@Robert-Hairgrove It seems that the scroll bars were sometimes lagging behind after moving the objects; the objects were not really clipped, but the view was not completely scrolled which made it look like they were clipped.
Here is my current changed version of diagramscene.h and diagramscene.cpp including additional headers which needed #include directives:
diagramscene.h:
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of The Qt Company Ltd nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef DIAGRAMSCENE_H
#define DIAGRAMSCENE_H
#include "diagramitem.h"
#include "diagramtextitem.h"
#include <QGraphicsScene>
QT_BEGIN_NAMESPACE
class QGraphicsSceneMouseEvent;
class QMenu;
class QPointF;
class QGraphicsLineItem;
class QFont;
class QGraphicsTextItem;
class QColor;
QT_END_NAMESPACE
#define DIAGRAMSCENE_BORDER_WIDTH 10
//! [0]
class DiagramScene : public QGraphicsScene
{
Q_OBJECT
public:
enum Mode { InsertItem, InsertLine, InsertText, MoveItem };
explicit DiagramScene(QMenu *itemMenu, QObject *parent = nullptr);
QFont font() const { return myFont; }
QColor textColor() const { return myTextColor; }
QColor itemColor() const { return myItemColor; }
QColor lineColor() const { return myLineColor; }
void setLineColor(const QColor &color);
void setTextColor(const QColor &color);
void setItemColor(const QColor &color);
void setFont(const QFont &font);
public slots:
void setMode(Mode mode);
void setItemType(DiagramItem::DiagramType type);
void editorLostFocus(DiagramTextItem *item);
signals:
void itemInserted(DiagramItem *item);
void textInserted(QGraphicsTextItem *item);
void itemSelected(QGraphicsItem *item);
protected:
void mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent) override;
void mouseMoveEvent(QGraphicsSceneMouseEvent *mouseEvent) override;
void mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent) override;
private:
bool isItemChange(int type) const;
// Added:-----
void adjustDragPositions(QGraphicsView *pv,
qreal border = DIAGRAMSCENE_BORDER_WIDTH);
//------------
DiagramItem::DiagramType myItemType;
QMenu *myItemMenu;
Mode myMode;
bool leftButtonDown;
QPointF startPoint;
QGraphicsLineItem *line;
QFont myFont;
DiagramTextItem *textItem;
QColor myTextColor;
QColor myItemColor;
QColor myLineColor;
};
//! [0]
#endif // DIAGRAMSCENE_H
diagramscene.cpp:
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of The Qt Company Ltd nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "diagramscene.h"
#include "arrow.h"
#include <QApplication>
#include <QGraphicsSceneMouseEvent>
#include <QGraphicsItem>
#include <QGraphicsView>
#include <QScrollBar>
#include <QTextCursor>
//! [0]
DiagramScene::DiagramScene(QMenu *itemMenu, QObject *parent)
: QGraphicsScene(parent)
{
myItemMenu = itemMenu;
myMode = MoveItem;
myItemType = DiagramItem::Step;
line = nullptr;
textItem = nullptr;
myItemColor = Qt::white;
myTextColor = Qt::black;
myLineColor = Qt::black;
}
//! [0]
//! [1]
void DiagramScene::setLineColor(const QColor &color)
{
myLineColor = color;
if (isItemChange(Arrow::Type)) {
Arrow *item = qgraphicsitem_cast<Arrow *>(selectedItems().first());
item->setColor(myLineColor);
update();
}
}
//! [1]
//! [2]
void DiagramScene::setTextColor(const QColor &color)
{
myTextColor = color;
if (isItemChange(DiagramTextItem::Type)) {
DiagramTextItem *item = qgraphicsitem_cast<DiagramTextItem *>(selectedItems().first());
item->setDefaultTextColor(myTextColor);
}
}
//! [2]
//! [3]
void DiagramScene::setItemColor(const QColor &color)
{
myItemColor = color;
if (isItemChange(DiagramItem::Type)) {
DiagramItem *item = qgraphicsitem_cast<DiagramItem *>(selectedItems().first());
item->setBrush(myItemColor);
}
}
//! [3]
//! [4]
void DiagramScene::setFont(const QFont &font)
{
myFont = font;
if (isItemChange(DiagramTextItem::Type)) {
QGraphicsTextItem *item = qgraphicsitem_cast<DiagramTextItem *>(selectedItems().first());
//At this point the selection can change so the first selected item might not be a DiagramTextItem
if (item)
item->setFont(myFont);
}
}
//! [4]
void DiagramScene::setMode(Mode mode)
{
myMode = mode;
}
void DiagramScene::setItemType(DiagramItem::DiagramType type)
{
myItemType = type;
}
//! [5]
void DiagramScene::editorLostFocus(DiagramTextItem *item)
{
QTextCursor cursor = item->textCursor();
cursor.clearSelection();
item->setTextCursor(cursor);
if (item->toPlainText().isEmpty()) {
removeItem(item);
item->deleteLater();
}
}
//! [5]
//! [6]
void DiagramScene::mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent)
{
if (mouseEvent->button() != Qt::LeftButton)
return;
DiagramItem *item;
switch (myMode) {
case InsertItem:
item = new DiagramItem(myItemType, myItemMenu);
item->setBrush(myItemColor);
addItem(item);
item->setPos(mouseEvent->scenePos());
emit itemInserted(item);
break;
//! [6] //! [7]
case InsertLine:
line = new QGraphicsLineItem(QLineF(mouseEvent->scenePos(),
mouseEvent->scenePos()));
line->setPen(QPen(myLineColor, 2));
addItem(line);
break;
//! [7] //! [8]
case InsertText:
textItem = new DiagramTextItem();
textItem->setFont(myFont);
textItem->setTextInteractionFlags(Qt::TextEditorInteraction);
textItem->setZValue(1000.0);
connect(textItem, &DiagramTextItem::lostFocus,
this, &DiagramScene::editorLostFocus);
connect(textItem, &DiagramTextItem::selectedChange,
this, &DiagramScene::itemSelected);
addItem(textItem);
textItem->setDefaultTextColor(myTextColor);
textItem->setPos(mouseEvent->scenePos());
emit textInserted(textItem);
//! [8] //! [9]
default:
;
}
QGraphicsScene::mousePressEvent(mouseEvent);
}
//! [9]
//! [10]
void DiagramScene::mouseMoveEvent(QGraphicsSceneMouseEvent *mouseEvent)
{
static bool IN_EVENT = false;
// Find the current view:
QGraphicsView* pv = nullptr;
if (mouseEvent->widget())
pv = qobject_cast<QGraphicsView *>(mouseEvent->widget()->parentWidget());
if (!IN_EVENT) {
if (myMode == InsertLine && line != nullptr) {
QLineF newLine(line->line().p1(), mouseEvent->scenePos());
line->setLine(newLine);
} else if (myMode == MoveItem) {
//--------------------------------------
if (pv) {
IN_EVENT = true;
QGraphicsScene::mouseMoveEvent(mouseEvent);
adjustDragPositions(pv);
IN_EVENT = false;
}
//--------------------------------------
}
}
}
//! [10]
//! [11]
void DiagramScene::mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent)
{
if (line != nullptr && myMode == InsertLine) {
QList<QGraphicsItem *> startItems = items(line->line().p1());
if (startItems.count() && startItems.first() == line)
startItems.removeFirst();
QList<QGraphicsItem *> endItems = items(line->line().p2());
if (endItems.count() && endItems.first() == line)
endItems.removeFirst();
removeItem(line);
delete line;
//! [11] //! [12]
if (startItems.count() > 0 && endItems.count() > 0 &&
startItems.first()->type() == DiagramItem::Type &&
endItems.first()->type() == DiagramItem::Type &&
startItems.first() != endItems.first()) {
DiagramItem *startItem = qgraphicsitem_cast<DiagramItem *>(startItems.first());
DiagramItem *endItem = qgraphicsitem_cast<DiagramItem *>(endItems.first());
Arrow *arrow = new Arrow(startItem, endItem);
arrow->setColor(myLineColor);
startItem->addArrow(arrow);
endItem->addArrow(arrow);
arrow->setZValue(-1000.0);
addItem(arrow);
arrow->updatePosition();
}
}
//! [12] //! [13]
line = nullptr;
QGraphicsScene::mouseReleaseEvent(mouseEvent);
}
//! [13]
//! [14]
bool DiagramScene::isItemChange(int type) const
{
const QList<QGraphicsItem *> items = selectedItems();
const auto cb = [type](const QGraphicsItem *item) { return item->type() == type; };
return std::find_if(items.begin(), items.end(), cb) != items.end();
}
//! [14]
void DiagramScene::adjustDragPositions(QGraphicsView *pv, qreal border)
{
Q_ASSERT_X(pv, __func__, "Pointer to view was NULL.");
if (border < DIAGRAMSCENE_BORDER_WIDTH)
border = DIAGRAMSCENE_BORDER_WIDTH;
// Get the selected items:
QList<QGraphicsItem*> selected = selectedItems();
if (selected.isEmpty()) return;
QGraphicsItemGroup * gp = createItemGroup(selected);
if (gp) {
QRectF br = gp->boundingRect();
qreal diffX = 0;
qreal diffY = 0;
// check left border:
if (br.x() < border) {
diffX = border - br.x();
}
// check right border:
if (br.x()+br.width() > this->width() - border) {
Q_ASSERT_X(diffX == 0, __func__, "diffX was already set for left border "
"adjustment.");
diffX = -((br.x() + br.width()) - (width() - border));
}
// check top border:
if (br.y() < border) {
diffY = border - br.y();
}
// check bottom border:
if (br.y()+br.height() > this->height() - border) {
Q_ASSERT_X(diffY == 0, __func__, "diffY was already set for top border "
"adjustment.");
diffY = -((br.y() + br.height()) - (height() - border));
}
if (diffX == 0.0 && diffY == 0.0) {
pv->ensureVisible(gp, border, border);
} else {
// move the group:
gp->moveBy(diffX, diffY);
QScrollBar *sb = nullptr;
if (diffX) {
// Scroll all the way to the left or right
// depending on whether diffX is positive or negative:
sb = pv->horizontalScrollBar();
if (sb) {
if (diffX > 0) {
// we adjusted the left:
sb->setValue(sb->minimum());
} else {
// we adjusted the right:
sb->setValue(sb->maximum());
}
}
}
if (diffY) {
// Scroll all the way to the top or bottom
// depending on whether diffX is positive or negative:
sb = pv->verticalScrollBar();
if (sb) {
if (diffY > 0) {
// we adjusted the top:
sb->setValue(sb->minimum());
} else {
// we adjusted the bottom:
sb->setValue(sb->maximum());
}
}
}
QApplication::processEvents();
}
destroyItemGroup(gp);
}
}
You will notice the extra code in DiagramScene::adjustDragPosition() which adjusts the scroll factor if needed, then calls QApplication::processEvents() to ensure that everything runs smoothly.
