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[android_camera_camerax] Fix incorrect camera mirroring for front cameras on devices using ImageReader Impeller backend #9233

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[android_camera_camerax] Fix incorrect camera mirroring for front cameras on devices using ImageReader Impeller backend #9233

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7b3809a
mirror camera
camsim99 May 8, 2025
1351c20
fix tests + bump version
camsim99 May 9, 2025
ceb9865
added mirroring tests
jesswrd Jun 2, 2025
50897b2
resolved conflicts
jesswrd Jun 2, 2025
fe4ffb3
updated changelog
jesswrd Jun 2, 2025
bdf32a7
formatted files
jesswrd Jun 2, 2025
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4 changes: 4 additions & 0 deletions packages/camera/camera_android_camerax/CHANGELOG.md
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Original file line number Diff line number Diff line change
@@ -1,3 +1,7 @@
## 0.6.18+1

* Fixes incorrect camera preview mirroring for front cameras of devices using the `ImageReader` Impeller backend.

## 0.6.18

* Adds support for the `MediaSettings.enableAudio` setting, which determines whether or not audio is
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14 changes: 13 additions & 1 deletion packages/camera/camera_android_camerax/lib/src/image_reader_rotated_preview.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -157,9 +157,21 @@ final class _ImageReaderRotatedPreviewState
sign: widget.facingSign,
);

// If the camera is front facing, mirror the camera preview
// according to the current device orientation.
Widget cameraPreview = widget.child;
if (widget.facingSign == 1) {
if (deviceOrientation == DeviceOrientation.portraitDown ||
deviceOrientation == DeviceOrientation.portraitUp) {
cameraPreview = Transform.scale(scaleY: -1, child: cameraPreview);
} else {
cameraPreview = Transform.scale(scaleX: -1, child: cameraPreview);
}
}

return RotatedBox(
quarterTurns: rotationDegrees ~/ 90,
child: widget.child,
child: cameraPreview,
);
} else {
return const SizedBox.shrink();
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2 changes: 1 addition & 1 deletion packages/camera/camera_android_camerax/pubspec.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ name: camera_android_camerax
description: Android implementation of the camera plugin using the CameraX library.
repository: https://github.com/flutter/packages/tree/main/packages/camera/camera_android_camerax
issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+camera%22
version: 0.6.18
version: 0.6.18+1

environment:
sdk: ^3.7.0
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185 changes: 162 additions & 23 deletions packages/camera/camera_android_camerax/test/preview_rotation_test.dart
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Expand Up @@ -7,7 +7,7 @@ import 'package:camera_android_camerax/src/camerax_library.dart';
import 'package:camera_android_camerax/src/camerax_proxy.dart';
import 'package:camera_platform_interface/camera_platform_interface.dart';
import 'package:flutter/services.dart';
import 'package:flutter/widgets.dart' show RotatedBox, Texture;
import 'package:flutter/widgets.dart' show RotatedBox, Texture, Transform;
import 'package:flutter_test/flutter_test.dart';
import 'package:mockito/mockito.dart';

Expand Down Expand Up @@ -1167,8 +1167,19 @@ void main() {
find.byType(RotatedBox),
);

expect(rotatedBox.child, isA<Texture>());
expect((rotatedBox.child! as Texture).textureId, cameraId);
// We expect a Transform widget to wrap the RotatedBox with the camera
// preview to mirror the preview, since the front camera is being
// used.
expect(rotatedBox.child, isA<Transform>());

final Transform transformedPreview = rotatedBox.child! as Transform;
final Matrix4 transformedPreviewMatrix =
transformedPreview.transform;

// Since the front camera is in portrait mode, we expect the camera
// preview to be mirrored across the y-axis.
expect(transformedPreviewMatrix.storage[5], closeTo(-1.0, 0.0001));
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What do you think about creating a helper method for these sorts of checks? Something like checkYAxisIsMirrored(double matrixArg5) and checkXAxisIsMirrored(double matrixArg0) with docs for both explaining why this checks what we think? I think this may help for clarity in the future.

expect((transformedPreview.child! as Texture).textureId, cameraId);
expect(
rotatedBox.quarterTurns,
expectedQuarterTurns,
Expand Down Expand Up @@ -1216,8 +1227,20 @@ void main() {
final RotatedBox rotatedBox = tester.widget<RotatedBox>(
find.byType(RotatedBox),
);
expect(rotatedBox.child, isA<Texture>());
expect((rotatedBox.child! as Texture).textureId, cameraId);

// We expect a Transform widget to wrap the RotatedBox with the camera
// preview to mirror the preview, since the front camera is being
// used.
expect(rotatedBox.child, isA<Transform>());

final Transform transformedPreview = rotatedBox.child! as Transform;
final Matrix4 transformedPreviewMatrix =
transformedPreview.transform;

// Since the front camera is in landscape mode, we expect the camera
// preview to be mirrored across the x-axis.
expect(transformedPreviewMatrix.storage[0], closeTo(-1.0, 0.0001));
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I assume the closeTo is because a precision error? If there's no workaround for that, can you add a comment here (or to the helper methods if you're open to adding them) about that?

expect((transformedPreview.child! as Texture).textureId, cameraId);
expect(
rotatedBox.quarterTurns,
expectedQuarterTurns,
Expand Down Expand Up @@ -1265,8 +1288,20 @@ void main() {
final RotatedBox rotatedBox = tester.widget<RotatedBox>(
find.byType(RotatedBox),
);
expect(rotatedBox.child, isA<Texture>());
expect((rotatedBox.child! as Texture).textureId, cameraId);

// We expect a Transform widget to wrap the RotatedBox with the camera
// preview to mirror the preview, since the front camera is being
// used.
expect(rotatedBox.child, isA<Transform>());

final Transform transformedPreview = rotatedBox.child! as Transform;
final Matrix4 transformedPreviewMatrix =
transformedPreview.transform;

// Since the front camera is in portrait mode, we expect the camera
// preview to be mirrored across the y-axis.
expect(transformedPreviewMatrix.storage[5], closeTo(-1.0, 0.0001));
expect((transformedPreview.child! as Texture).textureId, cameraId);
expect(
rotatedBox.quarterTurns,
expectedQuarterTurns,
Expand Down Expand Up @@ -1314,8 +1349,20 @@ void main() {
final RotatedBox rotatedBox = tester.widget<RotatedBox>(
find.byType(RotatedBox),
);
expect(rotatedBox.child, isA<Texture>());
expect((rotatedBox.child! as Texture).textureId, cameraId);

// We expect a Transform widget to wrap the RotatedBox with the camera
// preview to mirror the preview, since the front camera is being
// used.
expect(rotatedBox.child, isA<Transform>());

final Transform transformedPreview = rotatedBox.child! as Transform;
final Matrix4 transformedPreviewMatrix =
transformedPreview.transform;

// Since the front camera is in landscape mode, we expect the camera
// preview to be mirrored across the x-axis.
expect(transformedPreviewMatrix.storage[0], closeTo(-1.0, 0.0001));
expect((transformedPreview.child! as Texture).textureId, cameraId);
expect(
rotatedBox.quarterTurns,
expectedQuarterTurns,
Expand Down Expand Up @@ -1406,8 +1453,19 @@ void main() {
find.byType(RotatedBox),
);

expect(rotatedBox.child, isA<Texture>());
expect((rotatedBox.child! as Texture).textureId, cameraId);
// We expect a Transform widget to wrap the RotatedBox with the camera
// preview to mirror the preview, since the front camera is being
// used.
expect(rotatedBox.child, isA<Transform>());

final Transform transformedPreview = rotatedBox.child! as Transform;
final Matrix4 transformedPreviewMatrix =
transformedPreview.transform;

// Since the front camera is in landscape mode, we expect the camera
// preview to be mirrored across the x-axis.
expect(transformedPreviewMatrix.storage[0], closeTo(-1.0, 0.0001));
expect((transformedPreview.child! as Texture).textureId, cameraId);
expect(
rotatedBox.quarterTurns,
expectedQuarterTurns,
Expand Down Expand Up @@ -1455,9 +1513,22 @@ void main() {
final RotatedBox rotatedBox = tester.widget<RotatedBox>(
find.byType(RotatedBox),
);

// We expect a Transform widget to wrap the RotatedBox with the camera
// preview to mirror the preview, since the front camera is being
// used.
expect(rotatedBox.child, isA<Transform>());

final Transform transformedPreview = rotatedBox.child! as Transform;
final Matrix4 transformedPreviewMatrix =
transformedPreview.transform;

// Since the front camera is in landscape mode, we expect the camera
// preview to be mirrored across the x-axis.
expect(transformedPreviewMatrix.storage[0], closeTo(-1.0, 0.0001));
expect((transformedPreview.child! as Texture).textureId, cameraId);

final int clockwiseQuarterTurns = rotatedBox.quarterTurns + 4;
expect(rotatedBox.child, isA<Texture>());
expect((rotatedBox.child! as Texture).textureId, cameraId);
expect(
clockwiseQuarterTurns,
expectedQuarterTurns,
Expand Down Expand Up @@ -1503,9 +1574,22 @@ void main() {
final RotatedBox rotatedBox = tester.widget<RotatedBox>(
find.byType(RotatedBox),
);

// We expect a Transform widget to wrap the RotatedBox with the camera
// preview to mirror the preview, since the front camera is being
// used.
expect(rotatedBox.child, isA<Transform>());

final Transform transformedPreview = rotatedBox.child! as Transform;
final Matrix4 transformedPreviewMatrix =
transformedPreview.transform;

// Since the front camera is in landscape mode, we expect the camera
// preview to be mirrored across the x-axis.
expect(transformedPreviewMatrix.storage[0], closeTo(-1.0, 0.0001));
expect((transformedPreview.child! as Texture).textureId, cameraId);

final int clockwiseQuarterTurns = rotatedBox.quarterTurns + 4;
expect(rotatedBox.child, isA<Texture>());
expect((rotatedBox.child! as Texture).textureId, cameraId);
expect(
clockwiseQuarterTurns,
expectedQuarterTurns,
Expand Down Expand Up @@ -1553,9 +1637,22 @@ void main() {
final RotatedBox rotatedBox = tester.widget<RotatedBox>(
find.byType(RotatedBox),
);

// We expect a Transform widget to wrap the RotatedBox with the camera
// preview to mirror the preview, since the front camera is being
// used.
expect(rotatedBox.child, isA<Transform>());

final Transform transformedPreview = rotatedBox.child! as Transform;
final Matrix4 transformedPreviewMatrix =
transformedPreview.transform;

// Since the front camera is in landscape mode, we expect the camera
// preview to be mirrored across the x-axis.
expect(transformedPreviewMatrix.storage[0], closeTo(-1.0, 0.0001));
expect((transformedPreview.child! as Texture).textureId, cameraId);

final int clockwiseQuarterTurns = rotatedBox.quarterTurns + 4;
expect(rotatedBox.child, isA<Texture>());
expect((rotatedBox.child! as Texture).textureId, cameraId);
expect(
clockwiseQuarterTurns,
expectedQuarterTurns,
Expand Down Expand Up @@ -1662,12 +1759,24 @@ void main() {
final RotatedBox rotatedBox = tester.widget<RotatedBox>(
find.byType(RotatedBox),
);

// We expect a Transform widget to wrap the RotatedBox with the camera
// preview to mirror the preview, since the front camera is being
// used.
expect(rotatedBox.child, isA<Transform>());

final Transform transformedPreview = rotatedBox.child! as Transform;
final Matrix4 transformedPreviewMatrix = transformedPreview.transform;

// Since the front camera is in landscape mode, we expect the camera
// preview to be mirrored across the x-axis.
expect(transformedPreviewMatrix.storage[0], closeTo(-1.0, 0.0001));
expect((transformedPreview.child! as Texture).textureId, cameraId);

final int clockwiseQuarterTurns =
rotatedBox.quarterTurns < 0
? rotatedBox.quarterTurns + 4
: rotatedBox.quarterTurns;
expect(rotatedBox.child, isA<Texture>());
expect((rotatedBox.child! as Texture).textureId, cameraId);
expect(
clockwiseQuarterTurns,
expectedQuarterTurns,
Expand Down Expand Up @@ -1760,12 +1869,30 @@ void main() {
final RotatedBox rotatedBox = tester.widget<RotatedBox>(
find.byType(RotatedBox),
);

// We expect a Transform widget to wrap the RotatedBox with the camera
// preview to mirror the preview, since the front camera is being
// used.
expect(rotatedBox.child, isA<Transform>());

final Transform transformedPreview = rotatedBox.child! as Transform;
final Matrix4 transformedPreviewMatrix = transformedPreview.transform;

// When the front camera is in landscape mode, we expect the camera
// preview to be mirrored across the x-axis. When the front camera
// is in portrait mode, we expect the camera preview to be mirrored
// across the y-axis.
if (currentDeviceOrientation == DeviceOrientation.landscapeLeft ||
currentDeviceOrientation == DeviceOrientation.landscapeRight) {
expect(transformedPreviewMatrix.storage[0], closeTo(-1.0, 0.0001));
} else {
expect(transformedPreviewMatrix.storage[5], closeTo(-1.0, 0.0001));
}
expect((transformedPreview.child! as Texture).textureId, cameraId);
final int clockwiseQuarterTurns =
rotatedBox.quarterTurns < 0
? rotatedBox.quarterTurns + 4
: rotatedBox.quarterTurns;
expect(rotatedBox.child, isA<Texture>());
expect((rotatedBox.child! as Texture).textureId, cameraId);
expect(
clockwiseQuarterTurns,
expectedQuarterTurns,
Expand Down Expand Up @@ -2013,8 +2140,20 @@ void main() {
final RotatedBox rotatedBox = tester.widget<RotatedBox>(
find.byType(RotatedBox),
);
expect(rotatedBox.child, isA<Texture>());
expect((rotatedBox.child! as Texture).textureId, cameraId);

// We expect a Transform widget to wrap the RotatedBox with the camera
// preview to mirror the preview, since the front camera is being
// used.
expect(rotatedBox.child, isA<Transform>());

final Transform transformedPreview = rotatedBox.child! as Transform;
final Matrix4 transformedPreviewMatrix =
transformedPreview.transform;

// Since the front camera is in landscape mode, we expect the camera
// preview to be mirrored across the x-axis.
expect(transformedPreviewMatrix.storage[0], closeTo(-1.0, 0.0001));
expect((transformedPreview.child! as Texture).textureId, cameraId);
expect(
rotatedBox.quarterTurns,
expectedQuarterTurns,
Expand Down