最近做的專案，客戶臨時要求改版，我真的是最煩這個，要求跟換主頁面的背景，換上新的背景圖，要求是動態的。

效果（我隨便拿的五個圖片做的gif）：

方案:

幀動畫方案:

        缺點:1.好像只能imageview才能播放幀動畫 

                2.容易OOM（播三四張還行，播九十張以上，且，每張都在300k左右就有OOM問題）

                3.看到網上方案解決幀動畫OOM，是一次播放十張，再往裡面添十張，再播放。問題就有了，動畫有一個                      新增十個圖片的時間卡頓。

surfaceview方案:

         因為imageview要是以一張一張換，效能必定不如surfaceview。核心應該是

      canvas = surfaceHolder.lockCanvas(rect);
      canvas.drawBitmap(lruCache.get(folderName + "/" + assets[position]), null, rect, null);

        surfaceHolder = sv_main.getHolder();
        lruCache = new StringBitmapLruCache();
        surfaceHolder.addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {

            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {


                rect = new Rect(0, 0, width, height);

                //獲取主題
                SharedPreferences sp = getSharedPreferences("setting", Context.MODE_PRIVATE);
                String theme = sp.getString("theme", "bgone");
                switch (theme) {
                    case "bgone":
                        folderName = "bgone";
                        break;
                    case "bgtwo":
                        folderName = "bgtwo";
                        break;
                    case "bgthree":
                        folderName = "bgthree";
                        break;
                }

                try {
                    assetManager = getAssets();
                    assets = assetManager.list(folderName);
                    totalCount = assets.length;
                    if (lruCache.get(folderName + "/" + assets[0]) == null) {
                        Bitmap bitmap = BitmapFactory.decodeStream(assetManager.open(folderName + "/" + assets[0]));
                        lruCache.put(folderName + "/" + assets[0], bitmap);
                    }
                    canvas = surfaceHolder.lockCanvas(rect);
                    canvas.drawBitmap(lruCache.get(folderName + "/" + assets[0]), null, rect, null);
                    holder.unlockCanvasAndPost(canvas);

                    if (!isFlag) {
                        startDecodeThread();
                        isFlag = true;
                    }


                } catch (IOException e) {
                    e.printStackTrace();
                }

                isFlag = true;


            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                RxUtils.unsubscribe(animationSub);
            }
        });
 

 private void startDecodeThread() {

        RxUtils.unsubscribe(animationSub);
        animationSub = Observable.interval(200, TimeUnit.MILLISECONDS).subscribeOn(Schedulers.io()).subscribe(new Subscriber<Long>() {
            @Override
            public void onCompleted() {

            }

            @Override
            public void onError(Throwable e) {

            }

            @Override
            public void onNext(Long aLong) {
                Logger.i("DDSSK::" + position);
                if (position >= totalCount) {
                    position = 0;
                }

                canvas = surfaceHolder.lockCanvas(rect);
                // if (canvas != null) {

                canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
                if (lruCache.get(folderName + "/" + assets[position]) == null) {
                    try {
                        Bitmap bitmap = BitmapFactory.decodeStream(assetManager.open(folderName + "/" + assets[position]));
                        lruCache.put(folderName + "/" + assets[position], bitmap);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                canvas.drawBitmap(lruCache.get(folderName + "/" + assets[position]), null, rect, null);
                surfaceHolder.unlockCanvasAndPost(canvas);


              /*  try {
                    Bitmap bitmap = BitmapFactory.decodeStream(assetManager.open(folderName + "/" + assets[0]));
                    canvas.drawBitmap(bitmap, null, rect, null);
                    surfaceHolder.unlockCanvasAndPost(canvas);

                } catch (IOException e) {
                    e.printStackTrace();
                }*/

                position++;
            }
        });
    }
 

1.surfaceview準備的時候，介面是一片黑。所以在surfacechanged的時候我要展示動畫的第一張圖，這樣就不黑了

2.canvas為空？因為canvas是從surfaceview獲得的，如果surfaceview沒有準備好，它絕對為空

3.如果介面跳轉再返回，surfaceview還會建立，但是我點了黑屏再亮屏，surfaceview就不會在建立，動畫就播不了，所以要寫一個開關，在onresume裡寫程式碼觸發動畫

4.surfaceview的優化，因為播放太多的圖片，佔用太多資源，導致其他的元件超卡。因為surfaceview可以在子執行緒跟新UI,所以我們可以起執行緒輪播圖

附件:

package utils;

import android.graphics.Bitmap;
import android.support.v4.util.LruCache;

/**
 * Created by Administrator on 2017/6/23 0023.
 */

public class StringBitmapLruCache extends LruCache<String, Bitmap> {
    public StringBitmapLruCache() {
        // 構造方法傳入當前應用可用最大記憶體的八分之一
        super((int) (Runtime.getRuntime().maxMemory() / 1024 / 8));
    }

    @Override
    // 重寫sizeOf方法，並計算返回每個Bitmap物件佔用的記憶體
    protected int sizeOf(String key, Bitmap value) {
        return value.getByteCount() / 1024;
    }

    @Override
    // 當快取被移除時呼叫，第一個引數是表明快取移除的原因，true表示被LruCache移除，false表示被主動remove移除，可不重寫
    protected void entryRemoved(boolean evicted, String key, Bitmap oldValue, Bitmap
            newValue) {
        super.entryRemoved(evicted, key, oldValue, newValue);
    }

    @Override
    // 當get方法獲取不到快取的時候呼叫，如果需要建立自定義預設快取，可以在這裡新增邏輯，可不重寫
    protected Bitmap create(String key) {
        return super.create(key);
    }
}