LibGfx: Implement alternative `Rect` right/bottom edge calculations

For `IntRect`, we assume that the right/bottom edge is offset by minus
one. This obviously will not work for `FloatRect`, since those edges are
infinitely small.

Specialize `right()` and `bottom()` and add a `FIXME` to get rid of the
offset in the future.

1 files changed, 37 insertions, 13 deletions

diff --git a/Userland/Libraries/LibGfx/Rect.h b/Userland/Libraries/LibGfx/Rect.h
index 7210ec17e1..b18598fe69 100644
--- a/Userland/Libraries/LibGfx/Rect.h
+++ b/Userland/Libraries/LibGfx/Rect.h
@@ -353,30 +353,54 @@ public:
         return right();
     }
 
+    // FIXME: for integral types of T, we assume that the right/bottom edges are offset by minus one.
+    //        Although there are cases where this makes sense, for consistency it would be best if we
+    //        can drop the `- 1` altogether and not specialize these methods.
     [[nodiscard]] ALWAYS_INLINE T left() const { return x(); }
-    [[nodiscard]] ALWAYS_INLINE T right() const { return x() + width() - 1; }
+    [[nodiscard]] ALWAYS_INLINE T right() const
+    requires(IsIntegral<T>)
+    {
+        return x() + width() - 1;
+    }
+    [[nodiscard]] ALWAYS_INLINE T right() const
+    requires(!IsIntegral<T>)
+    {
+        return x() + width();
+    }
     [[nodiscard]] ALWAYS_INLINE T top() const { return y(); }
-    [[nodiscard]] ALWAYS_INLINE T bottom() const { return y() + height() - 1; }
-
-    ALWAYS_INLINE void set_left(T left)
+    [[nodiscard]] ALWAYS_INLINE T bottom() const
+    requires(IsIntegral<T>)
     {
-        set_x(left);
+        return y() + height() - 1;
     }
-
-    ALWAYS_INLINE void set_top(T top)
+    [[nodiscard]] ALWAYS_INLINE T bottom() const
+    requires(!IsIntegral<T>)
     {
-        set_y(top);
+        return y() + height();
     }
 
+    ALWAYS_INLINE void set_left(T left) { set_x(left); }
     ALWAYS_INLINE void set_right(T right)
+    requires(IsIntegral<T>)
     {
         set_width(right - x() + 1);
     }
-
+    ALWAYS_INLINE void set_right(T right)
+    requires(!IsIntegral<T>)
+    {
+        set_width(right - x());
+    }
+    ALWAYS_INLINE void set_top(T top) { set_y(top); }
     ALWAYS_INLINE void set_bottom(T bottom)
+    requires(IsIntegral<T>)
     {
         set_height(bottom - y() + 1);
     }
+    ALWAYS_INLINE void set_bottom(T bottom)
+    requires(!IsIntegral<T>)
+    {
+        set_height(bottom - y());
+    }
 
     void set_right_without_resize(T new_right)
     {
@@ -505,10 +529,10 @@ public:
             return;
         }
 
-        m_location.set_x(l);
-        m_location.set_y(t);
-        m_size.set_width((r - l) + 1);
-        m_size.set_height((b - t) + 1);
+        set_x(l);
+        set_y(t);
+        set_right(r);
+        set_bottom(b);
     }
 
     [[nodiscard]] static Rect<T> centered_on(Point<T> const& center, Size<T> const& size)