QFlags 类提供存储枚举值 OR 组合的类型安全方式。 更多...
| 头： | #include <QFlags> |
| qmake: | QT += core |
| typedef | Int |
| typedef | enum_type |
| QFlags (std::initializer_list<Enum> flags ) | |
| QFlags (QFlag flag ) | |
| QFlags (Enum flags ) | |
| QFlags () | |
| QFlags (const QFlags<T> & other ) | |
| QFlags<T> & | operator= (const QFlags<T> & other ) |
| QFlags<T> & | setFlag (Enum flag , bool on = true) |
| bool | testFlag (Enum flag ) const |
| QFlags::Int | operator QFlags::Int () const |
| bool | operator! () const |
| QFlags<T> | operator& (int mask ) const |
| QFlags<T> | operator& (uint mask ) const |
| QFlags<T> | operator& (Enum other ) const |
| QFlags<T> & | operator&= (int mask ) |
| QFlags<T> & | operator&= (uint mask ) |
| QFlags<T> & | operator&= (Enum mask ) |
| QFlags<T> | operator^ (QFlags<T> other ) const |
| QFlags<T> | operator^ (Enum other ) const |
| QFlags<T> & | operator^= (QFlags<T> other ) |
| QFlags<T> & | operator^= (Enum other ) |
| QFlags<T> | operator| (QFlags<T> other ) const |
| QFlags<T> | operator| (Enum other ) const |
| QFlags<T> & | operator|= (QFlags<T> other ) |
| QFlags<T> & | operator|= (Enum other ) |
| QFlags<T> | operator~ () const |
| Q_DECLARE_FLAGS ( Flags , Enum ) | |
| Q_DECLARE_OPERATORS_FOR_FLAGS ( Flags ) |
QFlags<Enum> 类是模板类，其中 Enum 是枚举类型。QFlags 在整个 Qt 中用于存储枚举值的组合。
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 使用 QFlags 提供类型安全性。例如，
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
{ }
, is legal:
label->setAlignment(Qt::AlignLeft | Qt::AlignTop); label->setAlignment({ });
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。
The 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 QFlags 对象初始化采用所有 flags combined using the bitwise OR operator.
该函数在 Qt 5.4 引入。
另请参阅 operator|= () 和 operator| ().
构造 QFlags 对象初始化采用整数 flag .
The
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 对象存储 flags .
构造没有设置标志的 QFlags 对象。
该函数在 Qt 5.15 引入。
构造副本为 other .
赋值 other 到此对象并返回此对象的引用。
Sets the flag
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
若标志
flag
被设置，否则
false
.
注意：
if
flag
contains multiple bits set to 1 (for instance, if it's an enumerator equal to the bitwise-OR of other enumerators) then this function will return
true
if and only if all the bits are set in this flags object. On the other hand, if
flag
contains no bits set to 1 (that is, its value as a integer is 0), then this function will return
true
if and only if this flags object also has no bits set to 1.
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。
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 ().
