读取图片资源转化为bitmap对象

public Bitmap convertToBitmap(String path, int w, int h) {
		BitmapFactory.Options opts = new BitmapFactory.Options();
		// 设置为ture只获取图片大小
		opts.inJustDecodeBounds = true;
		opts.inPreferredConfig = Bitmap.Config.ARGB_8888;
		// 返回为空
		BitmapFactory.decodeFile(path, opts);
		int width = opts.outWidth;
		int height = opts.outHeight;
		float scaleWidth = 0.f, scaleHeight = 0.f;
		if (width > w || height > h) {
			// 缩放
			scaleWidth = ((float) width) / w;
			scaleHeight = ((float) height) / h;
		}
		opts.inJustDecodeBounds = false;
		float scale = Math.max(scaleWidth, scaleHeight);
		opts.inSampleSize = (int) scale;
		WeakReference<Bitmap> weak = new WeakReference<Bitmap>(