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unity.scopes.qt.QPreviewQueryBaseAPI
Abstract base class to represent a particular preview. More...
#include <unity/scopes/qt/QPreviewQueryBaseAPI.h>
Inheritance diagram for unity::scopes::qt::QPreviewQueryBaseAPI:
src="https://assets.ubuntu.com/v1/0bdc01e5-classunity_1_1scopes_1_1qt_1_1_q_preview_query_base_a_p_i__inherit__graph.png" border="0" alt="Inheritance graph"/>
Public Member Functions | |
| virtual void | run (unity::scopes::PreviewReplyProxy const &reply) final |
| Called by scopes run time to start the query. More... | |
| virtual void | cancelled () final |
| Called by the scopes run time when the query originator cancels a query. More... | |
| Result | result () const |
| Get result for this preview request. More... | |
| ActionMetadata | action_metadata () const |
| Get metadata for this preview request. More... | |
| bool | valid () const |
| Check whether this query is still valid. More... | |
| unity::scopes::VariantMap | settings () const |
| Returns a dictionary with the scope's current settings. More... | |
Additional Inherited Members | |
| PreviewQueryBase (Result const &result, ActionMetadata const &metadata) | |
| Instantiates a PreviewQueryBase. 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().
This is the class that links scope API calls with the main QThread. The instance of this class is moved to the main QThread and pushes events to the Qt event loop.
- 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
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finalvirtual |
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.)
Implements unity::scopes::QueryBase.
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finalvirtual |
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
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reply The proxy on which to push results for the query.
Implements unity::scopes::PreviewQueryBase.