[Android应用开发]-（13）屏幕截图功能--截取全屏，无需Root（附源码）

12-07-18 来源：[db:作者]

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由于要做说明书，或者给客户看效果图，不得不通过截图的方式把屏幕接下来（当然了，还可以通过拍照来达到目的）。于是就Google找到一些需要Root权限，和不需要Root权限的截图应用，有些失望，多数不可用。于是就想自己开发一个截图的应用。在View 中提供一个getDrawingCache的方法，可以通过次方法获取View的截屏，但仅仅是截取View的。如果要截取状态栏呢？

其实不然，在ICS中的SystemUI就实现了截图的功能，按组合键Power+Volume Add/Volume sub就能截取图片。代码目录：
frameworks/base/packages/SystemUI/src/com/android/systemui/screenshot/在此目录下就两个文件，主要的截图方法在GlobalScreenshot中，本文就通过移植SystemUI中截图的代码实现截图功能。

首先是直接移植SystemUI的代码，实现截图效果，这部分的代码就不贴出来了，直接去下载代码吧，关键的代码没有几句，最最主要的是：Surface.screenshot()，请看代码吧。

[java]
<SPAN style="FONT-SIZE: 16px">package org.winplus.ss;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.Display;
import android.view.Surface;
import android.view.WindowManager;
import android.os.SystemProperties;

public class SimpleScreenshotActivity extends Activity {

    private Display mDisplay;
    private WindowManager mWindowManager;
    private DisplayMetrics mDisplayMetrics;
    private Bitmap mScreenBitmap;
    private Matrix mDisplayMatrix;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        new Thread(new Runnable() {

            @Override
            public void run() {
                takeScreenshot();

            }
        }).start();
    }

    private float getDegreesForRotation(int value) {
        switch (value) {
        case Surface.ROTATION_90:
            return 360f - 90f;
        case Surface.ROTATION_180:
            return 360f - 180f;
        case Surface.ROTATION_270:
            return 360f - 270f;
        }
        return 0f;
    }

    private void takeScreenshot() {
        mWindowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
        mDisplay = mWindowManager.getDefaultDisplay();
        mDisplayMetrics = new DisplayMetrics();
        mDisplay.getRealMetrics(mDisplayMetrics);
        mDisplayMatrix = new Matrix();
        float[] dims = { mDisplayMetrics.widthPixels,
                mDisplayMetrics.heightPixels };

        int value = mDisplay.getRotation();
        String hwRotation = SystemProperties.get("ro.sf.hwrotation", "0");
        if (hwRotation.equals("270") || hwRotation.equals("90")) {
            value = (value + 3) % 4;
        }
        float degrees = getDegreesForRotation(value);

        boolean requiresRotation = (degrees > 0);
        if (requiresRotation) {
            // Get the dimensions of the device in its native orientation
            mDisplayMatrix.reset();
            mDisplayMatrix.preRotate(-degrees);
            mDisplayMatrix.mapPoints(dims);

            dims[0] = Math.abs(dims[0]);
            dims[1] = Math.abs(dims[1]);
        }

        mScreenBitmap = Surface.screenshot((int) dims[0], (int) dims[1]);

        if (requiresRotation) {
            // Rotate the screenshot to the current orientation
            Bitmap ss = Bitmap.createBitmap(mDisplayMetrics.widthPixels,
                    mDisplayMetrics.heightPixels, Bitmap.Config.ARGB_8888);
            Canvas c = new Canvas(ss);
            c.translate(ss.getWidth() / 2, ss.getHeight() / 2);
            c.rotate(degrees);
            c.translate(-dims[0] / 2, -dims[1] / 2);
            c.drawBitmap(mScreenBitmap, 0, 0, null);
            c.setBitmap(null);
            mScreenBitmap = ss;
        }

        // If we couldn't take the screenshot, notify the user
        if (mScreenBitmap == null) {
            return;
        }

        // Optimizations
        mScreenBitmap.setHasAlpha(false);
        mScreenBitmap.prepareToDraw();

        try {
            saveBitmap(mScreenBitmap);
        } catch (IOException e) {
            System.out.println(e.getMessage());
        }
    }

    public void saveBitmap(Bitmap bitmap) throws IOException {
        String imageDate = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss")
                .format(new Date(System.currentTimeMillis()));
        File file = new File("/mnt/sdcard/Pictures/"+imageDate+".png");
        if(!file.exists()){
            file.createNewFile();
        }
        FileOutputStream out;
        try {
            out = new FileOutputStream(file);
            if (bitmap.compress(Bitmap.CompressFormat.PNG, 70, out)) {
                out.flush();
                out.close();
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
</SPAN>

package org.winplus.ss;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.Display;
import android.view.Surface;
import android.view.WindowManager;
import android.os.SystemProperties;

public class SimpleScreenshotActivity extends Activity {

private Display mDisplay;
private WindowManager mWindowManager;
private DisplayMetrics mDisplayMetrics;
private Bitmap mScreenBitmap;
private Matrix mDisplayMatrix;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

new Thread(new Runnable() {

   @Override
   public void run() {
    takeScreenshot();

}
}).start();
}

private float getDegreesForRotation(int value) {
  switch (value) {
  case Surface.ROTATION_90:
   return 360f - 90f;
  case Surface.ROTATION_180:
   return 360f - 180f;
  case Surface.ROTATION_270:
   return 360f - 270f;
  }
  return 0f;
}

private void takeScreenshot() {
  mWindowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
  mDisplay = mWindowManager.getDefaultDisplay();
  mDisplayMetrics = new DisplayMetrics();
  mDisplay.getRealMetrics(mDisplayMetrics);
  mDisplayMatrix = new Matrix();
  float[] dims = { mDisplayMetrics.widthPixels,
    mDisplayMetrics.heightPixels };

  int value = mDisplay.getRotation();
  String hwRotation = SystemProperties.get("ro.sf.hwrotation", "0");
  if (hwRotation.equals("270") || hwRotation.equals("90")) {
   value = (value + 3) % 4;
  }
  float degrees = getDegreesForRotation(value);

  boolean requiresRotation = (degrees > 0);
  if (requiresRotation) {
   // Get the dimensions of the device in its native orientation
   mDisplayMatrix.reset();
   mDisplayMatrix.preRotate(-degrees);
   mDisplayMatrix.mapPoints(dims);

   dims[0] = Math.abs(dims[0]);
   dims[1] = Math.abs(dims[1]);
  }

mScreenBitmap = Surface.screenshot((int) dims[0], (int) dims[1]);

  if (requiresRotation) {
            // Rotate the screenshot to the current orientation
            Bitmap ss = Bitmap.createBitmap(mDisplayMetrics.widthPixels,
                    mDisplayMetrics.heightPixels, Bitmap.Config.ARGB_8888);
            Canvas c = new Canvas(ss);
            c.translate(ss.getWidth() / 2, ss.getHeight() / 2);
            c.rotate(degrees);
            c.translate(-dims[0] / 2, -dims[1] / 2);
            c.drawBitmap(mScreenBitmap, 0, 0, null);
            c.setBitmap(null);
            mScreenBitmap = ss;
        }

        // If we couldn't take the screenshot, notify the user
        if (mScreenBitmap == null) {
            return;
        }

        // Optimizations
        mScreenBitmap.setHasAlpha(false);
        mScreenBitmap.prepareToDraw();

  try {
   saveBitmap(mScreenBitmap);
  } catch (IOException e) {
   System.out.println(e.getMessage());
  }
}

public void saveBitmap(Bitmap bitmap) throws IOException {
  String imageDate = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss")
    .format(new Date(System.currentTimeMillis()));
  File file = new File("/mnt/sdcard/Pictures/"+imageDate+".png");
  if(!file.exists()){
   file.createNewFile();
  }
  FileOutputStream out;
  try {
   out = new FileOutputStream(file);
   if (bitmap.compress(Bitmap.CompressFormat.PNG, 70, out)) {
    out.flush();
    out.close();
   }
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
}
}

PS：1、需要在AndroidManifest.xml中加入代码：android:sharedUserId="android.uid.system"

2、由于调用了@hide的API，所以编译得时候请使用makefile编译。或者通过在Eclipse中添加Jar文件通过编译。

3、此代码只在Android4.0中使用过，2.3的就没去做测试了。

作者：tangcheng_ok

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