Text input (#143)

* update: iced 0.10.0

* wip: text input

* wip: text inputs with icons and buttons

* wip: improve text input

* refactor: text input styling

* chore: add scale factor

* chore(text_input): add winit example and do some cleanup

src/widget/text_input/editor.rs

@@ -0,0 +1,65 @@
+use super::{cursor::Cursor, value::Value};
+
+pub struct Editor<'a> {
+    value: &'a mut Value,
+    cursor: &'a mut Cursor,
+}
+
+impl<'a> Editor<'a> {
+    pub fn new(value: &'a mut Value, cursor: &'a mut Cursor) -> Editor<'a> {
+        Editor { value, cursor }
+    }
+
+    #[must_use]
+    pub fn contents(&self) -> String {
+        self.value.to_string()
+    }
+
+    pub fn insert(&mut self, character: char) {
+        if let Some((left, right)) = self.cursor.selection(self.value) {
+            self.cursor.move_left(self.value);
+            self.value.remove_many(left, right);
+        }
+
+        self.value.insert(self.cursor.end(self.value), character);
+        self.cursor.move_right(self.value);
+    }
+
+    pub fn paste(&mut self, content: Value) {
+        let length = content.len();
+        if let Some((left, right)) = self.cursor.selection(self.value) {
+            self.cursor.move_left(self.value);
+            self.value.remove_many(left, right);
+        }
+
+        self.value.insert_many(self.cursor.end(self.value), content);
+
+        self.cursor.move_right_by_amount(self.value, length);
+    }
+
+    pub fn backspace(&mut self) {
+        if let Some((start, end)) = self.cursor.selection(self.value) {
+            self.cursor.move_left(self.value);
+            self.value.remove_many(start, end);
+        } else {
+            let start = self.cursor.start(self.value);
+
+            if start > 0 {
+                self.cursor.move_left(self.value);
+                self.value.remove(start - 1);
+            }
+        }
+    }
+
+    pub fn delete(&mut self) {
+        if self.cursor.selection(self.value).is_some() {
+            self.backspace();
+        } else {
+            let end = self.cursor.end(self.value);
+
+            if end < self.value.len() {
+                self.value.remove(end);
+            }
+        }
+    }
+}