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
在截屏功能中，有时需要截取全屏的内容，有时需要截取超过一屏的内容（比如：Listview，Scrollview，RecyclerView）。下面介绍各种场景获取Bitmap的方法
普通截屏的实现
获取当前Window的DrawingCache的方式，即decorView的DrawingCache
/** * shot the current screen ,with the status but the status is trans * * * @param ctx current activity */ public static Bitmap shotActivity(Activity ctx) { View view = ctx.getWindow().getDecorView(); view.setDrawingCacheEnabled(true); view.buildDrawingCache(); Bitmap bp = Bitmap.createBitmap(view.getDrawingCache(), 0, 0, view.getMeasuredWidth(), view.getMeasuredHeight()); view.setDrawingCacheEnabled(false); view.destroyDrawingCache(); return bp; }复制代码 获取当前View的DrawingCache
public static Bitmap getViewBp(View v) { if (null == v) { return null; } v.setDrawingCacheEnabled(true); v.buildDrawingCache(); if (Build.VERSION.SDK_INT >= 11) { v.measure(MeasureSpec.makeMeasureSpec(v.getWidth(), MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec( v.getHeight(), MeasureSpec.EXACTLY)); v.layout((int) v.getX(), (int) v.getY(), (int) v.getX() + v.getMeasuredWidth(), (int) v.getY() + v.getMeasuredHeight()); } else { v.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)); v.layout(0, 0, v.getMeasuredWidth(), v.getMeasuredHeight()); } Bitmap b = Bitmap.createBitmap(v.getDrawingCache(), 0, 0, v.getMeasuredWidth(), v.getMeasuredHeight()); v.setDrawingCacheEnabled(false); v.destroyDrawingCache(); return b; }复制代码 开源方案
在滚动视图中，如果当前View并没有在视图中全部绘制出来，我们可以利用View的ScrollTo()和ScrollBy()方法来移动画布，同时获取当前View的可视部分的DrawingCache，最后进行拼接得到其Bitmap，参考:。
Scrollview截屏
三个截屏中，ScrollView最简单，因为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
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; }复制代码 listview截屏
而ListView就是会回收与重用Item，并且只会绘制在屏幕上显示的ItemView，根据stackoverflow上大神的建议，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。
public static Bitmap shotListView(ListView listview) { ListAdapter adapter = listview.getAdapter(); int itemscount = adapter.getCount(); int allitemsheight = 0; List 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; }复制代码 RecyclerView截屏
我们都知道，在新的Android版本中，已经可以用RecyclerView来代替使用ListView的场景，相比较ListView，RecyclerView对Item View的缓存支持的更好。可以采用和ListView相同的方案，这里也是在stackoverflow上看到的方案。
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 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; }复制代码 上面的方法在截取存在异步加载图片的RecyclerView时候会出现加载不出图片的情况,这里再补充一种滚动式截屏的方法
public static void screenShotRecycleView(final RecyclerView mRecyclerView, final RecycleViewRecCallback callBack) { if (mRecyclerView == null) { return; } BaseListFragment.MyAdapter adapter = (BaseListFragment.MyAdapter) mRecyclerView.getAdapter(); final Paint paint = new Paint(); 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 bitmaCache = new LruCache<>(cacheSize); final int oneScreenHeight = mRecyclerView.getMeasuredHeight(); int shotHeight = 0; if (adapter != null && adapter.getData().size() > 0) { int headerSize = adapter.getHeaderLayoutCount(); int dataSize = adapter.getData().size(); for (int i = 0; i < headerSize + dataSize; i++) { BaseViewHolder holder = (BaseViewHolder) adapter.createViewHolder(mRecyclerView, adapter.getItemViewType(i)); if (i >= headerSize) adapter.startConvert(holder, adapter.getData().get(i - headerSize)); holder.itemView.measure( View.MeasureSpec.makeMeasureSpec(mRecyclerView.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(); //holder.itemView.destroyDrawingCache();//释放缓存占用的资源 if (drawingCache != null) { bitmaCache.put(String.valueOf(i), drawingCache); } shotHeight += holder.itemView.getHeight(); if (shotHeight > 12000) { //设置截图最大值 if (callBack != null) callBack.onRecFinished(null); return; } } //添加底部高度(加载更多或loading布局高度,此处为固定值:) final int footHight = Util.dip2px(mRecyclerView.getContext(), 42); shotHeight += footHight; //返回到顶部 while (mRecyclerView.canScrollVertically(-1)) { mRecyclerView.scrollBy(0, -oneScreenHeight); } //绘制截图的背景 final Bitmap bigBitmap = Bitmap.createBitmap(mRecyclerView.getMeasuredWidth(), shotHeight, Bitmap.Config.ARGB_8888); final Canvas bigCanvas = new Canvas(bigBitmap); Drawable lBackground = mRecyclerView.getBackground(); if (lBackground instanceof ColorDrawable) { ColorDrawable lColorDrawable = (ColorDrawable) lBackground; int lColor = lColorDrawable.getColor(); bigCanvas.drawColor(lColor); } final int[] drawOffset = {0}; final Canvas canvas = new Canvas(); if (shotHeight <= oneScreenHeight) { //仅有一页 Bitmap bitmap = Bitmap.createBitmap(mRecyclerView.getWidth(), mRecyclerView.getHeight(), Bitmap.Config.ARGB_8888); canvas.setBitmap(bitmap); mRecyclerView.draw(canvas); if (callBack != null) callBack.onRecFinished(bitmap); } else { //超过一页 final int finalShotHeight = shotHeight; mRecyclerView.postDelayed(new Runnable() { @Override public void run() { if ((drawOffset[0] + oneScreenHeight < finalShotHeight)) { //超过一屏 Bitmap bitmap = Bitmap.createBitmap(mRecyclerView.getWidth(), mRecyclerView.getHeight(), Bitmap.Config.ARGB_8888); canvas.setBitmap(bitmap); mRecyclerView.draw(canvas); bigCanvas.drawBitmap(bitmap, 0, drawOffset[0], paint); drawOffset[0] += oneScreenHeight; mRecyclerView.scrollBy(0, oneScreenHeight); try { bitmap.recycle(); } catch (Exception ex) { ex.printStackTrace(); } mRecyclerView.postDelayed(this, 10); } else { //不足一屏时的处理 int leftHeight = finalShotHeight - drawOffset[0] - footHight; mRecyclerView.scrollBy(0, leftHeight); int top = oneScreenHeight - (finalShotHeight - drawOffset[0]); if (top > 0 && leftHeight > 0) { Bitmap bitmap = Bitmap.createBitmap(mRecyclerView.getWidth(), mRecyclerView.getHeight(), Bitmap.Config.ARGB_8888); canvas.setBitmap(bitmap); mRecyclerView.draw(canvas); //截图,只要补足的那块图 bitmap = Bitmap.createBitmap(bitmap, 0, top, bitmap.getWidth(), leftHeight, null, false); bigCanvas.drawBitmap(bitmap, 0, drawOffset[0], paint); try { bitmap.recycle(); } catch (Exception ex) { ex.printStackTrace(); } } if (callBack != null) callBack.onRecFinished(bigBitmap); } } }, 10); } } } public interface RecycleViewRecCallback { void onRecFinished(Bitmap bitmap); }复制代码 相信有不少小伙伴用BRVH第三方库来做recycleview的适配器的。使用这个库的话再用上面的方法会报角标越界的错误，看了BRVH的源码
public void onBindViewHolder(ViewHolder holder, int positions) { int viewType = holder.getItemViewType(); switch(viewType) { case 0: this.convert((BaseViewHolder)holder, this.mData.get(holder.getLayoutPosition() - this.getHeaderLayoutCount())); case 273: case 819: case 1365: break; case 546: this.addLoadMore(holder); break; default: this.convert((BaseViewHolder)holder, this.mData.get(holder.getLayoutPosition() - this.getHeaderLayoutCount())); this.onBindDefViewHolder((BaseViewHolder)holder, this.mData.get(holder.getLayoutPosition() - this.getHeaderLayoutCount())); } }复制代码 在调用adapter.onBindViewHolder时，因为里面的position参数未使用，里面用的计算holder.getLayoutPosition() - this.getHeaderLayoutCount()的值一直是-1导致角标越界报错。
本人理解，RecyclerView的截屏原理是，首先构造每个item的ViewHolder，然后调用具体设置数据到每个item的方法，此时cache中就存有item的内容，此时绘制就能获取到完整的内容。采用v7包中的onBindViewHolder方法即可，或者是BRVH的convert方法，可以看到BRVH中没有暴露出这个方法，而且唯一暴露出的onBindViewHolder还会报角标越界错误，此时我们就需要在BRVH的基础上暴露出convert即可，代码如下
public class MyAdapter extends BaseQuickAdapter{ public MyAdapter() { super(getItemLayoutResId(), datas); } /** * 用于对外暴露convert方法,构造缓存视图(截屏用) * @param viewHolder * @param t */ public void startConvert(BaseViewHolder viewHolder, T t){ convert(viewHolder,t); } @Override protected void convert(BaseViewHolder viewHolder, T t) { bindView(viewHolder, t); } }复制代码
然后将上面所述的获取Bitmap方法修改一下
/** * 截取recycler view */ public static Bitmap getRecyclerViewScreenshot(RecyclerView view) { BaseListFragment.MyAdapter adapter = (BaseListFragment.MyAdapter) view.getAdapter(); Bitmap bigBitmap = null; if (adapter != null) { int size = adapter.getData().size(); 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 bitmaCache = new LruCache<>(cacheSize); for (int i = 0; i < size; i++) { BaseViewHolder holder = (BaseViewHolder) adapter.createViewHolder(view, adapter.getItemViewType(i)); //此处需要调用convert方法，否则绘制出来的都是空的item adapter.startConvert(holder, adapter.getData().get(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; }复制代码 合成Bitmap
比如四张合成一张
/** * 将四张图拼成一张 * * @param pic1 图一 * @param pic2 图二 * @param pic3 图三 * @param pic4 图四 * @return only_bitmap * 详情见说明：{@link com.bertadata.qxb.util.ScreenShotUtils} */ public static Bitmap combineBitmapsIntoOnlyOne(Bitmap pic1, Bitmap pic2, Bitmap pic3, Bitmap pic4, Activity context) { int w_total = pic2.getWidth(); int h_total = pic1.getHeight() + pic2.getHeight() + pic3.getHeight() + pic4.getHeight(); int h_pic1 = pic1.getHeight(); int h_pic4 = pic4.getHeight(); int h_pic12 = pic1.getHeight() + pic2.getHeight(); //此处为防止OOM需要对高度做限制 if (h_total > HEIGHTLIMIT) { return null; } Bitmap only_bitmap = Bitmap.createBitmap(w_total, h_total, Bitmap.Config.ARGB_4444); Canvas canvas = new Canvas(only_bitmap); canvas.drawColor(ContextCompat.getColor(context, R.color.color_content_bg)); canvas.drawBitmap(pic1, 0, 0, null); canvas.drawBitmap(pic2, 0, h_pic1, null); canvas.drawBitmap(pic3, 0, h_pic12, null); canvas.drawBitmap(pic4, 0, h_total - h_pic4, null); return only_bitmap; }复制代码 图片后期处理
/** * 将传入的Bitmap合理压缩后输出到系统截屏目录下 * 命名格式为：Screenshot+时间戳+启信宝报名.jpg * 同时通知系统重新扫描系统文件 * * @param pic1 图一 标题栏截图 * @param pic2 图二 scrollview截图 * @param context 用于通知重新扫描文件系统，为提升性能可去掉 * 详情见说明：{@link com.bertadata.qxb.util.ScreenShotUtils} */ public static void savingBitmapIntoFile(final Bitmap pic1, final Bitmap pic2, final Activity context, final BitmapAndFileCallBack callBack) { if (context == null || context.isFinishing()) { return; } Thread thread = new Thread(new Runnable() { @Override public void run() { String fileReturnPath = ""; int w = pic1.getWidth(); Bitmap bottom = BitmapFactory.decodeResource(context.getResources(), R.drawable.ic_picture_combine_bottom); Bitmap top_banner = BitmapFactory.decodeResource(context.getResources(), R.drawable.ic_picture_combine_top); Bitmap bitmap_bottom = anyRatioCompressing(bottom, (float) w / bottom.getWidth(), (float) w / bottom.getWidth()); Bitmap bitmap_top = anyRatioCompressing(top_banner, (float) w / bottom.getWidth(), (float) w / bottom.getWidth()); final Bitmap only_bitmap = combineBitmapsIntoOnlyOne(bitmap_top, pic1, pic2, bitmap_bottom, context); // 获取当前时间 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss-ms", Locale.getDefault()); String data = sdf.format(new Date()); // 获取内存路径 // 设置图片路径+命名规范 // 声明输出文件 String storagePath = Environment.getExternalStorageDirectory().getAbsolutePath(); String fileTitle = "Screenshot_" + data + "_com.bertadata.qxb.biz_info.jpg"; String filePath = storagePath + "/DCIM/"; final String fileAbsolutePath = filePath + fileTitle; File file = new File(fileAbsolutePath); /** * 质压与比压结合 * 分级压缩 * 输出文件 */ if (only_bitmap != null) { try { // 首先，对原图进行一步质量压缩,形成初步文件 FileOutputStream fos = new FileOutputStream(file); only_bitmap.compress(Bitmap.CompressFormat.JPEG, 50, fos); // 另建一个文件other_file预备输出 String other_fileTitle = "Screenshot_" + data + "_com.bertadata.qxb.jpg"; String other_fileAbsolutePath = filePath + other_fileTitle; File other_file = new File(other_fileAbsolutePath); FileOutputStream other_fos = new FileOutputStream(other_file); // 其次，要判断质压之后的文件大小，按文件大小分级进行处理 long file_size = file.length() / 1024; // size of file(KB) if (file_size < 0 || !(file.exists())) { // 零级： 文件判空 throw new NullPointerException(); } else if (file_size > 0 && file_size <= 256) { // 一级： 直接输出 deleteFile(other_file); // 通知刷新文件系统，显示最新截取的图文件 fileReturnPath = fileAbsolutePath; context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + fileAbsolutePath))); } else if (file_size > 256 && file_size <= 768) { // 二级： 简单压缩:压缩为原比例的3/4，质压为50% anyRatioCompressing(only_bitmap, (float) 3 / 4, (float) 3 / 4).compress(Bitmap.CompressFormat.JPEG, 40, other_fos); deleteFile(file); // 通知刷新文件系统，显示最新截取的图文件 fileReturnPath = other_fileAbsolutePath; context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + other_fileAbsolutePath))); } else if (file_size > 768 && file_size <= 1280) { // 三级： 中度压缩：压缩为原比例的1/2，质压为40% anyRatioCompressing(only_bitmap, (float) 1 / 2, (float) 1 / 2).compress(Bitmap.CompressFormat.JPEG, 40, other_fos); deleteFile(file); // 通知刷新文件系统，显示最新截取的图文件 fileReturnPath = other_fileAbsolutePath; context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + other_fileAbsolutePath))); } else if (file_size > 1280 && file_size <= 2048) { // 四级： 大幅压缩：压缩为原比例的1/3，质压为40% anyRatioCompressing(only_bitmap, (float) 1 / 3, (float) 1 / 3).compress(Bitmap.CompressFormat.JPEG, 40, other_fos); deleteFile(file); // 通知刷新文件系统，显示最新截取的图文件 fileReturnPath = other_fileAbsolutePath; context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + other_fileAbsolutePath))); } else if (file_size > 2048) { // 五级： 中度压缩：压缩为原比例的1/2，质压为40% anyRatioCompressing(only_bitmap, (float) 1 / 2, (float) 1 / 2).compress(Bitmap.CompressFormat.JPEG, 40, other_fos); deleteFile(file); // 通知刷新文件系统，显示最新截取的图文件 fileReturnPath = other_fileAbsolutePath; context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + other_fileAbsolutePath))); } // 注销fos; fos.flush(); other_fos.flush(); other_fos.close(); fos.close(); //callback用于回传保存成功的路径以及Bitmap callBack.onSuccess(only_bitmap, fileReturnPath); } catch (Exception e) { e.printStackTrace(); } } else callBack.onSuccess(null, ""); } }); thread.start(); }复制代码 /** * 可实现任意宽高比例压缩（宽高压比可不同）的压缩方法（主要用于微压） * * @param bitmap 源图 * @param width_ratio 宽压比（float）（0<&&<1) * @param height_ratio 高压比（float）（0<&&<1) * @return 目标图片 **/ public static Bitmap anyRatioCompressing(Bitmap bitmap, float width_ratio, float height_ratio) { Matrix matrix = new Matrix(); matrix.postScale(width_ratio, height_ratio); return Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, false); }复制代码
本文参考http://www.cnblogs.com/BoBoMEe/p/4556917.html，并结合自己实际项目操作完成
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