Android截屏

　　Android截屏的原理：获取具体需要截屏的区域的Bitmap，然后绘制在画布上，保存为图片后进行分享或者其它用途

一、Activity截屏

1、截Activity界面（包含空白的状态栏）

/**
     * 根据指定的Activity截图（带空白的状态栏）
     *
     * @param context 要截图的Activity
     * @return Bitmap
     */
    public static Bitmap shotActivity(Activity context) {
        View view = context.getWindow().getDecorView();
        view.setDrawingCacheEnabled(true);
        view.buildDrawingCache();

        Bitmap bitmap = Bitmap.createBitmap(view.getDrawingCache(), 0, 0, view.getMeasuredWidth(), view.getMeasuredHeight());
        view.setDrawingCacheEnabled(false);
        view.destroyDrawingCache();
        return bitmap;
    }

2、截Activity界面（去除状态栏）

/**
     * 根据指定的Activity截图（去除状态栏）
     *
     * @param activity 要截图的Activity
     * @return Bitmap
     */
    public Bitmap shotActivityNoStatusBar(Activity activity) {
        // 获取windows中最顶层的view
        View view = activity.getWindow().getDecorView();
        view.buildDrawingCache();

        // 获取状态栏高度
        Rect rect = new Rect();
        view.getWindowVisibleDisplayFrame(rect);
        int statusBarHeights = rect.top;
        Display display = activity.getWindowManager().getDefaultDisplay();

        // 获取屏幕宽和高
        int widths = display.getWidth();
        int heights = display.getHeight();

        // 允许当前窗口保存缓存信息
        view.setDrawingCacheEnabled(true);

        // 去掉状态栏
        Bitmap bmp = Bitmap.createBitmap(view.getDrawingCache(), 0,
                statusBarHeights, widths, heights - statusBarHeights);

        // 销毁缓存信息
        view.destroyDrawingCache();

        return bmp;
    }

二、View截屏

    /**
     * 根据指定的view截图
     *
     * @param v 要截图的view
     * @return Bitmap
     */
    public static Bitmap getViewBitmap(View v) {
        if (null == v) {
            return null;
        }
        v.setDrawingCacheEnabled(true);
        v.buildDrawingCache();
        if (Build.VERSION.SDK_INT >= 11) {
            v.measure(View.MeasureSpec.makeMeasureSpec(v.getWidth(), View.MeasureSpec.EXACTLY),
                    View.MeasureSpec.makeMeasureSpec(v.getHeight(), View.MeasureSpec.EXACTLY));
            v.layout((int) v.getX(), (int) v.getY(), (int) v.getX() + v.getMeasuredWidth(), (int) v.getY() + v.getMeasuredHeight());
        } else {
            v.measure(View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
                    View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
            v.layout(0, 0, v.getMeasuredWidth(), v.getMeasuredHeight());
        }

        Bitmap bitmap = Bitmap.createBitmap(v.getDrawingCache(), 0, 0, v.getMeasuredWidth(), v.getMeasuredHeight());
        v.setDrawingCacheEnabled(false);
        v.destroyDrawingCache();
        return bitmap;
    }

三、ScrollView截屏：ScrollView只有一个childView，虽然没有全部显示在界面上，但是已经全部渲染绘制，因此可以直接 调用scrollView.draw(canvas)来完成截图

    /**
     * Scrollview截屏
     *
     * @param scrollView 要截图的ScrollView
     * @return Bitmap
     */
    public static Bitmap shotScrollView(ScrollView scrollView) {
        int h = 0;
        Bitmap bitmap = null;
        for (int i = 0; i < scrollView.getChildCount(); i++) {
            h += scrollView.getChildAt(i).getHeight();
            scrollView.getChildAt(i).setBackgroundColor(Color.parseColor("#ffffff"));
        }
        bitmap = Bitmap.createBitmap(scrollView.getWidth(), h, Bitmap.Config.RGB_565);
        final Canvas canvas = new Canvas(bitmap);
        scrollView.draw(canvas);
        return bitmap;
    }

四、ListView截屏：ListView是会回收与重用Item，并且只会绘制在屏幕上显示的ItemView，下面的方法采用一个List来存储Item的视图，这种方案依然不够好，当Item足够多的时候，可能会发生oom。

    /**
     * ListView截图
     *
     * @param listView 要截图的ListView
     * @return Bitmap
     */
    public static Bitmap shotListView(ListView listView) {
        ListAdapter adapter = listView.getAdapter();
        int itemsCount = adapter.getCount();
        int allItemsHeight = 0;

        ArrayList<Bitmap> bmps = new ArrayList<>();
        for (int i = 0; i < itemsCount; i++) {
            View childView = adapter.getView(i, null, listView);
            childView.measure(View.MeasureSpec.makeMeasureSpec(listView.getWidth(),View.MeasureSpec.EXACTLY),
                    View.MeasureSpec.makeMeasureSpec(0,View.MeasureSpec.UNSPECIFIED));

            childView.layout(0, 0, childView.getMeasuredWidth(), childView.getMeasuredHeight());
            childView.setDrawingCacheEnabled(true);
            childView.buildDrawingCache();
            bmps.add(childView.getDrawingCache());
            allItemsHeight += childView.getMeasuredHeight();
        }

        Bitmap bigBitmap = Bitmap.createBitmap(listView.getMeasuredWidth(), allItemsHeight, Bitmap.Config.ARGB_8888);
        Canvas bigCanvas = new Canvas(bigBitmap);

        Paint paint = new Paint();
        int iHeight = 0;

        for (int i = 0; i < bmps.size(); i++) {
            Bitmap bmp = bmps.get(i);
            bigCanvas.drawBitmap(bmp, 0, iHeight, paint);
            iHeight += bmp.getHeight();

            bmp.recycle();
            bmp = null;
        }
        return bigBitmap;
    }

五、RecycleView截屏

/**
     * RecyclerView截屏
     *
     * @param view 要截图的RecyclerView
     * @return Bitmap
     */
    public static Bitmap shotRecyclerView(RecyclerView view) {
        RecyclerView.Adapter adapter = view.getAdapter();
        Bitmap bigBitmap = null;
        if (adapter != null) {
            int size = adapter.getItemCount();
            int height = 0;
            Paint paint = new Paint();
            int iHeight = 0;
            final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);

            // Use 1/8th of the available memory for this memory cache.
            final int cacheSize = maxMemory / 8;
            LruCache<String, Bitmap> bitmaCache = new LruCache<>(cacheSize);
            for (int i = 0; i < size; i++) {
                RecyclerView.ViewHolder holder = adapter.createViewHolder(view, adapter.getItemViewType(i));
                adapter.onBindViewHolder(holder, i);
                holder.itemView.measure(
                        View.MeasureSpec.makeMeasureSpec(view.getWidth(), View.MeasureSpec.EXACTLY),
                        View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
                holder.itemView.layout(0, 0, holder.itemView.getMeasuredWidth(),
                        holder.itemView.getMeasuredHeight());
                holder.itemView.setDrawingCacheEnabled(true);
                holder.itemView.buildDrawingCache();
                Bitmap drawingCache = holder.itemView.getDrawingCache();
                if (drawingCache != null) {

                    bitmaCache.put(String.valueOf(i), drawingCache);
                }
                height += holder.itemView.getMeasuredHeight();
            }

            bigBitmap = Bitmap.createBitmap(view.getMeasuredWidth(), height, Bitmap.Config.ARGB_8888);
            Canvas bigCanvas = new Canvas(bigBitmap);
            Drawable lBackground = view.getBackground();
            if (lBackground instanceof ColorDrawable) {
                ColorDrawable lColorDrawable = (ColorDrawable) lBackground;
                int lColor = lColorDrawable.getColor();
                bigCanvas.drawColor(lColor);
            }

            for (int i = 0; i < size; i++) {
                Bitmap bitmap = bitmaCache.get(String.valueOf(i));
                bigCanvas.drawBitmap(bitmap, 0f, iHeight, paint);
                iHeight += bitmap.getHeight();
                bitmap.recycle();
            }
        }
        return bigBitmap;
    }

六、WebView截屏

1、截取webView可视区域的截图

 /**  
    * 截取webView可视区域的截图  
    * @param webView 前提：WebView要设置webView.setDrawingCacheEnabled(true);  
    * @return  
    */  
private Bitmap captureWebViewVisibleSize(WebView webView){  
    Bitmap bmp = webView.getDrawingCache();  
    return bmp;  
}  

2、截取webView的整个页面

/**  
 * 截取webView快照(webView加载的整个内容的大小)  
 * @param webView  
 * @return  
 */  
private Bitmap captureWebView(WebView webView){  
    Picture snapShot = webView.capturePicture();  
      
    Bitmap bmp = Bitmap.createBitmap(snapShot.getWidth(),snapShot.getHeight(), Bitmap.Config.ARGB_8888);  
    Canvas canvas = new Canvas(bmp);  
    snapShot.draw(canvas);  
    return bmp;  
}  

3、截取手机屏幕，获取界面展示的webview

    /**
     * 截屏
     *
     * @param context
     * @return
     */
    private Bitmap captureScreen(Activity context) {
        View cv = context.getWindow().getDecorView();
        Bitmap bmp = Bitmap.createBitmap(cv.getWidth(), cv.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bmp);
        cv.draw(canvas);
        return bmp;
    }

Android截屏截图方法汇总（Activity、View、ScrollView、ListView、RecycleView、WebView截屏截图）