QVirtualKeyboardTrace Class

Detailed Description

Trace provides the data model for coordinate data and other optional data associated with a single stroke.

A typical use case for the trace object is as follows:

• TraceInputArea or other input device initiates the trace event by calling InputEngine.traceBegin() method.
• If the current input method accepts the event it creates a trace object and configures the required data channels (if any).
• TraceInputArea collects the data for the Trace object.
• TraceInputArea calls the InputEngine.traceEnd() method to finish the trace and passing the trace object back to input method.
• The input method processes the data and discards the object when it is no longer needed.

The coordinate data is retrieved using the points() function.

In addition to coordinate based data, it is possible to attach an arbitrary data channel for each data point.

The data channels must be defined before the points are added. The data channels supported by the TraceInputArea are listed below:

• "t" Collects time for each data point. The time is the number of milliseconds since 1970/01/01:

For example, to configure the object to collect the times for each point:

 QVirtualKeyboardTrace *trace = new QVirtualKeyboardTrace(this);
 trace->setChannels(QStringList() << "t");

The collected data can be accessed using the channelData() function:

 QVariantList timeData = trace->channelData("t");

QVirtualKeyboardTrace objects are owned by their creator, which is the input method in normal case. This means the objects are constructed in the InputMethod.traceBegin() (QML) method.

By definition, the trace object can be destroyed at earliest in the InputMethod.traceEnd() (QML) method.