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Cursor Position Mapping

Overview

Maps cursor positions between displayed text (rendered without markdown formatting) and raw text (containing markdown markers like **, *, etc.). This enables accurate cursor placement when clicking on formatted content to enter edit mode.

Key Files

  • src/markdown/editor.rs - Contains map_displayed_to_raw() function (~line 2467)

Implementation Details

The Problem

When a user clicks on formatted markdown content like **bold** text, the rendered view shows just bold. The click position is captured relative to the displayed text, but the cursor needs to be placed in the raw text which includes the ** markers.

Example:

  • Raw text: *h**e**re* (nested italic + bold)
  • Displayed: here
  • Click on 'r' (displayed index 2) → needs raw index 7

Solution: map_displayed_to_raw()

fn map_displayed_to_raw(displayed_idx: usize, raw_text: &str) -> usize

The function walks through the raw text character by character, skipping formatting markers while counting displayed characters. When the displayed count reaches the target index, it returns the raw position.

Formatting Markers Handled

Marker Pattern Description
Bold ** or __ Skips 2 chars
Italic * or _ Skips 1 char (when not part of bold)
Code ` Skips backticks
Strikethrough ~~ Skips 2 chars
Links [text](url) Skips [, ](url), keeps text

Algorithm

  1. Walk through raw text character by character
  2. Check for formatting marker patterns in priority order (double-char first)
  3. Skip marker characters without advancing displayed position
  4. For regular content, advance both raw and displayed positions
  5. Return raw position when displayed count reaches target

Link Handling

Links require special handling since the structure is [visible text](hidden url):

  • Skip opening [
  • Count text characters normally (they're displayed)
  • Skip ](url) entirely, including nested parentheses

Integration Points

The mapping is used in three click handlers in src/markdown/editor.rs:

  1. Formatted paragraph (first location) - ~line 1554
  2. Formatted paragraph (second location) - ~line 2268
  3. List items - ~line 3228

Each handler:

  1. Computes displayed_idx using compute_displayed_cursor_index() (Galley-based)
  2. Maps to raw_idx using map_displayed_to_raw()
  3. Sets pending_cursor_pos for the edit state

Related Documentation

Testing

Test with formatted content:

  • - This is **bold** text - Click on "bold" word
  • - Click *here* to edit - Click on "here"
  • - Link [example](https://example.com) text - Click on "example"
  • - Nested ***bold italic*** test - Click in middle

Verify cursor appears within 1-2 characters of click position in edit mode.