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 {

    // 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...

  }

}