#61 prevent qscrollarea in imagewidget from scrolling on zoom

imagewidget.cpp

@@ -65,6 +65,7 @@
 #include <QScrollBar>
 #include <QPixmap>
 #include <algorithm>
+#include "mousewheelctrleatereventfilter.h"
 
 #include <QDebug>
 
@@ -81,6 +82,8 @@ ImageWidget::ImageWidget(QWidget *parent) : QWidget(parent),
     imageLabel_m->setScaledContents(true);
     imageLabel_m->setVisible(false);
 
+    MouseWheelCtrlEaterEventFilter *wheelFilter = new MouseWheelCtrlEaterEventFilter(scrollArea_m);
+    scrollArea_m->viewport()->installEventFilter(wheelFilter);
     scrollArea_m->setObjectName("imageWidgetBackground");
     scrollArea_m->setAlignment(Qt::AlignCenter);
     scrollArea_m->setWidget(imageLabel_m);
@@ -228,7 +231,7 @@ void ImageWidget::clearImage()
 void ImageWidget::zoomIn()
 {
     if(!imageAttached()) return;
-    float tmpScalar = scalar_m * 1.125;
+    float tmpScalar = scalar_m * 1.125f;
     if (tmpScalar * imageLabel_m->width() > 32768 ||
             tmpScalar * imageLabel_m->height() > 32768)
     {
@@ -249,7 +252,7 @@ void ImageWidget::zoomIn()
 void ImageWidget::zoomOut()
 {
     if(!imageAttached()) return;
-    scalar_m *= 0.889;
+    scalar_m *= 0.889f;
     imageLabel_m->resize(scalar_m * attachedImage_m->size());
     if (fillScrollArea_m == true)
     {

imagewidget.h

@@ -60,6 +60,7 @@ class QImage;
 class QMenu;
 class QMutex;
 class QPixmap;
+class MouseWheelCtrlEaterEventFilter;
 
 class ImageWidget : public QWidget
 {
@@ -114,6 +115,7 @@ public slots:
     QAction *zoomActualAction_m;
     QScrollArea *scrollArea_m;
     const QImage *attachedImage_m = nullptr;
+    MouseWheelCtrlEaterEventFilter *wheelFilter;
     float scalar_m;
     bool fillScrollArea_m = true;
 };

mousewheelctrleatereventfilter.cpp

@@ -1,6 +1,61 @@
+/***********************************************************************
+* FILENAME :    mousewheeleatereventfilter.h
+*
+* LICENSE:
+*       qcvTouchUp provides an image processing toolset for editing
+*       photographs, purposed and packaged for use in a desktop application
+*       user environment. Copyright (C) 2018,  Matthew R. Miller
+*
+*       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 (version 3 of the License).
+*
+*       The framework and libraries used to create this software are licenced
+*       under the  GNU Lesser General Public License (LGPL) version 3 and the
+*       3-clause BSD License as agreed upon through the use of the Qt toolkit
+*       and OpenCV libraries respectively. Copies of the appropriate licenses
+*       for qcvTouchup, and its source code, can be found in LICENSE.txt,
+*       LICENSE.Qt.txt, and LICENSE.CV.txt. If not, please see
+*       <http://www.gnu.org/licenses/> and <https://opencv.org/license.html>
+*       for further information on licensing.
+*
+*       This program is distributed in the hope that it will be useful,
+*       but WITHOUT ANY WARRANTY; without even the implied warranty of
+*       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+*       GNU General Public License for more details.
+*
+*       If you wish to contact the developer about this project, please do so
+*       through their account at <https://github.com/mattrussmill>
+*
+* DESCRIPTION :
+*       This object is an event filter to disable mouse scroll wheel interactions
+*       when the ctrl key is held down.
+*
+* NOTES :
+*       Some QWidgets have scroll wheel interactions which cannot be disabled.
+*
+* AUTHOR :  Matthew R. Miller       START DATE :    March 6, 2018
+*
+* CHANGES : N/A - N/A
+*
+* VERSION       DATE            WHO                     DETAIL
+* 0.1           November 30, 2019      Matthew R. Miller       Initial Rev
+*
+************************************************************************/
 #include "mousewheelctrleatereventfilter.h"
+#include <QEvent>
+#include <QApplication>
 
 MouseWheelCtrlEaterEventFilter::MouseWheelCtrlEaterEventFilter(QObject *parent) : QObject(parent)
 {
 
 }
+
+//If the event is a mouse scroll wheel event with the ctrl modifier, eventFilter returns true to disable further processing
+bool MouseWheelCtrlEaterEventFilter::eventFilter(QObject *watched, QEvent *event)
+{
+    if(QApplication::queryKeyboardModifiers() & Qt::ControlModifier)
+        if(event->type() == QEvent::Wheel)
+            return true;
+    return false;
+}

mousewheelctrleatereventfilter.h

@@ -1,3 +1,47 @@
+/***********************************************************************
+* FILENAME :    mousewheeleatereventfilter.h
+*
+* LICENSE:
+*       qcvTouchUp provides an image processing toolset for editing
+*       photographs, purposed and packaged for use in a desktop application
+*       user environment. Copyright (C) 2018,  Matthew R. Miller
+*
+*       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 (version 3 of the License).
+*
+*       The framework and libraries used to create this software are licenced
+*       under the  GNU Lesser General Public License (LGPL) version 3 and the
+*       3-clause BSD License as agreed upon through the use of the Qt toolkit
+*       and OpenCV libraries respectively. Copies of the appropriate licenses
+*       for qcvTouchup, and its source code, can be found in LICENSE.txt,
+*       LICENSE.Qt.txt, and LICENSE.CV.txt. If not, please see
+*       <http://www.gnu.org/licenses/> and <https://opencv.org/license.html>
+*       for further information on licensing.
+*
+*       This program is distributed in the hope that it will be useful,
+*       but WITHOUT ANY WARRANTY; without even the implied warranty of
+*       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+*       GNU General Public License for more details.
+*
+*       If you wish to contact the developer about this project, please do so
+*       through their account at <https://github.com/mattrussmill>
+*
+* DESCRIPTION :
+*       This object is an event filter to disable mouse scroll wheel interactions
+*       when the ctrl key is held down.
+*
+* NOTES :
+*       Some QWidgets have scroll wheel interactions which cannot be disabled.
+*
+* AUTHOR :  Matthew R. Miller       START DATE :    March 6, 2018
+*
+* CHANGES : N/A - N/A
+*
+* VERSION       DATE            WHO                     DETAIL
+* 0.1           November 30, 2019      Matthew R. Miller       Initial Rev
+*
+************************************************************************/
 #ifndef MOUSEWHEELCTRLEATEREVENTFILTER_H
 #define MOUSEWHEELCTRLEATEREVENTFILTER_H
 
@@ -9,9 +53,8 @@ class MouseWheelCtrlEaterEventFilter : public QObject
 public:
     explicit MouseWheelCtrlEaterEventFilter(QObject *parent = nullptr);
 
-signals:
-
-public slots:
+protected:
+    bool eventFilter(QObject *watched, QEvent *event);
 };
 
 #endif // MOUSEWHEELCTRLEATEREVENTFILTER_H

mousewheeleatereventfilter.cpp

@@ -42,7 +42,6 @@
 *
 ************************************************************************/
 #include "mousewheeleatereventfilter.h"
-#include <QObject>
 #include <QEvent>
 
 //Autogenerated constructor

qcvTouchUp.pro

@@ -34,6 +34,7 @@ SOURCES += \
         main.cpp \
         mainwindow.cpp \
     imagewidget.cpp \
+    mousewheelctrleatereventfilter.cpp \
     quickmenu.cpp \
     adjustmenu.cpp \
     mousewheeleatereventfilter.cpp \
@@ -58,6 +59,7 @@ HEADERS += \
     imagesavewebpmenu.h \
         mainwindow.h \
     imagewidget.h \
+    mousewheelctrleatereventfilter.h \
     quickmenu.h \
     adjustmenu.h \
     mousewheeleatereventfilter.h \