我正在开发一个Mac应用程序,我想知道手指在触控板上的位置.
有可能吗,如果是的话,怎么办？
解决方法
您的视图需要设置为接受触摸([self setAcceptsTouchEvents：YES]).当你得到一个触摸事件,如-touchesBeganWithEvent：,你可以通过查看它的normalizedPosition(范围是[0.0,1.0] x [0.0,1.0]),根据它的deviceSize的大点来确定手指的位置(有72磅/英寸).触控板的左下角被视为零起点.
所以,例如：
- (id)initWithFrame:(NSRect)frameRect {
self = [super initWithFrame:frameRect];
if (!self) return nil;
/* You need to set this to receive any touch event messages. */
[self setAcceptsTouchEvents:YES];
/* You only need to set this if you actually want resting touches.
* If you don't,a touch will "end" when it starts resting and
* "begin" again if it starts moving again. */
[self setWantsRestingTouches:YES]
return self;
}
/* One of many touch event handling methods. */
- (void)touchesBeganWithEvent:(NSEvent *)ev {
NSSet *touches = [ev touchesMatchingPhase:NSTouchPhaseBegan inView:self];
for (NSTouch *touch in touches) {
/* Once you have a touch,getting the position is dead simple. */
NSPoint fraction = touch.normalizedPosition;
NSSize whole = touch.deviceSize;
NSPoint wholeInches = {whole.width / 72.0,whole.height / 72.0};
NSPoint pos = wholeInches;
pos.x *= fraction.x;
pos.y *= fraction.y;
NSLog(@"%s: Finger is touching %g inches right and %g inches up "
@"from lower left corner of trackpad.",__func__,pos.x,pos.y);
}
}
