- Qt 5.15
- Qt Core
- C++ Classes
- QMimeType
- Qt 5.15.15 Reference Documentation

# QMimeType Class

The QMimeType class describes types of file or data, represented by a MIME type string. More...

Header: | #include <QMimeType>
qmake: | QT += core
Since: | Qt 5.0

This class was introduced in Qt 5.0.

- List of all members, including inherited members

## Properties

- aliases : const QStringList
- allAncestors : const QStringList
- comment : const QString
- filterString : const QString
- genericIconName : const QString
- globPatterns : const QStringList
- iconName : const QString

- isDefault : const bool
- name : const QString
- parentMimeTypes : const QStringList
- preferredSuffix : const QString
- suffixes : const QStringList
- valid : const bool

## Public Functions

| QMimeType(const QMimeType &other)
| QMimeType()
QMimeType & | operator=(QMimeType &&other)
QMimeType & | operator=(const QMimeType &other)
| ~QMimeType()
QStringList | aliases() const
QStringList | allAncestors() const
QString | comment() const
QString | filterString() const
QString | genericIconName() const
QStringList | globPatterns() const
QString | iconName() const
bool | inherits(const QString &mimeTypeName) const
bool | isDefault() const
bool | isValid() const
QString | name() const
QStringList | parentMimeTypes() const
QString | preferredSuffix() const
QStringList | suffixes() const
void | swap(QMimeType &other)
bool | operator!=(const QMimeType &other) const
bool | operator==(const QMimeType &other) const

## Related Non-Members

uint | qHash(const QMimeType &key, uint seed = 0)

## Detailed Description

For instance a file named "readme.txt" has the MIME type "text/plain". The MIME type can be determined from the file name, or from the file contents, or from both. MIME type determination can also be done on buffers of data not coming from files.

Determining the MIME type of a file can be useful to make sure your application supports it. It is also useful in file-manager-like applications or widgets, in order to display an appropriate icon for the file, or even the descriptive comment in detailed views.

To check if a file has the expected MIME type, you should use inherits() rather than a simple string comparison based on the name(). This is because MIME types can inherit from each other: for instance a C source file is a specific type of plain text file, so text/x-csrc inherits text/plain.

See also QMimeDatabase and MIME Type Browser Example.

## Property Documentation

### aliases : const QStringList

This property holds the list of aliases of this mimetype

For instance, for text/csv, the returned list would be: text/x-csv, text/x-comma-separated-values.

Note that all QMimeType instances refer to proper mimetypes, never to aliases directly.

The order of the aliases in the list is undefined.

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

QStringList | aliases() const

### allAncestors : const QStringList

This property holds the names of direct and indirect parent MIME types

Return all the parent mimetypes of this mimetype, direct and indirect. This includes the parent(s) of its parent(s), etc.

For instance, for image/svg+xml the list would be: application/xml, text/plain, application/octet-stream.

Note that application/octet-stream is the ultimate parent for all types of files (but not directories).

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

QStringList | allAncestors() const

### comment : const QString

This property holds the description of the MIME type to be displayed on user interfaces

The default language (QLocale().name()) is used to select the appropriate translation.

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

QString | comment() const

### filterString : const QString

This property holds a filter string usable for a file dialog

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

QString | filterString() const

### genericIconName : const QString

This property holds the file name of a generic icon that represents the MIME type

This should be used if the icon returned by iconName() cannot be found on the system. It is used for categories of similar types (like spreadsheets or archives) that can use a common icon. The freedesktop.org Icon Naming Specification lists a set of such icon names.

The icon name can be given to QIcon::fromTheme() in order to load the icon.

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

QString | genericIconName() const

### globPatterns : const QStringList

This property holds the list of glob matching patterns

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

QStringList | globPatterns() const

### iconName : const QString

This property holds the file name of an icon image that represents the MIME type

The icon name can be given to QIcon::fromTheme() in order to load the icon.

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

QString | iconName() const

### isDefault : const bool

`true` if this MIME type is the default MIME type which applies to all files: application/octet-stream.

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

bool | isDefault() const

### name : const QString

This property holds the name of the MIME type

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

QString | name() const

### parentMimeTypes : const QStringList

This property holds the names of parent MIME types

A type is a subclass of another type if any instance of the first type is also an instance of the second. For example, all image/svg+xml files are also text/xml, text/plain and application/octet-stream files. Subclassing is about the format, rather than the category of the data (for example, there is no 'generic spreadsheet' class that all spreadsheets inherit from). Conversely, the parent mimetype of image/svg+xml is text/xml.

A mimetype can have multiple parents. For instance application/x-perl has two parents: application/x-executable and text/plain. This makes it possible to both execute perl scripts, and to open them in text editors.

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

QStringList | parentMimeTypes() const

### preferredSuffix : const QString

This property holds the preferred suffix for the MIME type

No leading dot is included, so for instance this would return "pdf" for application/pdf. The return value can be empty, for mime types which do not have any suffixes associated.

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

QString | preferredSuffix() const

### suffixes : const QStringList

This property holds the known suffixes for the MIME type

No leading dot is included, so for instance this would return "jpg", "jpeg" for image/jpeg.

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

QStringList | suffixes() const

### valid : const bool

`true` if the QMimeType object contains valid data, `false` otherwise

A valid MIME type has a non-empty name(). The invalid MIME type is the default-constructed QMimeType.

While this property was introduced in 5.10, the corresponding accessor method has always been there.

Access functions:

bool | isValid() const

## Member Function Documentation

### QMimeType::QMimeType(const QMimeType &other)

Constructs this QMimeType object as a copy of other.

### QMimeType::QMimeType()

Constructs this QMimeType object initialized with default property values that indicate an invalid MIME type.

### QMimeType &QMimeType::operator=(QMimeType &&other)

Move-assigns other to this QMimeType instance.

This function was introduced in Qt 5.2.

### QMimeType &QMimeType::operator=(const QMimeType &other)

Assigns the data of other to this QMimeType object, and returns a reference to this object.

### QMimeType::~QMimeType()

Destroys the QMimeType object, and releases the d pointer.

### bool QMimeType::inherits(const QString &mimeTypeName) const

Returns `true` if this mimetype is mimeTypeName, or inherits mimeTypeName (see parentMimeTypes()), or mimeTypeName is an alias for this mimetype.

This method has been made invokable from QML since 5.10.

Note: This function can be invoked via the meta-object system and from QML. See Q_INVOKABLE.

### void QMimeType::swap(QMimeType &other)

Swaps QMimeType other with this QMimeType object.

This operation is very fast and never fails.

The swap() method helps with the implementation of assignment operators in an exception-safe way. For more information consult More C++ Idioms - Copy-and-swap.

### bool QMimeType::operator!=(const QMimeType &other) const

Returns `true` if other does not equal this QMimeType object, otherwise returns `false`.

### bool QMimeType::operator==(const QMimeType &other) const

Returns `true` if other equals this QMimeType object, otherwise returns `false`. The name is the unique identifier for a mimetype, so two mimetypes with the same name, are equal.

## Related Non-Members

### uint qHash(const QMimeType &key, uint seed = 0)

Returns the hash value for key, using seed to seed the calculation.

This function was introduced in Qt 5.6.