Engauge Digitizer  2
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PdfFrameHandle.cpp
1 /******************************************************************************************************
2  * (C) 2014 markummitchell@github.com. This file is part of Engauge Digitizer, which is released *
3  * under GNU General Public License version 2 (GPLv2) or (at your option) any later version. See file *
4  * LICENSE or go to gnu.org/licenses for details. Distribution requires prior written permission. *
5  ******************************************************************************************************/
6 
7 #include "PdfCropping.h"
8 #include "PdfFrameHandle.h"
9 #include <QBrush>
10 #include <QGraphicsScene>
11 #include <QGraphicsView>
12 #include <qmath.h>
13 #include <QStyleOptionGraphicsItem>
14 
15 const double HANDLE_SIZE_AS_FRACTION_OF_WINDOW_SIZE = 30;
16 
17 PdfFrameHandle::PdfFrameHandle (QGraphicsScene &scene,
18  QGraphicsView &view,
19  const QPointF &pointReference,
20  int orientationFlags,
21  PdfCropping &pdfCropping,
22  int zValue) :
23  m_pdfCropping (pdfCropping),
24  m_orientationFlags (orientationFlags),
25  m_disableEventsWhileMovingAutomatically (false),
26  m_scene (scene),
27  m_view (view)
28 {
29  const double SUBTLE_OPACITY = 0.2;
30 
31  // Advantages of using ItemIgnoresTransformations:
32  // 1) handles do not get bigger or smaller depending on the size of the image
33  // 2) handles never get ugly when zoomed in
34  // 3) handles never get too tiny when zoomed out
35  // Disadvantages of using ItemIgnoresTransformation:
36  // 1) Resizing the preview window with ItemIgnoresTransformations moves the handles out of position
37  // 2) More conversions back and forth between untransformed and transformed coordinates. This was the deal breaker since
38  // the transformations were undocumented and ultimately too difficult
39  // The solution is to have constant-size handles WITHOUT ItemIgnoresTransformations. This means resizing the window
40  // also involves resizing the handles, but everything else is pretty easy
41  //
42  // ItemIgnoresTransformations flag must agree with the QGraphicsRectItem used for the frame box by PdfCropping
43  setFlags (QGraphicsItem::ItemIsMovable |
44  QGraphicsItem::ItemIsSelectable |
45  QGraphicsItem::ItemSendsScenePositionChanges);
46 
47  // Fill with nice color for better visibility. Note that the pen is disabled by overriding the paint method
48  setBrush (QBrush (Qt::blue));
49  setVisible (true);
50  setZValue (zValue);
51  setOpacity (SUBTLE_OPACITY);
52  setPos (pointReference); // Point position is handled in scene/view coordinates
53 
54  // Add to scene
55  scene.addItem (this);
56 
57  QSize handleSize = m_pdfCropping.windowSize() / HANDLE_SIZE_AS_FRACTION_OF_WINDOW_SIZE;
58 
59  // Adjust positions of handles that are not at the top left so handles are laid out symmetrically
60  QPointF pointPos = pointReference;
61  if ((orientationFlags & PdfCropping::PDF_CROPPING_LEFT) != 0) {
62  pointPos.setX (pointPos.x() - handleSize.width() / 2.0);
63  } else if ((orientationFlags & PdfCropping::PDF_CROPPING_RIGHT) != 0) {
64  pointPos.setX (pointPos.x() + handleSize.width() / 2.0);
65  }
66  if ((orientationFlags & PdfCropping::PDF_CROPPING_TOP) != 0) {
67  pointPos.setY (pointPos.y() - handleSize.height() / 2.0);
68  } else if ((orientationFlags & PdfCropping::PDF_CROPPING_BOTTOM) != 0) {
69  pointPos.setY (pointPos.y() + handleSize.height() / 2.0);
70  }
71 
72  // Start with geometry. Since point positions are handled in scene/view coordinates, we have to convert
73  // to local coordinates for the rectangle
74  QPointF topLeftLocal = mapFromScene (pointPos);
75 
76  setRect (QRectF (topLeftLocal,
77  handleSize));
78 }
79 
80 QVariant PdfFrameHandle::itemChange (GraphicsItemChange change,
81  const QVariant &value)
82 {
83  QVariant valueFiltered = value;
84 
85  if (change == ItemPositionChange && scene()) {
86 
87  QPointF sizeAsPointF (boundingRect().size().width(),
88  boundingRect().size().height());
89 
90  // New position is in the value argument
91  QPointF newPos = valueFiltered.toPointF();
92  QPointF oldPos = pos ();
93 
94  // This sequence is from http://www.qtcentre.org/threads/47248-How-to-efficiently-get-position-of-a-QGraphicsItem-in-view-coordinates
95  QRectF newRectItem (newPos,
96  QSize (qFloor (boundingRect().size().width()),
97  qFloor (boundingRect().size().height())));
98  QPolygonF newRectScene = mapToScene (newRectItem);
99  QPolygon newRectView = m_view.mapFromScene (newRectScene.boundingRect());
100 
101  // Skip moving of this handle if it will go outside of the window
102  QRectF rectWindow = m_scene.sceneRect();
103  if (!rectWindow.contains (newRectView.boundingRect())) {
104 
105  // Keep the item inside the scene rectangle
106  newPos.setX (qMin (rectWindow.right(), qMax (newPos.x(), rectWindow.left())));
107  newPos.setY (qMin (rectWindow.bottom(), qMax (newPos.y(), rectWindow.top())));
108 
109  valueFiltered = (newPos);
110 
111  }
112 
113  // Skip moving of other handles, in response to the move of this handle, if event handling is (temporarily) off,
114  // to prevent an infinite loop
115  if (!m_disableEventsWhileMovingAutomatically) {
116 
117  bool left = ((m_orientationFlags & PdfCropping::PDF_CROPPING_LEFT ) != 0);
118  bool right = ((m_orientationFlags & PdfCropping::PDF_CROPPING_RIGHT ) != 0);
119  bool top = ((m_orientationFlags & PdfCropping::PDF_CROPPING_TOP ) != 0);
120  bool bottom = ((m_orientationFlags & PdfCropping::PDF_CROPPING_BOTTOM) != 0);
121 
122  if (left && top) {
123  m_pdfCropping.moveTL (newPos, oldPos);
124  } else if (right && top) {
125  m_pdfCropping.moveTR (newPos, oldPos);
126  } else if (right && bottom) {
127  m_pdfCropping.moveBR (newPos, oldPos);
128  } else if (left && bottom) {
129  m_pdfCropping.moveBL (newPos, oldPos);
130  }
131  }
132  }
133 
134  return QGraphicsItem::itemChange(change, valueFiltered);
135 }
136 
137 void PdfFrameHandle::paint (QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
138 {
139  // Temporarily remove the selected option
140  QStyleOptionGraphicsItem scrubbed (*option);
141  scrubbed.state &= ~QStyle::State_Selected;
142  QGraphicsRectItem::paint (painter, &scrubbed, widget);
143 }
144 
146 {
147  m_disableEventsWhileMovingAutomatically = disable;
148 }
void moveTL(const QPointF &newPos, const QPointF &oldPos)
Top left corner handle was moved.
PdfFrameHandle(QGraphicsScene &scene, QGraphicsView &view, const QPointF &pointReference, int orientationFlags, PdfCropping &pdfCropping, int zValue)
Single constructor.
void moveBR(const QPointF &newPos, const QPointF &oldPos)
Bottom right corner handle was moved.
static const int PDF_CROPPING_RIGHT
Bit flag when handle is aligned with right edge at reference point.
Definition: PdfCropping.h:52
static const int PDF_CROPPING_TOP
Bit flag when handle is aligned with top edge at reference point.
Definition: PdfCropping.h:53
virtual void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
Override the paint method so the dashed-border-when-selected can be removed.
This class shows a frame around the selected portion of the pdf import preview window.
Definition: PdfCropping.h:24
static const int PDF_CROPPING_BOTTOM
Bit flag when handle is aligned with bottom edge at reference point.
Definition: PdfCropping.h:50
void moveBL(const QPointF &newPos, const QPointF &oldPos)
Bottom left corner handle was moved.
Definition: PdfCropping.cpp:83
static const int PDF_CROPPING_LEFT
Bit flag when handle is aligned with left edge at reference point.
Definition: PdfCropping.h:51
void moveTR(const QPointF &newPos, const QPointF &oldPos)
Top right corner handle was moved.
virtual QVariant itemChange(GraphicsItemChange change, const QVariant &value)
Intercept the drags and process them, which is the whole point of handles.
void setDisableEventsWhileMovingAutomatically(bool disable)
Temporarily disable event handling so code can move this object without triggering a cascade of event...
QSize windowSize() const
Size of window in scene coordinates.