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; }

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