vendor

egui/crates/epaint/src/text/cursor.rs

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+//! Different types of text cursors, i.e. ways to point into a [`super::Galley`].
+
+/// Character cursor
+#[derive(Clone, Copy, Debug, Default)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub struct CCursor {
+    /// Character offset (NOT byte offset!).
+    pub index: usize,
+
+    /// If this cursors sits right at the border of a wrapped row break (NOT paragraph break)
+    /// do we prefer the next row?
+    /// This is *almost* always what you want, *except* for when
+    /// explicitly clicking the end of a row or pressing the end key.
+    pub prefer_next_row: bool,
+}
+
+impl CCursor {
+    pub fn new(index: usize) -> Self {
+        Self {
+            index,
+            prefer_next_row: false,
+        }
+    }
+}
+
+/// Two `CCursor`s are considered equal if they refer to the same character boundary,
+/// even if one prefers the start of the next row.
+impl PartialEq for CCursor {
+    fn eq(&self, other: &CCursor) -> bool {
+        self.index == other.index
+    }
+}
+
+impl std::ops::Add<usize> for CCursor {
+    type Output = CCursor;
+
+    fn add(self, rhs: usize) -> Self::Output {
+        CCursor {
+            index: self.index.saturating_add(rhs),
+            prefer_next_row: self.prefer_next_row,
+        }
+    }
+}
+
+impl std::ops::Sub<usize> for CCursor {
+    type Output = CCursor;
+
+    fn sub(self, rhs: usize) -> Self::Output {
+        CCursor {
+            index: self.index.saturating_sub(rhs),
+            prefer_next_row: self.prefer_next_row,
+        }
+    }
+}
+
+impl std::ops::AddAssign<usize> for CCursor {
+    fn add_assign(&mut self, rhs: usize) {
+        self.index = self.index.saturating_add(rhs);
+    }
+}
+
+impl std::ops::SubAssign<usize> for CCursor {
+    fn sub_assign(&mut self, rhs: usize) {
+        self.index = self.index.saturating_sub(rhs);
+    }
+}
+
+/// Row Cursor
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub struct RCursor {
+    /// 0 is first row, and so on.
+    /// Note that a single paragraph can span multiple rows.
+    /// (a paragraph is text separated by `\n`).
+    pub row: usize,
+
+    /// Character based (NOT bytes).
+    /// It is fine if this points to something beyond the end of the current row.
+    /// When moving up/down it may again be within the next row.
+    pub column: usize,
+}
+
+/// Paragraph Cursor
+#[derive(Clone, Copy, Debug, Default)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub struct PCursor {
+    /// 0 is first paragraph, and so on.
+    /// Note that a single paragraph can span multiple rows.
+    /// (a paragraph is text separated by `\n`).
+    pub paragraph: usize,
+
+    /// Character based (NOT bytes).
+    /// It is fine if this points to something beyond the end of the current paragraph.
+    /// When moving up/down it may again be within the next paragraph.
+    pub offset: usize,
+
+    /// If this cursors sits right at the border of a wrapped row break (NOT paragraph break)
+    /// do we prefer the next row?
+    /// This is *almost* always what you want, *except* for when
+    /// explicitly clicking the end of a row or pressing the end key.
+    pub prefer_next_row: bool,
+}
+
+/// Two `PCursor`s are considered equal if they refer to the same character boundary,
+/// even if one prefers the start of the next row.
+impl PartialEq for PCursor {
+    fn eq(&self, other: &PCursor) -> bool {
+        self.paragraph == other.paragraph && self.offset == other.offset
+    }
+}
+
+/// All different types of cursors together.
+/// They all point to the same place, but in their own different ways.
+/// pcursor/rcursor can also point to after the end of the paragraph/row.
+/// Does not implement `PartialEq` because you must think which cursor should be equivalent.
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub struct Cursor {
+    pub ccursor: CCursor,
+    pub rcursor: RCursor,
+    pub pcursor: PCursor,
+}