截屏如何实现？一串代码带你了解

Android 截屏分为四种：View 截屏、WebView 截屏、系统截屏 和 adb 截屏

1、View 截屏

View 截图是将当前 View 界面截取下来，而对于屏幕上其他信息比如：状态栏或其他应用的界面将无法截取。

1.1 截取除了导航栏之外的屏幕

// 开始截屏
private static byte[] screenshotView() {
  View view = getWindow().getDecorView();
  // view.setDrawingCacheEnabled(true); // 设置缓存，可用于实时截图
  Bitmap bitmap = Bitmap.createBitmap(view.getWidth(), view.getHeight(), Bitmap.Config.ARGB_8888);
  Canvas canvas = new Canvas(bitmap);
  view.draw(canvas);
  // view.setDrawingCacheEnabled(false); // 清空缓存，可用于实时截图
  byte[] drawByte = getBitmapByte(bitmap); // 位图转为 Byte
  return drawByte;
}
​
// 位图转 Base64 String
private static String getBitmapString(Bitmap bitmap) {
  String result = null;
  ByteArrayOutputStream out = null;
  try {
    if (bitmap != null) {
      out = new ByteArrayOutputStream();
      bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
​
      out.flush();
      out.close();
​
      byte[] bitmapBytes = out.toByteArray();
      result = Base64.encodeToString(bitmapBytes, Base64.DEFAULT);
    }
  } catch (IOException e) {
      e.printStackTrace();
  } finally {
    try {
      if (out != null) {
          out.flush();
          out.close();
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
  return result;
}
​
// 位图转 Byte
private static byte[] getBitmapByte(Bitmap bitmap){
  ByteArrayOutputStream out = new ByteArrayOutputStream();
  // 参数1转换类型，参数2压缩质量，参数3字节流资源
  bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
  try {
      out.flush();
      out.close();
  } catch (IOException e) {
      e.printStackTrace();
  }
  return out.toByteArray();
}

1.2 截取某个控件或者区域

// 方法1
private static byte[] screenshotView1() {
  View view = title;
  view.setDrawingCacheEnabled(true);
  view.buildDrawingCache();
  Bitmap bitmap = Bitmap.createBitmap(view.getDrawingCache());
  byte[] drawByte = getBitmapByte(bitmap);
  return drawByte;
}
​
// 方法2
private static byte[] screenshotView2() {
  View view = title;
  Bitmap bitmap = Bitmap.createBitmap(view.getWidth(), view.getHeight(), Bitmap.Config.ARGB_8888);
  // 使用 Canvas，调用自定义 view 控件的 onDraw 方法，绘制图片
  Canvas canvas = new Canvas(bitmap);
  dView.draw(canvas);
  byte[] drawByte = getBitmapByte(bitmap);
  return drawByte;
}

2、WebView 截屏

WebView 截屏有四种方式

2.1 使用 capturePicture() 方法（已废弃）

private static byte[] screenshotWebView() {
  Picture picture = webview.capturePicture();
  //创建位图
  Bitmap bitmap = Bitmap.createBitmap(picture.getWidth(), picture.getHeight(), Bitmap.Config.ARGB_8888);
  Canvas canvas = new Canvas(bitmap);
  // 绘制(会调用 native 方法，完成图形绘制)
  picture.draw(canvas);
  byte[] drawByte = getBitmapByte(bitmap);
  return drawByte;
}

2.2 使用 getScale() 方法（已废弃）

private static byte[] screenshotWebView() {
  float scale = webView.getScale();
  int webViewHeight = (int) (webView.getContentHeight()*scale+0.5);
  Bitmap bitmap = Bitmap.createBitmap(webView.getWidth(),webViewHeight, Bitmap.Config.ARGB_8888);
  Canvas canvas = new Canvas(bitmap);
  webView.draw(canvas);
  byte[] drawByte = getBitmapByte(bitmap);
  return drawByte;
}

2.3 使用 getDrawingCache() 方法

private static byte[] screenshotWebView() {
  Bitmap bitmap = webView.getDrawingCache();
  byte[] drawByte = getBitmapByte(bmp);
  return drawByte;
}

2.4 使用 draw() 方法

private static byte[] screenshotWebView() {
  // webView.setDrawingCacheEnabled(true); // 设置缓存
  Bitmap bitmap = Bitmap.createBitmap(webView.getWidth(), webView.getHeight(), Bitmap.Config.ARGB_8888);
  Canvas canvas = new Canvas(bitmap);
  webView.draw(canvas);
  webView.destroyDrawingCache();
  byte[] drawByte = getBitmapByte(bitmap);
  // webView.setDrawingCacheEnabled(false); // 清空缓存
  return drawByte;
}

2.5 截长图配置

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
  WebView.enableSlowWholeDocumentDraw();
}
setContentView(R.layout.activity_webview);

WebView 截图可能截取不到 cavans 元素，原因是开启了硬件加速，可在 AndroidManifest.xml 中设置属性 android:hardwareAccelerated="false"

关闭硬件加速可能导致页面出现意外情况

3、系统截屏

3.1 MediaProjection

public static final int REQUEST_MEDIA_PROJECTION = 10001;
// 申请截屏权限
private void getScreenShotPower() {
  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
    MediaProjectionManager mProjectionManager = (MediaProjectionManager) getSystemService(Context.MEDIA_PROJECTION_SERVICE);
    if (mProjectionManager != null) {
      startActivityForResult(mProjectionManager.createScreenCaptureIntent(), REQUEST_MEDIA_PROJECTION);
    }
  }
}
​
private MediaProjection mMediaProjection;
// 回调
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  super.onActivityResult(requestCode, resultCode, data);
  if (requestCode == REQUEST_MEDIA_PROJECTION && data != null) {
    if (resultCode == RESULT_OK) {
      MediaProjection mediaProjection = mMediaProjectionManager.getMediaProjection(resultCode, data);
      if (mediaProjection == null) {
        Toast.makeText(this,"程序发生错误:MediaProjection@1",Toast.LENGTH_SHORT).show();
        return;
      }
      // mediaProjection 就是当前屏幕流
    } else if (resultCode == RESULT_CANCELED) {
      Log.d(TAG, "用户取消");
    }
  }
}

参考

• https://github.com/tangfuOK/AndroidTangFu
• https://www.cnblogs.com/tgyf/p/4851092.html

3.2 Surface（需要 root 权限）

使用前需要：

• 在 AndroidMenifest.xml 中添加 android:sharedUserId="android.uid.system" 属性
• 需要给程序添加系统签名
• 或者 root 系统

使用 Java 反射机制，调用系统 API 截图：

private void screenshotSystem() {
  Class surfaceClass;
  Method method = null;
  Bitmap bitmap = null;
  try {
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN_MR2) {
        surfaceClass = Class.forName("android.view.SurfaceControl");
    } else {
        surfaceClass = Class.forName("android.view.Surface");
    }
    method = surfaceClass.getDeclaredMethod("screenshot", Integer.TYPE, Integer.TYPE);
    method.setAccessible(true);
    bitmap =  (Bitmap)method.invoke((Object)null, webview.getWidth(), webview.getHeight());
    byte[] drawByte = getBitmapByte(bitmap);
  } catch (ClassNotFoundException e){
    e.printStackTrace();
  } catch (NoSuchMethodException e){
    e.printStackTrace();
  } catch (IllegalAccessException e){
    e.printStackTrace();
  } catch (InvocationTargetException e){
    e.printStackTrace();
  }
}

3.3 PixelCopy

private void screenshotSystem() {
  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    PixelCopy.request(getWindow(), bitmap, new PixelCopy.OnPixelCopyFinishedListener() {
        @Override
        public void onPixelCopyFinished(int copyResult){
            if (PixelCopy.SUCCESS == copyResult) {
                byte[] drawByte = getBitmapByte(bitmap);
            } else {
                // onErrorCallback()
            }
        }
    }, new Handler());
  }
}

3.4 framebuffer（需要 root 权限）

String DEVICE_NAME = "/dev/graphics/fb0";
File deviceFile = new File(DEVICE_NAME);
Process localProcess = Runtime.getRuntime().exec("supersu");
String str = "cat " + deviceFile.getAbsolutePath() + "\n";
localProcess.getOutputStream().write(str.getBytes());
return localProcess.getInputStream();

3.5 screencap 命令（需要 root 权限）

private static String getScreenshot(){
  Process process = null;
  String filePath = "mnt/sdcard/" + System.currentTimeMillis() + ".png";
  try {
    process = Runtime.getRuntime().exec("su");
    PrintStream outputStream = null;
    outputStream = new PrintStream(new BufferedOutputStream(process.getOutputStream(), 8192));
    outputStream.println("screencap -p " + filePath);
    outputStream.flush();
    outputStream.close();
    process.waitFor();
  } catch (Exception e) {
    e.printStackTrace();
  } finally {
    if(process != null){
          process.destroy();
    }
  }
  return filePath;
}

4、adb 截屏

$ adb shell
shell@ $ screencap /sdcard/screen.png
shell@ $ exit
$ adb pull /sdcard/screen.png

 

转自：Android截屏如何实现？一串代码带你了解 - 知乎