Document RefreshDeferrer

src/common/RefreshDeferrer.cpp

@@ -18,7 +18,9 @@ bool RefreshDeferrer::attemptRefresh(RefreshDeferrerParams params)
         return true;
     } else {
         dirty = true;
-        acc->accumulate(params);
+        if (acc) {
+            acc->accumulate(params);
+        }
         return false;
     }
 }
@@ -28,8 +30,10 @@ void RefreshDeferrer::registerFor(CutterDockWidget *dockWidget)
     this->dockWidget = dockWidget;
     connect(dockWidget, &CutterDockWidget::becameVisibleToUser, this, [this]() {
         if(dirty) {
-            emit refreshNow(acc->result());
+            emit refreshNow(acc ? acc->result() : nullptr);
-            acc->clear();
+            if (acc) {
+                acc->clear();
+            }
             dirty = false;
         }
     });

src/common/RefreshDeferrer.h

@@ -10,6 +10,9 @@ class RefreshDeferrer;
 using RefreshDeferrerParams = void *;
 using RefreshDeferrerParamsResult = void *;
 
+/*!
+ * \brief Abstract class for accumulating params in RefreshDeferrer
+ */
 class RefreshDeferrerAccumulator
 {
     friend class RefreshDeferrer;
@@ -18,12 +21,34 @@ public:
     virtual ~RefreshDeferrerAccumulator() = default;
 
 protected:
+    /*!
+     * \brief Add a new param to the accumulator
+     */
     virtual void accumulate(RefreshDeferrerParams params) =0;
+
+    /*!
+     * \brief Ignore the incoming params. Useful for freeing if necessary.
+     */
     virtual void ignoreParams(RefreshDeferrerParams params) =0;
+
+    /*!
+     * \brief Clear the current accumulator
+     */
     virtual void clear() =0;
+
+    /*!
+     * \brief Return the final result of the accumulation
+     */
     virtual RefreshDeferrerParamsResult result() =0;
 };
 
+
+/*!
+ * \brief Accumulator which simply replaces the current value by an incoming new one
+ * \tparam T The type of the param to store
+ *
+ * This accumulator takes the ownership of all params passed to it and deletes them automatically if not needed anymore!
+ */
 template<class T>
 class ReplacingRefreshDeferrerAccumulator: public RefreshDeferrerAccumulator
 {
@@ -32,6 +57,9 @@ private:
     bool replaceIfNull;
 
 public:
+    /*!
+     * \param Determines whether, if nullptr is passed, the current value should be replaced or kept.
+     */
     explicit ReplacingRefreshDeferrerAccumulator(bool replaceIfNull = true)
         : replaceIfNull(replaceIfNull) {}
 
@@ -67,6 +95,39 @@ protected:
     }
 };
 
+/*!
+ * \brief Helper class for deferred refreshing in Widgets
+ *
+ * This class can handle the logic necessary to defer the refreshing of widgets when they are not visible.
+ * It contains an optional RefreshDeferrerAccumulator, which can be used to accumulate incoming events while
+ * refreshing is deferred.
+ *
+ * Example (don't write it like this in practice, use the convenience methods in CutterDockWidget):
+ * ```
+ * // in the constructor of a widget
+ * this->refreshDeferrer = new RefreshDeferrer(new ReplacingRefreshDeferrerAccumulator(false), this);
+ * this->refreshDeferrer->registerFor(this);
+ * connect(this->refreshDeferrer, &RefreshDeferrer::refreshNow, this, [this](MyParam *param) {
+ *      // We attempted a refresh some time before, but it got deferred.
+ *      // Now the RefreshDeferrer tells us to do the refresh and gives us the accumulated param.
+ *      this->doRefresh(*param);
+ * }
+ *
+ * // ...
+ *
+ * void MyWidget::doRefresh(MyParam param)
+ * {
+ *      if (!this->refreshDeferrer->attemptRefresh(new MyParam(param))) {
+ *          // We shouldn't refresh right now.
+ *          // The RefreshDeferrer takes over the param we passed it in attemptRefresh()
+ *          // and gives it to the ReplacingRefreshDeferrerAccumulator.
+ *          return;
+ *      }
+ *      // do the actual refresh depending on param
+ * }
+ * ```
+ *
+ */
 class RefreshDeferrer : public QObject
 {
     Q_OBJECT
@@ -77,8 +138,11 @@ private:
     bool dirty = false;
 
 public:
-    RefreshDeferrer(RefreshDeferrerAccumulator *acc, QObject *parent = nullptr);
+    /*!
-    virtual ~RefreshDeferrer();
+     * \param acc The accumulator (can be nullptr). The RefreshDeferrer takes the ownership!
+     */
+    explicit RefreshDeferrer(RefreshDeferrerAccumulator *acc, QObject *parent = nullptr);
+    ~RefreshDeferrer() override;
 
     bool attemptRefresh(RefreshDeferrerParams params);
     void registerFor(CutterDockWidget *dockWidget);

src/widgets/CutterDockWidget.h

@@ -32,6 +32,26 @@ private:
 protected:
     void closeEvent(QCloseEvent *event) override;
 
+    /*!
+     * \brief Convenience method for creating and registering a RefreshDeferrer without any parameters
+     * \param refreshNowFunc lambda taking no parameters, called when a refresh should occur
+     */
+    template<typename Func>
+    RefreshDeferrer *createRefreshDeferrer(Func refreshNowFunc)
+    {
+        auto *deferrer = new RefreshDeferrer(nullptr, this);
+        deferrer->registerFor(this);
+        connect(deferrer, &RefreshDeferrer::refreshNow, this, [refreshNowFunc](const RefreshDeferrerParamsResult) {
+            refreshNowFunc();
+        });
+        return deferrer;
+    }
+
+    /*!
+     * \brief Convenience method for creating and registering a RefreshDeferrer with a replacing Accumulator
+     * \param replaceIfNull passed to the ReplacingRefreshDeferrerAccumulator
+     * \param refreshNowFunc lambda taking a single parameter of type ParamResult, called when a refresh should occur
+     */
     template<class ParamResult, typename Func>
     RefreshDeferrer *createReplacingRefreshDeferrer(bool replaceIfNull, Func refreshNowFunc)
     {