improve empty tools::Rectangle (width)

This is the width part, the height part will come next.

Instead of storing "empty" as a special value (which is easy to get
wrong, eg. some image filters pass in that special value, expecting it
to be a valid width), just use separate boolean values for width and
height empty.

Also lots of code was calling GetBottom() or GetRight() on an
empty rectangle, getting back that magic value and doing calculations
on it, resulting in completely bogus data.

So
(1) make the various Rectangle methods do something reasonable
when the empty flags are set
(2) fix various other code to handle empty better
(3) assert when code accesses Bottom or Right and the empty flag
is set.

Change-Id: I1163378cd2773dd8b386210f83400bb6b4701069
Reviewed-on: https://gerrit.libreoffice.org/73564
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

1 files changed, 56 insertions, 27 deletions

diff --git a/include/tools/gen.hxx b/include/tools/gen.hxx
index 0d9a81ebdcee..d84d359b543a 100644
--- a/include/tools/gen.hxx
+++ b/include/tools/gen.hxx
@@ -24,6 +24,7 @@
 #include <limits.h>
 #include <algorithm>
 #include <ostream>
+#include <cassert>
 
 class SvStream;
 namespace rtl
@@ -386,12 +387,12 @@ public:
                         Rectangle( const Point& rLT, const Size& rSize );
 
     long                Left() const    { return nLeft;   }
-    long                Right() const   { return nRight;  }
+    long                Right() const   { assert(!mbWidthEmpty); return nRight;  }
     long                Top() const     { return nTop;    }
     long                Bottom() const  { return nBottom; }
 
     void                SetLeft(long v)    { nLeft = v;   }
-    void                SetRight(long v)   { nRight = v;  }
+    void                SetRight(long v)   { nRight = v; mbWidthEmpty = false; }
     void                SetTop(long v)     { nTop = v;    }
     void                SetBottom(long v)  { nBottom = v; }
 
@@ -409,7 +410,17 @@ public:
     inline void         Move( long nHorzMoveDelta, long nVertMoveDelta );
     void                Move( Size const & s ) { Move(s.Width(), s.Height()); }
     long                AdjustLeft( long nHorzMoveDelta ) { nLeft += nHorzMoveDelta; return nLeft; }
-    long                AdjustRight( long nHorzMoveDelta ) { nRight += nHorzMoveDelta; return nRight; }
+    long                AdjustRight( long nHorzMoveDelta )
+    {
+        if (mbWidthEmpty)
+        {
+            mbWidthEmpty = false;
+            nRight = nLeft + nHorzMoveDelta - 1;
+        }
+        else
+            nRight += nHorzMoveDelta;
+        return nRight;
+    }
     long                AdjustTop( long nVertMoveDelta ) { nTop += nVertMoveDelta; return nTop; }
     long                AdjustBottom( long nVertMoveDelta ) { nBottom += nVertMoveDelta; return nBottom; }
     inline void         SetPos( const Point& rPoint );
@@ -432,11 +443,11 @@ public:
     bool                IsInside( const tools::Rectangle& rRect ) const;
     bool                IsOver( const tools::Rectangle& rRect ) const;
 
-    void                SetEmpty() { nRight = nBottom = RECT_EMPTY; }
-    void                SetWidthEmpty() { nRight = RECT_EMPTY; }
+    void                SetEmpty() { nRight = 0; nBottom = RECT_EMPTY; mbWidthEmpty = true; }
+    void                SetWidthEmpty() { nRight = 0; mbWidthEmpty = true; }
     void                SetHeightEmpty() { nBottom = RECT_EMPTY; }
     inline bool         IsEmpty() const;
-    bool                IsWidthEmpty() const { return nRight == RECT_EMPTY; }
+    bool                IsWidthEmpty() const { return mbWidthEmpty; }
     bool                IsHeightEmpty() const { return nBottom == RECT_EMPTY; }
 
     inline bool         operator == ( const tools::Rectangle& rRect ) const;
@@ -455,14 +466,19 @@ public:
     long                getX() const { return nLeft; }
     long                getY() const { return nTop; }
     /// Returns the difference between right and left, assuming the range includes one end, but not the other.
-    long                getWidth() const { return nRight - nLeft; }
+    long                getWidth() const { return mbWidthEmpty ? 0 : nRight - nLeft; }
     /// Returns the difference between bottom and top, assuming the range includes one end, but not the other.
     long                getHeight() const { return nBottom - nTop; }
     /// Set the left edge of the rectangle to x, preserving the width
-    void                setX( long x ) { nRight  += x - nLeft; nLeft = x; }
+    void                setX( long x )
+    {
+        if (!mbWidthEmpty)
+            nRight += x - nLeft;
+        nLeft = x;
+    }
     /// Set the top edge of the rectangle to y, preserving the height
     void                setY( long y ) { nBottom += y - nTop;  nTop  = y; }
-    void                setWidth( long n ) { nRight = nLeft + n; }
+    void                setWidth( long n ) { nRight = nLeft + n; mbWidthEmpty = false; }
     void                setHeight( long n ) { nBottom = nTop + n; }
     /// Returns the string representation of the rectangle, format is "x, y, width, height".
     rtl::OString        toString() const;
@@ -481,6 +497,7 @@ public:
     void                SaturatingSetY(long y);
 
 private:
+    bool                mbWidthEmpty : 1;
     long                nLeft;
     long                nTop;
     long                nRight;
@@ -491,7 +508,9 @@ private:
 inline tools::Rectangle::Rectangle()
 {
     nLeft = nTop = 0;
-    nRight = nBottom = RECT_EMPTY;
+    nRight = 0;
+    nBottom = RECT_EMPTY;
+    mbWidthEmpty = true;
 }
 
 inline tools::Rectangle::Rectangle( const Point& rLT, const Point& rRB )
@@ -500,6 +519,7 @@ inline tools::Rectangle::Rectangle( const Point& rLT, const Point& rRB )
     nTop    = rLT.Y();
     nRight  = rRB.X();
     nBottom = rRB.Y();
+    mbWidthEmpty = false;
 }
 
 inline tools::Rectangle::Rectangle( long _nLeft,  long _nTop,
@@ -509,26 +529,30 @@ inline tools::Rectangle::Rectangle( long _nLeft,  long _nTop,
     nTop    = _nTop;
     nRight  = _nRight;
     nBottom = _nBottom;
+    mbWidthEmpty = false;
 }
 
 inline tools::Rectangle::Rectangle( long _nLeft,  long _nTop )
 {
     nLeft   = _nLeft;
     nTop    = _nTop;
-    nRight = nBottom = RECT_EMPTY;
+    nRight  =  0;
+    nBottom = RECT_EMPTY;
+    mbWidthEmpty = true;
 }
 
 inline tools::Rectangle::Rectangle( const Point& rLT, const Size& rSize )
 {
     nLeft   = rLT.X();
     nTop    = rLT.Y();
-    nRight  = rSize.Width()  ? nLeft+(rSize.Width()-1) : RECT_EMPTY;
+    nRight  = rSize.Width()  ? nLeft+(rSize.Width()-1) : 0;
     nBottom = rSize.Height() ? nTop+(rSize.Height()-1) : RECT_EMPTY;
+    mbWidthEmpty  = rSize.Width() == 0;
 }
 
 inline bool tools::Rectangle::IsEmpty() const
 {
-    return (nRight == RECT_EMPTY) || (nBottom == RECT_EMPTY);
+    return mbWidthEmpty || (nBottom == RECT_EMPTY);
 }
 
 inline Point tools::Rectangle::TopLeft() const
@@ -538,7 +562,7 @@ inline Point tools::Rectangle::TopLeft() const
 
 inline Point tools::Rectangle::TopRight() const
 {
-    return Point( (nRight == RECT_EMPTY) ? nLeft : nRight, nTop );
+    return Point( mbWidthEmpty ? nLeft : nRight, nTop );
 }
 
 inline Point tools::Rectangle::BottomLeft() const
@@ -548,7 +572,7 @@ inline Point tools::Rectangle::BottomLeft() const
 
 inline Point tools::Rectangle::BottomRight() const
 {
-    return Point( (nRight  == RECT_EMPTY) ? nLeft : nRight,
+    return Point( mbWidthEmpty ? nLeft : nRight,
                   (nBottom == RECT_EMPTY) ? nTop  : nBottom );
 }
 
@@ -598,7 +622,7 @@ inline void tools::Rectangle::Move( long nHorzMove, long nVertMove )
 {
     nLeft += nHorzMove;
     nTop  += nVertMove;
-    if ( nRight != RECT_EMPTY )
+    if ( !mbWidthEmpty )
         nRight += nHorzMove;
     if ( nBottom != RECT_EMPTY )
         nBottom += nVertMove;
@@ -606,7 +630,7 @@ inline void tools::Rectangle::Move( long nHorzMove, long nVertMove )
 
 inline void tools::Rectangle::SetPos( const Point& rPoint )
 {
-    if ( nRight != RECT_EMPTY )
+    if ( !mbWidthEmpty )
         nRight += rPoint.X() - nLeft;
     if ( nBottom != RECT_EMPTY )
         nBottom += rPoint.Y() - nTop;
@@ -617,7 +641,7 @@ inline void tools::Rectangle::SetPos( const Point& rPoint )
 inline long tools::Rectangle::GetWidth() const
 {
     long n;
-    if ( nRight == RECT_EMPTY )
+    if ( mbWidthEmpty )
         n = 0;
     else
     {
@@ -670,22 +694,20 @@ inline bool tools::Rectangle::operator == ( const tools::Rectangle& rRect ) cons
     return (nLeft   == rRect.nLeft   ) &&
            (nTop    == rRect.nTop    ) &&
            (nRight  == rRect.nRight  ) &&
-           (nBottom == rRect.nBottom );
+           (nBottom == rRect.nBottom ) &&
+           (mbWidthEmpty == rRect.mbWidthEmpty);
 }
 
 inline bool tools::Rectangle::operator != ( const tools::Rectangle& rRect ) const
 {
-    return (nLeft   != rRect.nLeft   ) ||
-           (nTop    != rRect.nTop    ) ||
-           (nRight  != rRect.nRight  ) ||
-           (nBottom != rRect.nBottom );
+    return !(operator==(rRect));
 }
 
 inline tools::Rectangle& tools::Rectangle::operator +=( const Point& rPt )
 {
     nLeft += rPt.X();
     nTop  += rPt.Y();
-    if ( nRight != RECT_EMPTY )
+    if ( !mbWidthEmpty )
         nRight += rPt.X();
     if ( nBottom != RECT_EMPTY )
         nBottom += rPt.Y();
@@ -696,7 +718,7 @@ inline tools::Rectangle& tools::Rectangle::operator -= ( const Point& rPt )
 {
     nLeft -= rPt.X();
     nTop  -= rPt.Y();
-    if ( nRight != RECT_EMPTY )
+    if ( !mbWidthEmpty )
         nRight -= rPt.X();
     if ( nBottom != RECT_EMPTY )
         nBottom -= rPt.Y();
@@ -726,7 +748,13 @@ inline void tools::Rectangle::expand(long nExpandBy)
 {
     nLeft   -= nExpandBy;
     nTop    -= nExpandBy;
-    nRight  += nExpandBy;
+    if (mbWidthEmpty)
+    {
+        nRight  = nLeft + nExpandBy - 1;
+        mbWidthEmpty = false;
+    }
+    else
+        nRight  += nExpandBy;
     nBottom += nExpandBy;
 }
 
@@ -734,7 +762,8 @@ inline void tools::Rectangle::shrink(long nShrinkBy)
 {
     nLeft   += nShrinkBy;
     nTop    += nShrinkBy;
-    nRight  -= nShrinkBy;
+    if (!mbWidthEmpty)
+        nRight  -= nShrinkBy;
     nBottom -= nShrinkBy;
 }