Fix text cursor or input can be outside of the text field (#91698)

packages/flutter/lib/src/painting/text_painter.dart

@@ -780,7 +780,7 @@ class TextPainter {
 
       final double caretEnd = box.end;
       final double dx = box.direction == TextDirection.rtl ? caretEnd - caretPrototype.width : caretEnd;
-      return Rect.fromLTRB(min(dx, _paragraph!.width), box.top, min(dx, _paragraph!.width), box.bottom);
+      return Rect.fromLTRB(dx.clamp(0, _paragraph!.width), box.top, dx.clamp(0, _paragraph!.width), box.bottom);
     }
     return null;
   }
@@ -822,7 +822,7 @@ class TextPainter {
       final TextBox box = boxes.last;
       final double caretStart = box.start;
       final double dx = box.direction == TextDirection.rtl ? caretStart - caretPrototype.width : caretStart;
-      return Rect.fromLTRB(min(dx, _paragraph!.width), box.top, min(dx, _paragraph!.width), box.bottom);
+      return Rect.fromLTRB(dx.clamp(0, _paragraph!.width), box.top, dx.clamp(0, _paragraph!.width), box.bottom);
     }
     return null;
   }

packages/flutter/lib/src/rendering/editable.dart

@@ -1664,8 +1664,8 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       final Offset start = Offset(0.0, preferredLineHeight) + caretOffset + paintOffset;
       return <TextSelectionPoint>[TextSelectionPoint(start, null)];
     } else {
-      final Offset start = Offset(boxes.first.start, boxes.first.bottom) + paintOffset;
-      final Offset end = Offset(boxes.last.end, boxes.last.bottom) + paintOffset;
+      final Offset start = Offset(boxes.first.start.clamp(0, _textPainter.size.width), boxes.first.bottom) + paintOffset;
+      final Offset end = Offset(boxes.last.end.clamp(0, _textPainter.size.width), boxes.last.bottom) + paintOffset;
       return <TextSelectionPoint>[
         TextSelectionPoint(start, boxes.first.direction),
         TextSelectionPoint(end, boxes.last.direction),
@@ -2741,14 +2741,19 @@ class _TextHighlightPainter extends RenderEditablePainter {
     }
 
     highlightPaint.color = color;
-    final List<TextBox> boxes = renderEditable._textPainter.getBoxesForSelection(
+    final TextPainter textPainter = renderEditable._textPainter;
+    final List<TextBox> boxes = textPainter.getBoxesForSelection(
       TextSelection(baseOffset: range.start, extentOffset: range.end),
       boxHeightStyle: selectionHeightStyle,
       boxWidthStyle: selectionWidthStyle,
     );
 
     for (final TextBox box in boxes)
-      canvas.drawRect(box.toRect().shift(renderEditable._paintOffset), highlightPaint);
+      canvas.drawRect(
+        box.toRect().shift(renderEditable._paintOffset)
+          .intersect(Rect.fromLTWH(0, 0, textPainter.width, textPainter.height)),
+        highlightPaint,
+      );
   }
 
   @override

packages/flutter/test/material/text_field_test.dart

@@ -1097,6 +1097,33 @@ void main() {
     expect(cursorOffsetSpaces.dx, inputWidth - kCaretGap);
   });
 
+  testWidgets('Overflowing a line with spaces stops the cursor at the end (rtl direction)', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      overlay(
+        child: const TextField(
+          textDirection: TextDirection.rtl,
+          maxLines: null,
+        ),
+      ),
+    );
+
+    const String testValueOneLine = 'enough text to be exactly at the end of the line.';
+    const String testValueSpaces = '$testValueOneLine          ';
+
+    // Positioning the cursor at the end of a line overflowing with spaces puts
+    // it inside the input still.
+    await tester.enterText(find.byType(TextField), testValueSpaces);
+    await skipPastScrollingAnimation(tester);
+    await tester.tapAt(textOffsetToPosition(tester, testValueSpaces.length));
+    await tester.pump();
+
+    final Offset cursorOffsetSpaces = findRenderEditable(tester).getLocalRectForCaret(
+      const TextPosition(offset: testValueSpaces.length),
+    ).topLeft;
+
+    expect(cursorOffsetSpaces.dx >= 0, isTrue);
+  });
+
   testWidgets('mobile obscureText control test', (WidgetTester tester) async {
     await tester.pumpWidget(
       overlay(