Fixed issue with occasional mis-sized tile

It turns out that there were two issues at play here: rounding errors
meant that pixmaps were almost never the same size as pagePainter
thought the tiles should be, and the tile-is-the-size-it-should-be code
path was broken (but only hit in rare cases, seemingly at random).

To help with rounding errors in the future, I added a geometryF function
to NormalizedRect that returns a QRectF. In general,
device-independent-pixel points/rects should be floating point, and
device-pixel rects should be integer.

core/area.cpp

@@ -243,6 +243,13 @@ QRect NormalizedRect::roundedGeometry(int xScale, int yScale) const
     return QRect(l, t, r - l + 1, b - t + 1);
 }
 
+QRectF NormalizedRect::geometryF(float xScale, float yScale) const
+{
+    float l = (left * xScale), t = (top * yScale), r = (right * xScale), b = (bottom * yScale);
+
+    return QRectF(l, t, r - l, b - t);
+}
+
 void NormalizedRect::transform(const QTransform &matrix)
 {
     QRectF rect(left, top, right - left, bottom - top);

core/area.h

@@ -282,6 +282,11 @@ public:
      */
     QRect roundedGeometry(int xScale, int yScale) const;
 
+    /**
+     * Same functionality as geometry, but nothing is converted into int.
+     */
+    QRectF geometryF(float xScale, float yScale) const;
+
     /**
      * Returns the normalized bounding rectangle of the normalized rectangle
      * combined with the @p other normalized rectangle.

gui/pagepainter.cpp

@@ -247,18 +247,18 @@ void PagePainter::paintCroppedPageOnPainter(QPainter *destPainter,
             QList<Okular::Tile>::const_iterator tIt = tiles.constBegin(), tEnd = tiles.constEnd();
             while (tIt != tEnd) {
                 const Okular::Tile &tile = *tIt;
-                QRect tileRect = tile.rect().geometry(scaledWidth, scaledHeight).translated(-scaledCrop.topLeft());
+                QRectF tileRect = tile.rect().geometryF(scaledWidth, scaledHeight).translated(-scaledCrop.topLeft());
-                QRect dTileRect = QRectF(tileRect.x() * dpr, tileRect.y() * dpr, tileRect.width() * dpr, tileRect.height() * dpr).toAlignedRect();
+                QRect dTileRect = tile.rect().geometry(dScaledWidth, dScaledHeight).translated(-dScaledCrop.topLeft());
-                QRect limitsInTile = limits & tileRect;
+                QRectF limitsInTile = QRectF(limits) & tileRect;
-                QRectF dLimitsInTile = dLimits & dTileRect;
+                QRect dLimitsInTile = dLimits & dTileRect;
 
                 if (!limitsInTile.isEmpty()) {
                     QPixmap *tilePixmap = tile.pixmap();
 
                     if (tilePixmap->width() == dTileRect.width() && tilePixmap->height() == dTileRect.height()) {
-                        destPainter->drawPixmap(limitsInTile.topLeft(), *tilePixmap, dLimitsInTile.translated(-dTileRect.topLeft()));
+                        destPainter->drawPixmap(limitsInTile, *tilePixmap, dLimitsInTile.translated(-dTileRect.topLeft()));
                     } else {
-                        destPainter->drawPixmap(tileRect, *tilePixmap);
+                        destPainter->drawPixmap(tileRect, *tilePixmap, tilePixmap->rect());
                     }
                 }
                 tIt++;
@@ -284,16 +284,16 @@ void PagePainter::paintCroppedPageOnPainter(QPainter *destPainter,
             QList<Okular::Tile>::const_iterator tIt = tiles.constBegin(), tEnd = tiles.constEnd();
             while (tIt != tEnd) {
                 const Okular::Tile &tile = *tIt;
-                QRect tileRect = tile.rect().geometry(scaledWidth, scaledHeight).translated(-scaledCrop.topLeft());
+                QRectF tileRect = tile.rect().geometryF(scaledWidth, scaledHeight).translated(-scaledCrop.topLeft());
-                QRect dTileRect(QRectF(tileRect.x() * dpr, tileRect.y() * dpr, tileRect.width() * dpr, tileRect.height() * dpr).toAlignedRect());
+                QRect dTileRect = tile.rect().geometry(dScaledWidth, dScaledHeight).translated(-dScaledCrop.topLeft());
-                QRect limitsInTile = limits & tileRect;
+                QRectF limitsInTile = QRectF(limits) & tileRect;
                 QRect dLimitsInTile = dLimits & dTileRect;
 
                 if (!limitsInTile.isEmpty()) {
                     QPixmap *tilePixmap = tile.pixmap();
 
                     if (tilePixmap->width() == dTileRect.width() && tilePixmap->height() == dTileRect.height()) {
-                        p.drawPixmap(limitsInTile.translated(-limits.topLeft()).topLeft(), *tilePixmap, dLimitsInTile.translated(-dTileRect.topLeft()));
+                        p.drawPixmap(limitsInTile.translated(-limits.topLeft()), *tilePixmap, dLimitsInTile.translated(-dTileRect.topLeft()));
                     } else {
                         double xScale = tilePixmap->width() / (double)dTileRect.width();
                         double yScale = tilePixmap->height() / (double)dTileRect.height();