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An App Widget uses a special display control called RemoteViews. Unlike a regular View, a RemoteViews control is designed to display a collection of View controls in another process. Consequently, you can't simply add a button handler because that code would run in your application process, not in the process displaying the RemoteViews object (in this case, the Home Screen process).

In order to handle user interaction with an App Widget, the following tasks must be performed: Set a unique click handler for each App Widget control Have the click handler send a command to a registered receiver Process the command received and perform any action necessary Update the App Widget to reflect the changes

XLP Energy Harvesting Development Board The XLP 16-bit Energy Harvesting Development Kit is a true development platform for realizing energy harvesting applications. The Microchip nanoWatt XLP PIC MCUs are ideal for these low power applications with sleep currents down to 20nA, active mode currents down to 50uA/MHz, code execution efficiency, and multiple wake-up sources. Powered only by light, the XLP kit enables rapid prototyping of low power applications such as RF sensors, temperature/environmental sensors, utility meters, remote controls, and security sensors to name just a few. For software development and programming, the kit includes the PICkit 3 programmer/debugger for use with the Microchip’s free MPLAB™ Integrated Development Environment.

UART to USB bridge for use in prototyping and PC communication

Solar Energy Harvester with EnerChip storage devices providing backup power

Creating objects ahead of time is an important optimization. Views are redrawn very frequently, and many drawing objects require expensive initialization. Creating drawing objects within your onDraw() method significantly reduces performance and can make your UI appear sluggish.

If your view doesn't need special control over its size, you only need to override one method: onSizeChanged().

你可以在 EyE-Sight 站点了解到更多关于这一功能的消息，也可以通过下面的视频来了解更多细节。 继续观看视频：

手势相对于无趣的触摸和点击来说，给用户带来了的动态感。但是，缺乏一致性，操作的不易发觉，加上极易触发的不可恢复的操作，使得整个系统的可用性遭到损害。  我们迫切的需要回到基本原则，为这些系统开发可用性指南，这份指南应该基于交互设计的坚实原则，而不是某个公司在人机交互指导中的奇思，或者一些开发者的妙想

简单的宣称你的用户界面“有趣”和“自然”并不能证明你的界面可用，当你的用户使用软件时，对于如何操作茫然无措，并不是什么好玩的事情

1.Android 许多重要的功能是不可见的，除非你长按界面上的某东西，我经常对此感到懊恼

> Now I just want to update the GUI from this method. > Can I somehow call a method in PushEndpointDemo.java? No, for two reasons: 1. Because C2DMReceiver is a manifest-registered BroadcastReceiver and therefore has no access to any activities 2. There might not be an activity, since you have no control over the timing of when the C2DM message is received (e.g., the user pressed BACK, the user pressed HOME) > Do I need a Broadcast Intent to do this? Possibly. -- If you want to update an activity or else ignore the message, have C2DMReceiver send out a private broadcast, picked up by a receiver registered via registerReceiver() in the activity -- If you want to update an activity or else raise a notification, have C2DMReceiver send out an ordered broadcast, as described here: http://commonsware.com/blog/2010/08/11/activity-notification-ordered-... -- If you want to update a database, call startActivity() on an IntentService, and have it do the database I/O, plus possibly broadcast an Intent to update an activity/raise a notification.

Calling a Javascript method from your Java code: webView.loadUrl("javascript:jsToggle()"); Calling a Java method from Javascript: window.jsinterface.nativeToggle(); /*   // Before using the above code, you have to inject the interface object which   // has a name "jsinterface"   webView.addJavascriptInterface(jsInterface, "jsinterface"); */

As part of my job, I ran into memory leaks issues in Android applications and they are most of the time due to the same mistake: keeping a long-lived reference to a Context.

There are two easy ways to avoid context-related memory leaks. The most obvious one is to avoid escaping the context outside of its own scope. The example above showed the case of a static reference but inner classes and their implicit reference to the outer class can be equally dangerous. The second solution is to use the Application context. This context will live as long as your application is alive and does not depend on the activities life cycle. If you plan on keeping long-lived objects that need a context, remember the application object. You can obtain it easily by calling Context.getApplicationContext() or Activity.getApplication().

In summary, to avoid context-related memory leaks, remember the following: Do not keep long-lived references to a context-activity (a reference to an activity should have the same life cycle as the activity itself) Try using the context-application instead of a context-activity Avoid non-static inner classes in an activity if you don't control their life cycle, use a static inner class and make a weak reference to the activity inside. The solution to this issue is to use a static inner class with a WeakReference to the outer class, as done in ViewRoot and its W inner class for instance A garbage collector is not an insurance against memory leaks