问题描述
我注意到有些按钮似乎没有应有的响应.这同样适用于我的应用和我尝试过的大多数其他应用.
I have noticed that some Buttons don't seem as responsive as they could be. This applies equally to my app and to most other apps I've tried.
当我按下按钮时，按钮在按下状态点亮之前会有一点延迟(我估计大约 20-50 毫秒).一些应用程序已经设法消除了这种延迟，例如 RealCalc(在市场上有售)，它的按钮在您按下手指后立即切换到按下状态.
When I press a Button there is a tiny bit of lag ( I would estimate about 20-50 ms) before the Button lights up in the pressed state. Some apps have managed to remove this bit of lag, for instance RealCalc (available in the Market) whose Buttons switch to the pressed state immediately after you press your finger on them.
大多数时候这种滞后并不明显，但在我的情况下，按钮用于自定义数字键盘，这种微小的滞后对用户来说是破坏性的.RealCalc 感觉更加灵敏和优美，因为这种延迟已被消除.
Most of the time this lag is not noticeable, but in my case where the Buttons are used in a custom number pad, this tiny bit of lag is disruptive to the user. RealCalc feels so much more responsive and polished because this lag has been removed.
我的问题是 - 如何消除这种滞后?我知道我可以子类化，覆盖 onTouchEvent 并从那里继续，但我真的更喜欢只使用标准控件和选项的解决方案.我怀疑该解决方案也可能会干扰滚动，但我可以接受.
My question is - how do I remove this lag? I am aware that I could just subclass, override onTouchEvent and proceed from there, but I would really prefer a solution using just the standard controls and options. I suspect the solution may also interfere with scrolling, but I can live with that.
具体来说，提到的延迟是指从您将手指放在按钮上并保持在那里直到按钮切换到按下状态的时间.当您再次移开手指时，将调用 onClick 处理程序.
Specifically, the lag mentioned is the time from you put your finger on a button and hold it there until the button switches to the pressed state. The onClick handler is called when you remove your finger again.
一些答案建议将我的大部分 onClick 处理程序移动到一个线程.这不是问题.为了加倍确定，我已经删除了所有点击处理程序，微小的延迟仍然存在.
Some answers suggested moving the bulk of my onClick handler to a thread. This is not the issue. To make doubly sure, I have removed all click handlers, and the tiny lag is still there.
推荐答案
我已经深入研究了 Android 源代码，看看发生了什么.
I have dug into the Android source code to see what was going on.
事实证明，android.view.View 类(Button 派生自该类)在进入 PRESSED 状态之前进入了PREPRESSED"状态:
It turns out that the android.view.View class (from which Button derives) enters a "PREPRESSED" state before going into the PRESSED state:
android.view.View:
android.view.View:
1529 /**
1530 * Indicates a prepressed state;
1531 * the short time between ACTION_DOWN and recognizing
1532 * a 'real' press. Prepressed is used to recognize quick taps
1533 * even when they are shorter than ViewConfiguration.getTapTimeout().
1534 *
1535 * @hide
1536 */
1537 private static final int PREPRESSED = 0x02000000;
android.view.ViewConfiguration.getTapTimeout() 在我的 Nexus One 上为 115 毫秒，这比我估计的要长得多.
android.view.ViewConfiguration.getTapTimeout() is 115 ms on my Nexus One, which is a lot longer than my estimation.
android.view.ViewConfiguration:
android.view.ViewConfiguration:
67 /**
68 * Defines the duration in milliseconds we will wait to see if a touch event
69 * is a tap or a scroll. If the user does not move within this interval, it is
70 * considered to be a tap.
71 */
72 private static final int TAP_TIMEOUT = 115;
无论如何，从检查 View.onTouchEvent 来看，似乎没有办法通过任何标准选项来避免这种 PREPRESSED 状态.这真是一种耻辱.
Anyway, from examining View.onTouchEvent is doesn't look like there's a way to avoid this PREPRESSED state by any standard option. Which is a real shame.
好消息是，我现在已经证实避免这种滞后的方法是子类化和覆盖 onTouchEvent.
The good news is that I have now verified that the way to avoid this lag is to subclass and override onTouchEvent.
感谢讨论和回答.
这篇关于如何使按钮更具响应性?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，WP2