unity.scopes.qt.QPreviewQueryBase

Abstract base class to represent a particular preview. More...

#include <unity/scopes/qt/QPreviewQueryBase.h>

Inheritance diagram for unity::scopes::qt::QPreviewQueryBase: src="https://assets.ubuntu.com/v1/1c977384-classunity_1_1scopes_1_1qt_1_1_q_preview_query_base__inherit__graph.png" border="0" alt="Inheritance graph"/>

Public Member Functions

virtual void run (unity::scopes::qt::QPreviewReplyProxy const &reply)=0
 Called by scopes run time to start the query. More...
 
virtual void cancelled ()=0
 Called by the scopes run time when the query originator cancels a query. More...
 
QResult result () const
 Get result for this preview request. More...
 
QActionMetadata action_metadata () const
 Get metadata for this preview request. More...
 

Detailed Description

Abstract base class to represent a particular preview.

A scope must return an instance of this class from its implementation of ScopeBase::preview().

Note
The constructor of the instance must complete in a timely manner. Do not perform anything in the constructor that might block.

Member Function Documentation

QActionMetadata unity::scopes::qt::QPreviewQueryBase::action_metadata ( ) const

Get metadata for this preview request.

Returns
search metadata
Exceptions
unity::LogicExceptionif preview metadata was not initialized (the default ctor was used).
virtual void unity::scopes::qt::QPreviewQueryBase::cancelled ( )
pure virtual

Called by the scopes run time when the query originator cancels a query.

Your implementation of this method should ensure that the scope stops processing the current query as soon as possible. Any calls to a push() method once a query is cancelled are ignored, so continuing to push after cancellation only wastes CPU cycles. (push() returns false once a query is cancelled or exceeds its cardinality limit.)

QResult unity::scopes::qt::QPreviewQueryBase::result ( ) const

Get result for this preview request.

Exceptions
unity::LogicExceptionif result was not initialized (the default ctor was used).
Returns
result
virtual void unity::scopes::qt::QPreviewQueryBase::run ( unity::scopes::qt::QPreviewReplyProxy const &  reply)
pure virtual

Called by scopes run time to start the query.

Your implementation of run() can use the reply proxy to push results for the query. You can push results from within run(), in which case the query implicitly completes when run() returns. Alternatively, run() can store the reply proxy and return immediately. In this case, you can use the stored proxy to push results from another thread. It is safe to call push() from multiple threads without synchronization.

The query completes either when run() returns, or when the last stored reply proxy goes out of scope (whichever happens last).

Parameters
replyThe proxy on which to push results for the query.