NSEvent+MouseClamped

gistfile1.txt

//
//  NSEvent+MouseClamped.h
//  xScope
//
//  Created by Craig Hockenberry on 7/25/12.
//  Copyright (c) 2012 The Iconfactory. All rights reserved.
//

#import <Cocoa/Cocoa.h>

@interface NSEvent (MouseClamped)

+ (NSPoint)clampedMouseLocation;
+ (NSPoint)integralMouseLocation;
+ (NSPoint)clampedMouseLocationUsingBackingScaleFactor:(CGFloat)backingScaleFactor;

@end

//
//  NSEvent+MouseClamped.m
//  xScope
//
//  Created by Craig Hockenberry on 7/25/12.
//  Copyright (c) 2012 The Iconfactory. All rights reserved.
//

#import "NSEvent+MouseClamped.h"


@implementation NSEvent (MouseClamped)

+ (NSPoint)clampedMouseLocation
{
	// BUG: http://www.openradar.me/11905408 - nasty hack to make sure mouse location is within screen bounds

	NSPoint mouseLocation = [self mouseLocation];

	// find the screen that contains the mouse location, or the screen that's closest to the location
	float closestScreenDistance = MAXFLOAT;
	NSUInteger closestScreenIndex = 0;
	BOOL screenFound = NO;
	NSUInteger screenIndex = 0;
	for (NSScreen *screen in [NSScreen screens]) {
		NSRect screenFrame = [screen frame];
		if (NSPointInRect(mouseLocation, screenFrame)) {
			screenFound = YES;
			break;
		}
		float xDistance = 0.0;
		if (mouseLocation.x < NSMinX(screenFrame)) {
			xDistance = NSMinX(screenFrame) - mouseLocation.x;
		}
		else if (mouseLocation.x > NSMaxX(screenFrame)) {
			xDistance = mouseLocation.x - NSMaxX(screenFrame);
		}
		float yDistance = 0.0;
		if (mouseLocation.y < NSMinY(screenFrame)) {
			yDistance = NSMinY(screenFrame) - mouseLocation.y;
		}
		else if (mouseLocation.y > NSMaxY(screenFrame)) {
			yDistance = mouseLocation.y - NSMaxY(screenFrame);
		}
		
		float screenDistance = xDistance + yDistance;
		if (screenDistance < closestScreenDistance) {
			closestScreenDistance = screenDistance;
			closestScreenIndex = screenIndex;
		}
		
		screenIndex += 1;
	}

	CGFloat backingScaleFactor = 1.0;
	if (screenFound) {
		// get the scaling factor from the screen that was found
		NSScreen *screen = [[NSScreen screens] objectAtIndex:screenIndex];
		backingScaleFactor = [screen backingScaleFactor];
	}
	else {
		// get the scaling factor from the closest screen
		NSScreen *screen = [[NSScreen screens] objectAtIndex:closestScreenIndex];
		backingScaleFactor = [screen backingScaleFactor];
		
		// clamp the mouse location to bounds of that closest screen
		CGFloat inset = 1.0 / backingScaleFactor;
		NSRect screenFrame = [screen frame];
		if (mouseLocation.x > (NSMaxX(screenFrame) - inset)) {
			mouseLocation.x = (NSMaxX(screenFrame) - inset);
		}
		else if (mouseLocation.x < NSMinX(screenFrame)) {
			mouseLocation.x = NSMinX(screenFrame);
		}
		if (mouseLocation.y > (NSMaxY(screenFrame) - inset)) {
			mouseLocation.y = (NSMaxY(screenFrame) - inset);
		}
		else if (mouseLocation.y < NSMinY(screenFrame)) {
			mouseLocation.y = NSMinY(screenFrame);
		}
	}

	// make sure the mouse location falls on a pixel boundary (a full screen point on non-Retina, a half-point on Retina)
	mouseLocation.x = floor(mouseLocation.x * backingScaleFactor) / backingScaleFactor;
	mouseLocation.y = floor(mouseLocation.y * backingScaleFactor) / backingScaleFactor;

	return mouseLocation;
}

+ (NSPoint)integralMouseLocation
{
	NSPoint mouseLocation = [self clampedMouseLocation];

	mouseLocation.x = floor(mouseLocation.x);
	mouseLocation.y = floor(mouseLocation.y);
	
	return mouseLocation;
}

+ (NSPoint)clampedMouseLocationUsingBackingScaleFactor:(CGFloat)backingScaleFactor
{
	// the mouse location is clamped to the screen where the mouse is located
	NSPoint mouseLocation = [self clampedMouseLocation];

	// there are cases where you want to clamp the mouse's location to another scale factor (for example, a window that spans multiple screens)
	mouseLocation.x = floor(mouseLocation.x * backingScaleFactor) / backingScaleFactor;
	mouseLocation.y = floor(mouseLocation.y * backingScaleFactor) / backingScaleFactor;
	
	return mouseLocation;
}

@end

Hey Craig, what would be the usage license for this code please?!