Custom highlighting to fix UI bugs.

+ Selecting text caused blurry editor view.
+ Now prefers syntect theme background color over QML background color.

src/filesystem.rs

@@ -43,10 +43,13 @@ use cxx_qt_lib::{QModelIndex, QString};
 use dirs;
 use log::warn;
 use std::fs;
-use std::fs::FileType;
+use std::io::BufRead;
-use syntect::highlighting::{Style, ThemeSet};
+use syntect::easy::HighlightFile;
+use syntect::highlighting::ThemeSet;
+use syntect::html::{
+    IncludeBackground, append_highlighted_html_for_styled_line, start_highlighted_html_snippet,
+};
 use syntect::parsing::SyntaxSet;
-use syntect::html::highlighted_html_for_file;
 
 // TODO: Impleent a provider for QFileSystemModel::setIconProvider for icons.
 pub struct FileSystemImpl {
@@ -69,23 +72,42 @@ impl qobject::FileSystem {
         if path.is_empty() {
             return QString::default();
         }
-        if fs::metadata(path.to_string())
+        if !fs::metadata(path.to_string())
             .expect(format!("Failed to get file metadata {}", path).as_str())
             .is_file()
         {
-            let ps = SyntaxSet::load_defaults_nonewlines();
-            let ts = ThemeSet::load_defaults();
-
-            if let Ok(result) = highlighted_html_for_file(std::path::Path::new(&path.to_string()), &ps, &ts.themes["base16-ocean.dark"]) {
-                QString::from(result)
-            } else {
-                warn!("Failed to read file {}", path);
-                QString::default()
-            }
-        } else {
             warn!("Attempted to open file {} that is not a valid file", path);
-            QString::default()
+            return QString::default();
         }
+        let ss = SyntaxSet::load_defaults_nonewlines();
+        let ts = ThemeSet::load_defaults();
+        let theme = &ts.themes["base16-ocean.dark"];
+
+        let mut highlighter =
+            HighlightFile::new(path.to_string(), &ss, theme).expect("Failed to create highlighter");
+        let (mut output, _bg) = start_highlighted_html_snippet(theme);
+        let mut line = String::new();
+        while highlighter
+            .reader
+            .read_line(&mut line)
+            .expect("Failed to read file.")
+            > 0
+        {
+            let regions = highlighter
+                .highlight_lines
+                .highlight_line(&line, &ss)
+                .expect("Failed to highlight");
+
+            append_highlighted_html_for_styled_line(
+                &regions[..],
+                IncludeBackground::Yes,
+                &mut output,
+            )
+            .expect("Failed to insert highlighted html");
+            line.clear();
+        }
+        output.push_str("</pre>\n");
+        QString::from(output)
     }
 
     // There will never be more than one column.