Define inverted QRects consistently

Changes the definition of invalid QRects to be more consistent.
This simplifies the logic, and makes it possible for us to fix
normalized() so dimensions don't change.

The actual API is not changed except for inverted rects.

Only one use-case for the old normalized() function existed,
and has been reimplemented as QRect::span().

Fixes: QTBUG-22934
Change-Id: I29dad2952dc6c8e84a6d931898dc7e43d66780f3
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 92 insertions, 84 deletions

diff --git a/src/corelib/tools/qrect.cpp b/src/corelib/tools/qrect.cpp
index 2bdf1094da..45af85a4df 100644
--- a/src/corelib/tools/qrect.cpp
+++ b/src/corelib/tools/qrect.cpp
@@ -223,9 +223,14 @@ QT_BEGIN_NAMESPACE
 /*!
     \fn QRect::QRect(const QPoint &topLeft, const QPoint &bottomRight)
 
-    Constructs a rectangle with the given \a topLeft and \a bottomRight corners.
+    Constructs a rectangle with the given \a topLeft and \a bottomRight corners, both included.
 
-    \sa setTopLeft(), setBottomRight()
+    If \a bottomRight is to higher and to the left of \a topLeft, the rectangle defined
+    is instead non-inclusive of the corners.
+
+    \note To ensure both points are included regardless of relative order, use span().
+
+    \sa setTopLeft(), setBottomRight(), span()
 */
 
 
@@ -295,27 +300,22 @@ QT_BEGIN_NAMESPACE
     non-negative width and height.
 
     If width() < 0 the function swaps the left and right corners, and
-    it swaps the top and bottom corners if height() < 0.
+    it swaps the top and bottom corners if height() < 0. The corners
+    are at the same time changed from being non-inclusive to inclusive.
 
     \sa isValid(), isEmpty()
 */
 
 QRect QRect::normalized() const noexcept
 {
-    QRect r;
-    if (x2 < x1 - 1) {                                // swap bad x values
-        r.x1 = x2;
-        r.x2 = x1;
-    } else {
-        r.x1 = x1;
-        r.x2 = x2;
+    QRect r(*this);
+    if (x2 < x1) {                                // swap bad x values
+        r.x1 = x2 + 1;
+        r.x2 = x1 - 1;
     }
-    if (y2 < y1 - 1) {                                // swap bad y values
-        r.y1 = y2;
-        r.y2 = y1;
-    } else {
-        r.y1 = y1;
-        r.y2 = y2;
+    if (y2 < y1) {                                // swap bad y values
+        r.y1 = y2 + 1;
+        r.y2 = y1 - 1;
     }
     return r;
 }
@@ -824,8 +824,8 @@ bool QRect::contains(const QPoint &p, bool proper) const noexcept
 {
     int l, r;
     if (x2 < x1 - 1) {
-        l = x2;
-        r = x1;
+        l = x2 + 1;
+        r = x1 - 1;
     } else {
         l = x1;
         r = x2;
@@ -839,8 +839,8 @@ bool QRect::contains(const QPoint &p, bool proper) const noexcept
     }
     int t, b;
     if (y2 < y1 - 1) {
-        t = y2;
-        b = y1;
+        t = y2 + 1;
+        b = y1 - 1;
     } else {
         t = y1;
         b = y2;
@@ -890,16 +890,16 @@ bool QRect::contains(const QRect &r, bool proper) const noexcept
         return false;
 
     int l1 = x1;
-    int r1 = x1;
-    if (x2 - x1 + 1 < 0)
-        l1 = x2;
+    int r1 = x1 - 1;
+    if (x2 < x1 - 1)
+        l1 = x2 + 1;
     else
         r1 = x2;
 
     int l2 = r.x1;
-    int r2 = r.x1;
-    if (r.x2 - r.x1 + 1 < 0)
-        l2 = r.x2;
+    int r2 = r.x1 - 1;
+    if (r.x2 < r.x1 - 1)
+        l2 = r.x2 + 1;
     else
         r2 = r.x2;
 
@@ -912,16 +912,16 @@ bool QRect::contains(const QRect &r, bool proper) const noexcept
     }
 
     int t1 = y1;
-    int b1 = y1;
-    if (y2 - y1 + 1 < 0)
-        t1 = y2;
+    int b1 = y1 - 1;
+    if (y2 < y1 - 1)
+        t1 = y2 + 1;
     else
         b1 = y2;
 
     int t2 = r.y1;
-    int b2 = r.y1;
-    if (r.y2 - r.y1 + 1 < 0)
-        t2 = r.y2;
+    int b2 = r.y1 - 1;
+    if (r.y2 < r.y1 - 1)
+        t2 = r.y2 + 1;
     else
         b2 = r.y2;
 
@@ -970,30 +970,30 @@ QRect QRect::operator|(const QRect &r) const noexcept
         return *this;
 
     int l1 = x1;
-    int r1 = x1;
-    if (x2 - x1 + 1 < 0)
-        l1 = x2;
+    int r1 = x1 - 1;
+    if (x2 < x1 - 1)
+        l1 = x2 + 1;
     else
         r1 = x2;
 
     int l2 = r.x1;
-    int r2 = r.x1;
-    if (r.x2 - r.x1 + 1 < 0)
-        l2 = r.x2;
+    int r2 = r.x1 - 1;
+    if (r.x2 < r.x1 - 1)
+        l2 = r.x2 + 1;
     else
         r2 = r.x2;
 
     int t1 = y1;
-    int b1 = y1;
-    if (y2 - y1 + 1 < 0)
-        t1 = y2;
+    int b1 = y1 - 1;
+    if (y2 < y1 - 1)
+        t1 = y2 + 1;
     else
         b1 = y2;
 
     int t2 = r.y1;
-    int b2 = r.y1;
-    if (r.y2 - r.y1 + 1 < 0)
-        t2 = r.y2;
+    int b2 = r.y1 - 1;
+    if (r.y2 < r.y1 - 1)
+        t2 = r.y2 + 1;
     else
         b2 = r.y2;
 
@@ -1032,35 +1032,35 @@ QRect QRect::operator&(const QRect &r) const noexcept
         return QRect();
 
     int l1 = x1;
-    int r1 = x1;
-    if (x2 - x1 + 1 < 0)
-        l1 = x2;
-    else
-        r1 = x2;
+    int r1 = x2;
+    if (x2 < x1 - 1) {
+        l1 = x2 + 1;
+        r1 = x1 - 1;
+    }
 
     int l2 = r.x1;
-    int r2 = r.x1;
-    if (r.x2 - r.x1 + 1 < 0)
-        l2 = r.x2;
-    else
-        r2 = r.x2;
+    int r2 = r.x2;
+    if (r.x2 < r.x1 - 1) {
+        l2 = r.x2 + 1;
+        r2 = r.x1 - 1;
+    }
 
     if (l1 > r2 || l2 > r1)
         return QRect();
 
     int t1 = y1;
-    int b1 = y1;
-    if (y2 - y1 + 1 < 0)
-        t1 = y2;
-    else
-        b1 = y2;
+    int b1 = y2;
+    if (y2 < y1 - 1) {
+        t1 = y2 + 1;
+        b1 = y1 - 1;
+    }
 
     int t2 = r.y1;
-    int b2 = r.y1;
-    if (r.y2 - r.y1 + 1 < 0)
-        t2 = r.y2;
-    else
-        b2 = r.y2;
+    int b2 = r.y2;
+    if (r.y2 < r.y1 - 1) {
+        t2 = r.y2 + 1;
+        b2 = r.y1 - 1;
+    }
 
     if (t1 > b2 || t2 > b1)
         return QRect();
@@ -1104,35 +1104,35 @@ bool QRect::intersects(const QRect &r) const noexcept
         return false;
 
     int l1 = x1;
-    int r1 = x1;
-    if (x2 - x1 + 1 < 0)
-        l1 = x2;
-    else
-        r1 = x2;
+    int r1 = x2;
+    if (x2 < x1 - 1) {
+        l1 = x2 + 1;
+        r1 = x1 - 1;
+    }
 
     int l2 = r.x1;
-    int r2 = r.x1;
-    if (r.x2 - r.x1 + 1 < 0)
-        l2 = r.x2;
-    else
-        r2 = r.x2;
+    int r2 = r.x2;
+    if (r.x2 < r.x1 - 1) {
+        l2 = r.x2 + 1;
+        r2 = r.x1 - 1;
+    }
 
     if (l1 > r2 || l2 > r1)
         return false;
 
     int t1 = y1;
-    int b1 = y1;
-    if (y2 - y1 + 1 < 0)
-        t1 = y2;
-    else
-        b1 = y2;
+    int b1 = y2;
+    if (y2 < y1 - 1) {
+        t1 = y2 + 1;
+        b1 = y1 - 1;
+    }
 
     int t2 = r.y1;
-    int b2 = r.y1;
-    if (r.y2 - r.y1 + 1 < 0)
-        t2 = r.y2;
-    else
-        b2 = r.y2;
+    int b2 = r.y2;
+    if (r.y2 < r.y1 - 1) {
+        t2 = r.y2 + 1;
+        b2 = r.y1 - 1;
+    }
 
     if (t1 > b2 || t2 > b1)
         return false;
@@ -1225,6 +1225,14 @@ bool QRect::intersects(const QRect &r) const noexcept
     \since 5.1
 */
 
+/*!
+    \fn static QRect QRect::span(const QPoint &p1, const QPoint &p2)
+
+    Returns a rectangle spanning the two points, including both and everything
+    in between.
+
+    \since 6.0
+*/
 
 /*****************************************************************************
   QRect stream functions