订阅监听Mac OS X的全局鼠标事件
2011 11 10 04:16 AM 9450次查看
分类：Mac开发 标签：Objective-C, Mac开发
首先不能错过的是Cocoa Event-Handling Guide这篇文档。它详细介绍了Mac OS X下的事件机制，这里只简要说一下事件传播的流程。
考虑一个鼠标点击事件。鼠标硬件先接收到用户点击，然后交给鼠标驱动来处理。这个驱动是在Mac OS X内核运行的，处理完就通过I/O Kit传递给window server的事件队列。而window server则负责分派这些事件到对应进程的run-loop。
接着是Stack Overflow的这篇Global Mouse Moved Events in Cocoa，列出了监听全局鼠标事件的2个API。
其中之一是NSEvent的+ addGlobalMonitorForEventsMatchingMask:handler:方法。
这个方法有2点需要注意：
- 它是异步接收的，因此不能修改事件和阻止事件传播。
- 这个程序本身不能接收到自己的事件，但可以用+ addLocalMonitorForEventsMatchingMask:handler:。
不过拿来做其他的事倒也不错，于是我就写了个记录鼠标使用状况的程序。
先定义一下要用到的属性：
#import <Cocoa/Cocoa.h>
@interface AppDelegate : NSObject <NSApplicationDelegate> {
@private
NSInteger leftClicked;
NSInteger rightClicked;
NSInteger moved;
NSTextField *leftClickedText;
NSTextField *rightClickedText;
NSTextField *movedText;
}
@property (assign) IBOutlet NSWindow *window;
@property (retain) IBOutlet NSTextField *leftClickedText;
@property (retain) IBOutlet NSTextField *rightClickedText;
@property (retain) IBOutlet NSTextField *movedText;
@end实现也很简单：
#include "math.h"
#import "AppDelegate.h"
@implementation AppDelegate
@synthesize window = _window;
@synthesize leftClickedText;
@synthesize rightClickedText;
@synthesize movedText;
- (void)dealloc
{
[super dealloc];
[leftClickedText release];
[rightClickedText release];
[movedText release];
}
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
[NSEvent addGlobalMonitorForEventsMatchingMask:NSLeftMouseDownMask | NSRightMouseDownMask | NSMouseMovedMask | NSLeftMouseDraggedMask | NSRightMouseDraggedMask handler:^(NSEvent *event) {
NSString *text;
NSInteger delta;
switch (event.type) {
case NSLeftMouseDown:
text = [[NSString alloc] initWithFormat:@"%d", ++leftClicked];
leftClickedText.stringValue = text;
break;
case NSRightMouseDown:
text = [[NSString alloc] initWithFormat:@"%d", ++rightClicked];
rightClickedText.stringValue = text;
break;
case NSMouseMoved:
case NSLeftMouseDragged:
case NSRightMouseDragged:
delta = (NSInteger)sqrt(event.deltaX * event.deltaX + event.deltaY * event.deltaY);
moved += delta;
text = [[NSString alloc] initWithFormat:@"%d px", moved];
movedText.stringValue = text;
break;
default:
break;
}
[text release];
}];
}
@end最后测试一下，一切工作正常。唯一要担心的就是像素数实在增长太快了，看来显示时应该改下单位，例如转化成米或千米。
另一个方法则是使用CGEventTap，它更为底层，可以修改事件。
先来捕捉事件：
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
CGEventMask eventMask = CGEventMaskBit(kCGEventRightMouseDown) | CGEventMaskBit(kCGEventRightMouseUp);
CFMachPortRef eventTap = CGEventTapCreate(kCGHIDEventTap, kCGHeadInsertEventTap, kCGEventTapOptionDefault, eventMask, eventCallback, NULL);
CFRunLoopSourceRef runLoopSource = CFMachPortCreateRunLoopSource(kCFAllocatorDefault, eventTap, 0);
CFRunLoopAddSource(CFRunLoopGetCurrent(), runLoopSource, kCFRunLoopCommonModes);
CGEventTapEnable(eventTap, true);
CFRelease(eventTap);
CFRelease(runLoopSource);
}首先是eventMask，它是我要捕捉的事件掩码。这里我只是演示，因此就不捕捉拖动了。
接着是eventTap，它是一个CFMachPort对象，是与Mac OS X内核通信的通道。第一个参数有3种值，注意事件传播是沿着硬件系统 → window server → 用户session → 应用程序这条路径的，每个箭头处都可以捕捉事件，而这个参数就决定了在哪捕捉事件。kCGHeadInsertEventTap是指要放在其他event taps之前，避免事件被修改或停止传播。kCGEventTapOptionDefault是指可以修改或停止传播事件，用kCGEventTapOptionListenOnly的话就和上一种方法一样了。eventCallback是事件发生时会被调用的函数，稍后列出。最后一个参数是传给回调函数的值，这里我用不到，所以设为NULL。
然后是拿eventTap创建一个加到RunLoopSource对象，太抽象了也没啥好解释的。
再是把这个runLoopSource加到当前线程（即主线程）的RunLoop。
后面那行代码其实是多余的，用于启用eventTap。事实上添加到RunLoop后就已经启用了，要停用时可以将参数改成false。
再来看看刚才那个回调函数：
static CGEventRef eventCallback(CGEventTapProxy proxy, CGEventType type, CGEventRef event, void *refcon) {
CGPoint location = CGEventGetLocation(event);
NSInteger windowNumber = [NSWindow windowNumberAtPoint:location belowWindowWithWindowNumber:0];
CGWindowID windowID = (CGWindowID)windowNumber;
CFArrayRef array = CFArrayCreate(NULL, (const void **)&windowID, 1, NULL);
NSArray *windowInfos = (NSArray *)CGWindowListCreateDescriptionFromArray(array);
CFRelease(array);
if (windowInfos.count > 0) {
NSDictionary *windowInfo = [windowInfos objectAtIndex:0];
NSLog(@"Window name: %@", [windowInfo objectForKey:(NSString *)kCGWindowName]);
NSLog(@"Window owner: %@", [windowInfo objectForKey:(NSString *)kCGWindowOwnerName]);
}
[windowInfos release];
return NULL;
}NSEvent可以直接获取windowNumber，但CGEventRef能在事件传递到窗口之前就捕捉到，也就没法知道这个值了。于是我只能用了NSWindow的类方法来获得窗口，再获取该窗口的名字。
最后返回NULL，这样事件就不会被继续传播了。
接着再把右键改成左键：
static CGEventRef eventCallback(CGEventTapProxy proxy, CGEventType type, CGEventRef event, void *refcon) {
if (type == kCGEventRightMouseDown) {
CGEventSetType(event, kCGEventLeftMouseDown);
} else {
CGEventSetType(event, kCGEventLeftMouseUp);
}
return event;
}再试试把它替换成按回车键：
#include <Carbon/Carbon.h>
static CGEventRef createEventCallback(CGEventTapProxy proxy, CGEventType type, CGEventRef event, void *refcon) {
CGEventRef newEvent = CGEventCreateKeyboardEvent(NULL, kVK_Return, type == kCGEventRightMouseDown);
return newEvent;
}或者用CGEventTapPostEvent()和CGEventPost()来一次传递2个事件：
static CGEventRef createEventCallback(CGEventTapProxy proxy, CGEventType type, CGEventRef event, void *refcon) {
if (type == kCGEventRightMouseDown) {
return NULL;
} else {
CGEventRef newEvent = CGEventCreateKeyboardEvent(NULL, kVK_Return, true);
CGEventPost(kCGSessionEventTap, newEvent);
// CGEventTapPostEvent(proxy, newEvent);
CFRelease(newEvent);
return CGEventCreateKeyboardEvent(NULL, kVK_Return, false);
}
}如果要使用快捷键，不能直接模拟控制键按下的事件，而是要用CGEventSetFlags来设置。例如下面这段代码可以实现Shift + Command + T：
CGEventRef event = CGEventCreateKeyboardEvent(NULL, kVK_ANSI_T, true);
CGEventSetFlags(event, kCGEventFlagMaskShift | kCGEventFlagMaskCommand);
CGEventPost(kCGSessionEventTap, event);
CFRelease(event);
event = CGEventCreateKeyboardEvent(NULL, kVK_ANSI_T, false);
CGEventSetFlags(event, kCGEventFlagMaskShift | kCGEventFlagMaskCommand);
CGEventPost(kCGSessionEventTap, event);
CFRelease(event);接着附送些鼠标手势的算法和代码：
Mouse Gesture Recognition
鼠标手势算法
smoothgestures-chromium
最后也送上自己实现的一个4方向的手势检测：
typedef enum {
NONE,
RIGHT,
UP,
LEFT,
DOWN,
} DIRECTION;
static vector<DIRECTION> directions;
static CGPoint lastLocation;
static void updateDirections(CGEventRef event) {
CGPoint newLocation = CGEventGetLocation(event);
float deltaX = newLocation.x - lastLocation.x;
float deltaY = newLocation.y - lastLocation.y;
float absX = fabs(deltaX);
float absY = fabs(deltaY);
if (absX + absY < 20) {
return;
}
lastLocation = newLocation;
DIRECTION lastDirection = directions.empty() ? NONE : directions.back();
if (absX > absY) {
if (deltaX > 0) {
if (lastDirection != RIGHT) {
directions.push_back(RIGHT);
}
} else if (lastDirection != LEFT) {
directions.push_back(LEFT);
}
} else {
if (deltaY < 0) {
if (lastDirection != UP) {
directions.push_back(UP);
}
} else if (lastDirection != DOWN) {
directions.push_back(DOWN);
}
}
}
static CGEventRef eventCallback(CGEventTapProxy proxy, CGEventType type, CGEventRef event, void *refcon) {
switch (type) {
case kCGEventRightMouseDown:
lastLocation = CGEventGetLocation(event);
break;
case kCGEventRightMouseDragged:
updateDirections(event);
break;
case kCGEventRightMouseUp:
updateDirections(event);
for (vector<DIRECTION>::iterator iter = directions.begin(); iter != directions.end(); ++iter) {
NSLog(@"%d", *iter);
}
NSLog(@"----");
directions.clear();
break;
default:
return event;
break;
}
return NULL;
}如果不喜欢和CGEventRef打交道的话，也可以转换成NSEvent，不过注意Y轴的方向是相反的：
static NSPoint lastLocation;
static void updateDirections(NSEvent* event) {
NSPoint newLocation = event.locationInWindow;
float deltaX = newLocation.x - lastLocation.x;
float deltaY = newLocation.y - lastLocation.y;
float absX = fabs(deltaX);
float absY = fabs(deltaY);
if (absX + absY < 20) {
return;
}
lastLocation = newLocation;
DIRECTION lastDirection = directions.empty() ? NONE : directions.back();
if (absX > absY) {
if (deltaX > 0) {
if (lastDirection != RIGHT) {
directions.push_back(RIGHT);
}
} else if (lastDirection != LEFT) {
directions.push_back(LEFT);
}
} else {
if (deltaY > 0) {
if (lastDirection != UP) {
directions.push_back(UP);
}
} else if (lastDirection != DOWN) {
directions.push_back(DOWN);
}
}
}
static CGEventRef eventCallback(CGEventTapProxy proxy, CGEventType type, CGEventRef event, void *refcon) {
NSEvent *mouseEvent = [NSEvent eventWithCGEvent:event];
switch (mouseEvent.type) {
case NSRightMouseDown:
lastLocation = mouseEvent.locationInWindow;
break;
case NSRightMouseDragged:
updateDirections(mouseEvent);
break;
case NSRightMouseUp:
updateDirections(mouseEvent);
for (vector<DIRECTION>::iterator iter = directions.begin(); iter != directions.end(); ++iter) {
NSLog(@"%d", *iter);
}
NSLog(@"----");
directions.clear();
break;
default:
return event;
break;
}
return NULL;
}
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