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Separate alignment from line breaking
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,132 @@ | ||
| // Copyright 2024 the Parley Authors | ||
| // SPDX-License-Identifier: Apache-2.0 OR MIT | ||
|
|
||
| use super::{Alignment, BreakReason, LayoutData}; | ||
| use crate::style::Brush; | ||
|
|
||
| pub(crate) fn align<B: Brush>( | ||
| layout: &mut LayoutData<B>, | ||
| alignment_width: Option<f32>, | ||
| alignment: Alignment, | ||
| ) { | ||
| let alignment_width = alignment_width.unwrap_or_else(|| { | ||
| let max_line_length = layout | ||
| .lines | ||
| .iter() | ||
| .map(|line| line.metrics.advance) | ||
| .max_by(f32::total_cmp) | ||
| .unwrap_or(0.0); | ||
| max_line_length.min(max_line_length) | ||
| }); | ||
|
|
||
| // Apply alignment to line items | ||
| for line in &mut layout.lines { | ||
| // TODO: remove this field | ||
| line.alignment = alignment; | ||
|
|
||
| // Compute free space. | ||
| let free_space = alignment_width - line.metrics.advance + line.metrics.trailing_whitespace; | ||
|
|
||
| // Alignment only applies if free_space > 0 | ||
| if free_space <= 0. { | ||
| continue; | ||
| } | ||
|
|
||
| match alignment { | ||
| Alignment::Start => { | ||
| // Do nothing | ||
| } | ||
| Alignment::End => { | ||
| line.metrics.offset = free_space; | ||
| } | ||
| Alignment::Middle => { | ||
| line.metrics.offset = free_space * 0.5; | ||
| } | ||
| Alignment::Justified => { | ||
| if line.break_reason == BreakReason::None || line.num_spaces == 0 { | ||
| continue; | ||
| } | ||
|
|
||
| let adjustment = free_space / line.num_spaces as f32; | ||
| let mut applied = 0; | ||
| for line_item in layout.line_items[line.item_range.clone()] | ||
| .iter() | ||
| .filter(|item| item.is_text_run()) | ||
| { | ||
| // Iterate over clusters in the run | ||
| // - Iterate forwards for even bidi levels (which represent RTL runs) | ||
| // - Iterate backwards for odd bidi levels (which represent RTL runs) | ||
| let clusters = &mut layout.clusters[line_item.cluster_range.clone()]; | ||
| let bidi_level_is_odd = line_item.bidi_level & 1 != 0; | ||
| if bidi_level_is_odd { | ||
| for cluster in clusters.iter_mut().rev() { | ||
| if applied == line.num_spaces { | ||
| break; | ||
| } | ||
| if cluster.info.whitespace().is_space_or_nbsp() { | ||
| cluster.advance += adjustment; | ||
| applied += 1; | ||
| } | ||
| } | ||
| } else { | ||
| for cluster in clusters.iter_mut() { | ||
| if applied == line.num_spaces { | ||
| break; | ||
| } | ||
| if cluster.info.whitespace().is_space_or_nbsp() { | ||
| cluster.advance += adjustment; | ||
| applied += 1; | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /// Removes previous justification applied to clusters. | ||
| /// This is part of resetting state in preparation for re-linebreaking the same layout. | ||
| pub(crate) fn unjustify<B: Brush>(layout: &mut LayoutData<B>) { | ||
| for line in &layout.lines { | ||
| if line.alignment == Alignment::Justified | ||
| && line.max_advance.is_finite() | ||
| && line.max_advance < f32::MAX | ||
| { | ||
| let extra = line.max_advance - line.metrics.advance + line.metrics.trailing_whitespace; | ||
| if line.break_reason != BreakReason::None && line.num_spaces != 0 { | ||
| let adjustment = extra / line.num_spaces as f32; | ||
| let mut applied = 0; | ||
| for line_run in layout.line_items[line.item_range.clone()] | ||
| .iter() | ||
| .filter(|item| item.is_text_run()) | ||
| { | ||
| if line_run.bidi_level & 1 != 0 { | ||
| for cluster in layout.clusters[line_run.cluster_range.clone()] | ||
| .iter_mut() | ||
| .rev() | ||
| { | ||
| if applied == line.num_spaces { | ||
| break; | ||
| } | ||
| if cluster.info.whitespace().is_space_or_nbsp() { | ||
| cluster.advance -= adjustment; | ||
| applied += 1; | ||
| } | ||
| } | ||
| } else { | ||
| for cluster in layout.clusters[line_run.cluster_range.clone()].iter_mut() { | ||
| if applied == line.num_spaces { | ||
| break; | ||
| } | ||
| if cluster.info.whitespace().is_space_or_nbsp() { | ||
| cluster.advance -= adjustment; | ||
| applied += 1; | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } |
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