vb.net print barcode labels 4: All Fingers and Thumbs: Multitouch Interface Design and Implementation in Objective-C

Maker Data Matrix 2d barcode in Objective-C 4: All Fingers and Thumbs: Multitouch Interface Design and Implementation

CHAPTER 4: All Fingers and Thumbs: Multitouch Interface Design and Implementation
Generating Data Matrix ECC200 In Objective-C
Using Barcode printer for iPhone Control to generate, create DataMatrix image in iPhone applications.
www.OnBarcode.com
Barcode Creation In Objective-C
Using Barcode maker for iPhone Control to generate, create Barcode image in iPhone applications.
www.OnBarcode.com
Exploring the Multitouch API
Painting DataMatrix In Objective-C
Using Barcode generator for iPhone Control to generate, create Data Matrix image in iPhone applications.
www.OnBarcode.com
QR Code JIS X 0510 Encoder In Objective-C
Using Barcode generator for iPhone Control to generate, create QR-Code image in iPhone applications.
www.OnBarcode.com
To implement your own multitouch gestures, you need to: Arrange for touch messages to get routed to your code Understand the information passed to you Track and parse gestures from that information
Barcode Encoder In Objective-C
Using Barcode generator for iPhone Control to generate, create Barcode image in iPhone applications.
www.OnBarcode.com
Printing USS Code 128 In Objective-C
Using Barcode drawer for iPhone Control to generate, create USS Code 128 image in iPhone applications.
www.OnBarcode.com
Handling Events
Creating Code 39 In Objective-C
Using Barcode drawer for iPhone Control to generate, create Code 39 image in iPhone applications.
www.OnBarcode.com
GS1 - 8 Generator In Objective-C
Using Barcode drawer for iPhone Control to generate, create European Article Number 8 image in iPhone applications.
www.OnBarcode.com
If you re implementing your own custom controls, arranging for touch messages to get routed is easy; you just need to implement the relevant event handlers. There s a set of four with identical signatures, declared in UIResponder:
Data Matrix Decoder In .NET Framework
Using Barcode scanner for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Encoding Data Matrix In None
Using Barcode printer for Microsoft Word Control to generate, create Data Matrix 2d barcode image in Word applications.
www.OnBarcode.com
(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event; (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event; (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event; (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;
Barcode Scanner In VS .NET
Using Barcode reader for .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Code 39 Extended Generator In VB.NET
Using Barcode creation for VS .NET Control to generate, create Code 39 Extended image in .NET framework applications.
www.OnBarcode.com
You also need to ensure your view s userInteractionEnabled is set, as well as multipleTouchEnabled if appropriate. UIViews and most subclasses default to userInteractionEnabled, but multipleTouchEnabled is usually disabled. These four messages, plus the UIEvent class and the UITouch class, are the core of multitouch handling. The messages are pretty self-explanatory, but here s a quick note on the difference between touchesEnded and touchesCancelled: touches end when the user lifts a finger, but they re cancelled by the operating system itself, typically in response to asynchronous events such as incoming text messages or phone calls. A UITouch object represents a single finger in contact with the screen. It s created when a finger touches the screen, destroyed when the finger leaves it and, notably, is attached for its entire lifetime to a single UIView. The view the finger initially came into contact with is the only view that receives the touch events. This is why, for example, you can touch the slot machine style UIPickerView controls and drag your finger up and down across the entire screen height: the control captures the touch (see Figure 4-4). The UIEvent represents an entire gesture or sequence, encompassing up to five fingers. It s created when the first finger comes into contact with the screen (and you receive your first touchesBegan:withEvent:), containing that finger s UITouch, and it continues to exist with UITouches being added or removed as additional fingers come and go until all fingers are removed from the screen. Only then (after the final touchesEnded:withEvent: or touchesCancelled:withEvent: messages) is the UIEvent destroyed.
Generate DataMatrix In Java
Using Barcode creator for Android Control to generate, create ECC200 image in Android applications.
www.OnBarcode.com
Encoding Matrix Barcode In Visual Studio .NET
Using Barcode generation for ASP.NET Control to generate, create Matrix Barcode image in ASP.NET applications.
www.OnBarcode.com
CHAPTER 4: All Fingers and Thumbs: Multitouch Interface Design and Implementation
Code 128 Generator In Objective-C
Using Barcode printer for iPad Control to generate, create Code-128 image in iPad applications.
www.OnBarcode.com
Make UPC A In None
Using Barcode generator for Microsoft Excel Control to generate, create UPCA image in Microsoft Excel applications.
www.OnBarcode.com
For each of the touchesX:withEvent:, the touches set will only contain the changed touches, whereas the UIEvent always contains the complete set of active (or, in the case of ended/cancelled events, recently active) touches. Note also that you don t receive a message specifically telling you an event has ended. Combining these facts, we can detect a UIEvent ending by checking ended/cancelled touches: if the size of the changed touches set is the same as the size of the event s touchesForView set, we know the last fingers are being lifted from the screen. One of the issues that complicates multitouch handling is that the changed touches, the results of touchesForView, and the event s allTouches property are all unordered NSSets. If you need to track the movements of individual fingers, this can Figure 4-4. Once a finger is placed make life awkward, especially since UITouch objects on the scrolling view, it can be moved can t be used as NSDictionary keys and, according across the entire height of the screen to to Apple, should not be retained. A UITouch object s scroll the view, without disturbing the address does remain constant throughout its life, so multiple-choice buttons above it. Apple recommends using these addresses as keys in a CFDictionary (not NSDictionary). It s worth remembering, though, that for many gestures, especially when tracking two fingers, this solution may be way more complex than you need. A good approach is often to simply ignore the ordering of the touches, or the specific UITouch-to-finger mapping and concentrate only on the relationship between the touches. For example, if you re handling a pinch/unpinch gesture, all you really care about is the distance between the two touches, and the order is irrelevant. When measuring rotation, we can use a simple pointer-compare to order the touches so that the rotation doesn t flip by 180 degrees if the provided ordering changes (this is shown in the sample code later in this chapter). It turns out, a multitouch control rarely needs to track an individual touch for its lifetime. There s one final note on event handling before we start looking at specific gestures and detection techniques: if you re looking to modify existing controls, it can be tricky to get those events delivered to your code in the first place. If you subclass an existing view, you may find that you don t receive the events you re expecting, because many of the standard views are actually collections of views. When you create, for example, a UISlider, Cocoa actually creates several UIViews contained as subviews of the slider view.
Make QR Code 2d Barcode In Java
Using Barcode encoder for Java Control to generate, create QR Code JIS X 0510 image in Java applications.
www.OnBarcode.com
Barcode Creator In None
Using Barcode generator for Microsoft Word Control to generate, create Barcode image in Office Word applications.
www.OnBarcode.com
Generate ANSI/AIM Code 39 In None
Using Barcode drawer for Online Control to generate, create USS Code 39 image in Online applications.
www.OnBarcode.com
Decode Code 128C In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Copyright © OnBarcode.com . All rights reserved.