似乎无法从视图中的机器人获得的位图 [英] cannot seem to get bitmap from view in android

问题描述

我的问题是一个类似于在<一href="http://stackoverflow.com/questions/2339429/android-view-getdrawingcache-returns-null-only-null">Android View.getDrawingCache返回null，只有空。

使用的方法来工作，我的code

 私人位图getBitmapFromView（视图v）{
    v.setDrawingCacheEnabled（真正的）;
    v.measure（MeasureSpec.makeMeasureSpec（0，MeasureSpec.UNSPECIFIED），
        MeasureSpec.makeMeasureSpec（0，MeasureSpec.UNSPECIFIED））;
    v.layout（0，0，v.getMeasuredWidth（），v.getMeasuredHeight（））;
    v.buildDrawingCache（真正的）;
    位图B = Bitmap.createBitmap（v.getDrawingCache（））;
    v.setDrawingCacheEnabled（假）; //清晰的绘图缓存
    返回b;
}
 

但今天我改变了XML布局文件。由于改变我已经越来越NullPointerException异常的行位图B = Bitmap.createBitmap（v.getDrawingCache（））。所以，我试图改变方法 getBitmapFromView 到

 公共静态位图loadBitmapFromView（视图v）{
    位图B = Bitmap.createBitmap（v.getLayoutParams（）宽度，v.getLayoutParams（）高度，Bitmap.Config.ARGB_8888）;
    帆布C =新的Canvas（B）;
    v.layout（0，0，v.getLayoutParams（）宽度，v.getLayoutParams（）高度。）;
    v.draw（C）;
    返回b;
}
 

但是，这并没有帮助。我得到的第一行空。

的情况是这样的：我想视图转换成位图。但我这样做并没有先在屏幕上显示的视图。同样，这一切都用来工作，直到我换了XML布局文件的内容。这种变化甚至没有那么大。我刚搬的东西四周，删除 - 是去掉 - 一些子视图

在任何情况下，我知道肯定是没有问题，我的布局文件，因为我可以在屏幕上显示出来，如果​​我想要的;我已经做故障排除的一部分。

使用一个处理程序来调用有人建议 getDrawingCache（）。如果是这样的回答，我怎么会写code？

更新

 查看视图= activity.getLayoutInflater（）膨胀（R.layout.my_view，空，假的）。
    findViewsByIds（视图）; //我的充气子视图，并添加内容到他们。
 

解决方案

既然你不显示视图它更容易只是画在画布上的看法。 你已经尝试这样做，但我会合并这两种方法为一个没有使用绘图缓存。

 私人位图getBitmapFromView（视图v）{
    v.measure（MeasureSpec.makeMeasureSpec（0，MeasureSpec.UNSPECIFIED），
            MeasureSpec.makeMeasureSpec（0，MeasureSpec.UNSPECIFIED））;
    v.layout（0，0，v.getMeasuredWidth（），v.getMeasuredWidth（））;
    位图B = Bitmap.createBitmap（v.getMeasuredWidth（），v.getMeasuredWidth（），Bitmap.Config.ARGB_8888）;
    帆布C =新的Canvas（B）;
    v.draw（C）;
    返回b;
}
 

此外，检查 MeasureSpec.UNSPECIFIED ，未经布局视图的工作，所以你可能需要指定一个宽度和高度。

My problem is similar to the one in Android View.getDrawingCache returns null, only null.

My code used to work with the method

private Bitmap getBitmapFromView(View v) {
    v.setDrawingCacheEnabled(true);
    v.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED),
        MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
    v.layout(0, 0, v.getMeasuredWidth(), v.getMeasuredHeight());
    v.buildDrawingCache(true);
    Bitmap b = Bitmap.createBitmap(v.getDrawingCache());
    v.setDrawingCacheEnabled(false); // clear drawing cache
    return b;
}

But today I changed the xml layout file. Since the change I have been getting NullPointerException at the line Bitmap b = Bitmap.createBitmap(v.getDrawingCache()). So I tried changing the method getBitmapFromView to

public static Bitmap loadBitmapFromView(View v) {
    Bitmap b = Bitmap.createBitmap(v.getLayoutParams().width, v.getLayoutParams().height, Bitmap.Config.ARGB_8888);
    Canvas c = new Canvas(b);
    v.layout(0, 0, v.getLayoutParams().width, v.getLayoutParams().height);
    v.draw(c);
    return b;
}

But that didn't help. I get the null in the very first line.

The situation is this: I am trying to convert the view into a bitmap. But I am doing this without first displaying the view on screen. Again, this all used to work until I changed the content of the xml layout file. The change was not even that big. I just moved stuff around and removed -- yes removed -- some of the subviews.

In any case, I know for certain there is no problem with my layout file because I can display it on screen if I want; which I have done as part of troubleshooting.

Someone suggested using a handler to call getDrawingCache(). If that's the answer, how would I write that code?

UPDATE

View view = activity.getLayoutInflater().inflate(R.layout.my_view, null, false);
    findViewsByIds(view);//where I inflate subviews and add content to them.

解决方案

Since you are not showing the view it's easier to just draw the view on a canvas. You are already trying to do that but I would merge both methods into one without using drawing cache.

private Bitmap getBitmapFromView(View v) {
    v.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED),
            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
    v.layout(0, 0, v.getMeasuredWidth(), v.getMeasuredWidth());
    Bitmap b = Bitmap.createBitmap(v.getMeasuredWidth(), v.getMeasuredWidth(), Bitmap.Config.ARGB_8888);
    Canvas c = new Canvas(b);
    v.draw(c);
    return b;
}

Also check that MeasureSpec.UNSPECIFIED may not work well without the view in layout so you may need to specify a width and height.

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