Android 5.0及以上实现屏幕截图

在Android 5.0，API 21 之前想要截图系统屏幕必须Root才能完成，5.0之后开放了接口,下面看我们是怎么实现的。

1. 涉及到的相关类

1.

MediaProjectionManager

Context#getSystemService

MEDIA_PROJECTION_SERVICE

MediaProjection

2.

MediaProjection

3.

ImageReader

Surface

2. 上面三个类就可以完成我们截取屏幕图片的操作，那么下面我们将解释他们是怎么合作完成的

1. 首先获取用户授权，截图屏幕需要用户手动授权后才能操作

@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public void requestCapturePermission() {

if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
//5.0 之后才允许使用屏幕截图

return;
}

MediaProjectionManager mediaProjectionManager = (MediaProjectionManager)
getSystemService(Context.MEDIA_PROJECTION_SERVICE);
startActivityForResult(
mediaProjectionManager.createScreenCaptureIntent(),
REQUEST_MEDIA_PROJECTION);
}

startActivityForResult

createScreenCaptureIntent()

onActivityResult

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);

switch (requestCode) {
case REQUEST_MEDIA_PROJECTION:

if (resultCode == RESULT_OK && data != null) {
FloatWindowsService.setResultData(data);
startService(new Intent(getApplicationContext(), FloatWindowsService.class));
}

break;
}
}

这里我是用

FloatWindowsService

在桌面上显示一个悬浮按钮，点击截屏，下面我们看在

FloatWindowsService

是如何实现截图

2. 截取屏幕内容生成Bitmap

首先创建

ImageReader

实例

private void createImageReader() {

mImageReader = ImageReader.newInstance(mScreenWidth, mScreenHeight, PixelFormat.RGBA_8888, 2);

}

然后点击事件中触发

startScreenShot()

private void startScreenShot() {

mFloatView.setVisibility(View.GONE);

Handler handler = new Handler();
handler.postDelayed(new Runnable() {
public void run() {
//获取当前屏幕内容
startVirtual();
}
}, 5);

handler.postDelayed(new Runnable() {
public void run() {
//生成图片保存到本地
startCapture();

}
}, 30);
}

在

startVirtual()

方法中我们做一件事，就是获取当前屏幕内容

public void startVirtual() {
if (mMediaProjection != null) {
virtualDisplay();
} else {
setUpMediaProjection();
virtualDisplay();
}
}

与此同时需要获取

MediaProjection

实例，而

mResultData

是授权后返回的结果

public void setUpMediaProjection() {
if (mResultData == null) {
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_LAUNCHER);
startActivity(intent);
} else {
//mResultData是在Activity中用户授权后返回的结果
mMediaProjection = getMediaProjectionManager().getMediaProjection(Activity.RESULT_OK, mResultData);
}
}

最终得到当前屏幕的内容，注意这里

mImageReader.getSurface()

被传入，屏幕的数据也将会在ImageReader中的Surface中

private void virtualDisplay() {
mVirtualDisplay = mMediaProjection.createVirtualDisplay("screen-mirror",
mScreenWidth, mScreenHeight, mScreenDensity, DisplayManager.VIRTUAL_DISPLAY_FLAG_AUTO_MIRROR,
mImageReader.getSurface(), null, null);
}

最后把

mImageReader

得到的屏幕内容数据转换成图片,在AsyncTask中处理,

Image.Plane

image.close();

@Override
protected Bitmap doInBackground(Image... params) {

if (params == null || params.length < 1 || params[0] == null) {

return null;
}

Image image = params[0];

int width = image.getWidth();
int height = image.getHeight();
final Image.Plane[] planes = image.getPlanes();
final ByteBuffer buffer = planes[0].getBuffer();
//每个像素的间距
int pixelStride = planes[0].getPixelStride();
//总的间距
int rowStride = planes[0].getRowStride();
int rowPadding = rowStride - pixelStride * width;
Bitmap bitmap = Bitmap.createBitmap(width + rowPadding / pixelStride, height, Bitmap.Config.ARGB_8888);
bitmap.copyPixelsFromBuffer(buffer);
bitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height);
image.close();

源码

APK