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 {

[self setFrameColor:[NSColor redColor]];

[self setNeedsDisplay:YES];

}

- (void)mouseUp:(NSEvent *)theEvent {

[self setFrameColor:[NSColor greenColor]];

[self setNeedsDisplay:YES];

[NSApp sendAction:[self action] to:[self target] from:self];

}

- (SEL)action {return action; }

- (void)setAction:(SEL)newAction {

action = newAction;

}

- (id)target { return target; }

- (void)setTarget:(id)newTarget {

target = newTarget;

}

 

处理鼠标拖拽操做：

Application Kit通常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:（用鼠标左键操做）。每一个拖拽动做下，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看成一个单一的事件处理，NSResponder一般必须建立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。

这两种方法都有本身的优势和缺点。在应用程序拖动操做期间接管鼠标跟踪循环处理事件。然而，应用程序的主线程没法处理其余事件和NSTimer也不会触发。鼠标跟踪方法更有效，由于它一般须要更少的代码，容许全部拖动变量是局部。然而，全部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 {

// mouseInCloseBox and trackingCloseBoxHit are instance variables

if (mouseInCloseBox = NSPointInRect([self convertPoint:[theEvent locationInWindow] fromView:nil], closeBox)) {

trackingCloseBoxHit = YES;

[self setNeedsDisplayInRect:closeBox];

}

else if ([theEvent clickCount] > 1) {

[[self window] miniaturize:self];

return;

}

}

- (void)mouseDragged:(NSEvent *)theEvent {

NSPoint windowOrigin;

NSWindow *window = [self window];

if (trackingCloseBoxHit) {

mouseInCloseBox = NSPointInRect([self convertPoint:[theEvent locationInWindow] fromView:nil], closeBox);

[self setNeedsDisplayInRect:closeBox];

return;

}

windowOrigin = [window frame].origin;

[window setFrameOrigin:NSMakePoint(windowOrigin.x + [theEvent deltaX], windowOrigin.y - [theEvent deltaY])];

}

- (void)mouseUp:(NSEvent *)theEvent {

if (NSPointInRect([self convertPoint:[theEvent locationInWindow] fromView:nil], closeBox)) {

[self tryToCloseWindow];

return;

}

trackingCloseBoxHit = NO;

[self setNeedsDisplayInRect:closeBox];

}

 

下面跟踪鼠标循环方式，处理拖拽事件：（简单例子）

- (void)mouseDown:(NSEvent *)theEvent {

BOOL keepOn = YES;

BOOL isInside = YES;

NSPoint mouseLoc;

while (keepOn) {

theEvent = [[self window] nextEventMatchingMask: NSLeftMouseUpMask |

NSLeftMouseDraggedMask];

mouseLoc = [self convertPoint:[theEvent locationInWindow] fromView:nil];

isInside = [self mouse:mouseLoc inRect:[self bounds]];

switch ([theEvent type]) {

case NSLeftMouseDragged:

[self highlight:isInside];

break;

case NSLeftMouseUp:

if (isInside) [self doSomethingSignificant];

[self highlight:NO];

keepOn = NO;

break;

default:

/* Ignore any other kind of event. */

break;

}

};

return;

}

 

 

下面跟踪鼠标循环方式，处理拖拽事件：（复杂例子）

- (void)mouseDown:(NSEvent *)theEvent

{

if ([theEvent modifierFlags] & NSAlternateKeyMask) {

BOOL dragActive = YES;

NSPoint location = [renderView convertPoint:[theEvent locationInWindow] fromView:nil];

NSAutoreleasePool *myPool = nil;

NSEvent* event = NULL;

NSWindow *targetWindow = [renderView window];

myPool = [[NSAutoreleasePool alloc] init];

while (dragActive) {

event = [targetWindow nextEventMatchingMask:(NSLeftMouseDraggedMask | NSLeftMouseUpMask)

untilDate:[NSDate distantFuture]

inMode:NSEventTrackingRunLoopMode

dequeue:YES];

if(!event)

continue;

location = [renderView convertPoint:[event locationInWindow] fromView:nil];

switch ([event type]) {

case NSLeftMouseDragged:

annotationPeel = (location.x * 2.0 / [renderView bounds].size.width);

[imageLayer showLens:(annotationPeel <= 0.0)];

[peelOffFilter setValue:[NSNumber numberWithFloat:annotationPeel] forKey:@"inputTime"];

[self refresh];

break;

case NSLeftMouseUp:

dragActive = NO;

break;

default:

break;

}

}

[myPool release];

} else {

// other tasks handled here......

}

}

 

 

下面跟踪鼠标循环方式，处理拖拽事件：（经典例子）

- (void)mouseDown:(NSEvent *)theEvent {

NSPoint pos;

while ((theEvent = [[self window] nextEventMatchingMask:

NSLeftMouseUpMask | NSLeftMouseDraggedMask])) {

NSPoint pos = [self convertPoint:[theEvent locationInWindow]

fromView:nil];

if ([theEvent type] == NSLeftMouseUp)

break;

// Do some other processing...

}

}