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Cargoify servo
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1761 changed files with 8423 additions and 2294 deletions
327
components/layout/text.rs
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327
components/layout/text.rs
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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//! Text layout.
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#![deny(unsafe_block)]
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use flow::Flow;
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use fragment::{Fragment, ScannedTextFragment, ScannedTextFragmentInfo, UnscannedTextFragment};
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use gfx::font::{FontMetrics, FontStyle, RunMetrics};
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use gfx::font_context::FontContext;
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use gfx::text::glyph::CharIndex;
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use gfx::text::text_run::TextRun;
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use gfx::text::util::{CompressWhitespaceNewline, transform_text, CompressNone};
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use servo_util::geometry::Au;
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use servo_util::logical_geometry::{LogicalSize, WritingMode};
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use servo_util::range::Range;
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use style::ComputedValues;
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use style::computed_values::{font_family, line_height, text_orientation, white_space};
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use sync::Arc;
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struct NewLinePositions {
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new_line_pos: Vec<CharIndex>,
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}
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// A helper function.
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fn can_coalesce_text_nodes(fragments: &[Fragment], left_i: uint, right_i: uint) -> bool {
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assert!(left_i != right_i);
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fragments[left_i].can_merge_with_fragment(&fragments[right_i])
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}
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/// A stack-allocated object for scanning an inline flow into `TextRun`-containing `TextFragment`s.
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pub struct TextRunScanner {
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pub clump: Range<CharIndex>,
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}
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impl TextRunScanner {
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pub fn new() -> TextRunScanner {
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TextRunScanner {
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clump: Range::empty(),
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}
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}
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pub fn scan_for_runs(&mut self, font_context: &mut FontContext, flow: &mut Flow) {
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{
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let inline = flow.as_immutable_inline();
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debug!("TextRunScanner: scanning {:u} fragments for text runs...", inline.fragments.len());
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}
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let fragments = &mut flow.as_inline().fragments;
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let mut last_whitespace = true;
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let mut new_fragments = Vec::new();
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for fragment_i in range(0, fragments.fragments.len()) {
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debug!("TextRunScanner: considering fragment: {:u}", fragment_i);
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if fragment_i > 0 && !can_coalesce_text_nodes(fragments.fragments.as_slice(), fragment_i - 1, fragment_i) {
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last_whitespace = self.flush_clump_to_list(font_context,
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fragments.fragments.as_slice(),
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&mut new_fragments,
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last_whitespace);
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}
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self.clump.extend_by(CharIndex(1));
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}
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// Handle remaining clumps.
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if self.clump.length() > CharIndex(0) {
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drop(self.flush_clump_to_list(font_context,
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fragments.fragments.as_slice(),
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&mut new_fragments,
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last_whitespace))
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}
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debug!("TextRunScanner: swapping out fragments.");
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fragments.fragments = new_fragments;
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}
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/// A "clump" is a range of inline flow leaves that can be merged together into a single
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/// fragment. Adjacent text with the same style can be merged, and nothing else can.
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///
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/// The flow keeps track of the fragments contained by all non-leaf DOM nodes. This is necessary
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/// for correct painting order. Since we compress several leaf fragments here, the mapping must
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/// be adjusted.
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///
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/// FIXME(#2267, pcwalton): Stop cloning fragments. Instead we will need to replace each
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/// `in_fragment` with some smaller stub.
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fn flush_clump_to_list(&mut self,
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font_context: &mut FontContext,
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in_fragments: &[Fragment],
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out_fragments: &mut Vec<Fragment>,
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last_whitespace: bool)
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-> bool {
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assert!(self.clump.length() > CharIndex(0));
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debug!("TextRunScanner: flushing fragments in range={}", self.clump);
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let is_singleton = self.clump.length() == CharIndex(1);
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let is_text_clump = match in_fragments[self.clump.begin().to_uint()].specific {
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UnscannedTextFragment(_) => true,
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_ => false,
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};
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let mut new_whitespace = last_whitespace;
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match (is_singleton, is_text_clump) {
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(false, false) => {
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fail!("WAT: can't coalesce non-text nodes in flush_clump_to_list()!")
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}
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(true, false) => {
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// FIXME(pcwalton): Stop cloning fragments, as above.
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debug!("TextRunScanner: pushing single non-text fragment in range: {}", self.clump);
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let new_fragment = in_fragments[self.clump.begin().to_uint()].clone();
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out_fragments.push(new_fragment)
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},
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(true, true) => {
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let old_fragment = &in_fragments[self.clump.begin().to_uint()];
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let text = match old_fragment.specific {
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UnscannedTextFragment(ref text_fragment_info) => &text_fragment_info.text,
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_ => fail!("Expected an unscanned text fragment!"),
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};
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let font_style = old_fragment.font_style();
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let compression = match old_fragment.white_space() {
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white_space::normal => CompressWhitespaceNewline,
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white_space::pre => CompressNone,
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};
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let mut new_line_pos = vec![];
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let (transformed_text, whitespace) = transform_text(text.as_slice(),
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compression,
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last_whitespace,
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&mut new_line_pos);
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new_whitespace = whitespace;
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if transformed_text.len() > 0 {
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// TODO(#177): Text run creation must account for the renderability of text by
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// font group fonts. This is probably achieved by creating the font group above
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// and then letting `FontGroup` decide which `Font` to stick into the text run.
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let fontgroup = font_context.get_layout_font_group_for_style(&font_style);
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let run = box fontgroup.create_textrun(
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transformed_text.clone());
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debug!("TextRunScanner: pushing single text fragment in range: {} ({})",
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self.clump,
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*text);
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let range = Range::new(CharIndex(0), run.char_len());
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let new_metrics = run.metrics_for_range(&range);
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let bounding_box_size = bounding_box_for_run_metrics(
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&new_metrics, old_fragment.style.writing_mode);
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let new_text_fragment_info = ScannedTextFragmentInfo::new(Arc::new(run), range);
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let mut new_fragment = old_fragment.transform(
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bounding_box_size, ScannedTextFragment(new_text_fragment_info));
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new_fragment.new_line_pos = new_line_pos;
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out_fragments.push(new_fragment)
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}
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},
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(false, true) => {
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// TODO(#177): Text run creation must account for the renderability of text by
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// font group fonts. This is probably achieved by creating the font group above
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// and then letting `FontGroup` decide which `Font` to stick into the text run.
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let in_fragment = &in_fragments[self.clump.begin().to_uint()];
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let font_style = in_fragment.font_style();
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let fontgroup = font_context.get_layout_font_group_for_style(&font_style);
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let compression = match in_fragment.white_space() {
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white_space::normal => CompressWhitespaceNewline,
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white_space::pre => CompressNone,
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};
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let mut new_line_positions: Vec<NewLinePositions> = vec![];
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// First, transform/compress text of all the nodes.
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let mut last_whitespace_in_clump = new_whitespace;
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let transformed_strs: Vec<String> = Vec::from_fn(self.clump.length().to_uint(), |i| {
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let idx = CharIndex(i as int) + self.clump.begin();
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let in_fragment = match in_fragments[idx.to_uint()].specific {
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UnscannedTextFragment(ref text_fragment_info) => &text_fragment_info.text,
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_ => fail!("Expected an unscanned text fragment!"),
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};
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let mut new_line_pos = vec![];
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let (new_str, new_whitespace) = transform_text(in_fragment.as_slice(),
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compression,
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last_whitespace_in_clump,
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&mut new_line_pos);
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new_line_positions.push(NewLinePositions { new_line_pos: new_line_pos });
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last_whitespace_in_clump = new_whitespace;
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new_str
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});
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new_whitespace = last_whitespace_in_clump;
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// Next, concatenate all of the transformed strings together, saving the new
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// character indices.
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let mut run_str = String::new();
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let mut new_ranges: Vec<Range<CharIndex>> = vec![];
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let mut char_total = CharIndex(0);
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for i in range(0, transformed_strs.len() as int) {
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let added_chars = CharIndex(transformed_strs[i as uint].as_slice().char_len() as int);
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new_ranges.push(Range::new(char_total, added_chars));
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run_str.push_str(transformed_strs[i as uint].as_slice());
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char_total = char_total + added_chars;
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}
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// Now create the run.
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// TextRuns contain a cycle which is usually resolved by the teardown
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// sequence. If no clump takes ownership, however, it will leak.
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let clump = self.clump;
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let run = if clump.length() != CharIndex(0) && run_str.len() > 0 {
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Some(Arc::new(box TextRun::new(
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&mut *fontgroup.fonts[0].borrow_mut(),
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run_str.to_string())))
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} else {
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None
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};
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// Make new fragments with the run and adjusted text indices.
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debug!("TextRunScanner: pushing fragment(s) in range: {}", self.clump);
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for i in clump.each_index() {
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let logical_offset = i - self.clump.begin();
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let range = new_ranges[logical_offset.to_uint()];
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if range.length() == CharIndex(0) {
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debug!("Elided an `UnscannedTextFragment` because it was zero-length after \
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compression; {}", in_fragments[i.to_uint()]);
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continue
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}
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let new_text_fragment_info = ScannedTextFragmentInfo::new(run.get_ref().clone(), range);
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let old_fragment = &in_fragments[i.to_uint()];
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let new_metrics = new_text_fragment_info.run.metrics_for_range(&range);
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let bounding_box_size = bounding_box_for_run_metrics(
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&new_metrics, old_fragment.style.writing_mode);
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let mut new_fragment = old_fragment.transform(
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bounding_box_size, ScannedTextFragment(new_text_fragment_info));
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new_fragment.new_line_pos = new_line_positions[logical_offset.to_uint()].new_line_pos.clone();
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out_fragments.push(new_fragment)
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}
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}
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} // End of match.
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let end = self.clump.end(); // FIXME: borrow checker workaround
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self.clump.reset(end, CharIndex(0));
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new_whitespace
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} // End of `flush_clump_to_list`.
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}
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#[inline]
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fn bounding_box_for_run_metrics(metrics: &RunMetrics, writing_mode: WritingMode)
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-> LogicalSize<Au> {
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// This does nothing, but it will fail to build
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// when more values are added to the `text-orientation` CSS property.
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// This will be a reminder to update the code below.
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let dummy: Option<text_orientation::T> = None;
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match dummy {
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Some(text_orientation::sideways_right) |
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Some(text_orientation::sideways_left) |
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Some(text_orientation::sideways) |
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None => {}
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}
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// In vertical sideways or horizontal upgright text,
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// the "width" of text metrics is always inline
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// This will need to be updated when other text orientations are supported.
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LogicalSize::new(
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writing_mode,
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metrics.bounding_box.size.width,
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metrics.bounding_box.size.height)
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}
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/// Returns the metrics of the font represented by the given `FontStyle`, respectively.
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///
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/// `#[inline]` because often the caller only needs a few fields from the font metrics.
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#[inline]
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pub fn font_metrics_for_style(font_context: &mut FontContext, font_style: &FontStyle)
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-> FontMetrics {
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let fontgroup = font_context.get_layout_font_group_for_style(font_style);
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fontgroup.fonts[0].borrow().metrics.clone()
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}
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/// Converts a computed style to a font style used for rendering.
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///
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/// FIXME(pcwalton): This should not be necessary; just make the font part of the style sharable
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/// with the display list somehow. (Perhaps we should use an ARC.)
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pub fn computed_style_to_font_style(style: &ComputedValues) -> FontStyle {
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debug!("(font style) start");
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// FIXME: Too much allocation here.
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let mut font_families = style.get_font().font_family.iter().map(|family| {
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match *family {
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font_family::FamilyName(ref name) => (*name).clone(),
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}
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});
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debug!("(font style) font families: `{:?}`", font_families);
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let font_size = style.get_font().font_size.to_f64().unwrap() / 60.0;
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debug!("(font style) font size: `{:f}px`", font_size);
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FontStyle {
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pt_size: font_size,
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weight: style.get_font().font_weight,
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style: style.get_font().font_style,
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families: font_families.collect(),
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}
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}
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/// Returns the line block-size needed by the given computed style and font size.
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pub fn line_height_from_style(style: &ComputedValues, metrics: &FontMetrics) -> Au {
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let font_size = style.get_font().font_size;
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let from_inline = match style.get_inheritedbox().line_height {
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line_height::Normal => metrics.line_gap,
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line_height::Number(l) => font_size.scale_by(l),
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line_height::Length(l) => l
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};
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let minimum = style.get_inheritedbox()._servo_minimum_line_height;
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Au::max(from_inline, minimum)
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}
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