Android - BitmapFactory.decodeStream 在三星设备上返回 null

Question

这条线在三星 A5 和三星 Young 上失败了，在 HTC、摩托罗拉、索尼等上也失败了。

我测试了相同的 imageStream，但得到了不同的结果。

decodedBitmap = BitmapFactory.decodeStream(imageStream, null, decodingOptions);

decodedBitmap 的值在三星上总是为空，我不知道为什么。

在下图中，您可以查看decodeOptions 的当前值是多少。我试过不使用选项，但我得到了相同的结果。

这是我使用的代码。如您所见，我在使用通用图像加载和调试时发现了这个问题。

/*******************************************************************************
 * Copyright 2011-2014 Sergey Tarasevich
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *******************************************************************************/
package com.nostra13.universalimageloader.core.decode;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.graphics.Matrix;
import android.media.ExifInterface;
import com.nostra13.universalimageloader.core.assist.ImageScaleType;
import com.nostra13.universalimageloader.core.assist.ImageSize;
import com.nostra13.universalimageloader.core.download.ImageDownloader.Scheme;
import com.nostra13.universalimageloader.utils.ImageSizeUtils;
import com.nostra13.universalimageloader.utils.IoUtils;
import com.nostra13.universalimageloader.utils.L;

import java.io.IOException;
import java.io.InputStream;

/**
 * Decodes images to {@link Bitmap}, scales them to needed size
 *
 * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
 * @see ImageDecodingInfo
 * @since 1.8.3
 */
public class BaseImageDecoder implements ImageDecoder {

    protected static final String LOG_SUBSAMPLE_IMAGE = "Subsample original image (%1$s) to %2$s (scale = %3$d) [%4$s]";
    protected static final String LOG_SCALE_IMAGE = "Scale subsampled image (%1$s) to %2$s (scale = %3$.5f) [%4$s]";
    protected static final String LOG_ROTATE_IMAGE = "Rotate image on %1$d\u00B0 [%2$s]";
    protected static final String LOG_FLIP_IMAGE = "Flip image horizontally [%s]";
    protected static final String ERROR_NO_IMAGE_STREAM = "No stream for image [%s]";
    protected static final String ERROR_CANT_DECODE_IMAGE = "Image can't be decoded [%s]";

    protected final boolean loggingEnabled;

    /**
     * @param loggingEnabled Whether debug logs will be written to LogCat. Usually should match {@link
     *                       com.nostra13.universalimageloader.core.ImageLoaderConfiguration.Builder#writeDebugLogs()
     *                       ImageLoaderConfiguration.writeDebugLogs()}
     */
    public BaseImageDecoder(boolean loggingEnabled) {
        this.loggingEnabled = loggingEnabled;
    }

    /**
     * Decodes image from URI into {@link Bitmap}. Image is scaled close to incoming {@linkplain ImageSize target size}
     * during decoding (depend on incoming parameters).
     *
     * @param decodingInfo Needed data for decoding image
     * @return Decoded bitmap
     * @throws IOException                   if some I/O exception occurs during image reading
     * @throws UnsupportedOperationException if image URI has unsupported scheme(protocol)
     */
    @Override
    public Bitmap decode(ImageDecodingInfo decodingInfo) throws IOException {
        Bitmap decodedBitmap;
        ImageFileInfo imageInfo;

        InputStream imageStream = getImageStream(decodingInfo);
        if (imageStream == null) {
            L.e(ERROR_NO_IMAGE_STREAM, decodingInfo.getImageKey());
            return null;
        }
        try {
            imageInfo = defineImageSizeAndRotation(imageStream, decodingInfo);
            imageStream = resetStream(imageStream, decodingInfo);
            Options decodingOptions = prepareDecodingOptions(imageInfo.imageSize, decodingInfo);
            //================FAIL HERE============
            decodedBitmap = BitmapFactory.decodeStream(imageStream, null, decodingOptions);
        } finally {
            IoUtils.closeSilently(imageStream);
        }

        if (decodedBitmap == null) {
            L.e(ERROR_CANT_DECODE_IMAGE, decodingInfo.getImageKey());
        } else {
            decodedBitmap = considerExactScaleAndOrientatiton(decodedBitmap, decodingInfo, imageInfo.exif.rotation,
                    imageInfo.exif.flipHorizontal);
        }
        return decodedBitmap;
    }

    protected InputStream getImageStream(ImageDecodingInfo decodingInfo) throws IOException {
        return decodingInfo.getDownloader().getStream(decodingInfo.getImageUri(), decodingInfo.getExtraForDownloader());
    }

    protected ImageFileInfo defineImageSizeAndRotation(InputStream imageStream, ImageDecodingInfo decodingInfo)
            throws IOException {
        Options options = new Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(imageStream, null, options);

        ExifInfo exif;
        String imageUri = decodingInfo.getImageUri();
        if (decodingInfo.shouldConsiderExifParams() && canDefineExifParams(imageUri, options.outMimeType)) {
            exif = defineExifOrientation(imageUri);
        } else {
            exif = new ExifInfo();
        }
        return new ImageFileInfo(new ImageSize(options.outWidth, options.outHeight, exif.rotation), exif);
    }

    private boolean canDefineExifParams(String imageUri, String mimeType) {
        return "image/jpeg".equalsIgnoreCase(mimeType) && (Scheme.ofUri(imageUri) == Scheme.FILE);
    }

    protected ExifInfo defineExifOrientation(String imageUri) {
        int rotation = 0;
        boolean flip = false;
        try {
            ExifInterface exif = new ExifInterface(Scheme.FILE.crop(imageUri));
            int exifOrientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);
            switch (exifOrientation) {
                case ExifInterface.ORIENTATION_FLIP_HORIZONTAL:
                    flip = true;
                case ExifInterface.ORIENTATION_NORMAL:
                    rotation = 0;
                    break;
                case ExifInterface.ORIENTATION_TRANSVERSE:
                    flip = true;
                case ExifInterface.ORIENTATION_ROTATE_90:
                    rotation = 90;
                    break;
                case ExifInterface.ORIENTATION_FLIP_VERTICAL:
                    flip = true;
                case ExifInterface.ORIENTATION_ROTATE_180:
                    rotation = 180;
                    break;
                case ExifInterface.ORIENTATION_TRANSPOSE:
                    flip = true;
                case ExifInterface.ORIENTATION_ROTATE_270:
                    rotation = 270;
                    break;
            }
        } catch (IOException e) {
            L.w("Can't read EXIF tags from file [%s]", imageUri);
        }
        return new ExifInfo(rotation, flip);
    }

    protected Options prepareDecodingOptions(ImageSize imageSize, ImageDecodingInfo decodingInfo) {
        ImageScaleType scaleType = decodingInfo.getImageScaleType();
        int scale;
        if (scaleType == ImageScaleType.NONE) {
            scale = 1;
        } else if (scaleType == ImageScaleType.NONE_SAFE) {
            scale = ImageSizeUtils.computeMinImageSampleSize(imageSize);
        } else {
            ImageSize targetSize = decodingInfo.getTargetSize();
            boolean powerOf2 = scaleType == ImageScaleType.IN_SAMPLE_POWER_OF_2;
            scale = ImageSizeUtils.computeImageSampleSize(imageSize, targetSize, decodingInfo.getViewScaleType(), powerOf2);
        }
        if (scale > 1 && loggingEnabled) {
            L.d(LOG_SUBSAMPLE_IMAGE, imageSize, imageSize.scaleDown(scale), scale, decodingInfo.getImageKey());
        }

        Options decodingOptions = decodingInfo.getDecodingOptions();
        decodingOptions.inSampleSize = scale;
        return decodingOptions;
    }

    protected InputStream resetStream(InputStream imageStream, ImageDecodingInfo decodingInfo) throws IOException {
        if (imageStream.markSupported()) {
            try {
                imageStream.reset();
                return imageStream;
            } catch (IOException ignored) {
            }
        }
        IoUtils.closeSilently(imageStream);
        return getImageStream(decodingInfo);
    }

    protected Bitmap considerExactScaleAndOrientatiton(Bitmap subsampledBitmap, ImageDecodingInfo decodingInfo,
            int rotation, boolean flipHorizontal) {
        Matrix m = new Matrix();
        // Scale to exact size if need
        ImageScaleType scaleType = decodingInfo.getImageScaleType();
        if (scaleType == ImageScaleType.EXACTLY || scaleType == ImageScaleType.EXACTLY_STRETCHED) {
            ImageSize srcSize = new ImageSize(subsampledBitmap.getWidth(), subsampledBitmap.getHeight(), rotation);
            float scale = ImageSizeUtils.computeImageScale(srcSize, decodingInfo.getTargetSize(), decodingInfo
                    .getViewScaleType(), scaleType == ImageScaleType.EXACTLY_STRETCHED);
            if (Float.compare(scale, 1f) != 0) {
                m.setScale(scale, scale);

                if (loggingEnabled) {
                    L.d(LOG_SCALE_IMAGE, srcSize, srcSize.scale(scale), scale, decodingInfo.getImageKey());
                }
            }
        }
        // Flip bitmap if need
        if (flipHorizontal) {
            m.postScale(-1, 1);

            if (loggingEnabled) L.d(LOG_FLIP_IMAGE, decodingInfo.getImageKey());
        }
        // Rotate bitmap if need
        if (rotation != 0) {
            m.postRotate(rotation);

            if (loggingEnabled) L.d(LOG_ROTATE_IMAGE, rotation, decodingInfo.getImageKey());
        }

        Bitmap finalBitmap = Bitmap.createBitmap(subsampledBitmap, 0, 0, subsampledBitmap.getWidth(), subsampledBitmap
                .getHeight(), m, true);
        if (finalBitmap != subsampledBitmap) {
            subsampledBitmap.recycle();
        }
        return finalBitmap;
    }

    protected static class ExifInfo {

        public final int rotation;
        public final boolean flipHorizontal;

        protected ExifInfo() {
            this.rotation = 0;
            this.flipHorizontal = false;
        }

        protected ExifInfo(int rotation, boolean flipHorizontal) {
            this.rotation = rotation;
            this.flipHorizontal = flipHorizontal;
        }
    }

    protected static class ImageFileInfo {

        public final ImageSize imageSize;
        public final ExifInfo exif;

        protected ImageFileInfo(ImageSize imageSize, ExifInfo exif) {
            this.imageSize = imageSize;
            this.exif = exif;
        }
    }
}

Answer 1

如果无法解码，decodeStream 可能会返回 null。查看消息来源，有几种情况是正确的。 解码也是在本机代码中进行的。所以这取决于供应商。

编辑

您可以尝试从输入流读取字节数组并对其进行解码而不是流。在这种情况下，它会告诉您问题出在哪里：文件读取或解码。

您还可以阅读日志以获取一些有用的信息，例如缺少权限等。