强制视图重绘自身 [英] Force a View to redraw itself

问题描述

我已经创建了一个自定义视图（姑且称之为 MyView的），这基本上只是用绘制在画布上本身的一些文字。要绘制的文本使用全局变量被设置

在程序的执行过程中的某个时刻，我想改变全局变量，并具有 MyView的重绘自身更新的文本。我试过 findViewById（）然后无效（），但是这并没有什么。我怀疑，因为在任何的 MyView的发生了变化，它认为它没有理由叫的OnDraw（）。有没有什么办法来迫使一查看，即使它认为它并不需要重绘自己？

解决方案

  

如果我有一个存储的文本MyView的内部成员变量，并创建一个公共制定者，那么只需调用该方法会导致MyView的重绘自身

设置查看里面的变量将不会调用视图中的一个平局。事实上，同样没有查看系统知道，也不关心内部变量。

调用无效（）在View使其通过视图中绘制本身。你应该看看这个： http://developer.android.com/guide /topics/ui/custom-components.html 。

A 的TextView 在内部，当你调用无效本身的setText（），并用新文本通过设置重绘自己的setText（）通话。你也应该做同样的事情。

I have created a custom View (let's call it MyView) which basically just draws some text on itself using the canvas. The text to be drawn is set using a global variable.

At some point during the program's execution, I want to change the global variable, and have the MyView redraw itself to update the text. I tried findViewById() and then invalidate(), but this does nothing. I suspect that since nothing within the MyView has changed, it thinks it has no reason to call onDraw(). Is there any way to force a View to redraw itself even if it thinks it doesn't need to?

解决方案

If I have a member variable inside the MyView that stores the text, and create a public setter for it, then just calling that method causes the MyView to redraw itself

Setting a variable inside the View will not invoke a draw on the View. In fact, neither does the view system know nor care about internal variables.

Invoking invalidate() on a View causes it to draw itself via the View. You should check this out: http://developer.android.com/guide/topics/ui/custom-components.html.

A TextView internally invalidates itself when you invoke setText() and redraws itself with the new text set via the setText() call. You should also do something similar.

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