问题：项目加载webp图片不显示
背景：后台的图片从png转为了webp，出现部分图片不能显示。
原因：项目使用的glide 3.7 不支持带透明效果的webp格式图片
对策：
1.使用最新的glide 4.7.1。由于相比 glide 3.7 API改动太大，需要修改很多文件，比较麻烦。
2.修改glide 3.7 源码：按照4.7.1的代码，增加webp支持，重新打包。
以下是修改方法：
文件：com\bumptech\glide\load\resource\bitmap\ImageHeaderParser.java
加入枚举值WEBP 和WEBPA ,gettype() 方法加入webp解析 相关字段
public enum ImageType { /** GIF type. */ GIF(true), /** JPG type. */ JPEG(false), /** PNG type with alpha. */ PNG_A(true), /** PNG type without alpha. */ PNG(false), /** WebP type with alpha. */ WEBP_A(true), /** WebP type without alpha. */ WEBP(false), /** Unrecognized type. */ UNKNOWN(false); private final boolean hasAlpha; ImageType(boolean hasAlpha) { this.hasAlpha = hasAlpha; } public boolean hasAlpha() { return hasAlpha; } } //copy from glide 4.7.1 // WebP-related // "RIFF" private static final int RIFF_HEADER = 0x52494646; // "WEBP" private static final int WEBP_HEADER = 0x57454250; // "VP8" null. private static final int VP8_HEADER = 0x56503800; private static final int VP8_HEADER_MASK = 0xFFFFFF00; private static final int VP8_HEADER_TYPE_MASK = 0x000000FF; // 'X' private static final int VP8_HEADER_TYPE_EXTENDED = 0x00000058; // 'L' private static final int VP8_HEADER_TYPE_LOSSLESS = 0x0000004C; private static final int WEBP_EXTENDED_ALPHA_FLAG = 1 << 4; private static final int WEBP_LOSSLESS_ALPHA_FLAG = 1 << 3; public ImageType getType() throws IOException { final int firstTwoBytes = streamReader.getUInt16(); // JPEG. if (firstTwoBytes == EXIF_MAGIC_NUMBER) { return JPEG; } final int firstFourBytes = (firstTwoBytes << 16 & 0xFFFF0000) | (streamReader.getUInt16() & 0xFFFF); // PNG. if (firstFourBytes == PNG_HEADER) { // See: http://stackoverflow.com/questions/2057923/how-to-check-a-png-for-grayscale-alpha // -color-type streamReader.skip(25 - 4); int alpha = streamReader.getByte(); // A RGB indexed PNG can also have transparency. Better safe than sorry! return alpha >= 3 ? PNG_A : PNG; } // GIF from first 3 bytes. if (firstFourBytes >> 8 == GIF_HEADER) { return GIF; } // WebP (reads up to 21 bytes). See https://developers.google.com/speed/webp/docs/riff_container // for details. if (firstFourBytes != RIFF_HEADER) { return UNKNOWN; } // Bytes 4 - 7 contain length information. Skip these. streamReader.skip(4); final int thirdFourBytes = (streamReader.getUInt16() << 16 & 0xFFFF0000) | (streamReader.getUInt16() & 0xFFFF); if (thirdFourBytes != WEBP_HEADER) { return UNKNOWN; } final int fourthFourBytes = (streamReader.getUInt16() << 16 & 0xFFFF0000) | (streamReader.getUInt16() & 0xFFFF); if ((fourthFourBytes & VP8_HEADER_MASK) != VP8_HEADER) { return UNKNOWN; } if ((fourthFourBytes & VP8_HEADER_TYPE_MASK) == VP8_HEADER_TYPE_EXTENDED) { // Skip some more length bytes and check for transparency/alpha flag. streamReader.skip(4); return (streamReader.getByte() & WEBP_EXTENDED_ALPHA_FLAG) != 0 ? ImageType.WEBP_A : ImageType.WEBP; } if ((fourthFourBytes & VP8_HEADER_TYPE_MASK) == VP8_HEADER_TYPE_LOSSLESS) { // See chromium.googlesource.com/webm/libwebp/+/master/doc/webp-lossless-bitstream-spec.txt // for more info. streamReader.skip(4); return (streamReader.getByte() & WEBP_LOSSLESS_ALPHA_FLAG) != 0 ? ImageType.WEBP_A : ImageType.WEBP; } return ImageType.WEBP; }文件：com\bumptech\glide\load\resource\bitmap\Downsampler.java
TYPES_THAT_USE_POOL 集合内加入WEBP 和WEBPA
private static final Set<ImageHeaderParser.ImageType> TYPES_THAT_USE_POOL = EnumSet.of( ImageHeaderParser.ImageType.JPEG, ImageHeaderParser.ImageType.PNG_A, ImageHeaderParser.ImageType.PNG, ImageHeaderParser.ImageType.WEBP, ImageHeaderParser.ImageType.WEBP_A); 重新打包文件下载：https://download.csdn.net/download/u011809807/10498207
文章来源: Glide3.7 添加 Webp支持