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#Android multitouch androidThe horizontal and vertical position of the fingertip relative to the screen is then made available to us through the Android OS it is updated only when we touch or move a fingertip across the screen. A touch on the screen surface distorts the electrostatic field, causing a change in its electric capacitance, which can be located relative to the screen surface. When we interact with the touch screen surface, our fingertips act as electrical conductors-not very good ones, but good enough to be detected. The capacitive touch screen panel of an Android device consists of a glass insulator coated with a transparent conductor. Let's take a look at how the touch screen panel works. #Android multitouch installWe'll download and install the library step by step and take a quick look at the main Ketai classes. We'll work with Ketai throughout the book, as it also simplifies working with sensors, cameras, location, and networking-all the hardware features that are typically difficult to work with. ![]() To make working with multitouch gestures easy, we'll use the Ketai library for Processing, which greatly simplifies the process. In the sketch we'll develop, we'll manipulate the scale, position, rotation, and color of a rectangle using multitouch gestures. Building on the basic drawing sketch, we'll use the mouse speed to manipulate the hues of the ellipses we draw.įinally, we'll dedicate the second part of the chapter to the multitouch features of the Android touch screen and create a sketch that showcases the most common gestures, including the tap, double-tap, long press, flick, pinch, and rotate gestures. Then we'll dive into the different color modes Processing has to offer, an essential topic that we need to address to work with graphics and images throughout the book. In this chapter, we'll get started by learning to use the mouse callback methods available in Processing for Android. The two most common multitouch gestures are the pinch and rotate gestures, typically used for scaling and rotating objects on the screen. ![]() Multitouch allows us a variety of distinct finger gestures compared to the mouse, which we can only use to interact with the UI elements and other components displayed on the screen. We can work with two, five, even ten fingers on the Android, although more than three are rarely used. ![]() First and foremost, the capacitive touch screen panel affords us more than one mouse pointer. There are a number of advantages to the multitouch screen interface to point out. Typically the Android device uses audiovisual cues such as click sounds or small device vibrations for user feedback. In fact, we don't have a rollover or a physical "click" on the touch screen panel at all, hence UI interactions often require adjustments for the touch screen. First of all, we don't have one omnipresent mouse pointer for interacting with UI elements via rollovers, clicks, right-clicks, and double-clicks. User interaction (UI) with Android touch screens differs somewhat from that of a mouse on a traditional computer display. It's a device we've gotten so accustomed to that we hardly "see" it as the hardware sensor that it is. Virtually all Android devices ship today with a capacitive touch screen panel. The circle we want to draw to show where the finger touches should be displayed when it touches the screen and disappears when it touches the screen.Now that we've completed our first Android app, let's explore a device feature that has become particularly popular with mobile phones and tablets-multitouch. To be able to draw a circle that shows where the finger touches, we need to call the addCircle (x, y, 50, ) on a Path. In this way, by adding code, we can change and adjust our drawings in such a way that it can identify and show us the places where the finger touches. #Android multitouch codeIn this part of the article, we also want to add code to our previous drawings so that we can change their function. #Android multitouch simulatorIf you use a simulator to run this project, you can do so using the mouse cursor. 2- Set the activity that will be used in this project to SingleTouchActivity.ģ- Create the SingleTouchEventView class as follows and make the necessary changes.Ĥ- Now it's time to add the View you created to the View, as follows:Īfter you have made all the above changes and inserted the above code in the files, you will notice at runtime that you can draw on the phone screen with one finger. ![]()
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