qml中图片格式和后缀不一致时导致图片不显示的问题(ios and android)

修改原文件：

C:\Qt\Qt5.7.1\5.7\Src\qtbase\src\gui\image\qimagereader.cpp

将561行的 ignoresFormatAndExtension(false) 改为 ignoresFormatAndExtension(true) 

即忽略格式后缀，此时会根据文件内容判断格式而不是后缀

QImageReaderPrivate::QImageReaderPrivate(QImageReader *qq)

    : autoDetectImageFormat(true), ignoresFormatAndExtension(true)

{

    device = 0;

    deleteDevice = false;

    handler = 0;

    quality = -1;

    imageReaderError = QImageReader::UnknownError;

    autoTransform = UsePluginDefault;

    q = qq;

}

将1584行的

QImageIOHandler *handler = createReadHandlerHelper(device, format, /* autoDetectImageFormat = */ true, false);

改为：

QImageIOHandler *handler = createReadHandlerHelper(device, format, /* autoDetectImageFormat = */ true, true);