From ad091862295fc532d69ea8216b2149b81653a80f Mon Sep 17 00:00:00 2001
From: Uwe Rathmann <Uwe.Rathmann@tigertal.de>
Date: Mon, 23 Jan 2023 10:59:34 +0100
Subject: [PATCH] QskGradientDirection::contais added

---
 src/common/QskGradientDirection.cpp | 61 +++++++++++++++++++++++++++++
 src/common/QskGradientDirection.h   |  2 +
 src/nodes/QskBoxNode.cpp            |  6 ++-
 3 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/src/common/QskGradientDirection.cpp b/src/common/QskGradientDirection.cpp
index cab879c4..82434d5c 100644
--- a/src/common/QskGradientDirection.cpp
+++ b/src/common/QskGradientDirection.cpp
@@ -4,6 +4,7 @@
  *****************************************************************************/
 
 #include "QskGradientDirection.h"
+#include <qrect.h>
 
 static void qskRegisterGradientDirection()
 {
@@ -115,6 +116,66 @@ void QskLinearDirection::setInterval( Qt::Orientation orientation, qreal from, q
     }
 }
 
+static inline bool qskIntersectsTop(
+    qreal vx, qreal vy, qreal m, const QRectF& rect )
+{
+    const auto cx = vx - ( vy - rect.top() ) / m;
+    return cx > rect.left() && cx < rect.right();
+}
+
+static inline bool qskIntersectsBottom(
+    qreal vx, qreal vy, qreal m, const QRectF& rect )
+{
+    const auto cx = vx - ( vy - rect.bottom() ) / m;
+    return cx > rect.left() && cx < rect.right();
+}
+
+static inline bool qskIntersectsLeft(
+    qreal vx, qreal vy, qreal m, const QRectF& rect )
+{
+    const qreal cy = vy - ( vx - rect.left() ) * m;
+    return ( cy > rect.top() && cy < rect.bottom() );
+}
+
+static inline bool qskIntersectsRight(
+    qreal vx, qreal vy, qreal m, const QRectF& rect )
+{
+    const qreal cy = vy - ( vx - rect.right() ) * m;
+    return ( cy > rect.top() && cy < rect.bottom() );
+}
+
+bool QskLinearDirection::contains( const QRectF& rect ) const
+{
+    if ( m_y1 == m_y2 )
+    {
+        return ( m_x1 <= rect.left() && m_x2 >= rect.right() )
+            || ( m_x1 >= rect.right() && m_x2 <= rect.left() );
+    }
+
+
+    if ( m_x1 == m_x2 )
+    {
+        return ( m_y1 <= rect.top() && m_y2 >= rect.bottom() )
+            || ( m_y1 >= rect.bottom() && m_y2 <= rect.top() );
+    }
+
+    // are the normal vectors intersecting ?
+
+    const auto m = ( m_x2 - m_x1 ) / ( m_y1 - m_y2 ); // slope of the normal vectors
+
+    const bool intersecting =
+        qskIntersectsLeft( m_x1, m_y1, m, rect ) ||
+        qskIntersectsRight( m_x1, m_y1, m, rect ) ||
+        qskIntersectsTop( m_x1, m_y1, m, rect ) ||
+        qskIntersectsBottom( m_x1, m_y1, m, rect ) ||
+        qskIntersectsLeft( m_x2, m_y2, m, rect ) ||
+        qskIntersectsRight( m_x2, m_y2, m, rect ) ||
+        qskIntersectsTop( m_x2, m_y2, m, rect ) ||
+        qskIntersectsBottom( m_x2, m_y2, m, rect );
+
+    return !intersecting;
+}
+
 // -- QskConicDirection
 
 void QskConicDirection::setCenter( const QPointF& center ) noexcept
diff --git a/src/common/QskGradientDirection.h b/src/common/QskGradientDirection.h
index ff89b4bd..78e9408b 100644
--- a/src/common/QskGradientDirection.h
+++ b/src/common/QskGradientDirection.h
@@ -68,6 +68,8 @@ class QSK_EXPORT QskLinearDirection
     constexpr qreal y2() const noexcept;
     void setY2( qreal ) noexcept;
 
+    bool contains( const QRectF& ) const;
+
   private:
     qreal m_x1 = 0.0;
     qreal m_y1 = 0.0;
diff --git a/src/nodes/QskBoxNode.cpp b/src/nodes/QskBoxNode.cpp
index 66cc4fa4..d2caccc1 100644
--- a/src/nodes/QskBoxNode.cpp
+++ b/src/nodes/QskBoxNode.cpp
@@ -78,8 +78,10 @@ void QskBoxNode::updateNode( const QRectF& rect,
     }
 
     /*
-        QskBoxRectangleNode supports vertical/horizontal/diagonal gradients only.
-        If our gradient doesn't fall into this category we use a QskBoxFillNode.
+        QskBoxRectangleNode supports vertical/horizontal and many tilted 
+        linear gradients.  If our gradient doesn't fall into this category
+        we use a QskBoxFillNode.
+
         However the border is always done with a QskBoxRectangleNode
      */