c) => {
self.reset_fill_color_space();
self.content.set_fill_cmyk(f(c.c), f(c.m), f(c.y), f(c.k));
}
}
self.state.fill = Some(fill.clone());
}
}
fn set_fill_color_space(&mut self, space: Name<'static>) {
if self.state.fill_space != Some(space) {
self.content.set_fill_color_space(ColorSpaceOperand::Named(space));
self.state.fill_space = Some(space);
}
}
fn reset_fill_color_space(&mut self) {
self.state.fill_space = None;
}
fn set_stroke(&mut self, stroke: &Stroke) {
if self.state.stroke.as_ref() != Some(stroke) {
let Stroke {
paint,
thickness,
line_cap,
line_join,
dash_pattern,
miter_limit,
} = stroke;
let f = |c| c as f32 / 255.0;
let Paint::Solid(color) = paint;
match color {
Color::Luma(c) => {
self.set_stroke_color_space(D65_GRAY);
self.content.set_stroke_gray(f(c.0));
}
Color::Rgba(c) => {
self.set_stroke_color_space(SRGB);
self.content.set_stroke_color([f(c.r), f(c.g), f(c.b)]);
}
Color::Cmyk(c) => {
self.reset_stroke_color_space();
self.content.set_stroke_cmyk(f(c.c), f(c.m), f(c.y), f(c.k));
}
}
self.content.set_line_width(thickness.to_f32());
if self.state.stroke.as_ref().map(|s| &s.line_cap) != Some(line_cap) {
self.content.set_line_cap(line_cap.into());
}
if self.state.stroke.as_ref().map(|s| &s.line_join) != Some(line_join) {
self.content.set_line_join(line_join.into());
}
if self.state.stroke.as_ref().map(|s| &s.dash_pattern) != Some(dash_pattern) {
if let Some(pattern) = dash_pattern {
self.content.set_dash_pattern(
pattern.array.iter().map(|l| l.to_f32()),
pattern.phase.to_f32(),
);
} else {
self.content.set_dash_pattern([], 0.0);
}
}
if self.state.stroke.as_ref().map(|s| &s.miter_limit) != Some(miter_limit) {
self.content.set_miter_limit(miter_limit.0 as f32);
}
self.state.stroke = Some(stroke.clone());
}
}
fn set_stroke_color_space(&mut self, space: Name<'static>) {
if self.state.stroke_space != Some(space) {
self.content.set_stroke_color_space(ColorSpaceOperand::Named(space));
self.state.stroke_space = Some(space);
}
}
fn reset_stroke_color_space(&mut self) {
self.state.stroke_space = None;
}
}
/// Encode a frame into the content stream.
fn write_frame(ctx: &mut PageContext, frame: &Frame) {
for &(pos, ref item) in frame.items() {
let x = pos.x.to_f32();
let y = pos.y.to_f32();
match item {
FrameItem::Group(group) => write_group(ctx, pos, group),
FrameItem::Text(text) => write_text(ctx, x, y, text),
FrameItem::Shape(shape, _) => write_shape(ctx, x, y, shape),
FrameItem::Image(image, size, _) => write_image(ctx, x, y, image, *size),
FrameItem::Meta(meta, size) => match meta {
Meta::Link(dest) => write_link(ctx, pos, dest, *size),
Meta::Elem(_) => {}
Meta::Hide => {}
Meta::PageNumbering(_) => {}
},
}
}
}
/// Encode a group into the content stream.
fn write_group(ctx: &mut PageContext, pos: Point, group: &GroupItem) {
let translation = Transform::translate(pos.x, pos.y);
ctx.save_state();
ctx.transform(translation.pre_concat(group.transform));
if group.clips {
let size = group.frame.size();
let w = size.x.to_f32();
let h = size.y.to_f32();
ctx.content.move_to(0.0, 0.0);
ctx.content.line_to(w, 0.0);
ctx.content.line_to(w, h);
ctx.content.line_to(0.0, h);
ctx.content.clip_nonzero();
ctx.content.end_path();
}
write_frame(ctx, &group.frame);
ctx.restore_state();
}
/// Encode a text run into the content stream.
fn write_text(ctx: &mut PageContext, x: f32, y: f32, text: &TextItem) {
*ctx.parent.languages.entry(text.lang).or_insert(0) += text.glyphs.len();
let glyph_set = ctx.parent.glyph_sets.entry(text.font.clone()).or_default();
for g in &text.glyphs {
let segment = &text.text[g.range()];
glyph_set.entry(g.id).or_insert_with(|| segment.into());
}
ctx.set_fill(&text.fill);
ctx.set_font(&text.font, text.size);
ctx.set_opacities(None, Some(&text.fill));
ctx.content.begin_text();
// Positiosn the text.
ctx.content.set_text_matrix([1.0, 0.0, 0.0, -1.0, x, y]);
let mut positioned = ctx.content.show_positioned();
let mut items = positioned.items();
let mut adjustment = Em::zero();
let mut encoded = vec![];
// Write the glyphs with kerning adjustments.
for glyph in &text.glyphs {
adjustment += glyph.x_offset;
if !adjustment.is_zero() {
if !encoded.is_empty() {
items.show(Str(&encoded));
encoded.clear();
}
items.adjust(-adjustment.to_font_units());
adjustment = Em::zero();
}
encoded.push((glyph.id >> 8) as u8);
encoded.push((glyph.id & 0xff) as u8);
if let Some(advance) = text.font.advance(glyph.id) {
adjustment += glyph.x_advance - advance;
}
adjustment -= glyph.x_offset;
}
if !encoded.is_empty() {
items.show(Str(&encoded));
}
items.finish();
positioned.finish();
ctx.content.end_text();
}
/// Encode a geometrical shape into the content stream.
fn write_shape(ctx: &mut PageContext, x: f32, y: f32, shape: &Shape) {
let stroke = shape.stroke.as_ref().and_then(|stroke| {
if stroke.thickness.to_f32() > 0.0 {
Some(stroke)
} else {
None
}
});
if shape.fill.is_none() && stroke.is_none() {
return;
}
if let Some(fill) = &shape.fill {
ctx.set_fill(fill);
}
if let Some(stroke) = stroke {
ctx.set_stroke(stroke);
}
ctx.set_opacities(stroke, shape.fill.as_ref());
match shape.geometry {
Geometry::Line(target) => {
let dx = target.x.to_f32();
let dy = target.y.to_f32();
ctx.content.move_to(x, y);
ctx.content.line_to(x + dx, y + dy);
}
Geometry::Rect(size) => {
let w = size.x.to_f32();
let h = size.y.to_f32();
if w > 0.0 && h > 0.0 {
ctx.content.rect(x, y, w, h);
}
}
Geometry::Path(ref path) => {
write_path(ctx, x, y, path);
}
}
match (&shape.fill, stroke) {
(None, None) => unreachable!(),
(Some(_), None) => ctx.content.fill_nonzero(),
(None, Some(_)) => ctx.content.stroke(),
(Some(_), Some(_)) => ctx.content.fill_nonzero_and_stroke(),
};
}
/// Encode a bezier path into the content stream.
fn write_path(ctx: &mut PageContext, x: f32, y: f32, path: &geom::Path) {
for elem in &path.0 {
match elem {
geom::PathItem::MoveTo(p) => {
ctx.content.move_to(x + p.x.to_f32(), y + p.y.to_f32())
}
geom::PathItem::LineTo(p) => {
ctx.content.line_to(x + p.x.to_f32(), y + p.y.to_f32())
}
geom::PathItem::CubicTo(p1, p2, p3) => ctx.content.cubic_to(
x + p1.x.to_f32(),
y + p1.y.to_f32(),
x + p2.x.to_f32(),
y + p2.y.to_f32(),
x + p3.x.to_f32(),
y + p3.y.to_f32(),
),
geom::PathItem::ClosePath => ctx.content.close_path(),
};
}
}
/// Encode a vector or raster image into the content stream.
fn write_image(ctx: &mut PageContext, x: f32, y: f32, image: &Image, size: Size) {
ctx.parent.image_map.insert(image.clone());
let name = eco_format!("Im{}", ctx.parent.image_map.map(image.clone()));
let w = size.x.to_f32();
let h = size.y.to_f32();
ctx.content.save_state();
ctx.content.transform([w, 0.0, 0.0, -h, x, y + h]);
if let Some(alt) = image.alt() {
let mut image_span =
ctx.content.begin_marked_content_with_properties(Name(b"Span"));
let mut image_alt = image_span.properties();
image_alt.pair(Name(b"Alt"), pdf_writer::Str(alt.as_bytes()));
image_alt.finish();
image_span.finish();
ctx.content.x_object(Name(name.as_bytes()));
ctx.content.end_marked_content();
} else {
ctx.content.x_object(Name(name.as_bytes()));
}
ctx.content.restore_state();
}
/// Save a link for later writing in the annotations dictionary.
fn write_link(ctx: &mut PageContext, pos: Point, dest: &Destination, size: Size) {
let mut min_x = Abs::inf();
let mut min_y = Abs::inf();
let mut max_x = -Abs::inf();
let mut max_y = -Abs::inf();
// Compute the bounding box of the transformed link.
for point in [
pos,
pos + Point::with_x(size.x),
pos + Point::with_y(size.y),
pos + size.to_point(),
] {
let t = point.transform(ctx.state.transform);
min_x.set_min(t.x);
min_y.set_min(t.y);
max_x.set_max(t.x);
max_y.set_max(t.y);
}
let x1 = min_x.to_f32();
let x2 = max_x.to_f32();
let y1 = max_y.to_f32();
let y2 = min_y.to_f32();
let rect = Rect::new(x1, y1, x2, y2);
ctx.links.push((dest.clone(), rect));
}
impl From<&LineCap> for LineCapStyle {
fn from(line_cap: &LineCap) -> Self {
match line_cap {
LineCap::Butt => LineCapStyle::ButtCap,
LineCap::Round => LineCapStyle::RoundCap,
LineCap::Square => LineCapStyle::ProjectingSquareCap,
}
}
}
impl From<&LineJoin> for LineJoinStyle {
fn from(line_join: &LineJoin) -> Self {
match line_join {
LineJoin::Miter => LineJoinStyle::MiterJoin,
LineJoin::Round => LineJoinStyle::RoundJoin,
LineJoin::Bevel => LineJoinStyle::BevelJoin,
}
}
}