加載圖像隨機在畫布

Question

我正在遊戲，我想加載背景圖像canvas.ie背景應加載從隨機陣列和應該different.This是，我使用

int[] wallpaper={R.drawable.bg,R.drawable.bg_two,R.drawable.bg_three,R.drawable.bg_four, }; 

     if(globalBitmap == null){ 
     Random random = new Random(); 
     int n=random.nextInt(wallpaper.length); 
     BitmapDrawable bd = (BitmapDrawable) context.getResources().getDrawable(wallpaper[n]); 
     globalBitmap = bd.getBitmap(); 
    } 
    this.bitmap = globalBitmap; 

代碼但是，當我加載遊戲。只有相同的背景顯示。所有4背景不按隨機順序加載。任何一個可以幫助解決這個問題？

logcat的

02-14 14:38:04.757: E/AndroidRuntime(10518): FATAL EXCEPTION: main 
02-14 14:38:04.757: E/AndroidRuntime(10518): Process: com.themebowlapps.monkeyrun, PID: 10518 
02-14 14:38:04.757: E/AndroidRuntime(10518): java.lang.OutOfMemoryError 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.graphics.BitmapFactory.nativeDecodeAsset(Native Method) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:677) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java:507) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.graphics.drawable.Drawable.createFromResourceStream(Drawable.java:872) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.content.res.Resources.loadDrawable(Resources.java:3022) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.content.res.Resources.getDrawable(Resources.java:1586) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at com.themebowlapps.monkeyrun.Background.getRandom(Background.java:37) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at com.themebowlapps.monkeyrun.Background.testMethod(Background.java:43) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at com.themebowlapps.monkeyrun.Background.<init>(Background.java:30) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at com.themebowlapps.monkeyrun.Frontground.<init>(Frontground.java:19) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at com.themebowlapps.monkeyrun.GameView.<init>(GameView.java:50) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at com.themebowlapps.monkeyrun.Game.onCreate(Game.java:41) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.app.Activity.performCreate(Activity.java:5389) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2246) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2340) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.app.ActivityThread.access$800(ActivityThread.java:157) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.os.Handler.dispatchMessage(Handler.java:102) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.os.Looper.loop(Looper.java:157) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at android.app.ActivityThread.main(ActivityThread.java:5293) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at java.lang.reflect.Method.invokeNative(Native Method) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at java.lang.reflect.Method.invoke(Method.java:515) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1259) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075) 
02-14 14:38:04.757: E/AndroidRuntime(10518): at dalvik.system.NativeStart.main(Native Method) 

Answer 1

你globalBitmap只加載一次一次嘗試這種代碼，也許幫助ü

int[] wallpaper={R.drawable.bg,R.drawable.bg_two,R.drawable.bg_three,R.drawable.bg_four, }; 
    BitmapDrawable getRandom() { 
     Random random = new Random(); 
     int n = random.nextInt(wallpaper.length); 
     BitmapDrawable bd = (BitmapDrawable) context.getResources().getDrawable(wallpaper[n]); 
     return bd.getBitmap(); 
    } 

    void testMethod() { 
     this.bitmap = getRandom(); 
    } 

Answer 2

你得到一個OutOfMemoryError這意味着你正在運行你的應用程序中沒有按環境沒有足夠的內存可用於完全加載您嘗試加載的位圖。

解決方法是加載圖像的縮小版本，使其適合內存。所有的細節如何做到這一點，給出並解釋here，看看它，並重用他們的decodeSampledBitmapFromResource()方法，而不是隻調用Resources#getDrawable()。 請注意，除非您完全確定原始圖像的大小，否則應始終加載此類圖像。

然後，還有一個問題，就是你不知道第一手有多少內存可用，所以你不知道reqWidth和reqHeight這將使你可以確保沒有out的內存錯誤發生。這就是爲什麼我通常會打電話來解碼圖像的try塊捕捉OutOfMemoryError例外，並繞過它重試加載較小版本的圖像的情況下出現錯誤，直到找到一個可加載的大小。 這種味道的東西（聲明：代碼沒有測試）：

final int imageResourceId = ...; // do your random selection here 
Bitmap loadedBitmap = null; 
int reqWidth = DEFAULT_REQ_WIDTH, reqHeight = DEFAULT_REQ_HEIGHT; 
while (loadedBitmap == null && reqWidth >= MIN_REQ_WIDTH && reqHeight >= MIN_REQ_HEIGHT) { 
    try { 
     loadedBitmap = decodeSampledBitmapFromResource(getResources(), imageResourceId, reqWidth, reqHeight); 
    } catch (final OutOfMemoryError oOM) { 
     // not enough memory to load an image this size, retry with a smaller one 
     reqWidth /= 2; 
     reqHeight /= 2; 
    } 
}