Example: ansi_crossterm (#801)

* Example: ansi_crossterm

* Example: Added various methods to color and remove styles from text

cursive/Cargo.toml

@@ -83,6 +83,10 @@ required-features = ["toml"]
 name = "ansi"
 required-features = ["ansi"]
 
+[[example]]
+name = "colored_text"
+required-features = ["ansi", "crossterm-backend"]
+
 [[example]]
 name = "builder"
 required-features = ["builder"]

cursive/examples/Readme.md

@@ -91,6 +91,10 @@ This example shows the effect of the `Color::TerminalDefault` setting.
 
 This example draws a colorful square to show off true color support.
 
+## [`colored_text`](./colored_text.rs)
+
+This example showcasing various methods to color and remove text styles, highlighting the limitations of Crossterm's raw ANSI output.
+
 ## [`refcell_view`](./refcell_view.rs)
 
 Here we show how to access multiple views concurrently through their name.

cursive/examples/colored_text.rs

@@ -0,0 +1,85 @@
+use crossterm::style::Stylize;
+use cursive_core::style::BaseColor::{Black, Red};
+use cursive_core::style::ColorStyle;
+use cursive_core::theme::Style;
+use cursive_core::utils::markup::{cursup, StyledString};
+use cursive_core::views::{Dialog, LinearLayout, TextView};
+
+fn main() {
+    // Coloring text.
+    let crossterm_colored = crossterm_coloring_into_ansi("Crossterm colored text.");
+
+    let cursive_parsed_ansi = cursive_parse_ansi("Parsed ANSI");
+
+    let cursive_single_span = single_style_span("Cursive StyledString::single_span");
+
+    let cursup_markup = cursup_markup("/blue+bold{Cursup} /yellow+bold{markup}");
+
+    // Removing styles.
+
+    let cleared_by_iterating: String = iterating_spans(&cursive_parsed_ansi);
+
+    let cleared_by_canonicalize: String = canonicalize_clear(&cursive_single_span);
+
+    // Minimal application for text output
+    let mut siv = cursive::default();
+    siv.add_layer(
+        Dialog::new()
+            .content(
+                LinearLayout::vertical()
+                    .child(TextView::new(crossterm_colored))
+                    .child(TextView::new(cursive_parsed_ansi))
+                    .child(TextView::new(cursive_single_span))
+                    .child(TextView::new(cursup_markup))
+                    .child(TextView::new(cleared_by_iterating))
+                    .child(TextView::new(cleared_by_canonicalize)),
+            )
+            .button("Quit!", |s| s.quit()),
+    );
+    siv.run();
+}
+
+// Crossterm function for text styling and casting it to a string.
+// Results in raw text with ANSI codes.
+fn crossterm_coloring_into_ansi(str: &str) -> String {
+    str.red().to_string()
+}
+
+// Parsing ansi into StyledString
+// https://docs.rs/cursive/latest/cursive/utils/markup/ansi/fn.parse.html
+fn cursive_parse_ansi(str: &str) -> StyledString {
+    cursive::utils::markup::ansi::parse(str.red().to_string())
+}
+
+// Building cursive-native StyledString with StyledString::single_span (single style for entire string)
+// https://docs.rs/cursive/latest/cursive/utils/markup/type.StyledString.html#method.single_span
+fn single_style_span(str: &str) -> StyledString {
+    StyledString::single_span(
+        str,
+        Style {
+            effects: Default::default(),
+            color: ColorStyle::new(Red, Black),
+        },
+    )
+}
+
+// Cursup, a simple markup language.
+// https://docs.rs/cursive/latest/cursive/utils/markup/cursup/index.html
+fn cursup_markup(str: &str) -> StyledString {
+    cursup::parse(str)
+}
+
+// Iterating on the spans, and accumulating the span text content, ignoring the styles.
+fn iterating_spans(str: &StyledString) -> String {
+    str.spans().map(|span| span.content).collect()
+}
+
+// Use compact or canonicalize, which rebuilds the source to only include visible text (no markup), and then get the source.
+// Note that this technically modifies the StyledString, and requires mutable access.
+// https://docs.rs/cursive/latest/cursive/utils/span/struct.SpannedString.html#method.canonicalize
+// https://docs.rs/cursive/latest/cursive/utils/span/struct.SpannedString.html#method.compact
+fn canonicalize_clear(str: &StyledString) -> String {
+    let mut canonicalize_clear = str.clone();
+    canonicalize_clear.canonicalize();
+    canonicalize_clear.source().to_string()
+}