Initial commit

Lts/Common/LtsWidgets/LtsImageCropper/lts_image_cropper.cpp

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+/*
+ * @RDE_HEADER@
+ * graphicsview widget to resize qpixmaps/qimages with mouse drag and mwheel
+ * $Id$
+ * $HeadURL$
+ * $Author$
+ * Created by Jens Heilmann, SLTE, 2020-10-14
+ */
+
+#include "lts_image_cropper.h"
+#include <QGraphicsItem>
+#include <QMouseEvent>
+#include <QApplication>
+
+namespace LtsWidgets
+{
+
+LtsImageCropper::LtsImageCropper(QWidget *parent, const QSize &size, const QPixmap &pixmap)
+  : QGraphicsView(parent)
+  , m_scene(new QGraphicsScene(this))
+  , m_maxScale(2.0f)
+  , m_multiplier(1.0f)
+{
+  if(!size.isNull())
+    setFixedSize(size);
+
+  setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+  setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+  setFrameStyle(QFrame::NoFrame);
+  setDragMode(QGraphicsView::ScrollHandDrag);
+  setTransformationAnchor(QGraphicsView::AnchorViewCenter);
+
+  m_scene->setBackgroundBrush(Qt::Dense6Pattern);
+  setScene(m_scene);
+
+  setPixmap(pixmap);
+}
+
+LtsImageCropper::~LtsImageCropper()
+{
+  delete m_pixmapItem;
+}
+
+void LtsImageCropper::setPixmap(const QPixmap &pixmap)
+{
+  if(pixmap.isNull())
+    return;
+
+  delete m_pixmapItem; // delete previous pixmapitem
+
+  m_pixmapItem = new QGraphicsPixmapItem(pixmap);
+  m_scene->addItem(m_pixmapItem);
+
+  setTransform(QTransform()); // set a fresh transformation matrix
+  m_currentZoom = 1.0; // reset current zoom
+
+  //check if image size is min view, if not scale it
+  double sx = static_cast<double>(size().height()) / pixmap.height();
+  double sy = static_cast<double>(size().width()) / pixmap.width();
+  if(sx > 1 )
+    scale(sx,sx);
+  if(sy > 1)
+    scale(sy,sy);
+
+  // calculate min scale from qMin(width,height);
+  double ratioWidth  = 1.0 * size().width()  / pixmap.width();
+  double ratioHeight = 1.0 * size().height() / pixmap.height();
+  m_minScale = qMax(ratioHeight,ratioWidth);
+
+  calculateScaleStep();
+
+  // change scene boundaries to image rectangle and center scene on image center
+  m_scene->setSceneRect(pixmap.rect());
+  centerOn(m_scene->sceneRect().center());
+}
+
+void LtsImageCropper::setImage(const QImage &image)
+{
+  setPixmap(QPixmap::fromImage(image));
+}
+
+void LtsImageCropper::setMultiplier(double multiplier)
+{
+  m_multiplier = multiplier;
+  calculateScaleStep();
+}
+
+void LtsImageCropper::calculateScaleStep()
+{
+  m_stepScale = (m_maxScale - m_minScale) / 100.0;
+}
+
+QImage LtsImageCropper::image()
+{
+  return grab().toImage();
+}
+
+void LtsImageCropper::wheelEvent(QWheelEvent *event)
+{
+  if(!m_pixmapItem)
+    return;
+
+  auto value = event->pixelDelta();
+  if(value.isNull())
+    value = event->angleDelta() / 15.0;
+
+  // calculate scrollZoom value to be added to the current zoom
+  double scrollZoom = m_stepScale * value.y() * m_multiplier / 8.0;
+
+  m_currentZoom += scrollZoom;
+
+  if(m_currentZoom > m_maxScale)
+    m_currentZoom = m_maxScale;
+  else if (m_currentZoom < m_minScale)
+    m_currentZoom = m_minScale;
+
+  // scale the view
+  setTransform(QTransform(m_currentZoom, transform().m12(), transform().m13(),
+                          transform().m21(), m_currentZoom, transform().m23(),
+                          transform().m31(), transform().m32(), 1));
+}
+
+void LtsImageCropper::mousePressEvent(QMouseEvent *event)
+{
+  QApplication::setOverrideCursor(Qt::DragMoveCursor);
+  update();
+  QGraphicsView::mousePressEvent(event);
+}
+
+void LtsImageCropper::mouseReleaseEvent(QMouseEvent *event)
+{
+  QApplication::restoreOverrideCursor();
+  update();
+  QGraphicsView::mouseReleaseEvent(event);
+}
+
+}

Lts/Common/LtsWidgets/LtsImageCropper/lts_image_cropper.h

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+/*
+ * @RDE_HEADER@
+ * graphicsview widget to resize qpixmaps/qimages with mouse drag and mwheel
+ * $Id$
+ * $HeadURL$
+ * $Author$
+ * Created by Jens Heilmann, SLTE, 2020-10-14
+ */
+
+#pragma once
+
+#include "lts_widgets_export.h"
+#include <QGraphicsView>
+
+namespace LtsWidgets
+{
+
+/**
+ * @brief The ImageCropper class provides a graphicsview widget to crop images with mouse drag and mwheel scroll.
+ *        avatar() returns a pixmap of the current view (the cropped image).
+ */
+class LTSWIDGETS_EXPORT LtsImageCropper : public QGraphicsView
+{
+
+  Q_OBJECT
+
+  Q_PROPERTY(QPixmap  pixMap     READ pixmap     WRITE setPixmap)
+  Q_PROPERTY(double   multiplier READ multiplier WRITE setMultiplier)
+  Q_PROPERTY(double   maxZoom    READ maxZoom    WRITE setMaxZoom)
+
+public:
+  /**
+    * @brief ImageCropper
+    * @param parent
+    * @param size specifies the size of the graphicsview widget, aswell as the size of the cropped image.
+    * @param image to crop
+    */
+  LtsImageCropper(QWidget *parent = nullptr, const QSize &size = {} , const QPixmap &pixmap = {});
+  ~LtsImageCropper();
+
+  /**
+   * @brief setter for image
+   * @param image
+   */
+  void setPixmap(const QPixmap &pixmap);
+
+  /**
+   * @brief setter for image
+   * @param image
+   */
+  void setImage(const QImage &image);
+
+  /**
+   * @brief set the zoom mutliplier for mwheel scaling e.g. 1.03.
+   * @param multiplier
+   */
+  void setMultiplier(double multiplier);
+
+  /**
+   * @brief set the maximum zoom in scale e.g. 2.0 = 200% zoom in.
+   * @param maxZoom
+   */
+  void setMaxZoom(double maxZoom) { m_maxScale = maxZoom; }
+
+  /**
+   * @brief returns the current graphicsview view as a pixmap.
+   * @return qpixmap
+   */
+  QPixmap pixmap() { return grab(); }
+
+  /**
+   * @brief returns the current graphicsview view as qimage.
+   * @return qimage
+   */
+  QImage  image();
+
+  /**
+   * @brief returns the current multiplier
+   * @return double
+   */
+  double multiplier() const { return m_multiplier; }
+
+  /**
+   * @brief returns the current max zoom value
+   * @return double
+   */
+  double maxZoom() const { return m_maxScale; }
+
+private:
+  QGraphicsScene      *m_scene = nullptr;
+  QGraphicsPixmapItem *m_pixmapItem = nullptr;
+
+  double m_currentZoom;
+  double m_minScale;
+  double m_maxScale;
+  double m_stepScale;
+  double m_multiplier;
+
+  void calculateScaleStep();
+
+protected:
+  void wheelEvent(QWheelEvent *event) override;
+  void mousePressEvent(QMouseEvent *event) override;
+  void mouseReleaseEvent(QMouseEvent *event) override;
+
+};
+
+} // namespace LtsWidgets