Changeset 108410 in vbox

Timestamp:

Feb 27, 2025 11:14:17 AM (7 weeks ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

167778

Message:

FE/Qt: bugref:10450: Runtime UI: Fixing fractional scaling issue introduced with Qt6; Caching smallest dpr denominator to avoid calculating it on every paint call; So that on paint calls we are rounding rectangles to nearest denominator up or down if necessary and that's it.

File:

• trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIFrameBuffer.cpp (modified) (7 diffs)

trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIFrameBuffer.cpp

@@ -144 +144 @@
     double devicePixelRatio() const { return m_dDevicePixelRatio; }
     /** Defines device-pixel-ratio set for HiDPI frame-buffer. */
-    void setDevicePixelRatio(double dDevicePixelRatio) { m_dDevicePixelRatio = dDevicePixelRatio; }
+    void setDevicePixelRatio(double dDevicePixelRatio);
+
+    /** Returns smallest device-pixel-ratio denominator. */
+    int smallestDenominator() const { return m_iSmallestDenominator; }
 
     /** Returns whether frame-buffer should use unscaled HiDPI output. */
@@ -289 +292 @@
     /** Finds greatest common divisor for @a a and @a b. */
     static int greatestCommonDivisor(int a, int b);
-    /** Finds multiple of @a fScaleFactor which is @a fLarger than @a iNumber. */
-    static int findMultipleOfScaleFactor(double fScaleFactor, int iNumber, bool fLarger);
+    /** Rounds passed iNumber up to @a iNearest @a fUp. */
+    static int roundNumberUpToNearest(int iNumber, int iNearest, bool fUp);
 
     /** Holds the screen-id. */
@@ -360 +363 @@
     /** Holds device-pixel-ratio set for HiDPI frame-buffer. */
     double  m_dDevicePixelRatio;
+    /** Holds the smallest device-pixel-ratio denominator. */
+    int     m_iSmallestDenominator;
     /** Holds whether frame-buffer should use unscaled HiDPI output. */
     bool    m_fUseUnscaledHiDPIOutput;
@@ -394 +399 @@
     , m_enmScalingOptimizationType(ScalingOptimizationType_None)
     , m_dDevicePixelRatio(1.0)
+    , m_iSmallestDenominator(-1)
     , m_fUseUnscaledHiDPIOutput(false)
 {
@@ -488 +494 @@
     m_fUnused = fUnused;
     unlock();
+}
+
+void UIFrameBufferPrivate::setDevicePixelRatio(double dDevicePixelRatio)
+{
+    /* Make sure something changed: */
+    if (devicePixelRatio() == dDevicePixelRatio)
+        return;
+
+    /* Cache device-pixel-ratio (dpr): */
+    m_dDevicePixelRatio = dDevicePixelRatio;
+
+    /* For 100% host OS scale-factor we don't need denominator: */
+    if (devicePixelRatio() == 1.0)
+        m_iSmallestDenominator = -1;
+    else
+    {
+        /* Recalculate smallest dpr denominator: */
+        const int iDenominator = 100; // precision, cause scale-factor is percentage
+        const int iNumerator = static_cast<int>(devicePixelRatio() * iDenominator);
+        const int iGreatestCommonDivisor = greatestCommonDivisor(iNumerator, iDenominator);
+        /* We need smallest denominator after all: */
+        m_iSmallestDenominator = iDenominator / iGreatestCommonDivisor;
+    }
+    //printf("m_iSmallestDenominator = %d\n", m_iSmallestDenominator);
 }
 
@@ -1273 +1303 @@
     QRect paintRect = pEvent->rect();
     /* Adjust original rectangle the way that it can be fractionally upscaled to int values: */
-    if (devicePixelRatio() != 1.0)
-    {
-        paintRect.setLeft(findMultipleOfScaleFactor(devicePixelRatio(), paintRect.left(), false));
-        paintRect.setTop(findMultipleOfScaleFactor(devicePixelRatio(), paintRect.top(), false));
-        paintRect.setWidth(findMultipleOfScaleFactor(devicePixelRatio(), paintRect.width(), true));
-        paintRect.setHeight(findMultipleOfScaleFactor(devicePixelRatio(), paintRect.height(), true));
+    if (smallestDenominator() != -1)
+    {
+        paintRect.setLeft(roundNumberUpToNearest(paintRect.left(), smallestDenominator(), false /* up */));
+        paintRect.setTop(roundNumberUpToNearest(paintRect.top(), smallestDenominator(), false /* up */));
+        paintRect.setWidth(roundNumberUpToNearest(paintRect.width(), smallestDenominator(), true /* up */));
+        paintRect.setHeight(roundNumberUpToNearest(paintRect.height(), smallestDenominator(), true /* up */));
     }
     QRect paintRectHiDPI = paintRect;
@@ -1452 +1482 @@
 
 /* static */
-int UIFrameBufferPrivate::findMultipleOfScaleFactor(double fScaleFactor, int iNumber, bool fLarger)
-{
-    /* Approximate scale-factor as a fraction: */
-    int iDenominator = 100; // precision, scale-factor is percentage
-    int iNumerator = static_cast<int>(fScaleFactor * iDenominator);
-    int iCommonDivisor = greatestCommonDivisor(iNumerator, iDenominator);
-    /* We need smallest denominator after all: */
-    iDenominator /= iCommonDivisor;
-
-    /* Find the largest/smallest multiple
-     * of the denominator <=/>= iNumber: */
-    int iResult = (iNumber / iDenominator) * iDenominator;
-    /* Append denominator if requested: */
-    if (fLarger && iResult < iNumber)
-        iResult += iDenominator;
+int UIFrameBufferPrivate::roundNumberUpToNearest(int iNumber, int iNearest, bool fUp)
+{
+    /* Round passed iNumber up to iNearest: */
+    int iResult = (iNumber / iNearest) * iNearest;
+    /* Append iNearest if requested: */
+    if (fUp && iResult < iNumber)
+        iResult += iNearest;
     return iResult;
 }