ltk/print/
gtk.rs

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// SPDX-License-Identifier: LGPL-2.1-only
// Copyright (C) 2026 Liberux Labs, S. L. <info@liberux.net>

//! [`PrintOptions`] as the print portal carries them: GTK's print settings and page setup.

use std::collections::HashMap;

use super::{ Margins, Orientation, Paper, PrintOptions, Sides, PAPERS };

const MM_PER_POINT: f64 = 25.4 / 72.0;

/// A value of the page setup: names are strings and lengths are numbers, in millimetres.
#[ derive( Clone, Debug, PartialEq ) ]
pub enum PageValue
{
	Text( String ),
	Number( f64 ),
}

/// GTK's print settings for `options`, on `printer` when there is one.
pub fn settings( options: &PrintOptions, printer: Option<&str> ) -> Vec<( &'static str, String )>
{
	let mut out = vec![
		( "n-copies",    options.copies.to_string() ),
		( "orientation", orientation( options.orientation ).to_string() ),
		( "scale",       format!( "{}", ( options.scale * 100.0 ).round() ) ),
		( "use-color",   options.color.to_string() ),
		( "duplex",      match options.sides { Sides::One => "simplex", Sides::LongEdge => "horizontal", Sides::ShortEdge => "vertical" }.to_string() ),
		( "print-pages", if options.pages.is_empty() { "all" } else { "ranges" }.to_string() ),
	];
	if !options.pages.is_empty()
	{
		let ranges = options.pages.iter()
			.map( |&( start, end )| if end == u32::MAX { format!( "{}-", start - 1 ) } else if start == end { ( start - 1 ).to_string() } else { format!( "{}-{}", start - 1, end - 1 ) } )
			.collect::<Vec<_>>()
			.join( "," );
		out.push( ( "page-ranges", ranges ) );
	}
	if let Some( printer ) = printer { out.push( ( "printer", printer.to_string() ) ); }
	out
}

/// GTK's page setup for `options`.
pub fn page_setup( options: &PrintOptions ) -> Vec<( &'static str, PageValue )>
{
	let paper  = options.paper;
	let margin = options.margins.points() as f64 * MM_PER_POINT;
	let mm     = |points: f32| PageValue::Number( points as f64 * MM_PER_POINT );
	vec![
		( "PPDName",      PageValue::Text( paper.name.to_string() ) ),
		( "Name",         PageValue::Text( gtk_name( &paper ) ) ),
		( "DisplayName",  PageValue::Text( paper.name.to_string() ) ),
		( "Width",        mm( paper.width ) ),
		( "Height",       mm( paper.height ) ),
		( "MarginTop",    PageValue::Number( margin ) ),
		( "MarginBottom", PageValue::Number( margin ) ),
		( "MarginLeft",   PageValue::Number( margin ) ),
		( "MarginRight",  PageValue::Number( margin ) ),
		( "Orientation",  PageValue::Text( orientation( options.orientation ).to_string() ) ),
	]
}

/// The options GTK's settings and page setup describe, from `base` for what they leave out.
pub fn options( settings: &HashMap<String, String>, page: &HashMap<String, PageValue>, base: &PrintOptions ) -> PrintOptions
{
	let mut out = base.clone();
	let text    = |key: &str| settings.get( key ).map( |v| v.trim() );
	if let Some( copies ) = text( "n-copies" ).and_then( |v| v.parse::<u32>().ok() ) { out.copies = copies.clamp( 1, PrintOptions::MAX_COPIES ); }
	if let Some( scale ) = text( "scale" ).and_then( |v| v.parse::<f32>().ok() ).filter( |s| s.is_finite() )
	{
		out.scale = ( scale / 100.0 ).clamp( PrintOptions::MIN_SCALE, PrintOptions::MAX_SCALE );
	}
	if let Some( color ) = text( "use-color" ) { out.color = color != "false"; }
	match text( "duplex" )
	{
		Some( "horizontal" ) => out.sides = Sides::LongEdge,
		Some( "vertical" )   => out.sides = Sides::ShortEdge,
		Some( "simplex" )    => out.sides = Sides::One,
		_                    => {}
	}
	match text( "print-pages" )
	{
		Some( "ranges" ) => if let Some( ranges ) = text( "page-ranges" ).and_then( ranges ) { out.pages = ranges; },
		Some( _ )        => out.pages.clear(),
		None             => {}
	}
	let page_text = |key: &str| match page.get( key ) { Some( PageValue::Text( t ) ) => Some( t.as_str() ), _ => None };
	let page_mm   = |key: &str| match page.get( key ) { Some( PageValue::Number( n ) ) if n.is_finite() => Some( *n ), _ => None };
	if let Some( orientation ) = page_text( "Orientation" ).or( text( "orientation" ) )
	{
		out.orientation = if orientation.contains( "landscape" ) { Orientation::Landscape } else { Orientation::Portrait };
	}
	let named = page_text( "PPDName" ).and_then( |n| PAPERS.iter().find( |p| p.name.eq_ignore_ascii_case( n ) ) )
		.or_else( || page_text( "Name" ).and_then( |n| PAPERS.iter().find( |p| gtk_name( p ) == n || p.media == n ) ) );
	let sized = || match ( page_mm( "Width" ), page_mm( "Height" ) )
	{
		( Some( w ), Some( h ) ) => PAPERS.iter().find( |p| ( p.width as f64 * MM_PER_POINT - w ).abs() < 1.5 && ( p.height as f64 * MM_PER_POINT - h ).abs() < 1.5 ),
		_                        => None,
	};
	if let Some( paper ) = named.or_else( sized ) { out.paper = *paper; }
	if let Some( top ) = page_mm( "MarginTop" )
	{
		let points = top / MM_PER_POINT;
		out.margins = *Margins::ALL.iter()
			.min_by( |a, b| ( a.points() as f64 - points ).abs().total_cmp( &( b.points() as f64 - points ).abs() ) )
			.unwrap_or( &Margins::Default );
	}
	out
}

/// GTK's `page-ranges`, from 0, as the inclusive ranges from 1 that [`PrintOptions::pages`] holds.
fn ranges( text: &str ) -> Option<Vec<( u32, u32 )>>
{
	let shifted = text.split( ',' )
		.map( str::trim )
		.filter( |part| !part.is_empty() )
		.map( |part|
		{
			let one = |s: &str| s.trim().parse::<u32>().ok().map( |n| ( n + 1 ).to_string() );
			match part.split_once( '-' )
			{
				Some( ( start, end ) ) if end.trim().is_empty() => Some( format!( "{}-", one( start )? ) ),
				Some( ( start, end ) )                          => Some( format!( "{}-{}", one( start )?, one( end )? ) ),
				None                                            => one( part ),
			}
		} )
		.collect::<Option<Vec<_>>>()?
		.join( "," );
	super::parse_pages( &shifted )
}

fn orientation( orientation: Orientation ) -> &'static str
{
	match orientation
	{
		Orientation::Portrait  => "portrait",
		Orientation::Landscape => "landscape",
	}
}

/// GTK's name for the paper: the PWG name without its size.
fn gtk_name( paper: &Paper ) -> String
{
	paper.media.rsplit_once( '_' ).map_or( paper.media, |( name, _ )| name ).to_string()
}

#[ cfg( test ) ]
mod tests
{
	use super::*;

	fn round_trip( options: &PrintOptions ) -> PrintOptions
	{
		let settings: HashMap<String, String>  = settings( options, Some( "office" ) ).into_iter().map( |( k, v )| ( k.to_string(), v ) ).collect();
		let page: HashMap<String, PageValue>   = page_setup( options ).into_iter().map( |( k, v )| ( k.to_string(), v ) ).collect();
		super::options( &settings, &page, &PrintOptions::default() )
	}

	#[ test ]
	fn options_survive_the_portal()
	{
		let options = PrintOptions
		{
			copies:      3,
			pages:       vec![ ( 1, 3 ), ( 5, 5 ), ( 8, u32::MAX ) ],
			paper:       PAPERS[ 1 ],
			orientation: Orientation::Landscape,
			margins:     Margins::Wide,
			scale:       0.8,
			color:       false,
			sides:       Sides::ShortEdge,
			backgrounds: false,
		};
		assert_eq!( round_trip( &options ), options );
	}

	#[ test ]
	fn page_ranges_count_from_zero()
	{
		let settings = settings( &PrintOptions { pages: vec![ ( 1, 3 ), ( 5, 5 ) ], ..PrintOptions::default() }, None );
		assert!( settings.contains( &( "page-ranges", "0-2,4".to_string() ) ) );
	}

	#[ test ]
	fn gtk_names_a4_without_its_size()
	{
		assert_eq!( gtk_name( &PAPERS[ 0 ] ), "iso_a4" );
	}
}