iOS WebCore的WebEvent和EventHandler
WebEvent是iOS專有的類，負責封裝和攜帶從UIKit得到的系統事件信息，並由WebKit層的WAKResponder子類傳遞到WebCore的EventHandler。
開源碼中WebEvent的聲明為：
[cpp] typedef enum {
WebEventMouseDown,
WebEventMouseUp,
WebEventMouseMoved,
WebEventScrollWheel,
WebEventKeyDown,
WebEventKeyUp,
WebEventTouchBegin,
WebEventTouchChange,
WebEventTouchEnd,
WebEventTouchCancel
} WebEventType;
typedef enum {
WebEventTouchPhaseBegan,
WebEventTouchPhaseMoved,
WebEventTouchPhaseStationary,
WebEventTouchPhaseEnded,
WebEventTouchPhaseCancelled
} WebEventTouchPhaseType;
// These enum values are copied directly from GSEvent for compatibility.
typedef enum
{
WebEventFlagMaskAlphaShift = 0x00010000,
WebEventFlagMaskShift = 0x00020000,
WebEventFlagMaskControl = 0x00040000,
WebEventFlagMaskAlternate = 0x00080000,
WebEventFlagMaskCommand = 0x00100000,
} WebEventFlagValues;
typedef unsigned WebEventFlags;
// These enum values are copied directly from GSEvent for compatibility.
typedef enum
{
WebEventCharacterSetASCII = 0,
WebEventCharacterSetSymbol = 1,
WebEventCharacterSetDingbats = 2,
WebEventCharacterSetUnicode = 253,
WebEventCharacterSetFunctionKeys = 254,
} WebEventCharacterSet;
@interface WebEvent : NSObject {
@private
WebEventType _type;
CFTimeInterval _timestamp;
CGPoint _locationInWindow;
NSString *_characters;
NSString *_charactersIgnoringModifiers;
WebEventFlags _modifierFlags;
BOOL _keyRepeating;
BOOL _popupVariant;
uint16_t _keyCode;
BOOL _tabKey;
WebEventCharacterSet _characterSet;
float _deltaX;
float _deltaY;
unsigned _touchCount;
NSArray *_touchLocations;
NSArray *_touchIdentifiers;
NSArray *_touchPhases;
BOOL _isGesture;
float _gestureScale;
float _gestureRotation;
}
- (WebEvent *)initWithMouseEventType:(WebEventType)type
timeStamp:(CFTimeInterval)timeStamp
location:(CGPoint)point;
- (WebEvent *)initWithScrollWheelEventWithTimeStamp:(CFTimeInterval)timeStamp
location:(CGPoint)point
deltaX:(float)deltaX
deltaY:(float)deltaY;
- (WebEvent *)initWithTouchEventType:(WebEventType)type
timeStamp:(CFTimeInterval)timeStamp
location:(CGPoint)point
modifiers:(WebEventFlags)modifiers
touchCount:(unsigned)touchCount
touchLocations:(NSArray *)touchLocations
touchIdentifiers:(NSArray *)touchIdentifiers
touchPhases:(NSArray *)touchPhases isGesture:(BOOL)isGesture
gestureScale:(float)gestureScale
gestureRotation:(float)gestureRotation;
- (WebEvent *)initWithKeyEventType:(WebEventType)type
timeStamp:(CFTimeInterval)timeStamp
characters:(NSString *)characters
charactersIgnoringModifiers:(NSString *)charactersIgnoringModifiers
modifiers:(WebEventFlags)modifiers
isRepeating:(BOOL)repeating
isPopupVariant:(BOOL)popupVariant
keyCode:(uint16_t)keyCode
isTabKey:(BOOL)tabKey
characterSet:(WebEventCharacterSet)characterSet;
@property(nonatomic,readonly) WebEventType type;
@property(nonatomic,readonly) CFTimeInterval timestamp;
// Mouse
@property(nonatomic,readonly) CGPoint locationInWindow;
// Keyboard
@property(nonatomic,readonly,retain) NSString *characters;
@property(nonatomic,readonly,retain) NSString *charactersIgnoringModifiers;
@property(nonatomic,readonly) WebEventFlags modifierFlags;
@property(nonatomic,readonly,getter=isKeyRepeating) BOOL keyRepeating;
@property(nonatomic,readonly,getter=isPopupVariant) BOOL popupVariant;
@property(nonatomic,readonly) uint16_t keyCode;
@property(nonatomic,readonly,getter=isTabKey) BOOL tabKey;
@property(nonatomic,readonly) WebEventCharacterSet characterSet;
// Scroll Wheel
@property(nonatomic,readonly) float deltaX;
@property(nonatomic,readonly) float deltaY;
// Touch
@property(nonatomic,readonly) unsigned touchCount;
@property(nonatomic,readonly,retain) NSArray *touchLocations;
@property(nonatomic,readonly,retain) NSArray *touchIdentifiers;
@property(nonatomic,readonly,retain) NSArray *touchPhases;
// Gesture
@property(nonatomic,readonly) BOOL isGesture;
@property(nonatomic,readonly) float gestureScale;
@property(nonatomic,readonly) float gestureRotation;
@end
typedef enum {
WebEventMouseDown,
WebEventMouseUp,
WebEventMouseMoved,
WebEventScrollWheel,
WebEventKeyDown,
WebEventKeyUp,
WebEventTouchBegin,
WebEventTouchChange,
WebEventTouchEnd,
WebEventTouchCancel
} WebEventType;
typedef enum {
WebEventTouchPhaseBegan,
WebEventTouchPhaseMoved,
WebEventTouchPhaseStationary,
WebEventTouchPhaseEnded,
WebEventTouchPhaseCancelled
} WebEventTouchPhaseType;
// These enum values are copied directly from GSEvent for compatibility.
typedef enum
{
WebEventFlagMaskAlphaShift = 0x00010000,
WebEventFlagMaskShift = 0x00020000,
WebEventFlagMaskControl = 0x00040000,
WebEventFlagMaskAlternate = 0x00080000,
WebEventFlagMaskCommand = 0x00100000,
} WebEventFlagValues;
typedef unsigned WebEventFlags;
// These enum values are copied directly from GSEvent for compatibility.
typedef enum
{
WebEventCharacterSetASCII = 0,
WebEventCharacterSetSymbol = 1,
WebEventCharacterSetDingbats = 2,
WebEventCharacterSetUnicode = 253,
WebEventCharacterSetFunctionKeys = 254,
} WebEventCharacterSet;
@interface WebEvent : NSObject {
@private
WebEventType _type;
CFTimeInterval _timestamp;
CGPoint _locationInWindow;
NSString *_characters;
NSString *_charactersIgnoringModifiers;
WebEventFlags _modifierFlags;
BOOL _keyRepeating;
BOOL _popupVariant;
uint16_t _keyCode;
BOOL _tabKey;
WebEventCharacterSet _characterSet;
float _deltaX;
float _deltaY;
unsigned _touchCount;
NSArray *_touchLocations;
NSArray *_touchIdentifiers;
NSArray *_touchPhases;
BOOL _isGesture;
float _gestureScale;
float _gestureRotation;
}
- (WebEvent *)initWithMouseEventType:(WebEventType)type
timeStamp:(CFTimeInterval)timeStamp
location:(CGPoint)point;
- (WebEvent *)initWithScrollWheelEventWithTimeStamp:(CFTimeInterval)timeStamp
location:(CGPoint)point
deltaX:(float)deltaX
deltaY:(float)deltaY;
- (WebEvent *)initWithTouchEventType:(WebEventType)type
timeStamp:(CFTimeInterval)timeStamp
location:(CGPoint)point
modifiers:(WebEventFlags)modifiers
touchCount:(unsigned)touchCount
touchLocations:(NSArray *)touchLocations
touchIdentifiers:(NSArray *)touchIdentifiers
touchPhases:(NSArray *)touchPhases isGesture:(BOOL)isGesture
gestureScale:(float)gestureScale
gestureRotation:(float)gestureRotation;
- (WebEvent *)initWithKeyEventType:(WebEventType)type
timeStamp:(CFTimeInterval)timeStamp
characters:(NSString *)characters
charactersIgnoringModifiers:(NSString *)charactersIgnoringModifiers
modifiers:(WebEventFlags)modifiers
isRepeating:(BOOL)repeating
isPopupVariant:(BOOL)popupVariant
keyCode:(uint16_t)keyCode
isTabKey:(BOOL)tabKey
characterSet:(WebEventCharacterSet)characterSet;
@property(nonatomic,readonly) WebEventType type;
@property(nonatomic,readonly) CFTimeInterval timestamp;
// Mouse
@property(nonatomic,readonly) CGPoint locationInWindow;
// Keyboard
@property(nonatomic,readonly,retain) NSString *characters;
@property(nonatomic,readonly,retain) NSString *charactersIgnoringModifiers;
@property(nonatomic,readonly) WebEventFlags modifierFlags;
@property(nonatomic,readonly,getter=isKeyRepeating) BOOL keyRepeating;
@property(nonatomic,readonly,getter=isPopupVariant) BOOL popupVariant;
@property(nonatomic,readonly) uint16_t keyCode;
@property(nonatomic,readonly,getter=isTabKey) BOOL tabKey;
@property(nonatomic,readonly) WebEventCharacterSet characterSet;
// Scroll Wheel
@property(nonatomic,readonly) float deltaX;
@property(nonatomic,readonly) float deltaY;
// Touch
@property(nonatomic,readonly) unsigned touchCount;
@property(nonatomic,readonly,retain) NSArray *touchLocations;
@property(nonatomic,readonly,retain) NSArray *touchIdentifiers;
@property(nonatomic,readonly,retain) NSArray *touchPhases;
// Gesture
@property(nonatomic,readonly) BOOL isGesture;
@property(nonatomic,readonly) float gestureScale;
@property(nonatomic,readonly) float gestureRotation;
@end
WebEvent封裝了4種事件：鼠標（手指）、鍵盤、滾輪、觸摸，主要通過屬性WebEventType type來區分。
鼠標事件主要由單擊手勢來觸發，會產生mouseup，mousemove和mousedown事件。其中單擊就是同一RunLoop內連貫的mousedown和mouseup，而mousemove是模擬事件，可觸發mouseover消息。
鍵盤事件發生在編輯框內，按下iOS虛擬鍵盤的按鍵就會觸發。
滾輪由雙指平移手勢觸發，在輸入框內有效。
觸摸特指JavaScript監聽的touchstart、gesturestart等消息，由UIWebTouchEventsGestureRecognizer來計算。
這些事件觸發後，都會在主線程創建WebEvent，然後用GCD技術轉到WebThread執行。
開源碼的EventHandler.h中有如下幾行：
[cpp] #if PLATFORM(MAC) && defined(__OBJC__)
void mouseDown(WebEvent *);
void mouseUp(WebEvent *);
void mouseMoved(WebEvent *);
bool keyEvent(WebEvent *);
bool wheelEvent(WebEvent *);
void touchEvent(WebEvent *);
static WebEvent *currentEvent();
#endif
#if PLATFORM(MAC) && defined(__OBJC__)
void mouseDown(WebEvent *);
void mouseUp(WebEvent *);
void mouseMoved(WebEvent *);
bool keyEvent(WebEvent *);
bool wheelEvent(WebEvent *);
void touchEvent(WebEvent *);
static WebEvent *currentEvent();
#endif使用xdb也能找到，可是在EventHandler的實現中卻找不到，所以Apple是沒有完全公開iOS源碼的。
另有一個PlatformEventFactoryIOS.h的文件有如下聲明：
[cpp] class PlatformEventFactory {
public:
static PlatformMouseEvent createPlatformMouseEvent(WebEvent *);
static PlatformWheelEvent createPlatformWheelEvent(WebEvent *);
static PlatformKeyboardEvent createPlatformKeyboardEvent(WebEvent *);
static PlatformTouchEvent createPlatformTouchEvent(WebEvent *);
};
class PlatformEventFactory {
public:
static PlatformMouseEvent createPlatformMouseEvent(WebEvent *);
static PlatformWheelEvent createPlatformWheelEvent(WebEvent *);
static PlatformKeyboardEvent createPlatformKeyboardEvent(WebEvent *);
static PlatformTouchEvent createPlatformTouchEvent(WebEvent *);
};這些函數的作用就是把Objective-C類封裝的WebEvent轉換成WebCore裡C++的PlatformEvent。可以猜測，接受WebEvent型參數的EventHandler函數也就只是簡單做這個工作，轉換後再直接調用通用的函數就ok了。如：
[cpp] bool handleMousePressEvent(const PlatformMouseEvent&);
bool handleMouseMoveEvent(const PlatformMouseEvent&, HitTestResult* hoveredNode = 0, bool onlyUpdateScrollbars = false);
bool handleMouseReleaseEvent(const PlatformMouseEvent&);
bool handleWheelEvent(const PlatformWheelEvent&);
void defaultWheelEventHandler(Node*, WheelEvent*);
ENABLE(GESTURE_EVENTS)
bool handleGestureEvent(const PlatformGestureEvent&);
bool handleGestureTap(const PlatformGestureEvent&, Node* preTargetedNode = 0);
bool handleGestureScrollUpdate(const PlatformGestureEvent&);
if
bool handleMousePressEvent(const PlatformMouseEvent&);
bool handleMouseMoveEvent(const PlatformMouseEvent&, HitTestResult* hoveredNode = 0, bool onlyUpdateScrollbars = false);
bool handleMouseReleaseEvent(const PlatformMouseEvent&);
bool handleWheelEvent(const PlatformWheelEvent&);
void defaultWheelEventHandler(Node*, WheelEvent*);
#if ENABLE(GESTURE_EVENTS)
bool handleGestureEvent(const PlatformGestureEvent&);
bool handleGestureTap(const PlatformGestureEvent&, Node* preTargetedNode = 0);
bool handleGestureScrollUpdate(const PlatformGestureEvent&);
#endif
一個堆棧示例：
[plain] Thread 4 WebThread, Queue : (null)
#0 0x03385790 in WebCore::EventHandler::mouseMoved(WebCore::PlatformMouseEvent const&) ()
#1 0x0338ae0f in WebCore::EventHandler::mouseMoved(WebEvent*) ()
#2 0x02efd822 in -[WebHTMLView(WebPrivate) mouseMoved:] ()
#3 0x03f6c6ac in -[WAKView _selfHandleEvent:] ()
#4 0x03f6c603 in -[WAKView handleEvent:] ()
#5 0x03f6f94d in -[WAKWindow sendEventSynchronously:] ()
#6 0x03f6f75b in __23-[WAKWindow sendEvent:]_block_invoke ()
#7 0x03f83fe2 in _WebThreadRun ()
#8 0x03f83ee0 in WebThreadRun ()
#9 0x03f6f71c in -[WAKWindow sendEvent:] ()
#10 0x03f6fa0c in __46-[WAKWindow sendMouseMoveEvent:contentChange:]_block_invoke ()
#11 0x03f83fe2 in _WebThreadRun ()
#12 0x03f83ee0 in WebThreadRun ()
#13 0x03f6f9d2 in -[WAKWindow sendMouseMoveEvent:contentChange:] ()
#14 0x0023609d in __64-[UIWebDocumentView(Interaction) _sendMouseMoveAndAttemptClick:]_block_invoke ()
#15 0x03f844ea in HandleRunSource ()
#16 0x0226e33f in __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ ()
#17 0x0226dd95 in __CFRunLoopDoSources0 ()
#18 0x0228b124 in __CFRunLoopRun ()
#19 0x0228a59f in CFRunLoopRunSpecific ()
#20 0x0228a3eb in CFRunLoopRunInMode ()
#21 0x03f83c30 in RunWebThread(void*) ()
#22 0x05a5c65c in _pthread_body ()
#23 0x05a5c4e6 in _pthread_start ()
Thread 4 WebThread, Queue : (null)
#0 0x03385790 in WebCore::EventHandler::mouseMoved(WebCore::PlatformMouseEvent const&) ()
#1 0x0338ae0f in WebCore::EventHandler::mouseMoved(WebEvent*) ()
#2 0x02efd822 in -[WebHTMLView(WebPrivate) mouseMoved:] ()
#3 0x03f6c6ac in -[WAKView _selfHandleEvent:] ()
#4 0x03f6c603 in -[WAKView handleEvent:] ()
#5 0x03f6f94d in -[WAKWindow sendEventSynchronously:] ()
#6 0x03f6f75b in __23-[WAKWindow sendEvent:]_block_invoke ()
#7 0x03f83fe2 in _WebThreadRun ()
#8 0x03f83ee0 in WebThreadRun ()
#9 0x03f6f71c in -[WAKWindow sendEvent:] ()
#10 0x03f6fa0c in __46-[WAKWindow sendMouseMoveEvent:contentChange:]_block_invoke ()
#11 0x03f83fe2 in _WebThreadRun ()
#12 0x03f83ee0 in WebThreadRun ()
#13 0x03f6f9d2 in -[WAKWindow sendMouseMoveEvent:contentChange:] ()
#14 0x0023609d in __64-[UIWebDocumentView(Interaction) _sendMouseMoveAndAttemptClick:]_block_invoke ()
#15 0x03f844ea in HandleRunSource ()
#16 0x0226e33f in __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ ()
#17 0x0226dd95 in __CFRunLoopDoSources0 ()
#18 0x0228b124 in __CFRunLoopRun ()
#19 0x0228a59f in CFRunLoopRunSpecific ()
#20 0x0228a3eb in CFRunLoopRunInMode ()
#21 0x03f83c30 in RunWebThread(void*) ()
#22 0x05a5c65c in _pthread_body ()
#23 0x05a5c4e6 in _pthread_start ()
