Remove unnecessary scrollbar in TQIconView

Test case (using konqueror icon view):
- The first icons are being shown (no scrollbar yet)
- When there is no space left, a vertical scrollbar is needed
- The vertical scrollbar may cover the right edge of the icons
(in the last column) => an horizontal scrollbar is needed :-(

Solution:
When using ScrollBarMode::Auto, prevent TQt from drawing icons on the
scrollbar area (before the scrollbar is shown).

Related to KDE bug #69589
(cherry picked from commit 36ee984c64)

src/iconview/qiconview.cpp

@@ -1102,7 +1102,7 @@ void QIconViewItem::setText( const QString &text )
 
     if ( view ) {
 	if ( QRect( view->contentsX(), view->contentsY(),
-		    view->visibleWidth(), view->visibleHeight() ).
+		    view->visibleWidthSB(), view->visibleHeightSB() ).
 	     intersects( oR ) )
 	    view->repaintContents( oR.x() - 1, oR.y() - 1,
 				   oR.width() + 2, oR.height() + 2, FALSE );
@@ -1154,7 +1154,7 @@ void QIconViewItem::setPixmap( const QPixmap &icon )
 
     if ( view ) {
 	if ( QRect( view->contentsX(), view->contentsY(),
-		    view->visibleWidth(), view->visibleHeight() ).
+		    view->visibleWidthSB(), view->visibleHeightSB() ).
 	     intersects( oR ) )
 	    view->repaintContents( oR.x() - 1, oR.y() - 1,
 				   oR.width() + 2, oR.height() + 2, FALSE );
@@ -1190,7 +1190,7 @@ void QIconViewItem::setPicture( const QPicture &icon )
 
     if ( view ) {
 	if ( QRect( view->contentsX(), view->contentsY(),
-		    view->visibleWidth(), view->visibleHeight() ).
+		    view->visibleWidthSB(), view->visibleHeightSB() ).
 	     intersects( oR ) )
 	    view->repaintContents( oR.x() - 1, oR.y() - 1,
 				   oR.width() + 2, oR.height() + 2, FALSE );
@@ -1258,7 +1258,7 @@ void QIconViewItem::setPixmap( const QPixmap &icon, bool recalc, bool redraw )
 
 	    if ( view ) {
 		if ( QRect( view->contentsX(), view->contentsY(),
-			    view->visibleWidth(), view->visibleHeight() ).
+			    view->visibleWidthSB(), view->visibleHeightSB() ).
 		     intersects( oR ) )
 		    view->repaintContents( oR.x() - 1, oR.y() - 1,
 					   oR.width() + 2, oR.height() + 2, FALSE );
@@ -5633,8 +5633,8 @@ void QIconView::insertInGrid( QIconViewItem *item )
 	}
 	item->dirty = FALSE;
     } else {
-	QRegion r( QRect( 0, 0, QMAX( contentsWidth(), visibleWidth() ),
+	QRegion r( QRect( 0, 0, QMAX( contentsWidth(), visibleWidthSB() ),
-			  QMAX( contentsHeight(), visibleHeight() ) ) );
+			  QMAX( contentsHeight(), visibleHeightSB() ) ) );
 
 	QIconViewItem *i = d->firstItem;
 	int y = -1;
@@ -5897,7 +5897,7 @@ QIconViewItem *QIconView::makeRowLayout( QIconViewItem *begin, int &y, bool &cha
 	    QIconViewItem *item = begin;
 	    for (;;) {
 		x += d->spacing + item->width();
-		if ( x > visibleWidth() && item != begin ) {
+		if ( x > visibleWidthSB() && item != begin ) {
 		    item = item->prev;
 		    while (item && (item->isVisible() == FALSE)) {
 			item = item->prev;
@@ -5928,7 +5928,7 @@ QIconViewItem *QIconView::makeRowLayout( QIconViewItem *begin, int &y, bool &cha
 		int x;
 		if ( item == begin ) {
 		    if ( reverse )
-			x = visibleWidth() - d->spacing - item->width();
+			x = visibleWidthSB() - d->spacing - item->width();
 		    else
 			x = d->spacing;
 		} else {
@@ -5964,7 +5964,7 @@ QIconViewItem *QIconView::makeRowLayout( QIconViewItem *begin, int &y, bool &cha
 		    i += r;
 		    x = i * d->rastX + sp * d->spacing;
 		}
-		if ( x > visibleWidth() && item != begin ) {
+		if ( x > visibleWidthSB() && item != begin ) {
 		    item = item->prev;
 		    while (item && (item->isVisible() == FALSE)) {
 			item = item->prev;
@@ -6036,7 +6036,7 @@ QIconViewItem *QIconView::makeRowLayout( QIconViewItem *begin, int &y, bool &cha
 	    QIconViewItem *item = begin;
 	    for (;;) {
 		y += d->spacing + item->height();
-		if ( y > visibleHeight() && item != begin ) {
+		if ( y > visibleHeightSB() && item != begin ) {
 		    item = item->prev;
 		    while (item && (item->isVisible() == FALSE)) {
 			item = item->prev;
@@ -6600,4 +6600,24 @@ bool QIconView::isRenaming() const
 #endif
 }
 
+int QIconView::visibleWidthSB() const
+{
+    if ( vScrollBarMode() != Auto )
+        return visibleWidth();
+
+    int offset = verticalScrollBar()->isVisible() ? 0
+        : style().pixelMetric( QStyle::PM_ScrollBarExtent, verticalScrollBar() );
+    return QMAX( 0, visibleWidth() - offset );
+}
+
+int QIconView::visibleHeightSB() const
+{
+    if ( hScrollBarMode() != Auto )
+        return visibleHeight();
+
+    int offset = horizontalScrollBar()->isVisible() ? 0
+        : style().pixelMetric( QStyle::PM_ScrollBarExtent, horizontalScrollBar() );
+    return QMAX( 0, visibleHeight() - offset );
+}
+
 #endif // QT_NO_ICONVIEW

src/iconview/qiconview.h

@@ -504,6 +504,8 @@ private:
 			const QPoint &relativeTo,
 			const QIconViewItem *item ) const;
     QBitmap mask( QPixmap *pix ) const;
+    int visibleWidthSB() const;
+    int visibleHeightSB() const;
 
     QIconViewPrivate *d;