[FEATURE] Locked aspect ratio state for Save as image/PDF" (#4880)

Sponsored by Andreas Neumann.

images/images.qrc

@@ -467,6 +467,7 @@
         <file>themes/default/transformed.svg</file>
         <file>themes/default/transp-background_8x8.png</file>
         <file>themes/default/unlocked.svg</file>
+        <file>themes/default/unlockedGray.svg</file>
         <file>themes/default/user.svg</file>
         <file>flags/eu.png</file>
         <file>flags/bn.png</file>

python/gui/gui_auto.sip

@@ -124,6 +124,7 @@
 %Include qgslistwidget.sip
 %Include qgslegendfilterbutton.sip
 %Include qgslimitedrandomcolorrampdialog.sip
+%Include qgsratiolockbutton.sip
 %Include qgslonglongvalidator.sip
 %Include qgsludialog.sip
 %Include qgsmanageconnectionsdialog.sip

python/gui/qgsextentgroupbox.sip

@@ -163,6 +163,24 @@ class QgsExtentGroupBox : QgsCollapsibleGroupBox
 .. versionadded:: 3.0
 %End
 
+    void setRatio( QSize ratio );
+%Docstring
+ Sets a fixed aspect ratio to be used when dragging extent onto the canvas.
+ To unset a fixed aspect ratio, set the width and height to zero.
+ \param ratio aspect ratio's width and height
+.. versionadded:: 3.0
+ *
+%End
+
+    QSize ratio() const;
+%Docstring
+ Returns the current fixed aspect ratio to be used when dragging extent onto the canvas.
+ If the aspect ratio isn't fixed, the width and height will be set to zero.
+.. versionadded:: 3.0
+ *
+ :rtype: QSize
+%End
+
   signals:
 
     void extentChanged( const QgsRectangle &r );

python/gui/qgsratiolockbutton.sip

@@ -0,0 +1,69 @@
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/gui/qgsratiolockbutton.h                                         *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
+
+
+
+
+class QgsRatioLockButton : QToolButton
+{
+%Docstring
+ A cross platform button subclass used to represent a locked / unlocked ratio state.
+.. versionadded:: 3.0
+%End
+
+%TypeHeaderCode
+#include "qgsratiolockbutton.h"
+%End
+  public:
+
+    QgsRatioLockButton( QWidget *parent /TransferThis/ = 0 );
+%Docstring
+ Construct a new ratio lock button.
+ Use ``parent`` to attach a parent QWidget to the button.
+%End
+
+    void setLocked( const bool locked );
+%Docstring
+ Sets whether the button state is locked.
+ \param locked locked state
+.. seealso:: locked
+%End
+
+    bool locked() const;
+%Docstring
+ Returns whether the button state is locked.
+ :return: true if the button state is locked.
+.. seealso:: setLocked
+ :rtype: bool
+%End
+
+  signals:
+
+    void lockChanged( const bool locked );
+%Docstring
+ Emitted whenever the lock state changes.
+%End
+
+  protected:
+
+    virtual void changeEvent( QEvent *e );
+
+    virtual void showEvent( QShowEvent *e );
+
+    virtual void resizeEvent( QResizeEvent *event );
+
+
+};
+
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/gui/qgsratiolockbutton.h                                         *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/

src/app/qgsmapsavedialog.cpp

@@ -81,6 +81,7 @@ QgsMapSaveDialog::QgsMapSaveDialog( QWidget *parent, QgsMapCanvas *mapCanvas, QL
   connect( mOutputHeightSpinBox, static_cast < void ( QSpinBox::* )( int ) > ( &QSpinBox::valueChanged ), this, &QgsMapSaveDialog::updateOutputHeight );
   connect( mExtentGroupBox, &QgsExtentGroupBox::extentChanged, this, &QgsMapSaveDialog::updateExtent );
   connect( mScaleWidget, &QgsScaleWidget::scaleChanged, this, &QgsMapSaveDialog::updateScale );
+  connect( mLockAspectRatio, &QgsRatioLockButton::lockChanged, this, &QgsMapSaveDialog::lockChanged );
 
   updateOutputSize();
 
@@ -126,25 +127,51 @@ void QgsMapSaveDialog::updateOutputWidth( int width )
   double scale = ( double )width / mSize.width();
   double adjustment = ( ( mExtent.width() * scale ) - mExtent.width() ) / 2;
 
+  mSize.setWidth( width );
+
   mExtent.setXMinimum( mExtent.xMinimum() - adjustment );
   mExtent.setXMaximum( mExtent.xMaximum() + adjustment );
 
-  whileBlocking( mExtentGroupBox )->setOutputExtentFromUser( mExtent, mExtentGroupBox->currentCrs() );
+  if ( mLockAspectRatio->locked() )
+  {
+    int height = width * mExtentGroupBox->ratio().height() / mExtentGroupBox->ratio().width();
+    double scale = ( double )height / mSize.height();
+    double adjustment = ( ( mExtent.height() * scale ) - mExtent.height() ) / 2;
 
-  mSize.setWidth( width );
+    whileBlocking( mOutputHeightSpinBox )->setValue( height );
+    mSize.setHeight( height );
+
+    mExtent.setYMinimum( mExtent.yMinimum() - adjustment );
+    mExtent.setYMaximum( mExtent.yMaximum() + adjustment );
+  }
+
+  whileBlocking( mExtentGroupBox )->setOutputExtentFromUser( mExtent, mExtentGroupBox->currentCrs() );
 }
 
 void QgsMapSaveDialog::updateOutputHeight( int height )
 {
   double scale = ( double )height / mSize.height();
   double adjustment = ( ( mExtent.height() * scale ) - mExtent.height() ) / 2;
 
+  mSize.setHeight( height );
+
   mExtent.setYMinimum( mExtent.yMinimum() - adjustment );
   mExtent.setYMaximum( mExtent.yMaximum() + adjustment );
 
-  whileBlocking( mExtentGroupBox )->setOutputExtentFromUser( mExtent, mExtentGroupBox->currentCrs() );
+  if ( mLockAspectRatio->locked() )
+  {
+    int width = height * mExtentGroupBox->ratio().width() / mExtentGroupBox->ratio().height();
+    double scale = ( double )width / mSize.width();
+    double adjustment = ( ( mExtent.width() * scale ) - mExtent.width() ) / 2;
 
-  mSize.setHeight( height );
+    whileBlocking( mOutputWidthSpinBox )->setValue( height );
+    mSize.setWidth( width );
+
+    mExtent.setXMinimum( mExtent.xMinimum() - adjustment );
+    mExtent.setXMaximum( mExtent.xMaximum() + adjustment );
+  }
+
+  whileBlocking( mExtentGroupBox )->setOutputExtentFromUser( mExtent, mExtentGroupBox->currentCrs() );
 }
 
 void QgsMapSaveDialog::updateExtent( const QgsRectangle &extent )
@@ -153,6 +180,11 @@ void QgsMapSaveDialog::updateExtent( const QgsRectangle &extent )
   mSize.setHeight( mSize.height() * extent.height() / mExtent.height() );
   mExtent = extent;
 
+  if ( mLockAspectRatio->locked() )
+  {
+    mExtentGroupBox->setRatio( QSize( mSize.width(), mSize.height() ) );
+  }
+
   updateOutputSize();
 }
 
@@ -242,6 +274,18 @@ void QgsMapSaveDialog::applyMapSettings( QgsMapSettings &mapSettings )
   mapSettings.setExpressionContext( expressionContext );
 }
 
+void QgsMapSaveDialog::lockChanged( const bool locked )
+{
+  if ( locked )
+  {
+    mExtentGroupBox->setRatio( QSize( mOutputWidthSpinBox->value(), mOutputHeightSpinBox->value() ) );
+  }
+  else
+  {
+    mExtentGroupBox->setRatio( QSize( 0, 0 ) );
+  }
+}
+
 void QgsMapSaveDialog::accepted()
 {
   if ( mDialogType == Image )

src/app/qgsmapsavedialog.h

@@ -77,6 +77,7 @@ class APP_EXPORT QgsMapSaveDialog: public QDialog, private Ui::QgsMapSaveDialog
 
   private:
 
+    void lockChanged( const bool locked );
     void accepted();
 
     void updateDpi( int dpi );

src/gui/CMakeLists.txt

@@ -263,6 +263,7 @@ SET(QGIS_GUI_SRCS
   qgslistwidget.cpp
   qgslegendfilterbutton.cpp
   qgslimitedrandomcolorrampdialog.cpp
+  qgsratiolockbutton.cpp
   qgsludialog.cpp
   qgsmanageconnectionsdialog.cpp
   qgsmapcanvas.cpp
@@ -421,6 +422,7 @@ SET(QGIS_GUI_MOC_HDRS
   qgslistwidget.h
   qgslegendfilterbutton.h
   qgslimitedrandomcolorrampdialog.h
+  qgsratiolockbutton.h
   qgslonglongvalidator.h
   qgsludialog.h
   qgsmanageconnectionsdialog.h

src/gui/qgsextentgroupbox.cpp

@@ -277,6 +277,7 @@ void QgsExtentGroupBox::setOutputExtentFromDrawOnCanvas()
         mMapToolPrevious = nullptr;
       } );
     }
+    mMapToolExtent->setRatio( mRatio );
     mCanvas->setMapTool( mMapToolExtent.get() );
     window()->setVisible( false );
   }

src/gui/qgsextentgroupbox.h

@@ -177,6 +177,19 @@ class GUI_EXPORT QgsExtentGroupBox : public QgsCollapsibleGroupBox, private Ui::
      */
     void setOutputExtentFromDrawOnCanvas();
 
+    /** Sets a fixed aspect ratio to be used when dragging extent onto the canvas.
+     * To unset a fixed aspect ratio, set the width and height to zero.
+     * \param ratio aspect ratio's width and height
+     * \since QGIS 3.0
+     * */
+    void setRatio( QSize ratio ) { mRatio = ratio; }
+
+    /** Returns the current fixed aspect ratio to be used when dragging extent onto the canvas.
+     * If the aspect ratio isn't fixed, the width and height will be set to zero.
+     * \since QGIS 3.0
+     * */
+    QSize ratio() const { return mRatio; }
+
   signals:
 
     /**
@@ -223,6 +236,7 @@ class GUI_EXPORT QgsExtentGroupBox : public QgsCollapsibleGroupBox, private Ui::
     std::unique_ptr< QgsMapToolExtent > mMapToolExtent;
     QPointer< QgsMapTool > mMapToolPrevious = nullptr;
     QgsMapCanvas *mCanvas = nullptr;
+    QSize mRatio;
 
     void setExtentToLayerExtent( const QString &layerId );
 

src/gui/qgsratiolockbutton.cpp

@@ -0,0 +1,110 @@
+/***************************************************************************
+    qgsratiolockbutton.cpp - Lock button
+     --------------------------------------
+    Date                 : July, 2017
+    Copyright            : (C) 2017 by Mathieu Pellerin
+    Email                : nirvn dot asia at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgsratiolockbutton.h"
+
+#include <QApplication>
+#include <QMouseEvent>
+#include <QPainter>
+#include <QPushButton>
+#include <QWidget>
+
+QgsRatioLockButton::QgsRatioLockButton( QWidget *parent )
+  : QToolButton( parent )
+  , mLocked( false )
+
+{
+  setMinimumSize( QSize( 24, 24 ) );
+  setCheckable( true );
+  setAutoRaise( true );
+  connect( this, &QPushButton::clicked, this, &QgsRatioLockButton::buttonClicked );
+}
+
+void QgsRatioLockButton::setLocked( const bool locked )
+{
+  if ( mLocked != locked )
+    buttonClicked();
+}
+
+void QgsRatioLockButton::buttonClicked()
+{
+  mLocked = !mLocked;
+  setDown( mLocked );
+
+  emit lockChanged( mLocked );
+
+  drawButton();
+}
+
+void QgsRatioLockButton::changeEvent( QEvent *e )
+{
+  if ( e->type() == QEvent::EnabledChange )
+  {
+    drawButton();
+  }
+  QToolButton::changeEvent( e );
+}
+
+void QgsRatioLockButton::showEvent( QShowEvent *e )
+{
+  drawButton();
+  QToolButton::showEvent( e );
+}
+
+void QgsRatioLockButton::resizeEvent( QResizeEvent *event )
+{
+  QToolButton::resizeEvent( event );
+  drawButton();
+}
+
+void QgsRatioLockButton::drawButton()
+{
+  QSize currentIconSize;
+
+#ifdef Q_OS_WIN
+  currentIconSize = QSize( width() - 10, height() - 6 );
+#else
+  currentIconSize = QSize( width() - 10, height() - 12 );
+#endif
+
+  if ( !currentIconSize.isValid() || currentIconSize.width() <= 0 || currentIconSize.height() <= 0 )
+  {
+    return;
+  }
+
+  QPixmap pm;
+  pm = QPixmap( currentIconSize );
+  pm.fill( Qt::transparent );
+
+  QPainter painter;
+  QPen pen  = ( QColor( 136, 136, 136 ) );
+  pen.setWidth( 2 );
+
+  painter.begin( &pm );
+  painter.setPen( pen );
+
+  painter.drawLine( 1, 1, currentIconSize.width() / 2, 1 );
+  painter.drawLine( currentIconSize.width() / 2, 1, currentIconSize.width() / 2, currentIconSize.height() / 2 - 13 );
+  painter.drawLine( currentIconSize.width() / 2, currentIconSize.height() / 2 + 13, currentIconSize.width() / 2, currentIconSize.height() - 2 );
+  painter.drawLine( currentIconSize.width() / 2, currentIconSize.height() - 2, 1, currentIconSize.height() - 2 );
+
+  QImage image( mLocked ? QStringLiteral( ":/images/themes/default/lockedGray.svg" ) : QStringLiteral( ":/images/themes/default/unlockedGray.svg" ) );
+  painter.drawImage( QRectF( currentIconSize.width() / 2 - 8, currentIconSize.height() / 2 - 8, 16, 16 ), image, QRectF( 0, 0, 16, 16 ) );
+
+  painter.end();
+
+  setIconSize( currentIconSize );
+  setIcon( pm );
+}