Allow setting width/height spin boxes to link to QgsRatioLockButton

When set, these spin boxes will automatically be updated when their
accompanying spin box changes value so that the ratio is maintained.

python/gui/qgsratiolockbutton.sip

@@ -9,6 +9,7 @@
 
 
 
+
 class QgsRatioLockButton : QToolButton
 {
 %Docstring
@@ -42,6 +43,30 @@ class QgsRatioLockButton : QToolButton
  :rtype: bool
 %End
 
+    void setWidthSpinBox( QDoubleSpinBox *widget );
+%Docstring
+ Registers a spin box ``widget`` as the linked "width" spin box.
+
+ If both a width and height spin box are linked to the button, they will automatically
+ have their values updates when if the other spin box value is changed. I.e. changing the
+ width spin box will automatically update the height spin box to a value which keeps the
+ same locked ratio.
+
+.. seealso:: setHeightSpinBox()
+%End
+
+    void setHeightSpinBox( QDoubleSpinBox *widget );
+%Docstring
+ Registers a spin box ``widget`` as the linked "height" spin box.
+
+ If both a width and height spin box are linked to the button, they will automatically
+ have their values updates when if the other spin box value is changed. I.e. changing the
+ width spin box will automatically update the height spin box to a value which keeps the
+ same locked ratio.
+
+.. seealso:: setWidthSpinBox()
+%End
+
   signals:
 
     void lockChanged( const bool locked );

src/gui/qgsratiolockbutton.cpp

@@ -20,6 +20,7 @@
 #include <QPainter>
 #include <QPushButton>
 #include <QWidget>
+#include <QDoubleSpinBox>
 
 QgsRatioLockButton::QgsRatioLockButton( QWidget *parent )
   : QToolButton( parent )
@@ -48,6 +49,38 @@ void QgsRatioLockButton::buttonClicked()
   drawButton();
 }
 
+void QgsRatioLockButton::widthSpinBoxChanged( double value )
+{
+  if ( mUpdatingRatio || qgsDoubleNear( value, 0.0 ) || qgsDoubleNear( mPrevWidth, 0.0 )
+       || qgsDoubleNear( mPrevHeight, 0.0 ) || !mHeightSpinBox || !mLocked )
+  {
+    mPrevWidth = value;
+    return;
+  }
+
+  double oldRatio = mPrevHeight / mPrevWidth;
+  mUpdatingRatio = true;
+  mHeightSpinBox->setValue( oldRatio * value );
+  mUpdatingRatio = false;
+  mPrevWidth = value;
+}
+
+void QgsRatioLockButton::heightSpinBoxChanged( double value )
+{
+  if ( mUpdatingRatio || qgsDoubleNear( value, 0.0 ) || qgsDoubleNear( mPrevWidth, 0.0 )
+       || qgsDoubleNear( mPrevHeight, 0.0 ) || !mWidthSpinBox || !mLocked )
+  {
+    mPrevHeight = value;
+    return;
+  }
+
+  double oldRatio = mPrevWidth / mPrevHeight;
+  mUpdatingRatio = true;
+  mWidthSpinBox->setValue( oldRatio * value );
+  mUpdatingRatio = false;
+  mPrevHeight = value;
+}
+
 void QgsRatioLockButton::changeEvent( QEvent *e )
 {
   if ( e->type() == QEvent::EnabledChange )
@@ -108,3 +141,17 @@ void QgsRatioLockButton::drawButton()
   setIconSize( currentIconSize );
   setIcon( pm );
 }
+
+void QgsRatioLockButton::setWidthSpinBox( QDoubleSpinBox *widget )
+{
+  mWidthSpinBox = widget;
+  mPrevWidth = widget->value();
+  connect( mWidthSpinBox, static_cast<void ( QDoubleSpinBox::* )( double )>( &QDoubleSpinBox::valueChanged ), this, &QgsRatioLockButton::widthSpinBoxChanged );
+}
+
+void QgsRatioLockButton::setHeightSpinBox( QDoubleSpinBox *widget )
+{
+  mHeightSpinBox = widget;
+  mPrevHeight = widget->value();
+  connect( mHeightSpinBox, static_cast<void ( QDoubleSpinBox::* )( double )>( &QDoubleSpinBox::valueChanged ), this, &QgsRatioLockButton::heightSpinBoxChanged );
+}

src/gui/qgsratiolockbutton.h

@@ -22,6 +22,9 @@
 #include "qgis_gui.h"
 #include "qgis.h"
 
+#include <QPointer>
+class QDoubleSpinBox;
+
 /** \ingroup gui
  * \class QgsRatioLockButton
  * A cross platform button subclass used to represent a locked / unlocked ratio state.
@@ -51,6 +54,30 @@ class GUI_EXPORT QgsRatioLockButton : public QToolButton
      */
     bool locked() const { return mLocked; }
 
+    /**
+     * Registers a spin box \a widget as the linked "width" spin box.
+     *
+     * If both a width and height spin box are linked to the button, they will automatically
+     * have their values updates when if the other spin box value is changed. I.e. changing the
+     * width spin box will automatically update the height spin box to a value which keeps the
+     * same locked ratio.
+     *
+     * \see setHeightSpinBox()
+     */
+    void setWidthSpinBox( QDoubleSpinBox *widget );
+
+    /**
+     * Registers a spin box \a widget as the linked "height" spin box.
+     *
+     * If both a width and height spin box are linked to the button, they will automatically
+     * have their values updates when if the other spin box value is changed. I.e. changing the
+     * width spin box will automatically update the height spin box to a value which keeps the
+     * same locked ratio.
+     *
+     * \see setWidthSpinBox()
+     */
+    void setHeightSpinBox( QDoubleSpinBox *widget );
+
   signals:
 
     /** Emitted whenever the lock state changes.
@@ -69,10 +96,19 @@ class GUI_EXPORT QgsRatioLockButton : public QToolButton
 
     bool mLocked = false;
 
+    QPointer< QDoubleSpinBox > mWidthSpinBox;
+    double mPrevWidth = 0;
+    QPointer< QDoubleSpinBox > mHeightSpinBox;
+    double mPrevHeight = 0;
+    bool mUpdatingRatio = false;
+
   private slots:
 
     void buttonClicked();
 
+    void widthSpinBoxChanged( double value );
+    void heightSpinBoxChanged( double value );
+
 };
 
 #endif

tests/src/python/CMakeLists.txt

@@ -115,6 +115,7 @@ ADD_PYTHON_TEST(PyQgsRasterFileWriter test_qgsrasterfilewriter.py)
 ADD_PYTHON_TEST(PyQgsRasterFileWriterTask test_qgsrasterfilewritertask.py)
 ADD_PYTHON_TEST(PyQgsRasterLayer test_qgsrasterlayer.py)
 ADD_PYTHON_TEST(PyQgsRasterColorRampShader test_qgsrastercolorrampshader.py)
+ADD_PYTHON_TEST(PyQgsRatioLockButton test_qgsratiolockbutton.py)
 ADD_PYTHON_TEST(PyQgsRectangle test_qgsrectangle.py)
 ADD_PYTHON_TEST(PyQgsRelation test_qgsrelation.py)
 ADD_PYTHON_TEST(PyQgsRelationManager test_qgsrelationmanager.py)

tests/src/python/test_qgsratiolockbutton.py

@@ -0,0 +1,104 @@
+# -*- coding: utf-8 -*-
+"""QGIS Unit tests for QgsRatioLockButton
+
+.. note:: This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+"""
+__author__ = 'Nyall Dawson'
+__date__ = '18/07/2017'
+__copyright__ = 'Copyright 2017, The QGIS Project'
+# This will get replaced with a git SHA1 when you do a git archive
+__revision__ = '$Format:%H$'
+
+import qgis  # NOQA
+
+from qgis.gui import QgsRatioLockButton
+
+from qgis.PyQt.QtWidgets import QDoubleSpinBox
+
+from qgis.testing import start_app, unittest
+
+start_app()
+
+
+class TestQgsRatioLockButton(unittest.TestCase):
+
+    def testLinkedWidgets(self):
+        """ test linking spin boxes to combobox"""
+        w = qgis.gui.QgsRatioLockButton()
+
+        spin_width = QDoubleSpinBox()
+        spin_width.setMaximum(100000)
+        spin_height = QDoubleSpinBox()
+        spin_height.setMaximum(100000)
+
+        w.setWidthSpinBox(spin_width)
+        spin_width.setValue(1000)
+        self.assertEqual(spin_width.value(), 1000)
+
+        w.setLocked(True)
+        spin_width.setValue(2000)
+        self.assertEqual(spin_width.value(), 2000)
+        w.setLocked(False)
+
+        w.setHeightSpinBox(spin_height)
+        spin_width.setValue(1000)
+        self.assertEqual(spin_width.value(), 1000)
+        self.assertEqual(spin_height.value(), 0)
+
+        w.setLocked(True)
+        spin_width.setValue(2000)
+        self.assertEqual(spin_width.value(), 2000)
+        self.assertEqual(spin_height.value(), 0)
+
+        spin_height.setValue(1000)
+        self.assertEqual(spin_width.value(), 2000)
+        self.assertEqual(spin_height.value(), 1000)
+
+        # ok, that was all setup tests... let's check the real thing now
+        spin_width.setValue(1000)
+        self.assertEqual(spin_width.value(), 1000)
+        self.assertEqual(spin_height.value(), 500)
+        spin_height.setValue(1000)
+        self.assertEqual(spin_width.value(), 2000)
+        self.assertEqual(spin_height.value(), 1000)
+
+        w.setLocked(False)
+        spin_width.setValue(1000)
+        self.assertEqual(spin_width.value(), 1000)
+        self.assertEqual(spin_height.value(), 1000)
+        spin_height.setValue(2000)
+        self.assertEqual(spin_width.value(), 1000)
+        self.assertEqual(spin_height.value(), 2000)
+
+        w.setLocked(True)
+        spin_height.setValue(1000)
+        self.assertEqual(spin_width.value(), 500)
+        self.assertEqual(spin_height.value(), 1000)
+
+        # setting to 0 should "break" lock
+        spin_height.setValue(0)
+        self.assertEqual(spin_width.value(), 500)
+        self.assertEqual(spin_height.value(), 0)
+        spin_width.setValue(1000)
+        self.assertEqual(spin_width.value(), 1000)
+        self.assertEqual(spin_height.value(), 0)
+        spin_height.setValue(100)
+        self.assertEqual(spin_width.value(), 1000)
+        self.assertEqual(spin_height.value(), 100)
+
+        spin_width.setValue(0)
+        self.assertEqual(spin_width.value(), 0)
+        self.assertEqual(spin_height.value(), 100)
+        spin_height.setValue(1000)
+        self.assertEqual(spin_width.value(), 0)
+        self.assertEqual(spin_height.value(), 1000)
+        spin_width.setValue(200)
+        self.assertEqual(spin_width.value(), 200)
+        self.assertEqual(spin_height.value(), 1000)
+
+
+if __name__ == '__main__':
+    unittest.main()