QFlags class provides a type-safe way of storing OR-combinations of enum values. 更多...
| 头： | #include <QFlags> |
| qmake: | QT += core |
| typedef | Int |
| typedef | enum_type |
| QFlags (const QFlags & other ) | |
| QFlags (Enum flag ) | |
| QFlags (Zero zero = Q_NULLPTR) | |
| QFlags (QFlag value ) | |
| QFlags (std::initializer_list<Enum> flags ) | |
| QFlags & | setFlag (Enum flag , bool on = true) |
| bool | testFlag (Enum flag ) const |
| operator Int () const | |
| bool | operator! () const |
| QFlags | operator& (int mask ) const |
| QFlags | operator& (uint mask ) const |
| QFlags | operator& (Enum mask ) const |
| QFlags & | operator&= (int mask ) |
| QFlags & | operator&= (uint mask ) |
| QFlags & | operator&= (Enum mask ) |
| QFlags & | operator= (const QFlags & other ) |
| QFlags | operator^ (QFlags other ) const |
| QFlags | operator^ (Enum other ) const |
| QFlags & | operator^= (QFlags other ) |
| QFlags & | operator^= (Enum other ) |
| QFlags | operator| (QFlags other ) const |
| QFlags | operator| (Enum other ) const |
| QFlags & | operator|= (QFlags other ) |
| QFlags & | operator|= (Enum other ) |
| QFlags | operator~ () const |
| Q_DECLARE_FLAGS ( Flags , Enum ) | |
| Q_DECLARE_OPERATORS_FOR_FLAGS ( Flags ) |
QFlags class provides a type-safe way of storing OR-combinations of enum values.
QFlags <Enum> class is a template class, where Enum is an enum type. QFlags is used throughout Qt for storing combinations of enum values.
传统 C++ 存储枚举值 OR 组合的方式是使用
int
or
uint
variable. The inconvenience with this approach is that there's no type checking at all; any enum value can be OR'd with any other enum value and passed on to a function that takes an
int
or
uint
.
Qt uses QFlags to provide type safety. For example, the Qt::Alignment type is simply a typedef for QFlags < Qt::AlignmentFlag >. QLabel::setAlignment () takes a Qt::Alignment parameter, which means that any combination of Qt::AlignmentFlag values, or 0, is legal:
label->setAlignment(Qt::AlignLeft | Qt::AlignTop);
If you try to pass a value from another enum or just a plain integer other than 0, the compiler will report an error. If you need to cast integer values to flags in a untyped fashion, you can use the explicit QFlags constructor as cast operator.
If you want to use QFlags for your own enum types, use the Q_DECLARE_FLAGS () 和 Q_DECLARE_OPERATORS_FOR_FLAGS ().
范例：
class MyClass { public: enum Option { NoOptions = 0x0, ShowTabs = 0x1, ShowAll = 0x2, SqueezeBlank = 0x4 }; Q_DECLARE_FLAGS(Options, Option) ... }; Q_DECLARE_OPERATORS_FOR_FLAGS(MyClass::Options)
You can then use the
MyClass::Options
type to store combinations of
MyClass::Option
值。
Q_DECLARE_FLAGS () macro does not expose the flags to the meta-object system, so they cannot be used by Qt Script or edited in Qt Designer. To make the flags available for these purposes, the Q_FLAG () macro must be used:
Q_FLAG(Options)
A sensible naming convention for enum types and associated
QFlags
types is to give a singular name to the enum type (e.g.,
选项
) and a plural name to the
QFlags
type (e.g.,
选项
). When a singular name is desired for the
QFlags
type (e.g.,
Alignment
), you can use
Flag
as the suffix for the enum type (e.g.,
AlignmentFlag
).
另请参阅 QFlag .
Typedef for the integer type used for storage as well as for implicit conversion. Either
int
or
无符号 int
, depending on whether the enum's underlying type is signed or unsigned.
该 typedef 在 Qt 5.0 引入。
用于枚举模板类型的 Typedef。
构造副本为 other .
构造 QFlags object storing the given flag .
构造 QFlags object with no flags set. zero must be a literal 0 value.
构造 QFlags object initialized with the given integer value .
QFlag
type is a helper type. By using it here instead of
int
, we effectively ensure that arbitrary enum values cannot be cast to a
QFlags
, whereas untyped enum values (i.e.,
int
values) can.
构造 QFlags object initialized with all flags combined using the bitwise OR operator.
该函数在 Qt 5.4 引入。
另请参阅 operator|= () 和 operator| ().
Sets the indicated
flag
if
on
is
true
or unsets it if
on
is
false
。返回此对象的引用。
该函数在 Qt 5.7 引入。
返回
true
若
flag
被设置，否则
false
.
该函数在 Qt 4.2 引入。
返回值存储在 QFlags 对象作为整数。
另请参阅 Int .
返回
true
if no flag is set (i.e., if the value stored by the
QFlags
object is 0); otherwise returns
false
.
返回 QFlags object containing the result of the bitwise AND operation on this object and mask .
另请参阅 operator&= (), operator| (), operator^ ()，和 operator~ ().
这是重载函数。
这是重载函数。
Performs a bitwise AND operation with mask and stores the result in this QFlags object. Returns a reference to this object.
另请参阅 operator& (), operator|= ()，和 operator^= ().
这是重载函数。
这是重载函数。
赋值 other 到此对象并返回此对象的引用。
返回 QFlags object containing the result of the bitwise XOR operation on this object and other .
另请参阅 operator^= (), operator& (), operator| ()，和 operator~ ().
这是重载函数。
Performs a bitwise XOR operation with other and stores the result in this QFlags object. Returns a reference to this object.
另请参阅 operator^ (), operator&= ()，和 operator|= ().
这是重载函数。
返回 QFlags object containing the result of the bitwise OR operation on this object and other .
另请参阅 operator|= (), operator^ (), operator& ()，和 operator~ ().
这是重载函数。
Performs a bitwise OR operation with other and stores the result in this QFlags object. Returns a reference to this object.
另请参阅 operator| (), operator&= ()，和 operator^= ().
这是重载函数。
返回 QFlags 对象包含此对象的按位取反。
另请参阅 operator& (), operator| ()，和 operator^ ().
The Q_DECLARE_FLAGS() macro expands to
typedef QFlags<Enum> Flags;
Enum is the name of an existing enum type, whereas Flags is the name of the QFlags < Enum > typedef.
见 QFlags 文档编制了解细节。
另请参阅 Q_DECLARE_OPERATORS_FOR_FLAGS ().
Q_DECLARE_OPERATORS_FOR_FLAGS() 宏声明全局
operator|()
函数为
Flags
, which is of type
QFlags
<T>.
见 QFlags 文档编制了解细节。
另请参阅 Q_DECLARE_FLAGS ().
