Separate the requested and effective size of toolbar bitmaps

Add wxToolBarBase::DoSetToolBitmapSize() which does everything that
SetToolBitmapSize() used to do and make SetToolBitmapSize() itself also
remember the size passed to it in a new field, so that we could check
that we don't decrease the bitmap size below the size requested by the
application, while still being able to decrease it if necessary due to a
DPI change.

This allows SetToolBitmapSize() to continue working as before, i.e.
scale the bitmaps up if necessary without ever scaling them down, but
also allows them to resize in both directions when DPI changes.

Closes #22105.

src/common/tbarbase.cpp

@@ -433,12 +433,19 @@ void wxToolBarBase::ClearTools()
     }
 }
 
-void wxToolBarBase::SetToolBitmapSize(const wxSize& size)
+void wxToolBarBase::DoSetToolBitmapSize(const wxSize& size)
 {
     m_defaultWidth = size.x;
     m_defaultHeight = size.y;
 }
 
+void wxToolBarBase::SetToolBitmapSize(const wxSize& size)
+{
+    m_requestedBitmapSize = size;
+
+    DoSetToolBitmapSize(size);
+}
+
 wxSize wxToolBarBase::GetToolBitmapSize() const
 {
     return wxSize(m_defaultWidth, m_defaultHeight);
@@ -448,7 +455,7 @@ void wxToolBarBase::AdjustToolBitmapSize()
 {
     if ( HasFlag(wxTB_NOICONS) )
     {
-        SetToolBitmapSize(wxSize(0, 0));
+        DoSetToolBitmapSize(wxSize(0, 0));
         return;
     }
 
@@ -476,6 +483,11 @@ void wxToolBarBase::AdjustToolBitmapSize()
                                 sizeOrig
                                );
 
+        // Don't do anything if it doesn't change, our current size is supposed
+        // to satisfy any constraints we might have anyhow.
+        if ( sizePreferred == sizeOrig )
+            return;
+
         // This size is supposed to be in logical units for the platforms where
         // they differ from physical ones, so convert it.
         //
@@ -486,14 +498,16 @@ void wxToolBarBase::AdjustToolBitmapSize()
         // use the size computed here, this would need to be revisited.
         sizePreferred /= GetContentScaleFactor();
 
-        // Increase the bitmap size to the preferred one, as the default bitmap
-        // size is small and using larger bitmaps shouldn't shrink them to it.
-        // However intentionally setting a size larger than the actual bitmap
-        // size should scale them up, as people sometimes want to use bigger
-        // buttons and this is how it used to behave before wxBitmapBundle
-        // introduction.
-        if ( sizePreferred.x > sizeOrig.x || sizePreferred.y > sizeOrig.y )
-            SetToolBitmapSize(sizePreferred);
+        // Don't decrease the bitmap below the size requested by the application
+        // as using larger bitmaps shouldn't shrink them to the small default
+        // size.
+        sizePreferred.IncTo(m_requestedBitmapSize);
+
+        // Call DoSetToolBitmapSize() and not SetToolBitmapSize() to avoid
+        // changing the requested bitmap size: if we set our own adjusted size
+        // as the preferred one, we wouldn't decrease it later even if we ought
+        // to, as when moving from a monitor with higher DPI to a lower-DPI one.
+        DoSetToolBitmapSize(sizePreferred);
     }
 }