Auto merge of #2122 - jrmuizel:font-data, r=glennw

Support serializing NativeFontHandle on macOS

This fixes #2051

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Author: bors-servo

Cargo.lock

@@ -247,7 +247,7 @@ fn new_ct_font_with_variations(cg_font: &CGFont, size: f64, variations: &[FontVa
 
             val = val.max(min_val).min(max_val);
             if val != def_val {
-                vals.push((name, CFNumber::from_f64(val)));
+                vals.push((name, CFNumber::from(val)));
             }
         }
         if vals.is_empty() {

webrender/src/platform/macos/font.rs

@@ -27,6 +27,10 @@ osmesa-src = { git = "https://github.com/servo/osmesa-src", optional = true }
 webrender = {path = "../webrender", features=["debugger","profiler"]}
 serde = {version = "1.0", features = ["derive"] }
 
+[target.'cfg(target_os = "macos")'.dependencies]
+core-graphics = "0.12.4"
+core-foundation = "0.4"
+
 [features]
 headless = [ "osmesa-sys", "osmesa-src" ]
 logging = [ "env_logger" ]

wrench/Cargo.toml

@@ -0,0 +1,124 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use byteorder::{BigEndian, ByteOrder, ReadBytesExt, WriteBytesExt};
+use core_foundation::data::CFData;
+use core_graphics::font::CGFont;
+use std;
+use std::io::Cursor;
+use std::io::Read;
+use std::io::Write;
+
+
+fn calc_table_checksum<D: Read>(mut data: D) -> u32 {
+    let mut sum: u32 = 0;
+
+    while let Ok(x) = data.read_u32::<BigEndian>() {
+        sum = sum.wrapping_add(x);
+    }
+    // read the remaining bytes
+    let mut buf: [u8; 4] = [0; 4];
+    data.read(&mut buf).unwrap();
+    // if there was nothing left in buf we'll just read a 0
+    // which won't affect the checksum
+    sum = sum.wrapping_add(BigEndian::read_u32(&buf));
+    sum
+}
+
+fn max_pow_2_less_than(a: u16) -> u16 {
+    let x = 1;
+    let mut shift = 0;
+    while (x << (shift + 1)) < a {
+        shift += 1;
+    }
+    shift
+}
+
+struct TableRecord {
+    tag: u32,
+    checksum: u32,
+    offset: u32,
+    length: u32,
+    data: CFData
+}
+
+const CFF_TAG: u32 = 0x43464620; // 'CFF '
+const HEAD_TAG: u32 = 0x68656164; // 'head'
+const OTTO_TAG: u32 = 0x4f54544f; // 'OTTO'
+const TRUE_TAG: u32 = 0x00010000;
+
+pub fn font_to_data(font: CGFont) -> Result<Vec<u8>, std::io::Error> {
+    // We'll reconstruct a TTF font from the tables we can get from the CGFont
+    let mut cff = false;
+    let tags = font.copy_table_tags();
+    let count = tags.len() as u16;
+
+    let mut records = Vec::new();
+    let mut offset: u32 = 0;
+    offset += 4 * 3;
+    offset += 4 * 4 * (count as u32);
+    for tag in tags.iter() {
+        if tag == CFF_TAG {
+            cff = true;
+        }
+        let data = font.copy_table_for_tag(tag).unwrap();
+        let length = data.len() as u32;
+        let checksum;
+        if tag == HEAD_TAG {
+            // we need to skip the checksum field
+            checksum = calc_table_checksum(&data.bytes()[0..2])
+                .wrapping_add(calc_table_checksum(&data.bytes()[3..]))
+        } else {
+            checksum = calc_table_checksum(data.bytes());
+        }
+        records.push(TableRecord { tag, offset, data, length, checksum } );
+        offset += length;
+        // 32 bit align the tables
+        offset = (offset + 3) & !3;
+    }
+
+    let mut buf = Vec::new();
+    if cff {
+        buf.write_u32::<BigEndian>(OTTO_TAG)?;
+    } else {
+        buf.write_u32::<BigEndian>(TRUE_TAG)?;
+    }
+
+    buf.write_u16::<BigEndian>(count)?;
+    buf.write_u16::<BigEndian>((1 << max_pow_2_less_than(count)) * 16)?;
+    buf.write_u16::<BigEndian>(max_pow_2_less_than(count))?;
+    buf.write_u16::<BigEndian>(count * 16 - ((1 << max_pow_2_less_than(count)) * 16))?;
+
+    // write table record entries
+    for r in &records {
+        buf.write_u32::<BigEndian>(r.tag)?;
+        buf.write_u32::<BigEndian>(r.checksum)?;
+        buf.write_u32::<BigEndian>(r.offset)?;
+        buf.write_u32::<BigEndian>(r.length)?;
+    }
+
+    // write tables
+    let mut check_sum_adjustment_offset = 0;
+    for r in &records {
+        if r.tag == 0x68656164 {
+            check_sum_adjustment_offset = buf.len() + 2 * 4;
+        }
+        buf.write(r.data.bytes())?;
+        // 32 bit align the tables
+        while buf.len() & 3 != 0 {
+            buf.push(0);
+        }
+    }
+
+    let mut c = Cursor::new(buf);
+    c.set_position(check_sum_adjustment_offset as u64);
+    // clear the checksumAdjust field before checksumming the whole font
+    c.write_u32::<BigEndian>(0)?;
+    let sum = 0xb1b0afba_u32.wrapping_sub(calc_table_checksum(&c.get_mut()[..]));
+    // set checkSumAdjust to the computed checksum
+    c.set_position(check_sum_adjustment_offset as u64);
+    c.write_u32::<BigEndian>(sum)?;
+
+    Ok(c.into_inner())
+}

wrench/src/cgfont_to_data.rs

@@ -8,6 +8,10 @@ extern crate bincode;
 extern crate byteorder;
 #[macro_use]
 extern crate clap;
+#[cfg(target_os = "macos")]
+extern crate core_foundation;
+#[cfg(target_os = "macos")]
+extern crate core_graphics;
 extern crate crossbeam;
 #[cfg(target_os = "windows")]
 extern crate dwrote;
@@ -46,6 +50,8 @@ mod wrench;
 mod yaml_frame_reader;
 mod yaml_frame_writer;
 mod yaml_helper;
+#[cfg(target_os = "macos")]
+mod cgfont_to_data;
 
 use binary_frame_reader::BinaryFrameReader;
 use gleam::gl;