Add method to create QgsRectangle from center and size

qgis · Nov 7, 2017 · 53c8779 · 53c8779
1 parent 7924aa1
commit 53c8779
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Showing 4 changed files with 49 additions and 2 deletions.
diff --git a/python/core/geometry/qgsrectangle.sip b/python/core/geometry/qgsrectangle.sip
@@ -46,12 +46,20 @@ Copy constructor
 
     static QgsRectangle fromWkt( const QString &wkt );
 %Docstring
- Creates a new rectangle from a WKT string.
+ Creates a new rectangle from a ``wkt`` string.
  The WKT must contain only 5 vertices, representing a rectangle aligned with X and Y axes.
 .. versionadded:: 3.0
  :rtype: QgsRectangle
 %End
 
+    static QgsRectangle fromCenterAndSize( QgsPointXY center, double width, double height );
+%Docstring
+ Creates a new rectangle, given the specified ``center`` point
+ and ``width`` and ``height``.
+.. versionadded:: 3.0
+ :rtype: QgsRectangle
+%End
+
     void set( const QgsPointXY &p1, const QgsPointXY &p2 );
 %Docstring
  Sets the rectangle from two QgsPoints. The rectangle is

diff --git a/src/core/geometry/qgsrectangle.cpp b/src/core/geometry/qgsrectangle.cpp
@@ -80,6 +80,15 @@ QgsRectangle QgsRectangle::fromWkt( const QString &wkt )
     return QgsRectangle();
 }
 
+QgsRectangle QgsRectangle::fromCenterAndSize( QgsPointXY center, double width, double height )
+{
+  double xMin = center.x() - width / 2.0;
+  double xMax = xMin + width;
+  double yMin = center.y() - height / 2.0;
+  double yMax = yMin + height;
+  return QgsRectangle( xMin, yMin, xMax, yMax );
+}
+
 void QgsRectangle::set( const QgsPointXY &p1, const QgsPointXY &p2 )
 {
   mXmin = p1.x();

diff --git a/src/core/geometry/qgsrectangle.h b/src/core/geometry/qgsrectangle.h
@@ -54,12 +54,19 @@ class CORE_EXPORT QgsRectangle
     ~QgsRectangle() = default;
 
     /**
-    * Creates a new rectangle from a WKT string.
+    * Creates a new rectangle from a \a wkt string.
     * The WKT must contain only 5 vertices, representing a rectangle aligned with X and Y axes.
     * \since QGIS 3.0
     */
     static QgsRectangle fromWkt( const QString &wkt );
 
+    /**
+     * Creates a new rectangle, given the specified \a center point
+     * and \a width and \a height.
+     * \since QGIS 3.0
+     */
+    static QgsRectangle fromCenterAndSize( QgsPointXY center, double width, double height );
+
     /**
      * Sets the rectangle from two QgsPoints. The rectangle is
      * normalised after construction.

diff --git a/tests/src/core/testqgsrectangle.cpp b/tests/src/core/testqgsrectangle.cpp
@@ -27,6 +27,7 @@ class TestQgsRectangle: public QObject
   private slots:
     void isEmpty();
     void fromWkt();
+    void fromCenter();
     void manipulate();
     void regression6194();
     void operators();
@@ -76,6 +77,28 @@ void TestQgsRectangle::fromWkt()
   QVERIFY( QgsRectangle::fromWkt( QStringLiteral( "POLYGON((0 0,1 0,1 1,0 1))" ) ).isEmpty() );
 }
 
+void TestQgsRectangle::fromCenter()
+{
+  QgsRectangle rect = QgsRectangle::fromCenterAndSize( QgsPointXY( 12, 21 ), 20, 40 );
+  QVERIFY( ! rect.isEmpty() );
+  QCOMPARE( rect.xMinimum(), 2.0 );
+  QCOMPARE( rect.yMinimum(), 1.0 );
+  QCOMPARE( rect.xMaximum(), 22.0 );
+  QCOMPARE( rect.yMaximum(), 41.0 );
+
+  rect = QgsRectangle::fromCenterAndSize( QgsPointXY( 12, 21 ), 0, 40 );
+  QCOMPARE( rect.xMinimum(), 12.0 );
+  QCOMPARE( rect.yMinimum(), 1.0 );
+  QCOMPARE( rect.xMaximum(), 12.0 );
+  QCOMPARE( rect.yMaximum(), 41.0 );
+
+  rect = QgsRectangle::fromCenterAndSize( QgsPointXY( 12, 21 ), 20, 0 );
+  QCOMPARE( rect.xMinimum(), 2.0 );
+  QCOMPARE( rect.yMinimum(), 21.0 );
+  QCOMPARE( rect.xMaximum(), 22.0 );
+  QCOMPARE( rect.yMaximum(), 21.0 );
+}
+
 void TestQgsRectangle::manipulate()
 {
   // Set up two intersecting rectangles and normalize