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viewView 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;}
