tdf#103571: Avoid spurious heavy SalEvent::DisplayChanged callbacks

It seems that on some Macs that the
NSApplicationDidChangeScreenParametersNotification is sent for unknown
reasons quite often. I can reproduce the problem by changing the Dock
size in System Preferences while LibreOffice is running, but others
seem to get it without resorting to such trickery.

The code used to invoke the SalEvent::DisplayChanged callback in all
cases, which can be extremely heavy, as it involves re-measuring text
layouts all over the place in all open document windows.

Avoid that if the geometry in fact has not changed.

Sure, there still is the problem that LibreOffice can become
unresponsive for several seconds when the display geometry *does*
change, like when you attach or detach a display.

Change-Id: I659881e5e392bd599f6be190835e32a77d9f4725
Reviewed-on: https://gerrit.libreoffice.org/50249Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tor Lillqvist <tml@collabora.com>

vcl/inc/osx/salframe.h

@@ -82,6 +82,7 @@ public:
     PointerStyle                    mePointerStyle;         // currently active pointer style
 
     NSTrackingRectTag               mnTrackingRectTag;      // used to get enter/leave messages
+    NSRect                          maTrackingRect;
 
     CGMutablePathRef                mrClippingPath;         // used for "shaping"
     std::vector< CGRect >           maClippingRects;
@@ -95,6 +96,11 @@ public:
     // To prevent display sleep during presentation
     IOPMAssertionID                 mnAssertionID;
 
+    NSRect                          maFrameRect;
+    NSRect                          maContentRect;
+
+    bool                            mbGeometryDidChange;
+
 public:
     /** Constructor
 

vcl/osx/salframe.cxx

@@ -268,6 +268,10 @@ void AquaSalFrame::screenParametersChanged()
 
     if( mpGraphics )
         mpGraphics->updateResolution();
+
+    if (!mbGeometryDidChange)
+        return;
+
     CallCallback( SalEvent::DisplayChanged, nullptr );
 }
 
@@ -1522,6 +1526,9 @@ void AquaSalFrame::SetParent( SalFrame* pNewParent )
 
 void AquaSalFrame::UpdateFrameGeometry()
 {
+    bool bFirstTime = (mnTrackingRectTag == 0);
+    mbGeometryDidChange = false;
+
     if ( !mpNSWindow )
         return;
 
@@ -1534,38 +1541,65 @@ void AquaSalFrame::UpdateFrameGeometry()
     NSScreen * pScreen = [mpNSWindow screen];
     if( pScreen )
     {
-        maScreenRect = [pScreen frame];
+        NSRect aNewScreenRect = [pScreen frame];
+        if (bFirstTime || !NSEqualRects(maScreenRect, aNewScreenRect))
+        {
+            mbGeometryDidChange = true;
+            maScreenRect = aNewScreenRect;
+        }
         NSArray* pScreens = [NSScreen screens];
         if( pScreens )
-            maGeometry.nDisplayScreenNumber = [pScreens indexOfObject: pScreen];
+        {
+            unsigned int nNewDisplayScreenNumber = [pScreens indexOfObject: pScreen];
+            if (bFirstTime || maGeometry.nDisplayScreenNumber != nNewDisplayScreenNumber)
+            {
+                mbGeometryDidChange = true;
+                maGeometry.nDisplayScreenNumber = nNewDisplayScreenNumber;
+            }
+        }
     }
 
     NSRect aFrameRect = [mpNSWindow frame];
     NSRect aContentRect = [NSWindow contentRectForFrameRect: aFrameRect styleMask: mnStyleMask];
 
-    // release old track rect
-    [mpNSView removeTrackingRect: mnTrackingRectTag];
-    // install the new track rect
     NSRect aTrackRect = { NSZeroPoint, aContentRect.size };
-    mnTrackingRectTag = [mpNSView addTrackingRect: aTrackRect owner: mpNSView userData: nil assumeInside: NO];
+
+    if (bFirstTime || !NSEqualRects(maTrackingRect, aTrackRect))
+    {
+        mbGeometryDidChange = true;
+        maTrackingRect = aTrackRect;
+
+        // release old track rect
+        [mpNSView removeTrackingRect: mnTrackingRectTag];
+        // install the new track rect
+        mnTrackingRectTag = [mpNSView addTrackingRect: aTrackRect owner: mpNSView userData: nil assumeInside: NO];
+    }
 
     // convert to vcl convention
     CocoaToVCL( aFrameRect );
     CocoaToVCL( aContentRect );
 
-    maGeometry.nX = static_cast<int>(aContentRect.origin.x);
-    maGeometry.nY = static_cast<int>(aContentRect.origin.y);
+    if (bFirstTime || !NSEqualRects(maContentRect, aContentRect) || !NSEqualRects(maFrameRect, aFrameRect))
+    {
+        mbGeometryDidChange = true;
+
+        maContentRect = aContentRect;
+        maFrameRect = aFrameRect;
 
-    maGeometry.nLeftDecoration = static_cast<unsigned int>(aContentRect.origin.x - aFrameRect.origin.x);
-    maGeometry.nRightDecoration = static_cast<unsigned int>((aFrameRect.origin.x + aFrameRect.size.width) -
-                                  (aContentRect.origin.x + aContentRect.size.width));
+        maGeometry.nX = static_cast<int>(aContentRect.origin.x);
+        maGeometry.nY = static_cast<int>(aContentRect.origin.y);
 
-    maGeometry.nTopDecoration = static_cast<unsigned int>(aContentRect.origin.y - aFrameRect.origin.y);
-    maGeometry.nBottomDecoration = static_cast<unsigned int>((aFrameRect.origin.y + aFrameRect.size.height) -
-                                   (aContentRect.origin.y + aContentRect.size.height));
+        maGeometry.nLeftDecoration = static_cast<unsigned int>(aContentRect.origin.x - aFrameRect.origin.x);
+        maGeometry.nRightDecoration = static_cast<unsigned int>((aFrameRect.origin.x + aFrameRect.size.width) -
+                                      (aContentRect.origin.x + aContentRect.size.width));
 
-    maGeometry.nWidth = static_cast<unsigned int>(aContentRect.size.width);
-    maGeometry.nHeight = static_cast<unsigned int>(aContentRect.size.height);
+        maGeometry.nTopDecoration = static_cast<unsigned int>(aContentRect.origin.y - aFrameRect.origin.y);
+        maGeometry.nBottomDecoration = static_cast<unsigned int>((aFrameRect.origin.y + aFrameRect.size.height) -
+                                       (aContentRect.origin.y + aContentRect.size.height));
+
+        maGeometry.nWidth = static_cast<unsigned int>(aContentRect.size.width);
+        maGeometry.nHeight = static_cast<unsigned int>(aContentRect.size.height);
+    }
 }
 
 void AquaSalFrame::CaptureMouse( bool bCapture )