Question

我正在使用Picasso在我的应用程序中从Web加载图像。我注意到一些图像显示旋转了90度，但是当我在浏览器中打开图像时，我看到它正确定位。我假设这些图像有EXIF数据。有没有办法指示毕加索忽略EXIF？

Answer 1

众所周知，Picasso支持EXIF来自本地存储，这是通过Android内置Utils完成的。由于能够使用自定义Http加载库，因此无法轻松提供相同的功能。我的解决方案很简单：我们必须覆盖缓存并在缓存项目之前应用Exif轮换。

    OkHttpClient client = new OkHttpClient.Builder()
        .addNetworkInterceptor(chain -> {
            Response originalResponse = chain.proceed(chain.request());
            byte[] body = originalResponse.body().bytes();
            ResponseBody newBody = ResponseBody
                .create(originalResponse.body().contentType(), ImageUtils.processImage(body));
            return originalResponse.newBuilder().body(newBody).build();
        })
        .cache(cache)
        .build();

这里我们添加了NetworkInterceptor，它可以在缓存之前转换请求和响应。

public class ImageUtils {

    public static byte[] processImage(byte[] originalImg) {
        int orientation = Exif.getOrientation(originalImg);
        if (orientation != 0) {
            Bitmap bmp = BitmapFactory.decodeByteArray(originalImg, 0, originalImg.length);
            ByteArrayOutputStream stream = new ByteArrayOutputStream();
            rotateImage(orientation, bmp).compress(Bitmap.CompressFormat.PNG, 100, stream);

            return stream.toByteArray();
        }
        return originalImg;
    }

    private static Bitmap rotateImage(int angle, Bitmap bitmapSrc) {
        Matrix matrix = new Matrix();
        matrix.postRotate(angle);
        return Bitmap.createBitmap(bitmapSrc, 0, 0,
                bitmapSrc.getWidth(), bitmapSrc.getHeight(), matrix, true);
    }
}

Exif转换：

public class Exif {
    private static final String TAG = "Exif";

    // Returns the degrees in clockwise. Values are 0, 90, 180, or 270.
    public static int getOrientation(byte[] jpeg) {
        if (jpeg == null) {
            return 0;
        }

        int offset = 0;
        int length = 0;

        // ISO/IEC 10918-1:1993(E)
        while (offset + 3 < jpeg.length && (jpeg[offset++] & 0xFF) == 0xFF) {
            int marker = jpeg[offset] & 0xFF;

            // Check if the marker is a padding.
            if (marker == 0xFF) {
                continue;
            }
            offset++;

            // Check if the marker is SOI or TEM.
            if (marker == 0xD8 || marker == 0x01) {
                continue;
            }
            // Check if the marker is EOI or SOS.
            if (marker == 0xD9 || marker == 0xDA) {
                break;
            }

            // Get the length and check if it is reasonable.
            length = pack(jpeg, offset, 2, false);
            if (length < 2 || offset + length > jpeg.length) {
                Log.e(TAG, "Invalid length");
                return 0;
            }

            // Break if the marker is EXIF in APP1.
            if (marker == 0xE1 && length >= 8 &&
                    pack(jpeg, offset + 2, 4, false) == 0x45786966 &&
                    pack(jpeg, offset + 6, 2, false) == 0) {
                offset += 8;
                length -= 8;
                break;
            }

            // Skip other markers.
            offset += length;
            length = 0;
        }

        // JEITA CP-3451 Exif Version 2.2
        if (length > 8) {
            // Identify the byte order.
            int tag = pack(jpeg, offset, 4, false);
            if (tag != 0x49492A00 && tag != 0x4D4D002A) {
                Log.e(TAG, "Invalid byte order");
                return 0;
            }
            boolean littleEndian = (tag == 0x49492A00);

            // Get the offset and check if it is reasonable.
            int count = pack(jpeg, offset + 4, 4, littleEndian) + 2;
            if (count < 10 || count > length) {
                Log.e(TAG, "Invalid offset");
                return 0;
            }
            offset += count;
            length -= count;

            // Get the count and go through all the elements.
            count = pack(jpeg, offset - 2, 2, littleEndian);
            while (count-- > 0 && length >= 12) {
                // Get the tag and check if it is orientation.
                tag = pack(jpeg, offset, 2, littleEndian);
                if (tag == 0x0112) {
                    // We do not really care about type and count, do we?
                    int orientation = pack(jpeg, offset + 8, 2, littleEndian);
                    switch (orientation) {
                        case 1:
                            return 0;
                        case 3:
                            return 180;
                        case 6:
                            return 90;
                        case 8:
                            return 270;
                    }
                    Log.i(TAG, "Unsupported orientation");
                    return 0;
                }
                offset += 12;
                length -= 12;
            }
        }

        Log.i(TAG, "Orientation not found");
        return 0;
    }

    private static int pack(byte[] bytes, int offset, int length,
                            boolean littleEndian) {
        int step = 1;
        if (littleEndian) {
            offset += length - 1;
            step = -1;
        }

        int value = 0;
        while (length-- > 0) {
            value = (value << 8) | (bytes[offset] & 0xFF);
            offset += step;
        }
        return value;
    }
}

此解决方案是实验性的，必须进行泄漏测试并可能进行改进。在大多数情况下，三星和iO设备返回90°旋转，这个解决方案有效。其他情况也必须进行测试。

Answer 2

您可以发布您正在使用的图片吗？因为正如thread所述，从web加载的图像的exif方向被忽略（仅限内容提供者和本地文件）。

我也尝试在picasso 2.5.2中显示此image，图像的真实方向面向右侧（图像中的底部代码朝向右侧）。 exif方向，顺时针90deg。尝试用chrome打开它（chrome表示exif旋转），图像将面朝下（图像中的底部代码朝下）。

Answer 3

基于@ph0en1x 响应，此版本使用google exif 库和kotlin：将此拦截器添加到picasso 使用的okhttpclient

addNetworkInterceptor {
    val response = it.proceed(it.request())
    val body = response.body
    if (body?.contentType()?.type == "image") {
        val bytes = body.bytes()
        val degrees = bytes.inputStream().use { input ->
            when (ExifInterface(input).getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL)) {
                ExifInterface.ORIENTATION_ROTATE_270 -> 270
                ExifInterface.ORIENTATION_ROTATE_180 -> 180
                ExifInterface.ORIENTATION_ROTATE_90 -> 90
                else -> 0
            }
        }
        if (degrees != 0) {
            val bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.size)
            ByteArrayOutputStream().use { output ->
                Bitmap.createBitmap(bitmap, 0, 0, bitmap.width, bitmap.height, Matrix().apply { postRotate(degrees.toFloat()) }, true)
                    .compress(Bitmap.CompressFormat.PNG, 100, output)
                response.newBuilder().body(output.toByteArray().toResponseBody(body.contentType())).build()
            }
        } else
            response.newBuilder().body(bytes.toResponseBody(body.contentType())).build()
    } else
        response
}

Android Picasso自动旋转图像

3 个答案: