Avoid unnecessary update to main preview when opening first detail window, fixes #4368

rtengine/improccoordinator.cc

@@ -90,7 +90,7 @@ ImProcCoordinator::ImProcCoordinator ()
       pW (-1), pH (-1),
       plistener (nullptr), imageListener (nullptr), aeListener (nullptr), acListener (nullptr), abwListener (nullptr), awbListener (nullptr), frameCountListener (nullptr), imageTypeListener (nullptr), actListener (nullptr), adnListener (nullptr), awavListener (nullptr), dehaListener (nullptr), hListener (nullptr),
       resultValid (false), lastOutputProfile ("BADFOOD"), lastOutputIntent (RI__COUNT), lastOutputBPC (false), thread (nullptr), changeSinceLast (0), updaterRunning (false), destroying (false), utili (false), autili (false),
-      butili (false), ccutili (false), cclutili (false), clcutili (false), opautili (false), wavcontlutili (false), colourToningSatLimit (0.f), colourToningSatLimitOpacity (0.f)
+      butili (false), ccutili (false), cclutili (false), clcutili (false), opautili (false), wavcontlutili (false), colourToningSatLimit (0.f), colourToningSatLimitOpacity (0.f), highQualityComputed (false)
 {}
 
 void ImProcCoordinator::assign (ImageSource* imgsrc)
@@ -1388,5 +1388,26 @@ void ImProcCoordinator::endUpdateParams (int changeFlags)
     startProcessing ();
 }
 
+bool ImProcCoordinator::getHighQualComputed() {
+    // this function may only be called from detail windows
+    if(!highQualityComputed) {
+        if(options.prevdemo == PD_Sidecar) {
+            // we already have high quality preview
+            setHighQualComputed();
+        } else {
+            for (size_t i = 0; i < crops.size() - 1; ++i) { // -1, because last entry is the freshly created detail window
+                if (crops[i]->get_skip() == 1 ) {  // there is at least one crop with skip == 1 => we already have high quality preview
+                    setHighQualComputed();
+                    break;
+                }
+            }
+        }
+    }
+    return highQualityComputed;
+}
+
+void ImProcCoordinator::setHighQualComputed() {
+    highQualityComputed = true;
+}
 
 }

rtengine/improccoordinator.h

@@ -212,6 +212,7 @@ protected:
     void process ();
     float colourToningSatLimit;
     float colourToningSatLimitOpacity;
+    bool highQualityComputed;
 
 public:
 
@@ -266,7 +267,8 @@ public:
     void getCamWB    (double& temp, double& green);
     void getSpotWB   (int x, int y, int rectSize, double& temp, double& green);
     void getAutoCrop (double ratio, int &x, int &y, int &w, int &h);
-
+    bool getHighQualComputed();
+    void setHighQualComputed();
     void setMonitorProfile (const Glib::ustring& profile, RenderingIntent intent);
     void getMonitorProfile (Glib::ustring& profile, RenderingIntent& intent) const;
     void setSoftProofing   (bool softProof, bool gamutCheck);

rtengine/rtengine.h

@@ -440,6 +440,9 @@ public:
       * @return the height of the preview image */
     virtual int         getPreviewHeight () = 0;
 
+    virtual bool        getHighQualComputed() = 0;
+    virtual void        setHighQualComputed() = 0;
+
     virtual bool        updateTryLock() = 0;
 
     virtual void        updateUnLock() = 0;

rtgui/imagearea.cc

@@ -505,8 +505,9 @@ void ImageArea::addCropWindow ()
 
     mainCropWindow->setObservedCropWin (cropWins.front());
 
-    if(cropWins.size() == 1) { // after first detail window we already have high quality
+    if(!ipc->getHighQualComputed()) {
         ipc->startProcessing(M_HIGHQUAL);
+        ipc->setHighQualComputed();
     }
 }