TRTouchposeApplication.m

// Copyright 2012 Todd Reed
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.


#import <QuartzCore/QuartzCore.h>
#import <objc/runtime.h>

#import "TRTouchposeApplication.h"
#import "TRTouchposeCircleTouchView.h"

NSString *const TRTouchposeTouchesVisibleDidChange = @"TRTouchposeTouchesVisibleDidChange";

@interface TRTouchposeApplication ()

- (void)keyWindowChanged:(UIWindow *)window;
- (void)bringTouchViewToFront;

@end

/// The TRTouchposeTouchesView is an overlay view that is used as the superview for
/// TRTouchposeTouchView instances.
@interface TRTouchposeTouchesView : UIView

- (instancetype)initWithFrame:(CGRect)frame touchViewFactory:(id<TRTouchposeTouchViewFactory>)touchViewFactory;

@end

@implementation TRTouchposeTouchesView
{
    // Dictionary of touches being displayed. Keys are UITouch pointers and values are UIView pointers that visually represent
    // the touch on-screen. (A CFMutableDictionaryRef is used because NSDictionary requries its keys to conform to the
    // NSCopying protocol and UITouch doesn't. We don't need to retain either the UITouch or UIView instances because UITouch
    // objects are persistent throughout a multi-touch sequence, and the UIViews are retained by their superview.)
    CFMutableDictionaryRef _touchDictionary;
    id<TRTouchposeTouchViewFactory> _touchViewFactory;
}

#pragma mark - NSObject

- (void)dealloc
{
    CFRelease(_touchDictionary);
}

#pragma mark - UIView

- (instancetype)initWithFrame:(CGRect)frame
{
    return [self initWithFrame:frame touchViewFactory:[[TRTouchposeCircleTouchViewFactory alloc] init]];
}

- (instancetype)initWithFrame:(CGRect)frame touchViewFactory:(id<TRTouchposeTouchViewFactory>)touchViewFactory
{
    NSParameterAssert(touchViewFactory != nil);

    self = [super initWithFrame:frame];
    _touchDictionary = CFDictionaryCreateMutable(NULL, 10, NULL, NULL);
    _touchViewFactory = touchViewFactory;
    return self;
}

#pragma mark - TRTouchposeTouchesView

- (void)removeTouchesActiveTouches:(NSSet *)activeTouches
{
    CFIndex count = CFDictionaryGetCount(_touchDictionary);
    if (count > 0)
    {
        void const * keys[count];
        void const * values[count];
        CFDictionaryGetKeysAndValues(_touchDictionary, keys, values);
        for (CFIndex i = 0; i < count; ++i)
        {
            UITouch *touch = (__bridge UITouch *)keys[i];

            if (activeTouches == nil || ![activeTouches containsObject:touch])
            {
                UIView *view = (__bridge UIView *)values[i];
                CFDictionaryRemoveValue(_touchDictionary, (__bridge const void *)(touch));
                [view removeFromSuperview];
            }
        }
    }
}

- (void)updateTouches:(NSSet *)touches
{
    for (UITouch *touch in touches)
    {
        CGPoint point = [touch locationInView:self];
        UIView<TRTouchposeTouchView> *fingerView = (UIView<TRTouchposeTouchView> *)CFDictionaryGetValue(_touchDictionary, (__bridge const void *)(touch));

        if (touch.phase == UITouchPhaseCancelled || touch.phase == UITouchPhaseEnded)
        {
            // Note that there seems to be a bug in iOS: we won't observe all UITouches
            // in the UITouchPhaseEnded phase, resulting in some finger views being left
            // on the screen when they shouldn't be. See
            // https://discussions.apple.com/thread/1507669?start=0&tstart=0 for other's
            // comments about this issue. No workaround is implemented here.


            if (fingerView != nil)
            {
                // Remove the touch from the
                CFDictionaryRemoveValue(_touchDictionary, (__bridge const void *)(touch));
                [fingerView removeFromSuperview];
            }
        }
        else
        {
            if (fingerView == nil)
            {
                fingerView = [_touchViewFactory touchViewAtPoint:point];
                [self addSubview:fingerView];
                CFDictionarySetValue(_touchDictionary, (__bridge const void *)(touch), (__bridge const void *)(fingerView));
            }
            else
            {
                fingerView.touchPoint = point;
            }
        }
    }

    [self removeTouchesActiveTouches:touches];
}

@end


IMP SwizzleMethod(Class c, SEL sel, IMP newImplementation)
{
    Method method = class_getInstanceMethod(c, sel);
    IMP originalImplementation = method_getImplementation(method);
    if (!class_addMethod(c, sel, newImplementation, method_getTypeEncoding(method)))
        method_setImplementation(method, newImplementation);
    return originalImplementation;
}

static void (*UIWindow_orig_becomeKeyWindow)(UIWindow *, SEL);

// This method replaces -[UIWindow becomeKeyWindow] (but calls the original -becomeKeyWindow). This
// is used to move the overlay to the current key window.
static void UIWindow_new_becomeKeyWindow(UIWindow *window, SEL _cmd)
{
    TRTouchposeApplication *application = (TRTouchposeApplication *)[UIApplication sharedApplication];
    [application keyWindowChanged:window];
    (*UIWindow_orig_becomeKeyWindow)(window, _cmd);
}

static void (*UIWindow_orig_didAddSubview)(UIWindow *, SEL, UIView *);

// This method replaces -[UIWindow didAddSubview:] (but calls the original -didAddSubview:). This is
// used to keep the overlay view the top-most view of the window.
static void UIWindow_new_didAddSubview(UIWindow *window, SEL _cmd, UIView *view)
{
    if (![view conformsToProtocol:@protocol(TRTouchposeTouchView)])
    {
        TRTouchposeApplication *application = (TRTouchposeApplication *)[UIApplication sharedApplication];
        [application bringTouchViewToFront];
    }
    (*UIWindow_orig_didAddSubview)(window, _cmd, view);
}


@implementation TRTouchposeApplication
{
    TRTouchposeTouchesView *_touchesView;
}

#pragma mark - NSObject

- (instancetype)init
{
    if ((self = [super init]))
    {
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationDidFinishLaunching:) name:UIApplicationDidFinishLaunchingNotification object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(screenDidConnectNotification:) name:UIScreenDidConnectNotification object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(screenDidDisonnectNotification:) name:UIScreenDidDisconnectNotification object:nil];

        _automaticallyManageTouchesWhenScreenMirrored = YES;
        _touchViewFactory = [[TRTouchposeCircleTouchViewFactory alloc] init];

        _touchesView = [[TRTouchposeTouchesView alloc] init];
        _touchesView.backgroundColor = [UIColor clearColor];
        _touchesView.opaque = NO;
        _touchesView.userInteractionEnabled = NO;
    }
    return self;
}

- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

#pragma mark - UIApplication

- (void)sendEvent:(UIEvent *)event
{
    if (_showTouches)
        [_touchesView updateTouches:[event allTouches]];
    [super sendEvent:event];
}

#pragma mark - TRApplication

- (void)applicationDidFinishLaunching:(NSNotification *)notification
{
    // We intercept calls to -becomeKeyWindow and -didAddSubview of UIWindow to manage the
    // overlay view TRTouchposeTouchesView and ensure it remains the top-most window.
    UIWindow_orig_didAddSubview = (void (*)(UIWindow *, SEL, UIView *))SwizzleMethod([UIWindow class], @selector(didAddSubview:), (IMP)UIWindow_new_didAddSubview);
    UIWindow_orig_becomeKeyWindow = (void (*)(UIWindow *, SEL))SwizzleMethod([UIWindow class], @selector(becomeKeyWindow), (IMP)UIWindow_new_becomeKeyWindow);

    self.showTouches = _automaticallyManageTouchesWhenScreenMirrored || [self hasMirroredScreen];
}

- (void)screenDidConnectNotification:(NSNotification *)notification
{
    if (_automaticallyManageTouchesWhenScreenMirrored && [self hasMirroredScreen])
        self.showTouches = YES;
}

- (void)screenDidDisonnectNotification:(NSNotification *)notification
{
    if (_automaticallyManageTouchesWhenScreenMirrored && [self hasMirroredScreen])
        self.showTouches = NO;
}

- (void)keyWindowChanged:(UIWindow *)window
{
    if (_touchesView)
        [window addSubview:_touchesView];
}

- (void)bringTouchViewToFront
{
    if (_touchesView)
        [_touchesView.window bringSubviewToFront:_touchesView];
}

- (BOOL)hasMirroredScreen
{
    BOOL hasMirroredScreen = NO;
    NSArray *screens = [UIScreen screens];

    if ([screens count] > 1)
    {
        for (UIScreen *screen in screens)
        {
            if (screen.mirroredScreen != nil)
            {
                hasMirroredScreen = YES;
                break;
            }
        }
    }
    return hasMirroredScreen;
}

- (void)showTouchViews
{
    UIWindow *window = self.keyWindow;
    if (window)
    {
        _touchesView.frame = window.bounds;
        [window addSubview:_touchesView];
    }
}

- (void)hideTouchViews
{
    [_touchesView removeFromSuperview];
}

- (void)setShowTouches:(BOOL)showTouches
{
    BOOL equal = (_showTouches && showTouches) || (!_showTouches && !showTouches);
    if (!equal)
    {
        if (showTouches)
            [self showTouchViews];
        else
            [self hideTouchViews];
        _showTouches = showTouches;
        [[NSNotificationCenter defaultCenter] postNotificationName:TRTouchposeTouchesVisibleDidChange object:self];
    }
}

@end