Cocoa处理mouse事件
Apple的《Handling Mouse Events》文档中有几个列子记录一下
Listing 4-2 Simple handling of mouse click—sending an action message
- (void)mouseDown:(NSEvent *)theEvent {
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[self setFrameColor:[NSColor redColor]];
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[self setNeedsDisplay:YES];
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}
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- (void)mouseUp:(NSEvent *)theEvent {
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[self setFrameColor:[NSColor greenColor]];
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[self setNeedsDisplay:YES];
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[NSApp sendAction:[self action] to:[self target] from:self];
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}
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- (SEL)action {return action; }
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- (void)setAction:(SEL)newAction {
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action = newAction;
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}
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- (id)target { return target; }
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- (void)setTarget:(id)newTarget {
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target = newTarget;
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}
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处理鼠标拖拽操作：
Application Kit一般有两种方法处理鼠标拖动事件：
第一种方法重载NSResponder中mouseDown:, mouseDragged:, mouseUp:（用鼠标左键操作）。每个拖拽动作下，首先Application Kit发送一个MouseDown消息给NSResponder对象，接着发送一个或者多个mouseDragged消息，最后发送一个mouseUp：消息。
第二种方法将鼠标拖动系列事件当作一个单一的事件处理，NSResponder通常必须创建事件循环机制获取鼠标事件， NSApplication和NSWindow 都有nextEventMatchingMask:untilDate:inMode:dequeue: 方法获取事件。
这两种方法都有自己的优点和缺点。在应用程序拖动操作期间接管鼠标跟踪循环处理事件。然而，应用程序的主线程无法处理其他事件和NSTimer也不会触发。鼠标跟踪方法更有效，因为它通常需要更少的代码，允许所有拖动变量是局部。然而，所有拖动代码在子类中继承更困难。
而重载mouseDown:, mouseDragged:, mouseUp:方法相比前一种方法，更逻辑更清晰，范围也明确，子类也容易继承处理鼠标拖动事件。
下面是重载mouseDown:, mouseDragged:, mouseUp:
- (void)mouseDown:(NSEvent *)theEvent {
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// mouseInCloseBox and trackingCloseBoxHit are instance variables
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if (mouseInCloseBox = NSPointInRect([self convertPoint:[theEvent locationInWindow] fromView:nil], closeBox)) {
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trackingCloseBoxHit = YES;
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[self setNeedsDisplayInRect:closeBox];
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}
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else if ([theEvent clickCount] > 1) {
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[[self window] miniaturize:self];
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return;
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}
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}
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- (void)mouseDragged:(NSEvent *)theEvent {
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NSPoint windowOrigin;
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NSWindow *window = [self window];
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if (trackingCloseBoxHit) {
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mouseInCloseBox = NSPointInRect([self convertPoint:[theEvent locationInWindow] fromView:nil], closeBox);
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[self setNeedsDisplayInRect:closeBox];
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return;
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}
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windowOrigin = [window frame].origin;
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[window setFrameOrigin:NSMakePoint(windowOrigin.x + [theEvent deltaX], windowOrigin.y - [theEvent deltaY])];
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}
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- (void)mouseUp:(NSEvent *)theEvent {
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if (NSPointInRect([self convertPoint:[theEvent locationInWindow] fromView:nil], closeBox)) {
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[self tryToCloseWindow];
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return;
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}
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trackingCloseBoxHit = NO;
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[self setNeedsDisplayInRect:closeBox];
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}
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下面跟踪鼠标循环方式，处理拖拽事件：（简单例子）
- (void)mouseDown:(NSEvent *)theEvent {
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BOOL keepOn = YES;
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BOOL isInside = YES;
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NSPoint mouseLoc;
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while (keepOn) {
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theEvent = [[self window] nextEventMatchingMask: NSLeftMouseUpMask |
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NSLeftMouseDraggedMask];
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mouseLoc = [self convertPoint:[theEvent locationInWindow] fromView:nil];
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isInside = [self mouse:mouseLoc inRect:[self bounds]];
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switch ([theEvent type]) {
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case NSLeftMouseDragged:
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[self highlight:isInside];
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break;
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case NSLeftMouseUp:
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if (isInside) [self doSomethingSignificant];
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[self highlight:NO];
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keepOn = NO;
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break;
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default:
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/* Ignore any other kind of event. */
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break;
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}
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};
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return;
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}
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下面跟踪鼠标循环方式，处理拖拽事件：（复杂例子）
- (void)mouseDown:(NSEvent *)theEvent
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{
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if ([theEvent modifierFlags] & NSAlternateKeyMask) {
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BOOL dragActive = YES;
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NSPoint location = [renderView convertPoint:[theEvent locationInWindow] fromView:nil];
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NSAutoreleasePool *myPool = nil;
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NSEvent* event = NULL;
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NSWindow *targetWindow = [renderView window];
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myPool = [[NSAutoreleasePool alloc] init];
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while (dragActive) {
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event = [targetWindow nextEventMatchingMask:(NSLeftMouseDraggedMask | NSLeftMouseUpMask)
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untilDate:[NSDate distantFuture]
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inMode:NSEventTrackingRunLoopMode
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dequeue:YES];
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if(!event)
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continue;
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location = [renderView convertPoint:[event locationInWindow] fromView:nil];
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switch ([event type]) {
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case NSLeftMouseDragged:
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annotationPeel = (location.x * 2.0 / [renderView bounds].size.width);
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[imageLayer showLens:(annotationPeel <= 0.0)];
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[peelOffFilter setValue:[NSNumber numberWithFloat:annotationPeel] forKey:@"inputTime"];
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[self refresh];
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break;
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case NSLeftMouseUp:
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dragActive = NO;
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break;
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default:
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break;
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}
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}
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[myPool release];
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} else {
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// other tasks handled here......
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}
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}
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下面跟踪鼠标循环方式，处理拖拽事件：（经典例子）
- (void)mouseDown:(NSEvent *)theEvent {
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NSPoint pos;
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while ((theEvent = [[self window] nextEventMatchingMask:
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NSLeftMouseUpMask | NSLeftMouseDraggedMask])) {
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NSPoint pos = [self convertPoint:[theEvent locationInWindow]
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fromView:nil];
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if ([theEvent type] == NSLeftMouseUp)
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break;
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// Do some other processing...
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}
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}
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