Dustin Ingram

Intro #

Certain recent endeavors have lead me to desire a way to automatically get pixel-perfect screenshots of my physical Android device (Motorola Droid). I knew it was possible to use the “adb”, or Android Debug Bridge tool; however, the actual tool has a number of features I didn’t need, plus I wanted to automate the entire process.

References #

A number of mailing list posters and/or bloggers, some dating back a couple years, have attempted a solution, but almost every one either depended on an out-of-date library, or simply didn’t work. The majority of my solution is taken from Jon Larimer’s code, but I had to make a number of modifications to render the resulting image properly.

Starting the ADB #

I had a minor issue getting the ADB started. What happens is, if the ADB server isn’t started with the proper permissions (root), there will be no device access. The tricky thing is, if you’ve got Eclipse running with the Android plugins, it’ll have started up the ADB server already, with basic permissions. The following is an example of what you’ll get from a running server without enough permissions:

$ ./adb devices
List of devices attached
???????????? no permissions

The solution is:

$ ./adb kill-server
$ sudo ./adb start-server
* daemon not running. starting it now *
* daemon started successfully *
$ ./adb devices
List of devices attached
04XXXXXXXXXXXX13  device

Connecting to the ADB #

Create the DebugBridge as follows:

AndroidDebugBridge.init(false);
AndroidDebugBridge adb = AndroidDebugBridge.createBridge();

We’re going to add an instance of our class as a device change listener, so we’ll know when changes occur, like the connection to a device. This also means the class will implement IDeviceChangeListener.

Screenshot ss = new Screenshot();
AndroidDebugBridge.addDeviceChangeListener(ss);

Use this to collect all attached devices:

IDevice[] devices = adb.getDevices();

Getting the Raw Screenshot #

Get the RawImage from the device:

RawImage raw = device.getScreenshot();

Set up the BufferedImage with the appropriate dimensions:

Boolean landscape = false;
BufferedImage image = null;
Dimension size = new Dimension();
int width2 = landscape ? raw.height : raw.width;
int height2 = landscape ? raw.width : raw.height;

if (image == null) {
    image = new BufferedImage(width2, height2, BufferedImage.TYPE_INT_RGB);
        size.setSize(image.getWidth(), image.getHeight());
} else {
    if (image.getHeight() != height2 || image.getWidth() != width2) {
        image = new BufferedImage(width2, height2, BufferedImage.TYPE_INT_RGB);
        size.setSize(image.getWidth(), image.getHeight());
    }
}

Finally, make the appropriate adjustments to the RawImage’s RGB values:

int index = 0;
int indexInc = raw.bpp >> 3;
for (int y = 0; y < raw.height; y++) {
    for (int x = 0; x < raw.width; x++, index += indexInc) {
        int value = raw.getARGB(index);
        if (landscape)
            image.setRGB(y, raw.width - x - 1, value);
        else
            image.setRGB(x, y, value);
    }
}

There are also a number of overrides for our class to fill the requirements of the implementation, for the various changes

All together #

You can download the entire working class here.