From f4c2211f2c196b6662fdc023578e1498805f3377 Mon Sep 17 00:00:00 2001
From: Uwe Rathmann <Uwe.Rathmann@tigertal.de>
Date: Fri, 22 Nov 2024 17:37:47 +0100
Subject: [PATCH] API extended

---
 src/common/QskIntervalF.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/common/QskIntervalF.h b/src/common/QskIntervalF.h
index fdbf4289..c0c967c4 100644
--- a/src/common/QskIntervalF.h
+++ b/src/common/QskIntervalF.h
@@ -36,6 +36,8 @@ class QSK_EXPORT QskIntervalF
     constexpr qreal upperBound() const noexcept;
     void setUpperBound( qreal ) noexcept;
 
+    constexpr qreal center() const noexcept;
+
     void spanFromLowerBound( qreal ) noexcept;
     void spanFromUpperBound( qreal ) noexcept;
 
@@ -66,6 +68,9 @@ class QSK_EXPORT QskIntervalF
     void extend( qreal value ) noexcept;
     QskIntervalF extended( qreal value ) const noexcept;
 
+    void stretch( qreal length ) noexcept;
+    constexpr QskIntervalF stretched( qreal length ) const noexcept;
+
     QskIntervalF operator|( const QskIntervalF& ) const noexcept;
     QskIntervalF operator&( const QskIntervalF& ) const noexcept;
 
@@ -135,6 +140,11 @@ inline constexpr qreal QskIntervalF::upperBound() const noexcept
     return m_upperBound;
 }
 
+inline constexpr qreal QskIntervalF::center() const noexcept
+{
+    return m_lowerBound + 0.5 * ( m_upperBound - m_lowerBound );
+}
+
 inline constexpr qreal QskIntervalF::length() const noexcept
 {
     return ( m_upperBound > m_lowerBound ) ? ( m_upperBound - m_lowerBound ) : 0.0;
@@ -198,6 +208,18 @@ inline constexpr QskIntervalF QskIntervalF::normalized( qreal value1, qreal valu
     return ( value1 < value2 ) ? QskIntervalF( value1, value2 ) : QskIntervalF( value2, value1 );
 }
 
+inline void QskIntervalF::stretch( qreal length ) noexcept
+{
+    m_lowerBound = center() - 0.5 * length;
+    m_upperBound = m_lowerBound + length;
+}
+
+inline constexpr QskIntervalF QskIntervalF::stretched( qreal length ) const noexcept
+{
+    const auto lowerBound = center() - 0.5 * length;
+    return QskIntervalF( lowerBound, lowerBound + length );
+}
+
 inline QskIntervalF QskIntervalF::operator&( const QskIntervalF& other ) const noexcept
 {
     return intersected( other );