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I subclass a QGraphicsItem to Node, but when I set it's tooltip, it can't show tooltip when mouse touch it.
There is some of my code:
class Node : public QGraphicsItem {
public:
Node(int id);
~Node() {}
int id;
private:
QRectF boundingRect() const;
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);
};
void Node::paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
QWidget *widget) {
QPen pen(Qt::red);
painter->setPen(pen);
painter->setBrush(Qt::red);
painter->drawRoundRect(-10, -10, 10, 10);
}
QRectF Node::boundingRect() const {
QRectF rect;
rect.translate(-rect.center());
return rect;
}
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent), ui(new Ui::MainWindow) {
ui->setupUi(this);
view = new QGraphicsView(this);
scene = new QGraphicsScene(0, 0, 2000, 2000);
view->setScene(scene);
setCentralWidget(view);
generateMap();
ui->actionQuery_path->setToolTip(
"query the shortest path between to loactions");
view->show();
}
void MainWindow::generateMap() {
// waterhome
Node *waterhome = new Node(1);
waterhome->setToolTip("开水房");
waterhome->moveBy(100, 470);
scene->addItem(waterhome);
}
Now I can see my node, but can't see it's tooltip even the action's tooltip, I try to increase the Node's Z value, but it doesn't help, what's wrong?
The problem is with your boudingRect() function. Have a look at it and try to guess what is returns back.
If you copy-paste following code then the tooltip should appear:
QRectF Node::boundingRect() const
{
qreal penWidth = 1;
return QRectF(-10 - penWidth / 2, -10 - penWidth / 2,
20 + penWidth, 20 + penWidth);
}
void Node::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
QPen pen(Qt::red);
painter->setPen(pen);
painter->setBrush(Qt::red);
painter->drawRoundedRect(-10, -10, 20, 20, 2, 2);
}
I have a QGraphicsSvgItem subclass where I would like to modify the svg color. I want to use for that QGraphicsColorizeEffect, and it works great.
My items also have a custom selection rectangle, highlighted - similar to other item types.
When I apply the colorize effect, the highlight also turns to the same color...
I have tried to setEnabled(false); in paint but it seems to have no effect.
sample code:
file mysvg.h
#ifndef MYSVG_H
#define MYSVG_H
#include <QGraphicsSvgItem>
#include <QGraphicsColorizeEffect>
class MySvg : public QGraphicsSvgItem
{
public:
MySvg();
~MySvg();
virtual void paint(QPainter* painter,
const QStyleOptionGraphicsItem* option,
QWidget* widget = NULL);
private:
QGraphicsColorizeEffect* m_effect;
void drawSelectionRectangle(QPainter* painter, const QStyleOptionGraphicsItem* option, const QRectF& rectangle);
};
#endif // MYSVG_H
file mysvg.cpp
#include <QStyleOptionGraphicsItem>
#include <QStyle>
#include <QPainterPath>
#include <QPainter>
#include <QFileDialog>
#include <QSvgRenderer>
MySvg::MySvg()
{
m_effect = new QGraphicsColorizeEffect();
m_effect->setColor(Qt::red);
setGraphicsEffect(m_effect);
setFlags(QGraphicsItem::ItemIsMovable |
QGraphicsItem::ItemIsFocusable |
QGraphicsItem::ItemIsSelectable);
QString filename = QFileDialog::getOpenFileName(0, tr("Open Svg File"),
QString(), tr("Svg files (*.svg *.svgz)"));
setSharedRenderer(new QSvgRenderer(filename));
}
MySvg::~MySvg()
{
delete renderer();
delete m_effect;
}
void MySvg::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
QStyleOptionGraphicsItem opt(*option);
opt.state = QStyle::State_None;
QGraphicsSvgItem::paint(painter, &opt, widget);
//m_effect->setEnabled(false); // no effect though seemed logical
QRectF rectangle = boundingRect();
if (option->state & (QStyle::State_Selected))
drawSelectionRectangle(painter, option, rectangle);
//m_effect->setEnabled(true);
}
void MySvg::drawSelectionRectangle(QPainter *painter, const QStyleOptionGraphicsItem *option, const QRectF &rectangle)
{
painter->setPen(QPen(option->palette.windowText(), 0, Qt::DotLine));
painter->setBrush(QColor(255, 188, 0, 50));
painter->drawRect(rectangle);
}
file main.cpp
#include <QApplication>
#include <QGraphicsView>
#include "mysvg.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QGraphicsScene s;
QGraphicsView view;
view.setScene(&s);
s.setSceneRect(-50, -50, 500, 650);
view.show();
MySvg* svg = new MySvg();
s.addItem(svg);
return app.exec();
}
file mysvg.pro
QT += core gui svg
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = mysvg
TEMPLATE = app
SOURCES += main.cpp \
mysvg.cpp
HEADERS += mysvg.h
I have considered making a QGraphicsSvgItem a private member of the MySvg item - but the MySvg item has to do a lot of other things, and I don't know what to do with the renderer (who would own it...) - if I can figure out how to make a QGraphicsSvgItem subclass a member of the MySvg class, I can apply the colorize to the member and perform all other operations on the MySvg item...
Please help me figure a way to apply color to the svg, but not other drawing portion of the item.
Edit - I have tried to add a member item to the class and apply the colorize effect to the member - but it doesn't apply the colorize effect at all... The svg loads with all original colors.
Here is the code containing a member item:
new mysvg.h
class SvgMember : public QGraphicsSvgItem
{
public:
SvgMember (const QByteArray &content, const QColor& c);
~SvgMember ();
private:
QGraphicsColorizeEffect* m_effect;
};
class MySvg : public QGraphicsItem
{
public:
MySvg();
~MySvg();
virtual void paint(QPainter* painter,
const QStyleOptionGraphicsItem* option,
QWidget* widget = NULL);
virtual QRectF boundingRect() const;
virtual QPainterPath shape() const;
private:
void drawSelectionRectangle(QPainter* painter, const QStyleOptionGraphicsItem* option, const QRectF& rectangle);
SvgMember * m_member;
};
new mysvg.cpp
MySvg::MySvg()
{
setFlags(QGraphicsItem::ItemIsMovable |
QGraphicsItem::ItemIsFocusable |
QGraphicsItem::ItemIsSelectable);
QString filename = QFileDialog::getOpenFileName(0, QObject::tr("Open Svg File"),
QString(), QObject::tr("Svg files (*.svg *.svgz)"));
QFile f(filename);
f.open(QFile::ReadOnly | QFile::Text);
QByteArray svgContents = f.readAll();
f.close();
m_member = new SvgMember (svgContents, Qt::red);
}
MySvg::~MySvg()
{
delete m_member;
}
void MySvg::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
QStyleOptionGraphicsItem opt(*option);
opt.state = QStyle::State_None;
m_member->paint(painter, &opt, widget);
QRectF rectangle = boundingRect();
if (option->state & (QStyle::State_Selected))
drawSelectionRectangle(painter, option, rectangle);
}
/*! \brief reimplemented to use member rectangle */
QRectF MySvg::boundingRect() const
{
return m_member->boundingRect();
}
/*! \brief reimplemented to use member shape */
QPainterPath MySvg::shape() const
{
return m_member->shape();
}
void MySvg::drawSelectionRectangle(QPainter *painter, const QStyleOptionGraphicsItem *option, const QRectF &rectangle)
{
painter->setPen(QPen(option->palette.windowText(), 0, Qt::DotLine));
painter->setBrush(QColor(255, 188, 0, 50));
painter->drawRect(rectangle);
}
SvgMember ::SvgMember (const QByteArray &content, const QColor &c)
{
m_effect = new QGraphicsColorizeEffect();
setGraphicsEffect(m_effect);
m_effect->setColor(c);
setSharedRenderer(new QSvgRenderer(content));
}
SvgMember ::~SvgMember ()
{
delete renderer();
delete m_effect;
}
What can I do to apply the colorize effect to the svg - but not to the selection rectangle ?
The effect is a feature of the base class QGraphicsItem. It is applied to the entire graphics item and all its children. So, everything that is painted inside the item is affected by its effect.
The selection rectangle should be painted outside of the SVG item object.
It can be achieved by enclosing QGraphicsSvgItem by the composite class QGraphicsItemGroup.
When a QGraphicsItem is added to QGraphicsItemGroup it becomes reparented. Thus the item is destroyed when the group object is destroyed. So, it is not needed to delete it manually. QGraphicsItem takes ownership of effect, so it is not needed to delete the effect object.
The following class MyGraphicsItemGroup works as you expect.
Implementation "mygraphicsitemgroup.cpp"
#include "mygraphicsitemgroup.h"
#include <QGraphicsColorizeEffect>
#include <QGraphicsSvgItem>
#include <QStyleOptionGraphicsItem>
#include <QPainter>
#include <QFileDialog>
MyGraphicsItemGroup::MyGraphicsItemGroup()
{
setFlags(QGraphicsItem::ItemIsMovable |
QGraphicsItem::ItemIsFocusable |
QGraphicsItem::ItemIsSelectable);
QString filename = QFileDialog::getOpenFileName(0,
QObject::tr("Open Svg File"), QString(),
QObject::tr("Svg files (*.svg *.svgz)"));
QGraphicsColorizeEffect *effect = new QGraphicsColorizeEffect();
effect->setColor(Qt::red);
QGraphicsSvgItem *svg = new QGraphicsSvgItem(filename);
svg->setGraphicsEffect(effect);
addToGroup(svg);
}
void MyGraphicsItemGroup::paint(QPainter* painter,
const QStyleOptionGraphicsItem* option, QWidget* widget)
{
QStyleOptionGraphicsItem opt(*option);
opt.state = QStyle::State_None;
QGraphicsItemGroup::paint(painter, &opt, widget);
QRectF rectangle = boundingRect();
if (option->state & QStyle::State_Selected)
drawSelectionRectangle(painter, option, rectangle);
}
void MyGraphicsItemGroup::drawSelectionRectangle(QPainter *painter,
const QStyleOptionGraphicsItem *option, const QRectF &rectangle)
{
painter->setPen(QPen(option->palette.windowText(), 0, Qt::DotLine));
painter->setBrush(QColor(255, 188, 0, 50));
painter->drawRect(rectangle);
}
Header "mygraphicsitemgroup.h"
#ifndef MYGRAPHICSITEMGROUP_H
#define MYGRAPHICSITEMGROUP_H
#include <QGraphicsItemGroup>
class MyGraphicsItemGroup : public QGraphicsItemGroup
{
public:
MyGraphicsItemGroup();
virtual void paint(QPainter* painter,
const QStyleOptionGraphicsItem* option, QWidget* widget);
void drawSelectionRectangle(QPainter *painter,
const QStyleOptionGraphicsItem *option, const QRectF &rectangle);
};
#endif // MYGRAPHICSITEMGROUP_H
NetworkPageForm::NetworkPageForm(QWidget *parent) :
QWidget(parent),
ui(new Ui::NetworkPageForm),
devicesModel(NULL)
{
ui->setupUi(this);
devicesModel = new QStandardItemModel(0, 4, parent);
devicesModel->setHeaderData(0, Qt::Horizontal, QObject::tr("IP"));
devicesModel->setHeaderData(1, Qt::Horizontal, QObject::tr("Name"));
devicesModel->setHeaderData(2, Qt::Horizontal, QObject::tr("Last Online"));
devicesModel->setHeaderData(3, Qt::Horizontal, QObject::tr("Status"));
ui->devicesTableView->setModel(devicesModel);
ui->devicesTableView->resizeColumnsToContents();
}
void NetworkPageForm::addDevice(const QString &ip, int device_type) {
bool haveSameItem = false;
for(int i=0; i<devicesModel->rowCount(); i++) {
QStandardItem * ipItem = devicesModel->item(i, 0);
QStandardItem * nameItem = devicesModel->item(i, 1);
if(QString::compare(ipItem->text(), ip)== 0 && QString::compare(nameItem->text(), deviceStr)==0) {
devicesModel->setData(devicesModel->index(i, 2), BaseModel::now());
haveSameItem = true;
}
}
if(!haveSameItem)
{
int last = devicesModel->rowCount();
devicesModel->insertRow(last);
devicesModel->setData(devicesModel->index(last, 0), ip);
devicesModel->setData(devicesModel->index(last, 1), device_type);
devicesModel->setData(devicesModel->index(last, 2), BaseModel::now());
devicesModel->setData(devicesModel->index(last, 3), QIcon(":/res/images/online_icon.png"), Qt::DecorationRole);
// This function does not work, the icon is algin left.
// devicesModel->item(last, 3)->setTextAlignment(Qt::AlignCenter);
}
ui->devicesTableView->resizeColumnsToContents();
}
Is there a way to set QIcon item center in QTableView?
Update:
I create my own QStyledItemDelegate sub class as #RazrFalcon answered.
#include <QStyledItemDelegate>
class MyDelegate : public QStyledItemDelegate
{
Q_OBJECT
public:
MyDelegate(QWidget *parent = 0) : QStyledItemDelegate(parent) {}
void paint(QPainter *painter, const QStyleOptionViewItem &option,
const QModelIndex &index) const;
QSize sizeHint(const QStyleOptionViewItem &option,
const QModelIndex &index) const;
void setModelData(QWidget *editor, QAbstractItemModel *model,
const QModelIndex &index) const;
private slots:
};
void MyDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const {
if(index.column() == 3) {
// TODO
} else {
QStyledItemDelegate::paint(painter, option, index);
}
}
QSize MyDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const {
if(index.column() == 3) {
// TODO
} else {
return QStyledItemDelegate::sizeHint(option, index);
}
}
void MyDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const {
QStyledItemDelegate::setModelData(editor, model, index);
}
And set ui->devicesTableView->setItemDelegate(new MyDelegate);
Could someone help me how to set icon column center in QTableView?
There is no default way. You should implement your own QStyledItemDelegate.
UPD: example added
void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
Q_ASSERT(index.isValid());
QStyleOptionViewItemV4 opt = option;
initStyleOption(&opt, index);
// disable default icon
opt.icon = QIcon();
// draw default item
QApplication::style()->drawControl(QStyle::CE_ItemViewItem, &opt, painter, 0);
const QRect r = option.rect;
// get pixmap
QIcon icon = qvariant_cast<QIcon>(index.data(Qt::DecorationRole));
QPixmap pix = icon.pixmap(r.size());
// draw pixmap at center of item
const QPoint p = QPoint((r.width() - pix.width())/2, (r.height() - pix.height())/2);
painter->drawPixmap(r.topLeft() + p, pix);
}
It's no need to do it in delegate. The delegate will make your style sheet unavailable.
You can paint the icon in the middle of a rectangle pixmap which is as same size as the cell, and return it in the QAbstractItemModel::data() function with Qt::DecorationRole. Like this:
Qt::DecoratoinRole:
QPixmap pixmap(w, h); //w=cell width, h=cell
pixmap.fill(Qt::transparent); // draw a transparent rectangle
QPixmap iconPixmap(":/xx.png");
QPainter painter(&pixmap);
//Calculate the center coordinate x,y for iconPixmap
painter.draw(x, y, iconWidth, iconHeight, iconPixmap);
return pixmap;
I have a QTableView that works very well, the first column holds some thumbnails, in each cell of this column the thumbnails are vertically centered, but not horizontally centered.
Do I really need to use a delegate?
If yes, How to center them horizontally using QStyledItemDelegate?
Construct your own delegate and inherit QStyledItemDelegate. Override the paint method.
Then do something like this:
void
MyDelegate::paint(QPainter* painter, const QStyleOptionViewItem& option,
const QModelIndex& index) const
{
QPixmap pixmap;
pixmap.load("Your pixmap file path");
pixmap = pixmap.scaled(option.rect.width(), option.rect.height(), Qt::KeepAspectRatio);
// Position our pixmap
const int x = option.rect.center().x() - pixmap.rect().width() / 2;
const int y = option.rect.center().y() - pixmap.rect().height() / 2;
if (option.state & QStyle::State_Selected) {
painter->fillRect(option.rect, option.palette.highlight());
}
painter->drawPixmap(QRect(x, y, pixmap.rect().width(), pixmap.rect().height()), pixmap);
}
Drawing by yourself is not necessary, but a custom delegate - is. The styled item delegate uses the style's control element drawing code to draw a CE_ItemViewItem - see the source code for Qt 5.5.0. The drawing code takes the style option's decorationAlignment member into account. Unfortunately, there's no data role that would pass that alignment to the styles's implementation. Instead, you have to override the alignment in your delegate:
class DecorationAligningDelegate : public QStyledItemDelegate {
Q_OBJECT
Qt::Alignment const m_alignment;
public:
explicit DecorationAligningDelegate(Qt::Alignment alignment, QObject * parent = 0) :
QStyledItemDelegate(parent), m_alignment(alignment) {}
Qt::Alignment alignment() const { return m_alignment; }
void paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const {
auto opt = option;
opt.decorationAlignment = m_alignment;
QStyledItemDelegate::paint(painter, opt, index);
}
};
Then, to center the thumbnails:
view.setItemDelegateForColumn(0,
new DecorationAligningDelegate(Qt::AlignHCenter, &view));
//or
view->setItemDelegateForColumn(0,
new DecorationAligningDelegate(Qt::AlignHCenter, view));
If you really wished to paint it all yourself, even though it's unnecessary, the rectangle of the item to be painted is given in the style option (option.rect). To draw the pixmap centered in the item's rectangle, you could do as follows:
QStyleOption option;
QPixmap pix;
QPainter painter;
...
painter.save();
auto loc = option.rect.center() - pix.rect().center()
painter.drawPixmap(loc, pix);
painter.restore();
I will just leave my version that literary is a combination of the two answers.
class DecorationAligningDelegate : public QStyledItemDelegate
{
Q_OBJECT
public:
explicit DecorationAligningDelegate(Qt::Alignment alignment, QObject *parent = nullptr)
: QStyledItemDelegate(parent), m_alignment(alignment) {}
Qt::Alignment alignment() const { return m_alignment; }
void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
QIcon icon = QIcon(qvariant_cast<QIcon>(index.data(Qt::DecorationRole)));
if (option.state & QStyle::State_Selected)
{
painter->fillRect(option.rect, option.palette.highlight());
}
icon.paint(painter, option.rect, m_alignment);
}
private:
Q_DISABLE_COPY(VDecorationAligningDelegate)
Qt::Alignment const m_alignment;
};
I assume you define your item like this:
auto *item = new QTableWidgetItem();
item->setIcon(QIcon("Your pixmap file path"));
Don't forget about setting a delegate.
I have implemented grid in graphicsView using drawBackgroud method. Now I also want to add snap to the grid. By snap I mean that with mouse, you can't have point other than grid points. My code to grid drawn is as follows:
void CadGraphicsScene::drawBackground(QPainter *painter, const QRectF &rect)
{
const int gridSize = 50;
const int realLeft = static_cast<int>(std::floor(rect.left()));
const int realRight = static_cast<int>(std::ceil(rect.right()));
const int realTop = static_cast<int>(std::floor(rect.top()));
const int realBottom = static_cast<int>(std::ceil(rect.bottom()));
// Draw grid.
const int firstLeftGridLine = realLeft - (realLeft % gridSize);
const int firstTopGridLine = realTop - (realTop % gridSize);
QVarLengthArray<QLine, 100> lines;
for (qreal x = firstLeftGridLine; x <= realRight; x += gridSize)
lines.append(QLine(x, realTop, x, realBottom));
for (qreal y = firstTopGridLine; y <= realBottom; y += gridSize)
lines.append(QLine(realLeft, y, realRight, y));
painter->setPen(QPen(QColor(220, 220, 220), 0.0));
painter->drawLines(lines.data(), lines.size());
// Draw axes.
painter->setPen(QPen(Qt::lightGray, 0.0));
painter->drawLine(0, realTop, 0, realBottom);
painter->drawLine(realLeft, 0, realRight, 0);
}
Please help me solve the problem and complete the task.
I tried to do it using itemChange method but nothing happened:
My code to it is as follows:
snap.cpp
#include "snap.h"
#include <QApplication>
Snap::Snap(const QRect& rect, QGraphicsItem* parent,
QGraphicsScene* scene):
QGraphicsRectItem(QRectF())
{
setFlags(QGraphicsItem::ItemIsSelectable |
QGraphicsItem::ItemIsMovable |
QGraphicsItem::ItemSendsGeometryChanges);
}
void Snap::mousePressEvent(QGraphicsSceneMouseEvent *event){
offset = pos() - computeTopLeftGridPoint(pos());
QGraphicsRectItem::mousePressEvent(event);
}
QVariant Snap::itemChange(GraphicsItemChange change,
const QVariant &value)
{
if (change == ItemPositionChange && scene()) {
QPointF newPos = value.toPointF();
if(QApplication::mouseButtons() == Qt::LeftButton &&
qobject_cast<CadGraphicsScene*> (scene())){
QPointF closestPoint = computeTopLeftGridPoint(newPos);
return closestPoint+=offset;
}
else
return newPos;
}
else
return QGraphicsItem::itemChange(change, value);
}
QPointF Snap::computeTopLeftGridPoint(const QPointF& pointP){
CadGraphicsScene* customScene = qobject_cast<CadGraphicsScene*> (scene());
int gridSize = customScene->getGridSize();
qreal xV = floor(pointP.x()/gridSize)*gridSize;
qreal yV = floor(pointP.y()/gridSize)*gridSize;
return QPointF(xV, yV);
}
snap.h
#ifndef SNAP_H
#define SNAP_H
#include <QGraphicsRectItem>
#include "cadgraphicsscene.h"
class Snap : public QGraphicsRectItem
{
public:
Snap(const QRect& rect, QGraphicsItem* parent,
QGraphicsScene* scene);
protected:
void mousePressEvent(QGraphicsSceneMouseEvent *event);
QVariant itemChange(GraphicsItemChange change,
const QVariant &value);
private:
QPointF offset;
QPointF computeTopLeftGridPoint(const QPointF &pointP);
};
#endif // SNAP_H
Please help me out to snap to grid.