From 6b629e199e92fac0ffc2dd54307bb588012b21c3 Mon Sep 17 00:00:00 2001
From: Nyall Dawson <nyall.dawson@gmail.com>
Date: Tue, 17 Oct 2017 17:13:54 +1000
Subject: [PATCH] Port snappedAngle from composer

---
 python/core/layout/qgslayoututils.sip |  7 ++++
 src/core/layout/qgslayoututils.cpp    | 40 +++++++++++++++++++++
 src/core/layout/qgslayoututils.h      |  6 ++++
 tests/src/core/testqgslayoututils.cpp | 50 +++++++++++++++++++++++++++
 4 files changed, 103 insertions(+)

diff --git a/python/core/layout/qgslayoututils.sip b/python/core/layout/qgslayoututils.sip
index 205c81caff47..37940211b9fe 100644
--- a/python/core/layout/qgslayoututils.sip
+++ b/python/core/layout/qgslayoututils.sip
@@ -29,6 +29,13 @@ class QgsLayoutUtils
  :rtype: float
 %End
 
+    static double snappedAngle( double angle );
+%Docstring
+ Snaps an ``angle`` (in degrees) to its closest 45 degree angle.
+ :return: angle snapped to 0, 45/90/135/180/225/270 or 315 degrees
+ :rtype: float
+%End
+
     static QgsRenderContext createRenderContextForMap( QgsLayoutItemMap *map, QPainter *painter, double dpi = -1 );
 %Docstring
  Creates a render context suitable for the specified layout ``map`` and ``painter`` destination.
diff --git a/src/core/layout/qgslayoututils.cpp b/src/core/layout/qgslayoututils.cpp
index 004f78a50e74..f854cdde0ef3 100644
--- a/src/core/layout/qgslayoututils.cpp
+++ b/src/core/layout/qgslayoututils.cpp
@@ -36,6 +36,46 @@ double QgsLayoutUtils::normalizedAngle( const double angle, const bool allowNega
   return clippedAngle;
 }
 
+double QgsLayoutUtils::snappedAngle( double angle )
+{
+  //normalize angle to 0-360 degrees
+  double clippedAngle = normalizedAngle( angle );
+
+  //snap angle to 45 degree
+  if ( clippedAngle >= 22.5 && clippedAngle < 67.5 )
+  {
+    return 45.0;
+  }
+  else if ( clippedAngle >= 67.5 && clippedAngle < 112.5 )
+  {
+    return 90.0;
+  }
+  else if ( clippedAngle >= 112.5 && clippedAngle < 157.5 )
+  {
+    return 135.0;
+  }
+  else if ( clippedAngle >= 157.5 && clippedAngle < 202.5 )
+  {
+    return 180.0;
+  }
+  else if ( clippedAngle >= 202.5 && clippedAngle < 247.5 )
+  {
+    return 225.0;
+  }
+  else if ( clippedAngle >= 247.5 && clippedAngle < 292.5 )
+  {
+    return 270.0;
+  }
+  else if ( clippedAngle >= 292.5 && clippedAngle < 337.5 )
+  {
+    return 315.0;
+  }
+  else
+  {
+    return 0.0;
+  }
+}
+
 QgsRenderContext QgsLayoutUtils::createRenderContextForMap( QgsLayoutItemMap *map, QPainter *painter, double dpi )
 {
   if ( !map )
diff --git a/src/core/layout/qgslayoututils.h b/src/core/layout/qgslayoututils.h
index 25c98a5e4d7f..38698f408a18 100644
--- a/src/core/layout/qgslayoututils.h
+++ b/src/core/layout/qgslayoututils.h
@@ -41,6 +41,12 @@ class CORE_EXPORT QgsLayoutUtils
      */
     static double normalizedAngle( const double angle, const bool allowNegative = false );
 
+    /**
+     * Snaps an \a angle (in degrees) to its closest 45 degree angle.
+     * \returns angle snapped to 0, 45/90/135/180/225/270 or 315 degrees
+     */
+    static double snappedAngle( double angle );
+
     /**
      * Creates a render context suitable for the specified layout \a map and \a painter destination.
      * This method returns a new QgsRenderContext which matches the scale and settings of the
diff --git a/tests/src/core/testqgslayoututils.cpp b/tests/src/core/testqgslayoututils.cpp
index ad3f483ac6cf..d420d12ac89d 100644
--- a/tests/src/core/testqgslayoututils.cpp
+++ b/tests/src/core/testqgslayoututils.cpp
@@ -31,6 +31,7 @@ class TestQgsLayoutUtils: public QObject
     void init();// will be called before each testfunction is executed.
     void cleanup();// will be called after every testfunction.
     void normalizedAngle(); //test normalised angle function
+    void snappedAngle();
     void createRenderContextFromLayout();
     void createRenderContextFromMap();
     void relativePosition();
@@ -117,6 +118,55 @@ void TestQgsLayoutUtils::normalizedAngle()
   }
 }
 
+void TestQgsLayoutUtils::snappedAngle()
+{
+  QList< QPair< double, double > > testVals;
+  testVals << qMakePair( 0.0, 0.0 );
+  testVals << qMakePair( 10.0, 0.0 );
+  testVals << qMakePair( 20.0, 0.0 );
+  testVals << qMakePair( 30.0, 45.0 );
+  testVals << qMakePair( 40.0, 45.0 );
+  testVals << qMakePair( 50.0, 45.0 );
+  testVals << qMakePair( 60.0, 45.0 );
+  testVals << qMakePair( 70.0, 90.0 );
+  testVals << qMakePair( 80.0, 90.0 );
+  testVals << qMakePair( 90.0, 90.0 );
+  testVals << qMakePair( 100.0, 90.0 );
+  testVals << qMakePair( 110.0, 90.0 );
+  testVals << qMakePair( 120.0, 135.0 );
+  testVals << qMakePair( 130.0, 135.0 );
+  testVals << qMakePair( 140.0, 135.0 );
+  testVals << qMakePair( 150.0, 135.0 );
+  testVals << qMakePair( 160.0, 180.0 );
+  testVals << qMakePair( 170.0, 180.0 );
+  testVals << qMakePair( 180.0, 180.0 );
+  testVals << qMakePair( 190.0, 180.0 );
+  testVals << qMakePair( 200.0, 180.0 );
+  testVals << qMakePair( 210.0, 225.0 );
+  testVals << qMakePair( 220.0, 225.0 );
+  testVals << qMakePair( 230.0, 225.0 );
+  testVals << qMakePair( 240.0, 225.0 );
+  testVals << qMakePair( 250.0, 270.0 );
+  testVals << qMakePair( 260.0, 270.0 );
+  testVals << qMakePair( 270.0, 270.0 );
+  testVals << qMakePair( 280.0, 270.0 );
+  testVals << qMakePair( 290.0, 270.0 );
+  testVals << qMakePair( 300.0, 315.0 );
+  testVals << qMakePair( 310.0, 315.0 );
+  testVals << qMakePair( 320.0, 315.0 );
+  testVals << qMakePair( 330.0, 315.0 );
+  testVals << qMakePair( 340.0, 0.0 );
+  testVals << qMakePair( 350.0, 0.0 );
+  testVals << qMakePair( 360.0, 0.0 );
+
+  //test snapped angle helper function
+  QList< QPair< double, double > >::const_iterator it = testVals.constBegin();
+  for ( ; it != testVals.constEnd(); ++it )
+  {
+    QGSCOMPARENEAR( QgsLayoutUtils::snappedAngle( ( *it ).first ), ( *it ).second, 4 * DBL_EPSILON );
+  }
+}
+
 
 void TestQgsLayoutUtils::createRenderContextFromLayout()
 {