Right aligned backspace bug (#25229)
* Fix bug in calculation of downstream text distance when aligned: right
* After having affinity explained to me, match getOffset and tests to
expected behavior
* Clean up test formatting and fix analyze errors
* Improve test comments and reorganize a bit
* Specify logical pixels
diff --git a/packages/flutter/lib/src/painting/text_painter.dart b/packages/flutter/lib/src/painting/text_painter.dart
index 906fc92..2836883 100644
--- a/packages/flutter/lib/src/painting/text_painter.dart
+++ b/packages/flutter/lib/src/painting/text_painter.dart
@@ -417,6 +417,8 @@
// Unicode value for a zero width joiner character.
static const int _zwjUtf16 = 0x200d;
+ // Get the Offset of the cursor (in logical pixels) based off the near edge
+ // of the character upstream from the given string offset.
// TODO(garyq): Use actual extended grapheme cluster length instead of
// an increasing cluster length amount to achieve deterministic performance.
Offset _getOffsetFromUpstream(int offset, Rect caretPrototype) {
@@ -424,6 +426,7 @@
final int prevCodeUnit = _text.codeUnitAt(max(0, offset - 1));
if (prevCodeUnit == null)
return null;
+
// Check for multi-code-unit glyphs such as emojis or zero width joiner
final bool needsSearch = _isUtf16Surrogate(prevCodeUnit) || _text.codeUnitAt(offset) == _zwjUtf16;
int graphemeClusterLength = needsSearch ? 2 : 1;
@@ -447,6 +450,13 @@
continue;
}
final TextBox box = boxes.first;
+
+ // If the upstream character is a newline, cursor is at start of next line
+ const int NEWLINE_CODE_UNIT = 10;
+ if (prevCodeUnit == NEWLINE_CODE_UNIT) {
+ return Offset(_emptyOffset.dx, box.bottom);
+ }
+
final double caretEnd = box.end;
final double dx = box.direction == TextDirection.rtl ? caretEnd - caretPrototype.width : caretEnd;
return Offset(dx, box.top);
@@ -454,6 +464,8 @@
return null;
}
+ // Get the Offset of the cursor (in logical pixels) based off the near edge
+ // of the character downstream from the given string offset.
// TODO(garyq): Use actual extended grapheme cluster length instead of
// an increasing cluster length amount to achieve deterministic performance.
Offset _getOffsetFromDownstream(int offset, Rect caretPrototype) {
diff --git a/packages/flutter/test/painting/text_painter_test.dart b/packages/flutter/test/painting/text_painter_test.dart
index d2105e8..4a9af58 100644
--- a/packages/flutter/test/painting/text_painter_test.dart
+++ b/packages/flutter/test/painting/text_painter_test.dart
@@ -16,7 +16,10 @@
painter.text = TextSpan(text: text);
painter.layout();
- Offset caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0), ui.Rect.zero);
+ Offset caretOffset = painter.getOffsetForCaret(
+ const ui.TextPosition(offset: 0),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, 0);
caretOffset = painter.getOffsetForCaret(ui.TextPosition(offset: text.length), ui.Rect.zero);
expect(caretOffset.dx, painter.width);
@@ -62,7 +65,7 @@
// One three-person family, one four person family, one US flag.
const String text = '👩👩👦👩👩👧👧🇺🇸';
painter.text = const TextSpan(text: text);
- painter.layout();
+ painter.layout(maxWidth: 10000);
expect(text.length, 23);
@@ -293,112 +296,340 @@
final TextPainter painter = TextPainter()
..textDirection = TextDirection.ltr;
+ const double SIZE_OF_A = 14.0; // square size of "a" character
String text = 'aaa';
painter.text = TextSpan(text: text);
painter.layout();
- Offset caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0), ui.Rect.zero);
- expect(caretOffset.dx, closeTo(0.0, 0.0001));
- caretOffset = painter.getOffsetForCaret(ui.TextPosition(offset: text.length), ui.Rect.zero);
- expect(caretOffset.dx, painter.width);
+ // getOffsetForCaret in a plain one-line string is the same for either affinity.
+ int offset = 0;
+ painter.text = TextSpan(text: text);
+ painter.layout();
+ Offset caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ offset = 1;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ offset = 2;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ offset = 3;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
expect(caretOffset.dy, closeTo(0.0, 0.0001));
- // Check that getOffsetForCaret handles a trailing newline when affinity is downstream.
+ // For explicit newlines, getOffsetForCaret places the caret at the location
+ // indicated by offset regardless of affinity.
+ text = '\n\n';
+ painter.text = TextSpan(text: text);
+ painter.layout();
+ offset = 0;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ offset = 1;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
+ offset = 2;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.0001));
+
+ // getOffsetForCaret in an unwrapped string with explicit newlines is the
+ // same for either affinity.
+ text = '\naaa';
+ painter.text = TextSpan(text: text);
+ painter.layout();
+ offset = 0;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ offset = 1;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
+
+ // When text wraps on its own, getOffsetForCaret disambiguates between the
+ // end of one line and start of next using affinity.
+ text = 'aaaaaaaa'; // Just enough to wrap one character down to second line
+ painter.text = TextSpan(text: text);
+ painter.layout(maxWidth: 100); // SIZE_OF_A * text.length > 100, so it wraps
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: text.length - 1),
+ ui.Rect.zero,
+ );
+ // When affinity is downstream, cursor is at beginning of second line
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: text.length - 1, affinity: ui.TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ // When affinity is upstream, cursor is at end of first line
+ expect(caretOffset.dx, closeTo(98.0, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+
+ // When given a string with a newline at the end, getOffsetForCaret puts
+ // the cursor at the start of the next line regardless of affinity
text = 'aaa\n';
painter.text = TextSpan(text: text);
painter.layout();
- caretOffset = painter.getOffsetForCaret(ui.TextPosition(offset: text.length, affinity: TextAffinity.downstream), ui.Rect.zero);
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: text.length),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(14.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
+ offset = text.length;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
- // Check that getOffsetForCaret handles a trailing newline when affinity is upstream.
- text = 'aaa\n';
+ // Given a one-line right aligned string, positioning the cursor at offset 0
+ // means that it appears at the "end" of the string, after the character
+ // that was typed first, at x=0.
+ painter.textAlign = TextAlign.right;
+ text = 'aaa';
painter.text = TextSpan(text: text);
painter.layout();
- caretOffset = painter.getOffsetForCaret(ui.TextPosition(offset: text.length, affinity: TextAffinity.upstream), ui.Rect.zero);
- expect(caretOffset.dx, painter.width);
+ offset = 0;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ painter.textAlign = TextAlign.left;
- // Correctly moves through second line with downstream affinity.
+ // When given an offset after a newline in the middle of a string,
+ // getOffsetForCaret returns the start of the next line regardless of
+ // affinity.
text = 'aaa\naaa';
painter.text = TextSpan(text: text);
painter.layout();
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 4), ui.Rect.zero);
+ offset = 4;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(14.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
- // Correctly moves through second line with upstream affinity.
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 4, affinity: TextAffinity.upstream), ui.Rect.zero);
- expect(caretOffset.dx, closeTo(42.0, 0.0001));
- expect(caretOffset.dy, closeTo(0.0, 0.0001));
-
- // Correctly handles multiple trailing newlines.
+ // When given a string with multiple trailing newlines, places the caret
+ // in the position given by offset regardless of affinity.
text = 'aaa\n\n\n';
+ offset = 3;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(SIZE_OF_A * 3, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(SIZE_OF_A * 3, 0.0001));
+ expect(caretOffset.dy, closeTo(0.0, 0.0001));
+
+ offset = 4;
painter.text = TextSpan(text: text);
painter.layout();
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 4), ui.Rect.zero);
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(14.0, 0.001));
-
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 5), ui.Rect.zero);
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(28.0, 0.001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 6), ui.Rect.zero);
+ offset = 5;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(42.0, 0.0001));
-
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 6, affinity: TextAffinity.upstream), ui.Rect.zero);
+ expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(28.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.0001));
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 5, affinity: TextAffinity.upstream), ui.Rect.zero);
+ offset = 6;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(14.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A * 3, 0.0001));
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 4, affinity: TextAffinity.upstream), ui.Rect.zero);
- expect(caretOffset.dx, closeTo(42.0, 0.0001));
- expect(caretOffset.dy, closeTo(0.0, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A * 3, 0.0001));
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 3, affinity: TextAffinity.upstream), ui.Rect.zero);
- expect(caretOffset.dx, closeTo(42.0, 0.0001));
- expect(caretOffset.dy, closeTo(0.0, 0.0001));
-
- // Correctly handles multiple leading newlines
+ // When given a string with multiple leading newlines, places the caret in
+ // the position given by offset regardless of affinity.
text = '\n\n\naaa';
+ offset = 3;
painter.text = TextSpan(text: text);
painter.layout();
-
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 3), ui.Rect.zero);
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(42.0, 0.0001));
-
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 2), ui.Rect.zero);
+ expect(caretOffset.dy, closeTo(SIZE_OF_A * 3, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(28.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A * 3, 0.0001));
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 1), ui.Rect.zero);
+ offset = 2;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy,closeTo(14.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.0001));
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0), ui.Rect.zero);
+ offset = 1;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy,closeTo(SIZE_OF_A, 0.0001));
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
+ ui.Rect.zero,
+ );
+ expect(caretOffset.dx, closeTo(0.0, 0.0001));
+ expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
+
+ offset = 0;
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
expect(caretOffset.dy, closeTo(0.0, 0.0001));
-
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0, affinity: TextAffinity.upstream), ui.Rect.zero);
+ caretOffset = painter.getOffsetForCaret(
+ ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
+ ui.Rect.zero,
+ );
expect(caretOffset.dx, closeTo(0.0, 0.0001));
expect(caretOffset.dy, closeTo(0.0, 0.0001));
-
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 1, affinity: TextAffinity.upstream), ui.Rect.zero);
- expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(0.0, 0.0001));
-
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 2, affinity: TextAffinity.upstream), ui.Rect.zero);
- expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(14.0, 0.0001));
-
- caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 3, affinity: TextAffinity.upstream), ui.Rect.zero);
- expect(caretOffset.dx, closeTo(0.0, 0.0001));
- expect(caretOffset.dy, closeTo(28.0, 0.0001));
});
}
