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Android截圖方案

Android截圖

Android截圖的原理:獲取具體需要截圖的區域的Bitmap,然後繪製在畫布上,儲存為圖片後進行分享或者其它用途

在截圖功能中,有時需要擷取全屏的內容,有時需要擷取超過一屏的內容(比如:Listview,Scrollview,RecyclerView)。下面介紹各種場景獲取Bitmap的方法

普通截圖的實現

獲取當前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; }

獲取當前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; }

開源方案

在滾動檢視中,如果當前View並沒有在檢視中全部繪製出來,我們可以利用View的ScrollTo()和ScrollBy()方法來移動畫布,同時獲取當前View的可視部分的DrawingCache,最後進行拼接得到其Bitmap,參考:PGSSoft/[email protected][Github]

Scrollview截圖

三個截圖中,ScrollView最簡單,因為ScrollView只有一個childView,雖然沒有全部顯示在介面上,但是已經全部渲染繪製,因此可以直接 呼叫scrollView.draw(canvas)來完成截圖

  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;
  }

listview截圖

而ListView就是會回收與重用Item,並且只會繪製在螢幕上顯示的ItemView,根據stackoverflow上大神的建議,採用一個List來儲存Item的檢視,這種方案依然不夠好,當Item足夠多的時候,可能會發生oom。

  public static Bitmap shotListView(ListView listview) {

    ListAdapter adapter = listview.getAdapter();
    int itemscount = adapter.getCount();
    int allitemsheight = 0;
    List<Bitmap> bmps = new ArrayList<Bitmap>();

    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;
  }

RecyclerView截圖

我們都知道,在新的Android版本中,已經可以用RecyclerView來代替使用ListView的場景,相比較ListView,RecyclerView對Item View的快取支援的更好。可以採用和ListView相同的方案,這裡也是在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<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;
  }

相信有不少小夥伴用BRVH第三方庫來做recycleview的介面卡的。使用這個庫的話再用上面的方法會報角標越界的錯誤,看了BRVH的原始碼

 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()));
        }

    }

在呼叫adapter.onBindViewHolder時,因為裡面的position引數未使用,裡面用的計算holder.getLayoutPosition() - this.getHeaderLayoutCount()的值一直是-1導致角標越界報錯。

本人理解,RecyclerView的截圖原理是,首先構造每個item的ViewHolder,然後呼叫具體設定資料到每個item的方法,此時cache中就存有item的內容,此時繪製就能獲取到完整的內容。採用v7包中的onBindViewHolder方法即可,或者是BRVH的convert方法,可以看到BRVH中沒有暴露出這個方法,而且唯一暴露出的onBindViewHolder還會報角標越界錯誤,此時我們就需要在BRVH的基礎上暴露出convert即可,程式碼如下

 public class MyAdapter extends BaseQuickAdapter<T> {

        public MyAdapter() {
            super(getItemLayoutResId(), datas);
        }

        /**
         * 用於對外暴露convert方法,構造快取檢視(截圖用)
         * @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);
        }
    }

然後將上面所述的獲取Bitmap方法修改一下

 /**
     * 擷取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<String, Bitmap> bitmaCache = new LruCache<>(cacheSize);
            for (int i = 0; i < size; i++) {
                BaseViewHolder holder = (BaseViewHolder) adapter.createViewHolder(view, adapter.getItemViewType(i));
                //此處需要呼叫convert方法,否則繪製出來的都是空的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;
    }

合成Bitmap

比如四張合成一張

  /**
     * 將四張圖拼成一張
     *
     * @param pic1 圖一
     * @param pic2 圖二
     * @param pic3 圖三
     * @param pic4 圖四
     * @return only_bitmap
     * 詳情見說明:{@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();
        //此處為防止OOM需要對高度做限制
        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;
    }

圖片後期處理

 /**
     * 將傳入的Bitmap合理壓縮後輸出到系統截圖目錄下
     * 命名格式為:Screenshot+時間戳+啟信寶報名.jpg
     * 同時通知系統重新掃描系統檔案
     *
     * @param pic1    圖一 標題欄截圖
     * @param pic2    圖二 scrollview截圖
     * @param context 用於通知重新掃描檔案系統,為提升效能可去掉
     *                詳情見說明:{@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);

                // 獲取當前時間
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss-ms", Locale.getDefault());
                String data = sdf.format(new Date());

                // 獲取記憶體路徑
                // 設定圖片路徑+命名規範
                // 宣告輸出檔案
                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);

                /**
                 * 質壓與比壓結合
                 * 分級壓縮
                 * 輸出檔案
                 */
                if (only_bitmap != null) {
                    try {
                        // 首先,對原圖進行一步質量壓縮,形成初步檔案
                        FileOutputStream fos = new FileOutputStream(file);
                        only_bitmap.compress(Bitmap.CompressFormat.JPEG, 50, fos);

                        // 另建一個檔案other_file預備輸出
                        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,要判斷質壓之後的檔案大小,按檔案大小分級進行處理
                        long file_size = file.length() / 1024; // size of file(KB)
                        if (file_size < 0 || !(file.exists())) {
                            // 零級: 檔案判空
                            throw new NullPointerException();
                        } else if (file_size > 0 && file_size <= 256) {
                            // 一級: 直接輸出
                            deleteFile(other_file);
                            // 通知重新整理檔案系統,顯示最新擷取的圖檔案
                            fileReturnPath = fileAbsolutePath;
                            context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + fileAbsolutePath)));
                        } else if (file_size > 256 && file_size <= 768) {
                            // 二級: 簡單壓縮:壓縮為原比例的3/4,質壓為50%
                            anyRatioCompressing(only_bitmap, (float) 3 / 4, (float) 3 / 4).compress(Bitmap.CompressFormat.JPEG, 40, other_fos);
                            deleteFile(file);
                            // 通知重新整理檔案系統,顯示最新擷取的圖檔案
                            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) {
                            // 三級: 中度壓縮:壓縮為原比例的1/2,質壓為40%
                            anyRatioCompressing(only_bitmap, (float) 1 / 2, (float) 1 / 2).compress(Bitmap.CompressFormat.JPEG, 40, other_fos);
                            deleteFile(file);
                            // 通知重新整理檔案系統,顯示最新擷取的圖檔案
                            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) {
                            // 四級: 大幅壓縮:壓縮為原比例的1/3,質壓為40%
                            anyRatioCompressing(only_bitmap, (float) 1 / 3, (float) 1 / 3).compress(Bitmap.CompressFormat.JPEG, 40, other_fos);
                            deleteFile(file);
                            // 通知重新整理檔案系統,顯示最新擷取的圖檔案
                            fileReturnPath = other_fileAbsolutePath;
                            context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + other_fileAbsolutePath)));
                        } else if (file_size > 2048) {
                            // 五級: 中度壓縮:壓縮為原比例的1/2,質壓為40%
                            anyRatioCompressing(only_bitmap, (float) 1 / 2, (float) 1 / 2).compress(Bitmap.CompressFormat.JPEG, 40, other_fos);
                            deleteFile(file);
                            // 通知重新整理檔案系統,顯示最新擷取的圖檔案
                            fileReturnPath = other_fileAbsolutePath;
                            context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + other_fileAbsolutePath)));
                        }

                        // 登出fos;
                        fos.flush();
                        other_fos.flush();
                        other_fos.close();
                        fos.close();
                        //callback用於回傳儲存成功的路徑以及Bitmap
                        callBack.onSuccess(only_bitmap, fileReturnPath);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                } else callBack.onSuccess(null, "");
            }
        });
        thread.start();
    }
    /**
     * 可實現任意寬高比例壓縮(寬高壓比可不同)的壓縮方法(主要用於微壓)
     *
     * @param bitmap       源圖
     * @param width_ratio  寬壓比(float)(0<&&<1)
     * @param height_ratio 高壓比(float)(0<&&<1)
     * @return 目標圖片
     * <p>
     */
    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);
    }