QBuffer ¶

概要 ¶

详细描述 ¶

QBuffer allows you to access a QByteArray 使用 QIODevice 接口。 QByteArray 仅仅被视为标准随机访问文件。范例：

QBuffer buffer;
char ch;
buffer.open(QBuffer::ReadWrite);
buffer.write("Qt rocks!");
buffer.seek(0);
buffer.getChar(&ch);  // ch == 'Q'
buffer.getChar(&ch);  // ch == 't'
buffer.getChar(&ch);  // ch == ' '
buffer.getChar(&ch);  // ch == 'r'
											

默认情况下，内部 QByteArray buffer is created for you when you create a QBuffer . You can access this buffer directly by calling buffer() . You can also use QBuffer with an existing QByteArray 通过调用 setBuffer() , or by passing your array to QBuffer ‘s constructor.

调用 open() to open the buffer. Then call write() or putChar() to write to the buffer, and read() , readLine() , readAll() ，或 getChar() to read from it. size() returns the current size of the buffer, and you can seek to arbitrary positions in the buffer by calling seek() . When you are done with accessing the buffer, call close() .

下列代码片段展示如何把数据写入 QByteArray 使用 QDataStream and QBuffer :

QByteArray byteArray;
QBuffer buffer(&byteArray);
buffer.open(QIODevice::WriteOnly);
QDataStream out(&buffer);
out << QApplication::palette();
											

Effectively, we convert the application’s QPalette into a byte array. Here’s how to read the data from the QByteArray :

QPalette palette;
QBuffer buffer(&byteArray);
buffer.open(QIODevice::ReadOnly);
QDataStream in(&buffer);
in >> palette;
											

QTextStream and QDataStream also provide convenience constructors that take a QByteArray and that create a QBuffer behind the scenes.

QBuffer 发射 readyRead() when new data has arrived in the buffer. By connecting to this signal, you can use QBuffer to store temporary data before processing it. QBuffer also emits bytesWritten() every time new data has been written to the buffer.

另请参阅

QFile QDataStream QTextStream QByteArray

class QBuffer ( buf [ , parent=None ] ) ¶

QBuffer([parent=None])

param parent

QObject

param buf

QByteArray

构造 QBuffer that uses the QByteArray pointed to by byteArray as its internal buffer, and with the given parent . The caller is responsible for ensuring that byteArray remains valid until the QBuffer is destroyed, or until setBuffer() is called to change the buffer. QBuffer doesn’t take ownership of the QByteArray .

If you open the buffer in write-only mode or read-write mode and write something into the QBuffer , byteArray will be modified.

范例：

QByteArray byteArray("abc");
QBuffer buffer(&byteArray);
buffer.open(QIODevice::WriteOnly);
buffer.seek(3);
buffer.write("def", 3);
buffer.close();
// byteArray == "abcdef"
											

另请参阅

open() setBuffer() setData()

Constructs an empty buffer with the given parent . You can call setData() to fill the buffer with data, or you can open it in write mode and use write() .

另请参阅

open()

PySide2.QtCore.QBuffer. buffer ( ) ¶

返回类型

QByteArray

这是重载函数。

这如同 data() .

PySide2.QtCore.QBuffer. data ( ) ¶

返回类型

QByteArray

返回包含在缓冲中的数据。

这如同 buffer() .

另请参阅

setData() setBuffer()

PySide2.QtCore.QBuffer. setBuffer ( a ) ¶

参数

a – QByteArray

Makes QBuffer 使用 QByteArray pointed to by byteArray as its internal buffer. The caller is responsible for ensuring that byteArray remains valid until the QBuffer is destroyed, or until is called to change the buffer. QBuffer doesn’t take ownership of the QByteArray .

什么都不做若 isOpen() 为 true。

If you open the buffer in write-only mode or read-write mode and write something into the QBuffer , byteArray will be modified.

范例：

QByteArray byteArray("abc");
QBuffer buffer;
buffer.setBuffer(&byteArray);
buffer.open(QIODevice::WriteOnly);
buffer.seek(3);
buffer.write("def", 3);
buffer.close();
// byteArray == "abcdef"
											

若 byteArray is None , the buffer creates its own internal QByteArray to work on. This byte array is initially empty.

另请参阅

buffer() setData() open()

PySide2.QtCore.QBuffer. setData ( data ) ¶

参数

data – QByteArray

Sets the contents of the internal buffer to be data . This is the same as assigning data to buffer() .

什么都不做若 isOpen() 为 true。

另请参阅

data() setBuffer()