读取sd卡下图片,由图片路径转换为bitmap

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>(BitmapFactory.decodeFile(path, opts));
            return Bitmap.createScaledBitmap(weak.get(), w, h, true);
        }
 
其中w和h你需要转换的大小
 
path转换为bitmap:上面方法即可;
imageview获取drawable并转换为 bitmap :Bitmap bt= ((BitmapDrawable) mImageview.getDrawable()).getBitmap();
resourceid转换为bitmap:Bitmap bt = BitmapFactory.decodeResource(getResources(), R.drawable.resourceid);
Drawable转换为bitmap:Bitmap bt= ((BitmapDrawable) Drawable).getBitmap();
因为BitmapDrawable是继承Drawable,所以可以灵活的转换
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