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Added support for optimised reference image PNGs
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This allows to use apps like ImageOptim.app to optimise recorded
reference images. Optimising reference image can heavily reduce
its size, meaning we need to store less binary data in repo.
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@lukaskukacka
lukaskukacka committed Apr 13, 2019
1 parent c944c1f commit ee17d57
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Showing 6 changed files with 56 additions and 11 deletions.
12 changes: 12 additions & 0 deletions FBSnapshotTestCase.xcodeproj/project.pbxproj
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Expand Up @@ -36,6 +36,10 @@
827137A21C63AC0D00354E42 /* square-copy.png in Resources */ = {isa = PBXBuildFile; fileRef = B32447DA1AB78B5E00B1D6FF /* square-copy.png */; };
827137A31C63AC0D00354E42 /* square.png in Resources */ = {isa = PBXBuildFile; fileRef = B32447DB1AB78B5E00B1D6FF /* square.png */; };
827137A41C63AC0F00354E42 /* FBSnapshotControllerTests.m in Sources */ = {isa = PBXBuildFile; fileRef = B31988301AB784CB00B0A900 /* FBSnapshotControllerTests.m */; };
A9E093ED2261EEA400B1EDE3 /* square_with_graphics_imageoptim.png in Resources */ = {isa = PBXBuildFile; fileRef = A9E093EB2261EEA300B1EDE3 /* square_with_graphics_imageoptim.png */; };
A9E093EE2261EEA400B1EDE3 /* square_with_graphics_imageoptim.png in Resources */ = {isa = PBXBuildFile; fileRef = A9E093EB2261EEA300B1EDE3 /* square_with_graphics_imageoptim.png */; };
A9E093EF2261EEA400B1EDE3 /* square_with_graphics.png in Resources */ = {isa = PBXBuildFile; fileRef = A9E093EC2261EEA400B1EDE3 /* square_with_graphics.png */; };
A9E093F02261EEA400B1EDE3 /* square_with_graphics.png in Resources */ = {isa = PBXBuildFile; fileRef = A9E093EC2261EEA400B1EDE3 /* square_with_graphics.png */; };
B31987FC1AB782D100B0A900 /* FBSnapshotTestCase.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = B31987F01AB782D000B0A900 /* FBSnapshotTestCase.framework */; };
B31988281AB7849400B0A900 /* FBSnapshotTestCase.h in Headers */ = {isa = PBXBuildFile; fileRef = B31988201AB7849400B0A900 /* FBSnapshotTestCase.h */; settings = {ATTRIBUTES = (Public, ); }; };
B31988291AB7849400B0A900 /* FBSnapshotTestCase.m in Sources */ = {isa = PBXBuildFile; fileRef = B31988211AB7849400B0A900 /* FBSnapshotTestCase.m */; };
Expand Down Expand Up @@ -80,6 +84,8 @@
42F2B74320C0D7A400ABED24 /* rect_shade.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = rect_shade.png; sourceTree = "<group>"; };
8271377A1C63AB6F00354E42 /* FBSnapshotTestCase.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = FBSnapshotTestCase.framework; sourceTree = BUILT_PRODUCTS_DIR; };
827137831C63AB7000354E42 /* FBSnapshotTestCase tvOS Tests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = "FBSnapshotTestCase tvOS Tests.xctest"; sourceTree = BUILT_PRODUCTS_DIR; };
A9E093EB2261EEA300B1EDE3 /* square_with_graphics_imageoptim.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = square_with_graphics_imageoptim.png; sourceTree = "<group>"; };
A9E093EC2261EEA400B1EDE3 /* square_with_graphics.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = square_with_graphics.png; sourceTree = "<group>"; };
B31987F01AB782D000B0A900 /* FBSnapshotTestCase.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = FBSnapshotTestCase.framework; sourceTree = BUILT_PRODUCTS_DIR; };
B31987F41AB782D000B0A900 /* FBSnapshotTestCase-Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = "FBSnapshotTestCase-Info.plist"; sourceTree = "<group>"; };
B31987FB1AB782D100B0A900 /* FBSnapshotTestCase iOS Tests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = "FBSnapshotTestCase iOS Tests.xctest"; sourceTree = BUILT_PRODUCTS_DIR; };
Expand Down Expand Up @@ -196,6 +202,8 @@
children = (
42F2B74320C0D7A400ABED24 /* rect_shade.png */,
B76C68271C6BD68100586E5B /* rect.png */,
A9E093EB2261EEA300B1EDE3 /* square_with_graphics_imageoptim.png */,
A9E093EC2261EEA400B1EDE3 /* square_with_graphics.png */,
E5C2CD611B1F399A00669887 /* square_with_pixel.png */,
B32447D91AB78B5E00B1D6FF /* square_with_text.png */,
B32447DA1AB78B5E00B1D6FF /* square-copy.png */,
Expand Down Expand Up @@ -380,11 +388,13 @@
buildActionMask = 2147483647;
files = (
B76C682A1C6BD6D500586E5B /* rect.png in Resources */,
A9E093EE2261EEA400B1EDE3 /* square_with_graphics_imageoptim.png in Resources */,
827137A01C63AC0700354E42 /* square_with_pixel.png in Resources */,
827137A21C63AC0D00354E42 /* square-copy.png in Resources */,
827137A31C63AC0D00354E42 /* square.png in Resources */,
827137A11C63AC0900354E42 /* square_with_text.png in Resources */,
42F2B74520C0D7A400ABED24 /* rect_shade.png in Resources */,
A9E093F02261EEA400B1EDE3 /* square_with_graphics.png in Resources */,
);
runOnlyForDeploymentPostprocessing = 0;
};
Expand All @@ -400,11 +410,13 @@
buildActionMask = 2147483647;
files = (
B76C68291C6BD6D200586E5B /* rect.png in Resources */,
A9E093ED2261EEA400B1EDE3 /* square_with_graphics_imageoptim.png in Resources */,
B32447DC1AB78B5E00B1D6FF /* square_with_text.png in Resources */,
E5C2CD621B1F399A00669887 /* square_with_pixel.png in Resources */,
B32447DE1AB78B5E00B1D6FF /* square.png in Resources */,
B32447DD1AB78B5E00B1D6FF /* square-copy.png in Resources */,
42F2B74420C0D7A400ABED24 /* rect_shade.png in Resources */,
A9E093EF2261EEA400B1EDE3 /* square_with_graphics.png in Resources */,
);
runOnlyForDeploymentPostprocessing = 0;
};
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31 changes: 20 additions & 11 deletions FBSnapshotTestCase/Categories/UIImage+Compare.m
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Expand Up @@ -51,9 +51,15 @@ - (BOOL)fb_compareWithImage:(UIImage *)image perPixelTolerance:(CGFloat)perPixel
CGSize referenceImageSize = CGSizeMake(CGImageGetWidth(self.CGImage), CGImageGetHeight(self.CGImage));
CGSize imageSize = CGSizeMake(CGImageGetWidth(image.CGImage), CGImageGetHeight(image.CGImage));

// The images have the equal size, so we could use the smallest amount of bytes because of byte padding
size_t minBytesPerRow = MIN(CGImageGetBytesPerRow(self.CGImage), CGImageGetBytesPerRow(image.CGImage));
size_t referenceImageSizeBytes = referenceImageSize.height * minBytesPerRow;
// Find image which requires more bytes in memory. We have to normalise both images to context requiring "bigger" memory representation.
// This allows comparing 2 visually identic images even if their bit representation in file can be different
// (for example reference images optimised using ImageOptim app).
// Because both images have the same pixel size, image with more bytes per row is the image dictating the context confix for comparison.
UIImage *contextConfigImage = (CGImageGetBytesPerRow(image.CGImage) > CGImageGetBytesPerRow(self.CGImage) ? image : self);

// Create contexts for both images using the same configuration.
size_t bytesPerRow = CGImageGetBytesPerRow(contextConfigImage.CGImage);
size_t referenceImageSizeBytes = referenceImageSize.height * bytesPerRow;
void *referenceImagePixels = calloc(1, referenceImageSizeBytes);
void *imagePixels = calloc(1, referenceImageSizeBytes);

Expand All @@ -63,20 +69,23 @@ - (BOOL)fb_compareWithImage:(UIImage *)image perPixelTolerance:(CGFloat)perPixel
return NO;
}

size_t bitsPerComponent = CGImageGetBitsPerComponent(contextConfigImage.CGImage);
CGBitmapInfo bitmapInfo = (CGBitmapInfo)kCGImageAlphaPremultipliedLast;

CGContextRef referenceImageContext = CGBitmapContextCreate(referenceImagePixels,
referenceImageSize.width,
referenceImageSize.height,
CGImageGetBitsPerComponent(self.CGImage),
minBytesPerRow,
CGImageGetColorSpace(self.CGImage),
(CGBitmapInfo)kCGImageAlphaPremultipliedLast);
bitsPerComponent,
bytesPerRow,
CGImageGetColorSpace(contextConfigImage.CGImage),
bitmapInfo);
CGContextRef imageContext = CGBitmapContextCreate(imagePixels,
imageSize.width,
imageSize.height,
CGImageGetBitsPerComponent(image.CGImage),
minBytesPerRow,
CGImageGetColorSpace(image.CGImage),
(CGBitmapInfo)kCGImageAlphaPremultipliedLast);
bitsPerComponent,
bytesPerRow,
CGImageGetColorSpace(contextConfigImage.CGImage),
bitmapInfo);

if (!referenceImageContext || !imageContext) {
CGContextRelease(referenceImageContext);
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14 changes: 14 additions & 0 deletions FBSnapshotTestCaseTests/FBSnapshotControllerTests.m
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Expand Up @@ -48,6 +48,20 @@ - (void)testCompareReferenceImageToImageShouldNotBeEqual
XCTAssertEqual(error.code, FBSnapshotTestControllerErrorCodeImagesDifferent);
}

- (void)testCompareOptimisedReferenceImageToImageShouldBeEqual
{
UIImage *referenceImage = [self _bundledImageNamed:@"square_with_graphics_imageoptim" type:@"png"];
XCTAssertNotNil(referenceImage);
UIImage *testImage = [self _bundledImageNamed:@"square_with_graphics" type:@"png"];
XCTAssertNotNil(testImage);

id testClass = nil;
FBSnapshotTestController *controller = [[FBSnapshotTestController alloc] initWithTestClass:testClass];
NSError *error = nil;
XCTAssertTrue([controller compareReferenceImage:referenceImage toImage:testImage overallTolerance:0 error:&error]);
XCTAssertNil(error);
}

- (void)testCompareReferenceImageWithVeryLowToleranceShouldNotMatch
{
UIImage *referenceImage = [self _bundledImageNamed:@"square" type:@"png"];
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Binary file added FBSnapshotTestCaseTests/square_with_graphics.png
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Binary file added FBSnapshotTestCaseTests/square_with_graphics_imageoptim.png
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10 changes: 10 additions & 0 deletions README.md
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Expand Up @@ -79,6 +79,7 @@ Features
- Support for `CALayer` via `FBSnapshotVerifyLayer`.
- `usesDrawViewHierarchyInRect` to handle cases like `UIVisualEffect`, `UIAppearance` and Size Classes.
- `fileNameOptions` to control appending the device model (`iPhone`, `iPad`, `iPod Touch`, etc), OS version, screen size and screen scale to the images (allowing to have multiple tests for the same «snapshot» for different `OS`s and devices).
- Support of reference images optimized for reduced size.

Notes
-----
Expand All @@ -94,6 +95,15 @@ have separate targets for the two types.

Read more on this [here](docs/LibraryVsApplicationTestBundles.md).

Optimizing reference images to reduce size
------------------------------------------

Recorded reference image PNG can be optimised to reduce its size using lossless compression.

Once you have final reference images recorded, you can manually optimise them using tools like [ImageOptim](https://imageoptim.com). ImageOptim will reduce size of the image without loss of any visual information. The savings in image sizes can be significant (up to 80%+ depending on the original image).
If you are committing reference images to repository, optimizing them reduces their impact growing to repo size.
Authors
-------
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