Android从代码中截取屏幕截图，具有root访问权限

Question

I need to take a screenshot from a service running in the background. The screenshot can be of the app in the foreground, even if its not my app, which is why I can't use DrawingCache. I've searched around and found this

process = Runtime.getRuntime().exec("su -c cat /dev/graphics/fb0"); InputStream is = process.getInputStream();

But I don't know what to do with the stream. How do I get it into a bitmap? I don't need to save it to file I just need to keep it in a variable. This is for rooted phones.

Any help is much appreciated.

Answer 1

Well, seems I'm on my own with this one. So far this is what I've found, for those who have a similar problem. Note that this varies by version, and I am running 2.3 Gingerbread.

I found 2 files in /system/bin - screencap and screenshot .

screencap returns a bitmap in a format I don't know how to decode, while screenshot makes a regular bmp file called tmpshot.bmp at the root of the sdcard (Neither accept any kind of command parameters. They don't seem to accept -h,-help, --help etc either).

tmpshot.bmp seems a viable solution for now but I was looking to avoid writing and reading from sdcard as this is quite the bottleneck. I will keep searching, but for those who need a solution now, here you are.

EDIT: Upon further trials I found the screencap binary from another rom (MIUI to be specific) actually offers a few more options, where (miui) screencap -t png /sdcard/screen.png yields a valid png screenshot.

Answer 2

Try this

 Process sh = Runtime.getRuntime().exec("su", null,null);    
                    OutputStream  os = sh.getOutputStream();
                    os.write(("/system/bin/screencap -p " + "/sdcard/img.png").getBytes("ASCII"));
                    os.flush();          
                    os.close();
                    sh.waitFor();

put it in a try catch block