[macOS] Fix text input plugin editable transform (flutter#35979)

shell/platform/darwin/ios/framework/Source/FlutterTextInputPlugin.mm

@@ -1511,11 +1511,49 @@ - (void)setEditableTransform:(NSArray*)matrix {
   _cachedFirstRect = kInvalidFirstRect;
 }
 
+// Returns the bounding CGRect of the transformed incomingRect, in the view's
+// coordinates.
+- (CGRect)localRectFromFrameworkTransform:(CGRect)incomingRect {
+  CGPoint points[] = {
+      incomingRect.origin,
+      CGPointMake(incomingRect.origin.x, incomingRect.origin.y + incomingRect.size.height),
+      CGPointMake(incomingRect.origin.x + incomingRect.size.width, incomingRect.origin.y),
+      CGPointMake(incomingRect.origin.x + incomingRect.size.width,
+                  incomingRect.origin.y + incomingRect.size.height)};
+
+  CGPoint origin = CGPointMake(CGFLOAT_MAX, CGFLOAT_MAX);
+  CGPoint farthest = CGPointMake(-CGFLOAT_MAX, -CGFLOAT_MAX);
+
+  for (int i = 0; i < 4; i++) {
+    const CGPoint point = points[i];
+
+    CGFloat x = _editableTransform.m11 * point.x + _editableTransform.m21 * point.y +
+                _editableTransform.m41;
+    CGFloat y = _editableTransform.m12 * point.x + _editableTransform.m22 * point.y +
+                _editableTransform.m42;
+
+    const CGFloat w = _editableTransform.m14 * point.x + _editableTransform.m24 * point.y +
+                      _editableTransform.m44;
+
+    if (w == 0.0) {
+      return kInvalidFirstRect;
+    } else if (w != 1.0) {
+      x /= w;
+      y /= w;
+    }
+
+    origin.x = MIN(origin.x, x);
+    origin.y = MIN(origin.y, y);
+    farthest.x = MAX(farthest.x, x);
+    farthest.y = MAX(farthest.y, y);
+  }
+  return CGRectMake(origin.x, origin.y, farthest.x - origin.x, farthest.y - origin.y);
+}
+
 // The following methods are required to support force-touch cursor positioning
 // and to position the
 // candidates view for multi-stage input methods (e.g., Japanese) when using a
 // physical keyboard.
-
 - (CGRect)firstRectForRange:(UITextRange*)range {
   NSAssert([range.start isKindOfClass:[FlutterTextPosition class]],
            @"Expected a FlutterTextPosition for range.start (got %@).", [range.start class]);
@@ -1524,22 +1562,21 @@ - (CGRect)firstRectForRange:(UITextRange*)range {
   NSUInteger start = ((FlutterTextPosition*)range.start).index;
   NSUInteger end = ((FlutterTextPosition*)range.end).index;
   if (_markedTextRange != nil) {
-    // The candidates view can't be shown if _editableTransform is not affine,
-    // or markedRect is invalid.
-    if (CGRectEqualToRect(kInvalidFirstRect, _markedRect) ||
-        !CATransform3DIsAffine(_editableTransform)) {
+    // The candidates view can't be shown if the framework has not sent the
+    // first caret rect.
+    if (CGRectEqualToRect(kInvalidFirstRect, _markedRect)) {
       return kInvalidFirstRect;
     }
 
     if (CGRectEqualToRect(_cachedFirstRect, kInvalidFirstRect)) {
       // If the width returned is too small, that means the framework sent us
-      // the caret rect instead of the marked text rect. Expand it to 0.1 so
-      // the IME candidates view show up.
-      double nonZeroWidth = MAX(_markedRect.size.width, 0.1);
+      // the caret rect instead of the marked text rect. Expand it to 0.2 so
+      // the IME candidates view would show up.
       CGRect rect = _markedRect;
-      rect.size = CGSizeMake(nonZeroWidth, rect.size.height);
-      _cachedFirstRect =
-          CGRectApplyAffineTransform(rect, CATransform3DGetAffineTransform(_editableTransform));
+      if (CGRectIsEmpty(rect)) {
+        rect = CGRectInset(rect, -0.1, 0);
+      }
+      _cachedFirstRect = [self localRectFromFrameworkTransform:rect];
     }
 
     return _cachedFirstRect;

shell/platform/darwin/ios/framework/Source/FlutterTextInputPluginTest.mm

@@ -1167,6 +1167,13 @@ - (void)testUpdateFirstRectForRange {
   // yOffset = 200.
   NSArray* yOffsetMatrix = @[ @1, @0, @0, @0, @0, @1, @0, @0, @0, @0, @1, @0, @0, @200, @0, @1 ];
   NSArray* zeroMatrix = @[ @0, @0, @0, @0, @0, @0, @0, @0, @0, @0, @0, @0, @0, @0, @0, @0 ];
+  // This matrix can be generated by running this dart code snippet:
+  // Matrix4.identity()..scale(3.0)..rotateZ(math.pi/2)..translate(1.0, 2.0,
+  // 3.0);
+  NSArray* affineMatrix = @[
+    @(0.0), @(3.0), @(0.0), @(0.0), @(-3.0), @(0.0), @(0.0), @(0.0), @(0.0), @(0.0), @(3.0), @(0.0),
+    @(-6.0), @(3.0), @(9.0), @(1.0)
+  ];
 
   // Invalid since we don't have the transform or the rect.
   XCTAssertTrue(CGRectEqualToRect(kInvalidFirstRect, [inputView firstRectForRange:range]));
@@ -1200,6 +1207,12 @@ - (void)testUpdateFirstRectForRange {
   // Invalid marked rect is invalid.
   XCTAssertTrue(CGRectEqualToRect(kInvalidFirstRect, [inputView firstRectForRange:range]));
   XCTAssertTrue(CGRectEqualToRect(kInvalidFirstRect, [inputView firstRectForRange:range]));
+
+  // Use a 3d affine transform that does 3d-scaling, z-index rotating and 3d translation.
+  [inputView setEditableTransform:affineMatrix];
+  [inputView setMarkedRect:testRect];
+  XCTAssertTrue(
+      CGRectEqualToRect(CGRectMake(-306, 3, 300, 300), [inputView firstRectForRange:range]));
 }
 
 - (void)testFirstRectForRangeReturnsCorrectSelectionRect {

shell/platform/darwin/macos/framework/Source/FlutterTextInputPlugin.mm

@@ -824,24 +824,57 @@ - (NSAttributedString*)attributedSubstringForProposedRange:(NSRange)range
   return @[];
 }
 
-- (NSRect)firstRectForCharacterRange:(NSRange)range actualRange:(NSRangePointer)actualRange {
-  if (!self.flutterViewController.viewLoaded) {
-    return CGRectZero;
+// Returns the bounding CGRect of the transformed incomingRect, in screen
+// coordinates.
+- (CGRect)screenRectFromFrameworkTransform:(CGRect)incomingRect {
+  CGPoint points[] = {
+      incomingRect.origin,
+      CGPointMake(incomingRect.origin.x, incomingRect.origin.y + incomingRect.size.height),
+      CGPointMake(incomingRect.origin.x + incomingRect.size.width, incomingRect.origin.y),
+      CGPointMake(incomingRect.origin.x + incomingRect.size.width,
+                  incomingRect.origin.y + incomingRect.size.height)};
+
+  CGPoint origin = CGPointMake(CGFLOAT_MAX, CGFLOAT_MAX);
+  CGPoint farthest = CGPointMake(-CGFLOAT_MAX, -CGFLOAT_MAX);
+
+  for (int i = 0; i < 4; i++) {
+    const CGPoint point = points[i];
+
+    CGFloat x = _editableTransform.m11 * point.x + _editableTransform.m21 * point.y +
+                _editableTransform.m41;
+    CGFloat y = _editableTransform.m12 * point.x + _editableTransform.m22 * point.y +
+                _editableTransform.m42;
+
+    const CGFloat w = _editableTransform.m14 * point.x + _editableTransform.m24 * point.y +
+                      _editableTransform.m44;
+
+    if (w == 0.0) {
+      return CGRectZero;
+    } else if (w != 1.0) {
+      x /= w;
+      y /= w;
+    }
+
+    origin.x = MIN(origin.x, x);
+    origin.y = MIN(origin.y, y);
+    farthest.x = MAX(farthest.x, x);
+    farthest.y = MAX(farthest.y, y);
   }
-  // This only determines position of caret instead of any arbitrary range, but it's enough
-  // to properly position accent selection popup
-  if (CATransform3DIsAffine(_editableTransform) && !CGRectEqualToRect(_caretRect, CGRectNull)) {
-    CGRect rect =
-        CGRectApplyAffineTransform(_caretRect, CATransform3DGetAffineTransform(_editableTransform));
 
-    // convert to window coordinates
-    rect = [self.flutterViewController.flutterView convertRect:rect toView:nil];
+  const NSView* fromView = self.flutterViewController.flutterView;
+  const CGRect rectInWindow = [fromView
+      convertRect:CGRectMake(origin.x, origin.y, farthest.x - origin.x, farthest.y - origin.y)
+           toView:nil];
+  NSWindow* window = fromView.window;
+  return window ? [window convertRectToScreen:rectInWindow] : rectInWindow;
+}
 
-    // convert to screen coordinates
-    return [self.flutterViewController.flutterView.window convertRectToScreen:rect];
-  } else {
-    return CGRectZero;
-  }
+- (NSRect)firstRectForCharacterRange:(NSRange)range actualRange:(NSRangePointer)actualRange {
+  // This only determines position of caret instead of any arbitrary range, but it's enough
+  // to properly position accent selection popup
+  return !self.flutterViewController.viewLoaded || CGRectEqualToRect(_caretRect, CGRectNull)
+             ? CGRectZero
+             : [self screenRectFromFrameworkTransform:_caretRect];
 }
 
 - (NSUInteger)characterIndexForPoint:(NSPoint)point {

shell/platform/darwin/macos/framework/Source/FlutterTextInputPluginTest.mm

@@ -438,7 +438,6 @@ - (bool)testFirstRectForCharacterRange {
                     }];
 
   NSRect rect = [plugin firstRectForCharacterRange:NSMakeRange(0, 0) actualRange:nullptr];
-
   @try {
     OCMVerify(  // NOLINT(google-objc-avoid-throwing-exception)
         [windowMock convertRectToScreen:NSMakeRect(28, 10, 2, 19)]);
@@ -449,6 +448,148 @@ - (bool)testFirstRectForCharacterRange {
   return NSEqualRects(rect, NSMakeRect(38, 20, 2, 19));
 }
 
+- (bool)testFirstRectForCharacterRangeAtInfinity {
+  id engineMock = OCMClassMock([FlutterEngine class]);
+  id binaryMessengerMock = OCMProtocolMock(@protocol(FlutterBinaryMessenger));
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      [engineMock binaryMessenger])
+      .andReturn(binaryMessengerMock);
+  FlutterViewController* controllerMock = OCMClassMock([FlutterViewController class]);
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      [controllerMock engine])
+      .andReturn(engineMock);
+
+  id viewMock = OCMClassMock([NSView class]);
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      [viewMock bounds])
+      .andReturn(NSMakeRect(0, 0, 200, 200));
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      controllerMock.viewLoaded)
+      .andReturn(YES);
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      [controllerMock flutterView])
+      .andReturn(viewMock);
+
+  id windowMock = OCMClassMock([NSWindow class]);
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      [viewMock window])
+      .andReturn(windowMock);
+
+  FlutterTextInputPlugin* plugin =
+      [[FlutterTextInputPlugin alloc] initWithViewController:controllerMock];
+
+  FlutterMethodCall* call = [FlutterMethodCall
+      methodCallWithMethodName:@"TextInput.setEditableSizeAndTransform"
+                     arguments:@{
+                       @"height" : @(20.0),
+                       // Projects all points to infinity.
+                       @"transform" : @[
+                         @(1.0), @(0.0), @(0.0), @(0.0), @(0.0), @(1.0), @(0.0), @(0.0), @(0.0),
+                         @(0.0), @(1.0), @(0.0), @(20.0), @(10.0), @(0.0), @(0.0)
+                       ],
+                       @"width" : @(400.0),
+                     }];
+
+  [plugin handleMethodCall:call
+                    result:^(id){
+                    }];
+
+  call = [FlutterMethodCall methodCallWithMethodName:@"TextInput.setCaretRect"
+                                           arguments:@{
+                                             @"height" : @(19.0),
+                                             @"width" : @(2.0),
+                                             @"x" : @(8.0),
+                                             @"y" : @(0.0),
+                                           }];
+
+  [plugin handleMethodCall:call
+                    result:^(id){
+                    }];
+
+  NSRect rect = [plugin firstRectForCharacterRange:NSMakeRange(0, 0) actualRange:nullptr];
+  return NSEqualRects(rect, CGRectZero);
+}
+
+- (bool)testFirstRectForCharacterRangeWithEsotericAffineTransform {
+  id engineMock = OCMClassMock([FlutterEngine class]);
+  id binaryMessengerMock = OCMProtocolMock(@protocol(FlutterBinaryMessenger));
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      [engineMock binaryMessenger])
+      .andReturn(binaryMessengerMock);
+  FlutterViewController* controllerMock = OCMClassMock([FlutterViewController class]);
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      [controllerMock engine])
+      .andReturn(engineMock);
+
+  id viewMock = OCMClassMock([NSView class]);
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      [viewMock bounds])
+      .andReturn(NSMakeRect(0, 0, 200, 200));
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      controllerMock.viewLoaded)
+      .andReturn(YES);
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      [controllerMock flutterView])
+      .andReturn(viewMock);
+
+  id windowMock = OCMClassMock([NSWindow class]);
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      [viewMock window])
+      .andReturn(windowMock);
+
+  OCMExpect(  // NOLINT(google-objc-avoid-throwing-exception)
+      [viewMock convertRect:NSMakeRect(-18, 6, 3, 3) toView:nil])
+      .andReturn(NSMakeRect(-18, 6, 3, 3));
+
+  OCMExpect(  // NOLINT(google-objc-avoid-throwing-exception)
+      [windowMock convertRectToScreen:NSMakeRect(-18, 6, 3, 3)])
+      .andReturn(NSMakeRect(-18, 6, 3, 3));
+
+  FlutterTextInputPlugin* plugin =
+      [[FlutterTextInputPlugin alloc] initWithViewController:controllerMock];
+
+  FlutterMethodCall* call = [FlutterMethodCall
+      methodCallWithMethodName:@"TextInput.setEditableSizeAndTransform"
+                     arguments:@{
+                       @"height" : @(20.0),
+                       // This matrix can be generated by running this dart code snippet:
+                       // Matrix4.identity()..scale(3.0)..rotateZ(math.pi/2)..translate(1.0, 2.0,
+                       // 3.0);
+                       @"transform" : @[
+                         @(0.0), @(3.0), @(0.0), @(0.0), @(-3.0), @(0.0), @(0.0), @(0.0), @(0.0),
+                         @(0.0), @(3.0), @(0.0), @(-6.0), @(3.0), @(9.0), @(1.0)
+                       ],
+                       @"width" : @(400.0),
+                     }];
+
+  [plugin handleMethodCall:call
+                    result:^(id){
+                    }];
+
+  call = [FlutterMethodCall methodCallWithMethodName:@"TextInput.setCaretRect"
+                                           arguments:@{
+                                             @"height" : @(1.0),
+                                             @"width" : @(1.0),
+                                             @"x" : @(1.0),
+                                             @"y" : @(3.0),
+                                           }];
+
+  [plugin handleMethodCall:call
+                    result:^(id){
+                    }];
+
+  NSRect rect = [plugin firstRectForCharacterRange:NSMakeRange(0, 0) actualRange:nullptr];
+
+  @try {
+    OCMVerify(  // NOLINT(google-objc-avoid-throwing-exception)
+        [windowMock convertRectToScreen:NSMakeRect(-18, 6, 3, 3)]);
+  } @catch (...) {
+    return false;
+  }
+
+  return NSEqualRects(rect, NSMakeRect(-18, 6, 3, 3));
+}
+
 - (bool)testSetEditingStateWithTextEditingDelta {
   id engineMock = OCMClassMock([FlutterEngine class]);
   id binaryMessengerMock = OCMProtocolMock(@protocol(FlutterBinaryMessenger));
@@ -1226,6 +1367,15 @@ - (bool)testSelectorsAreForwardedToFramework {
   ASSERT_TRUE([[FlutterInputPluginTestObjc alloc] testFirstRectForCharacterRange]);
 }
 
+TEST(FlutterTextInputPluginTest, TestFirstRectForCharacterRangeAtInfinity) {
+  ASSERT_TRUE([[FlutterInputPluginTestObjc alloc] testFirstRectForCharacterRangeAtInfinity]);
+}
+
+TEST(FlutterTextInputPluginTest, TestFirstRectForCharacterRangeWithEsotericAffineTransform) {
+  ASSERT_TRUE([[FlutterInputPluginTestObjc alloc]
+      testFirstRectForCharacterRangeWithEsotericAffineTransform]);
+}
+
 TEST(FlutterTextInputPluginTest, TestSetEditingStateWithTextEditingDelta) {
   ASSERT_TRUE([[FlutterInputPluginTestObjc alloc] testSetEditingStateWithTextEditingDelta]);
 }