Page curl: state machine interface and its first tests

apple-tests/RNCPageCurlStateMachineTests.m

@@ -0,0 +1,134 @@
+#import <XCTest/XCTest.h>
+#import "RNCPageCurlStateMachine.h"
+
+static NSDictionary *Settle(NSInteger page, NSInteger chunk)
+{
+  return @{@"type": @"settled", @"page": @(page), @"totalPages": @10, @"chunkIndex": @(chunk), @"isLastChunk": @NO};
+}
+
+// one line per effect the controller has to carry out; notes are log lines only
+static NSArray<NSString *> *Describe(NSArray<RNCPageCurlEffect *> *effects)
+{
+  NSMutableArray<NSString *> *lines = [NSMutableArray array];
+  for (RNCPageCurlEffect *effect in effects) {
+    switch (effect.kind) {
+      case RNCPageCurlEffectEnterState:
+        [lines addObject:[NSString stringWithFormat:@"state %@ (%@)", RNCPageCurlStateName(effect.state), effect.reason]];
+        break;
+      case RNCPageCurlEffectBake:
+        [lines addObject:[NSString stringWithFormat:@"bake page %@ chunk %@", effect.settle[@"page"], effect.settle[@"chunkIndex"]]];
+        break;
+      case RNCPageCurlEffectBlankSlots:
+        [lines addObject:@"blank slots"];
+        break;
+      case RNCPageCurlEffectShowLandedPage:
+        [lines addObject:[NSString stringWithFormat:@"show landed %@", effect.direction]];
+        break;
+      case RNCPageCurlEffectShowCurrentPage:
+        [lines addObject:@"show current"];
+        break;
+      case RNCPageCurlEffectLand:
+        [lines addObject:[NSString stringWithFormat:@"land %@", effect.direction]];
+        break;
+      case RNCPageCurlEffectRequestSettle:
+        [lines addObject:@"request settle"];
+        break;
+      case RNCPageCurlEffectNote:
+        break;
+    }
+  }
+  return lines;
+}
+
+@interface RNCPageCurlStateMachineTests : XCTestCase
+@end
+
+@implementation RNCPageCurlStateMachineTests {
+  RNCPageCurlStateMachine *_machine;
+}
+
+- (void)setUp
+{
+  _machine = [RNCPageCurlStateMachine new];
+}
+
+// enabled, first page baked, idle
+- (void)bakeFirstPage
+{
+  [_machine enable];
+  [_machine settled:Settle(3, 1)];
+  [_machine bakeFinished:YES];
+}
+
+#pragma mark - the bake loop
+
+- (void)testStateNamesMatchTheLog
+{
+  XCTAssertEqualObjects(RNCPageCurlStateName(RNCPageCurlStateIdle), @"idle");
+  XCTAssertEqualObjects(RNCPageCurlStateName(RNCPageCurlStateAnimating), @"animating");
+  XCTAssertEqualObjects(RNCPageCurlStateName(RNCPageCurlStateBaking), @"baking");
+  XCTAssertEqualObjects(RNCPageCurlStateName(RNCPageCurlStateAwaitingSettle), @"awaitingSettle");
+  XCTAssertEqualObjects(RNCPageCurlStateName(RNCPageCurlStateAwaitingTapResult), @"awaitingTapResult");
+}
+
+- (void)testEnablingWaitsForTheFirstSettle
+{
+  XCTAssertEqualObjects(Describe([_machine enable]), (@[@"state awaitingSettle (enabled)"]));
+  XCTAssertEqual(_machine.state, RNCPageCurlStateAwaitingSettle);
+}
+
+- (void)testASettleStartsABake
+{
+  [_machine enable];
+  XCTAssertEqualObjects(Describe([_machine settled:Settle(3, 1)]), (@[@"state baking (settle)", @"bake page 3 chunk 1"]));
+  XCTAssertEqual(_machine.state, RNCPageCurlStateBaking);
+}
+
+- (void)testAFinishedBakeOpensInput
+{
+  [_machine enable];
+  [_machine settled:Settle(3, 1)];
+  XCTAssertEqualObjects(Describe([_machine bakeFinished:YES]), (@[@"state idle (baked)"]));
+  XCTAssertEqual(_machine.state, RNCPageCurlStateIdle);
+}
+
+- (void)testASettleWhileIdleBakesAgain
+{
+  [self bakeFirstPage];
+  XCTAssertEqualObjects(Describe([_machine settled:Settle(4, 1)]), (@[@"state baking (settle)", @"bake page 4 chunk 1"]));
+}
+
+- (void)testASettleDuringABakeIsKeptAndBakedAfter
+{
+  [_machine enable];
+  [_machine settled:Settle(3, 1)];
+  XCTAssertEqualObjects(Describe([_machine settled:Settle(4, 1)]), (@[]));
+  XCTAssertEqual(_machine.state, RNCPageCurlStateBaking);
+  XCTAssertEqualObjects(Describe([_machine bakeFinished:YES]), (@[@"bake page 4 chunk 1"]));
+  XCTAssertEqual(_machine.state, RNCPageCurlStateBaking);
+  XCTAssertEqualObjects(Describe([_machine bakeFinished:YES]), (@[@"state idle (baked)"]));
+}
+
+- (void)testOnlyTheLatestSettleKeptDuringABakeIsBaked
+{
+  [_machine enable];
+  [_machine settled:Settle(3, 1)];
+  [_machine settled:Settle(4, 1)];
+  [_machine settled:Settle(5, 1)];
+  XCTAssertEqualObjects(Describe([_machine bakeFinished:YES]), (@[@"bake page 5 chunk 1"]));
+}
+
+- (void)testEveryStateChangeMovesTheSerial
+{
+  NSUInteger initial = _machine.stateSerial;
+  [_machine enable];
+  NSUInteger enabled = _machine.stateSerial;
+  [_machine settled:Settle(3, 1)];
+  NSUInteger baking = _machine.stateSerial;
+  [_machine settled:Settle(4, 1)];
+  XCTAssertNotEqual(initial, enabled);
+  XCTAssertNotEqual(enabled, baking);
+  XCTAssertEqual(_machine.stateSerial, baking, @"a kept settle changes no state");
+}
+
+@end

apple/RNCPageCurlRenderer.mm

@@ -390,9 +390,43 @@ - (void)buildMeshes
     return nil;
   }
   CFTimeInterval start = CACurrentMediaTime();
-  // MTKTextureLoader refuses the snapshot's bitmap layout; redraw it as plain BGRA instead
   size_t width = CGImageGetWidth(cg);
   size_t height = CGImageGetHeight(cg);
+
+  // a WKWebView snapshot is 32-bit RGBA with alpha last; a UIGraphicsImageRenderer image is BGRA with alpha
+  // first. Metal reads both as-is given the matching pixel format, so neither needs a redraw.
+  CGBitmapInfo info = CGImageGetBitmapInfo(cg);
+  CGImageAlphaInfo alpha = (CGImageAlphaInfo)(info & kCGBitmapAlphaInfoMask);
+  CGBitmapInfo order = info & kCGBitmapByteOrderMask;
+  MTLPixelFormat directFormat = MTLPixelFormatInvalid;
+  if (CGImageGetBitsPerPixel(cg) == 32 && CGImageGetBitsPerComponent(cg) == 8) {
+    if (order == kCGBitmapByteOrder32Little && (alpha == kCGImageAlphaPremultipliedFirst || alpha == kCGImageAlphaNoneSkipFirst)) {
+      directFormat = MTLPixelFormatBGRA8Unorm;
+    } else if ((order == kCGBitmapByteOrderDefault || order == kCGBitmapByteOrder32Big) && (alpha == kCGImageAlphaPremultipliedLast || alpha == kCGImageAlphaNoneSkipLast)) {
+      directFormat = MTLPixelFormatRGBA8Unorm;
+    }
+  }
+
+  MTLTextureDescriptor *descriptor = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:directFormat != MTLPixelFormatInvalid ? directFormat : MTLPixelFormatBGRA8Unorm
+                                                                                        width:width
+                                                                                       height:height
+                                                                                    mipmapped:NO];
+  descriptor.usage = MTLTextureUsageShaderRead;
+  descriptor.storageMode = MTLStorageModeShared;
+  id<MTLTexture> texture = [self.device newTextureWithDescriptor:descriptor];
+
+  if (directFormat != MTLPixelFormatInvalid) {
+    CFDataRef data = CGDataProviderCopyData(CGImageGetDataProvider(cg));
+    if (data != nil) {
+      [texture replaceRegion:MTLRegionMake2D(0, 0, width, height) mipmapLevel:0 withBytes:CFDataGetBytePtr(data) bytesPerRow:CGImageGetBytesPerRow(cg)];
+      CFRelease(data);
+      RNCPageCurlLog(@"[page-curl] metal: texture %zux%zu in %.1fms (direct %@)", width, height, (CACurrentMediaTime() - start) * 1000.0, directFormat == MTLPixelFormatRGBA8Unorm ? @"rgba" : @"bgra");
+      return texture;
+    }
+  }
+
+  // any other layout is redrawn as plain BGRA first
+  RNCPageCurlLog(@"[page-curl] metal: snapshot layout bpp=%zu bpc=%zu bytesPerRow=%zu bitmapInfo=0x%x", CGImageGetBitsPerPixel(cg), CGImageGetBitsPerComponent(cg), CGImageGetBytesPerRow(cg), (unsigned)info);
   size_t bytesPerRow = width * 4;
   void *bytes = calloc(height, bytesPerRow);
   CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
@@ -406,16 +440,9 @@ - (void)buildMeshes
   }
   CGContextDrawImage(context, CGRectMake(0, 0, width, height), cg);
   CGContextRelease(context);
-  MTLTextureDescriptor *descriptor = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatBGRA8Unorm
-                                                                                        width:width
-                                                                                       height:height
-                                                                                    mipmapped:NO];
-  descriptor.usage = MTLTextureUsageShaderRead;
-  descriptor.storageMode = MTLStorageModeShared;
-  id<MTLTexture> texture = [self.device newTextureWithDescriptor:descriptor];
   [texture replaceRegion:MTLRegionMake2D(0, 0, width, height) mipmapLevel:0 withBytes:bytes bytesPerRow:bytesPerRow];
   free(bytes);
-  RNCPageCurlLog(@"[page-curl] metal: texture %zux%zu in %.1fms", width, height, (CACurrentMediaTime() - start) * 1000.0);
+  RNCPageCurlLog(@"[page-curl] metal: texture %zux%zu in %.1fms (redrawn)", width, height, (CACurrentMediaTime() - start) * 1000.0);
   return texture;
 }
 

apple/RNCPageCurlStateMachine.h

@@ -0,0 +1,84 @@
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+// the only state the controller keeps about the bake loop; input reaches the webview only when idle
+typedef NS_ENUM(NSInteger, RNCPageCurlState) {
+  RNCPageCurlStateIdle,
+  // a finger is turning a sheet, or the release animation is playing; the DOM does not move
+  RNCPageCurlStateAnimating,
+  // the slots are being snapshotted; runs to completion, a settle that arrives meanwhile is kept for after
+  RNCPageCurlStateBaking,
+  // the manager is moving the page (a tap, a jump, or a landed curl's page turn); its settle starts the bake
+  RNCPageCurlStateAwaitingSettle,
+  // a tap reached the webview; the manager answers with a settle (page turned) or touchEnd (nothing turned)
+  RNCPageCurlStateAwaitingTapResult,
+};
+
+FOUNDATION_EXPORT NSString *RNCPageCurlStateName(RNCPageCurlState state);
+
+typedef NS_ENUM(NSInteger, RNCPageCurlEffectKind) {
+  // the state changed; `state` and `reason`
+  RNCPageCurlEffectEnterState,
+  // snapshot every slot around the page `settle` names, then report bakeFinished:
+  RNCPageCurlEffectBake,
+  // the slots describe another page: no direction curls until the next bake
+  RNCPageCurlEffectBlankSlots,
+  // the turn toward `direction` landed: the cover shows that page
+  RNCPageCurlEffectShowLandedPage,
+  // the turn was cancelled: the cover shows the page it started on
+  RNCPageCurlEffectShowCurrentPage,
+  // ask the manager to turn the page toward `direction`, then report landingFinished:
+  RNCPageCurlEffectLand,
+  // ask the manager to settle again, then report settleRequestFinished:token: with `token`
+  RNCPageCurlEffectRequestSettle,
+  // nothing to do; `reason` is a line for the log
+  RNCPageCurlEffectNote,
+};
+
+@interface RNCPageCurlEffect : NSObject
+@property (nonatomic, readonly) RNCPageCurlEffectKind kind;
+@property (nonatomic, readonly) RNCPageCurlState state;
+@property (nonatomic, readonly, copy, nullable) NSString *reason;
+@property (nonatomic, readonly, copy, nullable) NSDictionary *settle;
+@property (nonatomic, readonly, copy, nullable) NSString *direction;
+@property (nonatomic, readonly) NSUInteger token;
+@end
+
+/**
+ * The page curl's bake loop as events in and effects out, with no views and no webview.
+ * The controller reports what happened and carries out the effects in order.
+ */
+@interface RNCPageCurlStateMachine : NSObject
+
+@property (nonatomic, readonly) RNCPageCurlState state;
+// changes on every state change and on teardown
+@property (nonatomic, readonly) NSUInteger stateSerial;
+@property (nonatomic, readonly) BOOL canBeginTurn;
+// state and what is being held, for the log
+@property (nonatomic, readonly) NSString *summary;
+
+- (NSArray<RNCPageCurlEffect *> *)enable;
+- (void)teardown;
+
+// messages from the manager
+- (NSArray<RNCPageCurlEffect *> *)settled:(NSDictionary *)settle;
+- (NSArray<RNCPageCurlEffect *> *)unsettled;
+- (NSArray<RNCPageCurlEffect *> *)touchEnded;
+
+// the finger
+- (NSArray<RNCPageCurlEffect *> *)tapped;
+- (NSArray<RNCPageCurlEffect *> *)turnBegan;
+- (NSArray<RNCPageCurlEffect *> *)turnFinishedToward:(NSString *)direction completed:(BOOL)completed;
+
+// results of effects
+- (NSArray<RNCPageCurlEffect *> *)bakeFinished:(BOOL)ok;
+- (NSArray<RNCPageCurlEffect *> *)landingFinished:(BOOL)ok;
+- (NSArray<RNCPageCurlEffect *> *)settleRequestFinished:(BOOL)ok token:(NSUInteger)token;
+
+// the bakes no longer match the page (resize, spine change)
+- (NSArray<RNCPageCurlEffect *> *)rebakeRequested:(NSString *)reason;
+
+@end
+
+NS_ASSUME_NONNULL_END

apple/RNCPageCurlStateMachine.m

@@ -0,0 +1,82 @@
+#import "RNCPageCurlStateMachine.h"
+
+NSString *RNCPageCurlStateName(RNCPageCurlState state)
+{
+  return @"?";
+}
+
+@implementation RNCPageCurlEffect
+@end
+
+@implementation RNCPageCurlStateMachine
+
+- (BOOL)canBeginTurn
+{
+  return NO;
+}
+
+- (NSString *)summary
+{
+  return @"";
+}
+
+- (NSArray<RNCPageCurlEffect *> *)enable
+{
+  return @[];
+}
+
+- (void)teardown
+{
+}
+
+- (NSArray<RNCPageCurlEffect *> *)settled:(NSDictionary *)settle
+{
+  return @[];
+}
+
+- (NSArray<RNCPageCurlEffect *> *)unsettled
+{
+  return @[];
+}
+
+- (NSArray<RNCPageCurlEffect *> *)touchEnded
+{
+  return @[];
+}
+
+- (NSArray<RNCPageCurlEffect *> *)tapped
+{
+  return @[];
+}
+
+- (NSArray<RNCPageCurlEffect *> *)turnBegan
+{
+  return @[];
+}
+
+- (NSArray<RNCPageCurlEffect *> *)turnFinishedToward:(NSString *)direction completed:(BOOL)completed
+{
+  return @[];
+}
+
+- (NSArray<RNCPageCurlEffect *> *)bakeFinished:(BOOL)ok
+{
+  return @[];
+}
+
+- (NSArray<RNCPageCurlEffect *> *)landingFinished:(BOOL)ok
+{
+  return @[];
+}
+
+- (NSArray<RNCPageCurlEffect *> *)settleRequestFinished:(BOOL)ok token:(NSUInteger)token
+{
+  return @[];
+}
+
+- (NSArray<RNCPageCurlEffect *> *)rebakeRequested:(NSString *)reason
+{
+  return @[];
+}
+
+@end

package.json

@@ -79,6 +79,7 @@
     "android/build.gradle",
     "android/gradle.properties",
     "apple",
+    "apple-tests",
     "ios",
     "macos",
     "windows",

react-native-webview.podspec

@@ -19,6 +19,13 @@ Pod::Spec.new do |s|
 
   s.source_files    = "apple/**/*.{h,m,mm,swift}"
 
+  # opt in from a Podfile with :testspecs => ['Tests']
+  s.test_spec 'Tests' do |test_spec|
+    test_spec.source_files = "apple-tests/**/*.{h,m}"
+    # the tests are Objective-C, but the bundle links the pod's C++ dependencies
+    test_spec.library = "c++"
+  end
+
   if defined?(install_modules_dependencies()) != nil
     install_modules_dependencies(s);
   else