Merge pull request #1299 from matrix-org/luke/fix-text-offsets-to-selection-state

Fix bugs in textOffsetsToSelectionState

src/RichText.js

@@ -202,27 +202,36 @@ export function selectionStateToTextOffsets(selectionState: SelectionState,
 export function textOffsetsToSelectionState({start, end}: SelectionRange,
                                             contentBlocks: Array<ContentBlock>): SelectionState {
     let selectionState = SelectionState.createEmpty();
+    // Subtract block lengths from `start` and `end` until they are less than the current
+    // block length (accounting for the NL at the end of each block). Set them to -1 to
+    // indicate that the corresponding selection state has been determined.
     for (const block of contentBlocks) {
         const blockLength = block.getLength();
-        if (start !== -1 && start < blockLength) {
+        // -1 indicating that the position start position has been found
+        if (start !== -1) {
+            if (start < blockLength + 1) {
                 selectionState = selectionState.merge({
                     anchorKey: block.getKey(),
                     anchorOffset: start,
                 });
-            start = -1;
+                start = -1; // selection state for the start calculated
             } else {
                 start -= blockLength + 1; // +1 to account for newline between blocks
             }
-        if (end !== -1 && end <= blockLength) {
+        }
+        // -1 indicating that the position end position has been found
+        if (end !== -1) {
+            if (end < blockLength + 1) {
                 selectionState = selectionState.merge({
                     focusKey: block.getKey(),
                     focusOffset: end,
                 });
-            end = -1;
+                end = -1; // selection state for the end calculated
             } else {
                 end -= blockLength + 1; // +1 to account for newline between blocks
             }
         }
+    }
     return selectionState;
 }