Take screenshot method inside Fragment

问题

I've been trying to get this code working inside a fragment. This code runs fine inside an Activity, but I can't make it to work inside the fragment.

When I click a button, it calls the takeScreenshot method.

This is the code for the screenshot:

public Bitmap takeScreenshot() {
    View rootView = findViewById(android.R.id.content).getRootView();
    rootView.setDrawingCacheEnabled(true);
    return rootView.getDrawingCache();
}

The "findViewById" it's not recognized due to being in a fragment.

I've tried:

View rootView = getView().findViewById(android.R.id.content).getRootView();

but it's not working either. I get

07-25 09:37:32.746: E/AndroidRuntime(31221): FATAL EXCEPTION: main
07-25 09:37:32.746: E/AndroidRuntime(31221): java.lang.NullPointerException
07-25 09:37:32.746: E/AndroidRuntime(31221):    at com.dream3ncore.thefinalwordcounts.level01.Song01.takeScreenshot(Song01.java:763)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at com.dream3ncore.thefinalwordcounts.level01.Song01.onClick(Song01.java:152)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at android.view.View.performClick(View.java:4211)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at android.view.View$PerformClick.run(View.java:17362)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at android.os.Handler.handleCallback(Handler.java:725)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at android.os.Handler.dispatchMessage(Handler.java:92)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at android.os.Looper.loop(Looper.java:137)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at android.app.ActivityThread.main(ActivityThread.java:5227)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at java.lang.reflect.Method.invokeNative(Native Method)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at java.lang.reflect.Method.invoke(Method.java:511)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
07-25 09:37:32.746: E/AndroidRuntime(31221):    at dalvik.system.NativeStart.main(Native Method)

Any help will be greatly appreciated.

回答1:

Your Fragment's UI is a subset of your Activity's UI. getView() in a Fragment will return only its own view hierarchy. You could just change your call to getView() to getActivity(), and that would work. Alternately, I believe you could just call getView().getRootView() and avoid the lookup of android.R.id.content in the first place.

回答2:

In the onCreateView method where the fragments view is inflated. That is the view that I tie the screenshot code too.

view.setDrawingCacheEnabled(true);
view.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);
Bitmap screenshot = Bitmap.createBitmap(view.getDrawingCache()));
view.setDrawingCacheEnabled(false);

For those that did not tie the screenshot to an action, I had to create a postDelay handler that checked with the fragment was ready. I used something like this

 private void waitForView() {
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                if (isVisible()) {
                    // create the view snapshot
                    view.setDrawingCacheEnabled(true);
                    view.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);
                    Bitmap screenshot = Bitmap.createBitmap(view.getDrawingCache()));
                    view.setDrawingCacheEnabled(false);
                } else {
                    waitForView();
                }
            }
        }, 100);
    }

This worked relatively well for the fragment and handling views that took time to generate.

来源：https://stackoverflow.com/questions/24944480/take-screenshot-method-inside-fragment

标签

android

android-fragments

findviewbyid