NullPointerException 无法从 oppo 设备上的 drawable 中找到位图

问题描述

我试图从 drawable 中获取 imageview 并调整它的大小我当前的代码适用于所有设备，除了 oppo 设备它在 crop() 方法内崩溃

我遇到的崩溃是在crop()方法的第一行，你可以在下面找到

Caused by: java.lang.NullPointerException: 

我目前的代码是：

public Bitmap getTileBitmap(int id,int size) {
    String string = tileUrls.get(id);
    if (string.contains(Themes.URI_DRAWABLE)) {
        String drawableResourceName = string.substring(Themes.URI_DRAWABLE.length());
        int drawableResourceId = Shared.context.getResources().getIdentifier(drawableResourceName,"drawable",Shared.context.getPackageName());
        Bitmap bitmap = Utils.scaleDown(drawableResourceId,size,size);
        return Utils.crop(bitmap,size);

    }
    return null;
}


public static Bitmap crop(Bitmap source,int newHeight,int newWidth) {
    int sourceWidth = source.getWidth();
    int sourceHeight = source.getHeight();
    float xScale = (float) newWidth / sourceWidth;
    float yScale = (float) newHeight / sourceHeight;
    float scale = Math.max(xScale,yScale);
    float scaledWidth = scale * sourceWidth;
    float scaledHeight = scale * sourceHeight;
    float left = (newWidth - scaledWidth) / 2;
    float top = (newHeight - scaledHeight) / 2;
    RectF targetRect = new RectF(left,top,left + scaledWidth,top + scaledHeight);
    Bitmap dest = Bitmap.createBitmap(newWidth,newHeight,source.getConfig());
    Canvas canvas = new Canvas(dest);
    canvas.drawBitmap(source,null,targetRect,null);

    return dest;
}

编辑：添加了可能导致问题的缩放方法

public static Bitmap scaleDown(int resource,int reqWidth,int reqHeight) {
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeResource(Shared.context.getResources(),resource);

    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options,reqWidth,reqHeight);

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    return BitmapFactory.decodeResource(Shared.context.getResources(),resource,options);
}

到目前为止，我不确定是什么导致了仅在 oppo 设备上崩溃

解决方法

试试这个：

options.inJustDecodeBounds = true;
options.inScaled = false;
options.inDensity = 0;
options.inMutable = true; //API 11. Pass to canvas? Might crash without this.
//Load the image here... BitmapFactory.decodeResource()...

... //Some calculations.

options.inJustDecodeBounds = false;
options.inPreferredConfig = Bitmap.Config.ARGB_8888;