Finally add forgotten SIP file

qgis · Jul 24, 2016 · 963ff92 · 963ff92
1 parent 940883b
commit 963ff92
Showing 1 changed file with 43 additions and 0 deletions.
diff --git a/python/core/qgsfeedback.sip b/python/core/qgsfeedback.sip
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+
+/** Base class for feedback objects to be used for cancellation of something running in a worker thread.
+ *
+ * The class may be used as is or it may be subclassed for extended functionality
+ * for a particular operation (e.g. report progress or pass some data for preview).
+ *
+ * When cancel() is called, the internal code has two options to check for cancellation state:
+ * - if the worker thread uses an event loop (e.g. for network communication), the code can
+ *   make a queued connection to cancelled() signal and handle the cancellation in its slot.
+ * - if the worker thread does not use an event loop, it can poll isCancelled() method regularly
+ *   to see if the operation should be cancelled.
+ *
+ * The class is meant to be created and destroyed in the main thread.
+ *
+ * For map rendering, the object may be created in constructor of a QgsMapLayerRenderer
+ * subclass and available with QgsMapLayerRenderer::feedback() method. When a map rendering job
+ * gets cancelled, the cancel() method is called on the feedback object of all layers.
+ *
+ * @note added in QGIS 3.0
+ */
+class QgsFeedback : QObject
+{
+%TypeHeaderCode
+#include <qgsfeedback.h>
+%End
+
+  public:
+    //! Construct a feedback object
+    QgsFeedback( QObject* parent /TransferThis/ = nullptr );
+
+    virtual ~QgsFeedback();
+
+    //! Tells the internal routines that the current operation should be cancelled. This should be run by the main thread
+    void cancel();
+
+    //! Tells whether the operation has been cancelled already
+    bool isCancelled() const;
+
+  signals:
+    //! Internal routines can connect to this signal if they use event loop
+    void cancelled();
+
+};