Scale image if the photo widget size is set to 0/0

src/gui/CMakeLists.txt

@@ -212,6 +212,7 @@ SET(QGIS_GUI_SRCS
   qgsnumericsortlistviewitem.cpp
   qgsoptionsdialogbase.cpp
   qgsowssourceselect.cpp
+  qgspixmaplabel.cpp
   qgspluginmanagerinterface.cpp
   qgsprojectbadlayerguihandler.cpp
   qgsprojectionselectionwidget.cpp
@@ -333,6 +334,7 @@ SET(QGIS_GUI_MOC_HDRS
   qgsnewvectorlayerdialog.h
   qgsoptionsdialogbase.h
   qgsowssourceselect.h
+  qgspixmaplabel.h
   qgspluginmanagerinterface.h
   qgsprevieweffect.h
   qgsprojectbadlayerguihandler.h

src/gui/editorwidgets/qgsphotowidgetwrapper.cpp

@@ -14,6 +14,7 @@
  ***************************************************************************/
 
 #include "qgsphotowidgetwrapper.h"
+#include "qgspixmaplabel.h"
 #include "qgsproject.h"
 
 #include <QGridLayout>
@@ -25,6 +26,7 @@
 QgsPhotoWidgetWrapper::QgsPhotoWidgetWrapper( QgsVectorLayer* vl, int fieldIdx, QWidget* editor, QWidget* parent )
     :  QgsEditorWidgetWrapper( vl, fieldIdx, editor, parent )
     , mPhotoLabel( 0 )
+    , mPhotoPixmapLabel( 0 )
     , mLineEdit( 0 )
     , mButton( 0 )
 {
@@ -79,10 +81,22 @@ void QgsPhotoWidgetWrapper::loadPixmap( const QString& fileName )
       size.setHeight( size.width() * pm.size().height() / pm.size().width() );
     }
 
-    pm = pm.scaled( size, Qt::KeepAspectRatio, Qt::SmoothTransformation );
+    if ( mPhotoPixmapLabel )
+    {
+      mPhotoPixmapLabel->setPixmap( pm );
 
-    mPhotoLabel->setPixmap( pm );
-    mPhotoLabel->setMinimumSize( size );
+      if ( size.width() != 0 || size.height() != 0 )
+      {
+        mPhotoPixmapLabel->setMinimumSize( size );
+        mPhotoPixmapLabel->setMaximumSize( size );
+      }
+    }
+    else // mPhotoLabel is checked in the outer if branch
+    {
+      mPhotoLabel->setMinimumSize( size );
+      pm = pm.scaled( size, Qt::KeepAspectRatio, Qt::SmoothTransformation );
+      mPhotoLabel->setPixmap( pm );
+    }
   }
 }
 
@@ -106,7 +120,7 @@ QWidget* QgsPhotoWidgetWrapper::createWidget( QWidget* parent )
   QWidget* container = new QWidget( parent );
   QGridLayout* layout = new QGridLayout( container );
   QgsFilterLineEdit* le = new QgsFilterLineEdit( container );
-  QLabel* label = new QLabel( parent );
+  QgsPixmapLabel* label = new QgsPixmapLabel( parent );
   label->setObjectName( "PhotoLabel" );
   QPushButton* pb = new QPushButton( tr( "..." ), container );
   pb->setObjectName( "FileChooserButton" );
@@ -154,6 +168,7 @@ void QgsPhotoWidgetWrapper::initWidget( QWidget* editor )
   if ( !mPhotoLabel )
     mPhotoLabel = container->findChild<QLabel*>();
 
+  mPhotoPixmapLabel = qobject_cast<QgsPixmapLabel*>( mPhotoLabel );
   if ( mButton )
     connect( mButton, SIGNAL( clicked() ), this, SLOT( selectFileName() ) );
 

src/gui/editorwidgets/qgsphotowidgetwrapper.h

@@ -17,6 +17,7 @@
 #define QGSPHOTOWIDGETWRAPPER_H
 
 #include "qgseditorwidgetwrapper.h"
+#include "qgspixmaplabel.h"
 
 #include <QLabel>
 #include <QPushButton>
@@ -61,6 +62,9 @@ class GUI_EXPORT QgsPhotoWidgetWrapper : public QgsEditorWidgetWrapper
   private:
     //! This label is used as a container to display the picture
     QLabel* mPhotoLabel;
+    //! This label is used as a container to display a picture that scales with the dialog layout.
+    //! It will always point to the same label as mPhotoLabel, but may be NULL if the widget is of type QLabel.
+    QgsPixmapLabel* mPhotoPixmapLabel;
 #ifdef WITH_QTWEBKIT
     //! This webview is used as a container to display the picture
     QWebView* mWebView;

src/gui/qgspixmaplabel.cpp

@@ -0,0 +1,47 @@
+/***************************************************************************
+
+               ----------------------------------------------------
+              date                 : 7.9.2015
+              copyright            : (C) 2015 by Matthias Kuhn
+              email                : matthias (at) opengis.ch
+ ***************************************************************************
+ *                                                                         *
+ *   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 "qgspixmaplabel.h"
+
+
+QgsPixmapLabel::QgsPixmapLabel( QWidget *parent ) :
+    QLabel( parent )
+{
+  this->setMinimumSize( 1, 1 );
+}
+
+void QgsPixmapLabel::setPixmap( const QPixmap & p )
+{
+  mPixmap = p;
+  QLabel::setPixmap( p );
+}
+
+int QgsPixmapLabel::heightForWidth( int width ) const
+{
+  return (( qreal )mPixmap.height()*width ) / mPixmap.width();
+}
+
+QSize QgsPixmapLabel::sizeHint() const
+{
+  int w = this->width();
+  return QSize( w, heightForWidth( w ) );
+}
+
+void QgsPixmapLabel::resizeEvent( QResizeEvent * e )
+{
+  QLabel::resizeEvent( e );
+  QLabel::setPixmap( mPixmap.scaled( this->size(),
+                                     Qt::KeepAspectRatio, Qt::SmoothTransformation ) );
+}

src/gui/qgspixmaplabel.h

@@ -0,0 +1,53 @@
+/***************************************************************************
+
+               ----------------------------------------------------
+              date                 : 7.9.2015
+              copyright            : (C) 2015 by Matthias Kuhn
+              email                : matthias (at) opengis.ch
+ ***************************************************************************
+ *                                                                         *
+ *   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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGSPIXMAPLABEL_H
+#define QGSPIXMAPLABEL_H
+
+#include <QLabel>
+
+/**
+ * @brief The QgsPixmapLabel class shows a pixmap and adjusts its size to the space given
+ * to the widget by the layout and keeping its aspect ratio.
+ */
+class QgsPixmapLabel : public QLabel
+{
+    Q_OBJECT
+
+  public:
+    explicit QgsPixmapLabel( QWidget *parent = 0 );
+    /**
+     * Calculates the height for the given width.
+     *
+     * @param width The width for the widget
+     * @return An appropriate height
+     */
+    virtual int heightForWidth( int width ) const;
+
+    /**
+     * An optimal size for the widget. Effectively using the height
+     * determined from the width with the given aspect ratio.
+     * @return A size hint
+     */
+    virtual QSize sizeHint() const;
+
+  public slots:
+    void setPixmap( const QPixmap & );
+    void resizeEvent( QResizeEvent * );
+  private:
+    QPixmap mPixmap;
+};
+
+#endif // QGSPIXMAPLABEL_H