From a433398d4331d6f4a7bf077d83f66295ce649edf Mon Sep 17 00:00:00 2001
From: Aditya Nrusimha <aditya.nrusimha@gmail.com>
Date: Tue, 25 Sep 2012 18:18:55 -0700
Subject: [PATCH] Added an example for TUIControl tracking with sliding tabs!
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It's pretty fun to play with sliding tabs…. :D
---
 ExampleProject/Example/ExampleTabBar.m | 86 +++++++++++++++++++++-----
 1 file changed, 70 insertions(+), 16 deletions(-)

diff --git a/ExampleProject/Example/ExampleTabBar.m b/ExampleProject/Example/ExampleTabBar.m
index cb0c17f..65117ef 100644
--- a/ExampleProject/Example/ExampleTabBar.m
+++ b/ExampleProject/Example/ExampleTabBar.m
@@ -16,35 +16,89 @@
 
 #import "ExampleTabBar.h"
 
-@interface ExampleTab : TUIView
+@interface ExampleTab : TUIControl
+
+@property (nonatomic, assign) CGFloat originalPosition;
+
 @end
+
 @implementation ExampleTab
 
-- (ExampleTabBar *)tabBar
-{
+// Convinience to call delegate methods, since by default, our
+// superview SHOULD be a tab bar, and nothing else. This will
+// horribly crash if you add an ExampleTab to anything but a tab bar.
+- (ExampleTabBar *)tabBar {
 	return (ExampleTabBar *)self.superview;
 }
 
-- (void)mouseDown:(NSEvent *)event
-{
-	[super mouseDown:event]; // always call super when overriding mouseXXX: methods - lots of plumbing happens in TUIView
+// If a tracking event occurs within a tab, we want to move the
+// tab around, so return YES.
+- (BOOL)beginTrackingWithEvent:(NSEvent *)event {
 	[self setNeedsDisplay];
+	
+	// So the tab doesn't move over just on mouse pressed.
+	self.originalPosition = [self convertPoint:[event locationInWindow] fromView:nil].x;
+	
+	return YES;
 }
 
-- (void)mouseUp:(NSEvent *)event
-{
-	[super mouseUp:event];
+// Find the tab that was being dragged- although this isn't the
+// most efficient way, this will suffice for now.
+- (BOOL)continueTrackingWithEvent:(NSEvent *)event {
 	
-	// rather than a simple -setNeedsDisplay, let's fade it back out
-	[TUIView animateWithDuration:0.5 animations:^{
-		[self redraw]; // -redraw forces a .contents update immediately based on drawRect, and it happens inside an animation block, so CoreAnimation gives us a cross-fade for free
+	// Offset the tab's x origin by whatever we dragged by.
+	// Animating it makes it fun if the drag goes pretty far.
+	CGFloat currentPosition = [self convertPoint:[event locationInWindow] fromView:nil].x;
+	[TUIView animateWithDuration:0.1 animations:^{
+		
+		// Setting an ease-in-out animation curve slows down
+		// the animation at the start and finish, but speeds it up
+		// during the middle. Just for that "don't slide me!" fun.
+		[TUIView setAnimationCurve:TUIViewAnimationCurveEaseInOut];
+		
+		CGRect draggedRect = self.frame;
+		draggedRect.origin.x += roundf(currentPosition - self.originalPosition);
+		self.frame = draggedRect;
 	}];
 	
-	if([self eventInside:event]) { // only perform the action if the mouse up happened inside our bounds - ignores mouse down, drag-out, mouse up
-		[[self tabBar].delegate tabBar:[self tabBar] didSelectTab:self.tag];
-	}
+	return YES;
 }
 
+// Restore tabs to their original condition.
+- (void)endTrackingWithEvent:(NSEvent *)event {
+	
+	// By nature, the event *must* be inside the tab's bounds, otherwise the
+	// tracking process will not be invoked. If we were dragged, we were NOT
+	// pressed, so don't call the delegate.
+	CGFloat currentPosition = [self convertPoint:[event locationInWindow] fromView:nil].x;
+	if(self.originalPosition == currentPosition)
+		[[self tabBar].delegate tabBar:[self tabBar] didSelectTab:self.tag];
+	
+	// Since tracking is done, move the tab back. This whole ordeal lets us
+	// "stretch" our tabs around.
+	float originalPoint = self.tag * (self.tabBar.bounds.size.width / self.tabBar.tabViews.count);
+	[TUIView animateWithDuration:0.2 animations:^{
+		CGRect draggedRect = self.frame;
+		draggedRect.origin.x = roundf(originalPoint);
+		self.frame = draggedRect;
+	}];
+	
+	// Rather than a simple -setNeedsDisplay, let's fade it back out.
+	[TUIView animateWithDuration:0.3 animations:^{
+		
+		// -redraw forces a .contents update immediately based on drawRect,
+		// and it happens inside an animation block, so CoreAnimation gives
+		// us a cross-fade for free.
+		[self redraw];
+	}];
+}
+
+@end
+
+@interface ExampleTabBar ()
+
+@property (nonatomic, assign) ExampleTab *draggingTab;
+
 @end
 
 @implementation ExampleTabBar
@@ -61,7 +115,7 @@
 			t.tag = i;
 			t.layout = ^(TUIView *v) { // the layout of an individual tab is a function of the superview bounds, the number of tabs, and the current tab index
 				CGRect b = v.superview.bounds; // reference the passed-in 'v' rather than 't' to avoid a retain cycle
-				float width = b.size.width / nTabs;
+				float width = (b.size.width / nTabs);
 				float x = i * width;
 				return CGRectMake(roundf(x), 0, roundf(width), b.size.height);
 			};