fix attributes_formatted, remove attributes_diff

also improve the documentation and add more tests

3 files changed, 31 insertions, 14 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4cbc4e8..fda293f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Changelog
 
+## [Unreleased]
+
+### Fixed
+
+* `Screen::attributes_formatted` now correctly resets previously set attributes
+  where necessary
+
+### Removed
+
+* Removed `Screen::attributes_diff`, since I can't actually think of any
+  situation where it does a thing that makes sense.
+
 ## [0.11.1] - 2021-03-07
 
 ### Changed
diff --git a/src/screen.rs b/src/screen.rs
index cb6b970..9affeef 100644
--- a/src/screen.rs
+++ b/src/screen.rs
@@ -485,6 +485,12 @@ impl Screen {
     /// * italic
     /// * underline
     /// * inverse
+    ///
+    /// This is not typically necessary, since `contents_formatted` will leave
+    /// the current active drawing attributes in the correct state, but this
+    /// can be useful in the case of drawing additional things on top of a
+    /// terminal output, since you will need to restore the terminal state
+    /// without the terminal contents necessarily being the same.
     #[must_use]
     pub fn attributes_formatted(&self) -> Vec<u8> {
         let mut contents = vec![];
@@ -493,26 +499,13 @@ impl Screen {
     }
 
     fn write_attributes_formatted(&self, contents: &mut Vec<u8>) {
+        crate::term::ClearAttrs::default().write_buf(contents);
         self.attrs.write_escape_code_diff(
             contents,
             &crate::attrs::Attrs::default(),
         );
     }
 
-    /// Returns terminal escape sequences sufficient to change the previous
-    /// terminal's drawing attributes to the drawing attributes enabled in the
-    /// current terminal.
-    #[must_use]
-    pub fn attributes_diff(&self, prev: &Self) -> Vec<u8> {
-        let mut contents = vec![];
-        self.write_attributes_diff(&mut contents, prev);
-        contents
-    }
-
-    fn write_attributes_diff(&self, contents: &mut Vec<u8>, prev: &Self) {
-        self.attrs.write_escape_code_diff(contents, &prev.attrs);
-    }
-
     /// Returns the `Cell` object at the given location in the terminal, if it
     /// exists.
     #[must_use]
diff --git a/tests/attr.rs b/tests/attr.rs
index 64f4bd4..34ac7af 100644
--- a/tests/attr.rs
+++ b/tests/attr.rs
@@ -9,3 +9,15 @@ fn colors() {
 fn attrs() {
     helpers::fixture("attrs");
 }
+
+#[test]
+fn attributes_formatted() {
+    let mut parser = vt100::Parser::default();
+    assert_eq!(parser.screen().attributes_formatted(), b"\x1b[m");
+    parser.process(b"\x1b[32mfoo\x1b[41mbar\x1b[33mbaz");
+    assert_eq!(parser.screen().attributes_formatted(), b"\x1b[m\x1b[33;41m");
+    parser.process(b"\x1b[1m\x1b[39m");
+    assert_eq!(parser.screen().attributes_formatted(), b"\x1b[m\x1b[41;1m");
+    parser.process(b"\x1b[m");
+    assert_eq!(parser.screen().attributes_formatted(), b"\x1b[m");
+}