为什么使用QGraphicsView::scale， 当scale的参数小于1时我的QGraphicsScene上的item就全部消失了？

superwavelet 2010-11-15 12:43:14
当scale的参数大于1时可以正确放大，但是scale的参数小于1时我的QGraphicsScene上的item就全部消失了？
求指教

部分代码如下：



#include "iitems.h"

#include <QtGui>

#include "Link.h"

#include "Node.h"

#include "propertiesdialog.h"

#include <QWidget>



extern float Xmax,Ymax;

extern int VisZoom;

extern float iData[6376][3];

extern float xx,yy;



iItems::iItems()

{

	QSplitter *MainSplitter = new QSplitter(Qt::Horizontal);

	QSplitter * WidgetRight = new QSplitter(Qt::Vertical);

	QWidget *SubWidget1 = new QWidget;

	QWidget *SubWidget2 = new QWidget;



	//QWidget *area= new QWidget;

	view = new QGraphicsView;



	spinBox1 = new QSpinBox;

	QSlider *slider1 = new QSlider(Qt::Horizontal);

	spinBox1->setRange(1, 9);

	spinBox1->setValue(1);

	SpinBoxValue1=spinBox1->value();

    VisZoom=10;

	slider1->setRange(1, 9);



	QObject::connect(spinBox1, SIGNAL(valueChanged(int)),

		slider1, SLOT(setValue(int)));

	QObject::connect(slider1, SIGNAL(valueChanged(int)),

		spinBox1, SLOT(setValue(int)));

	QObject::connect(spinBox1, SIGNAL(valueChanged(int)),

		this, SLOT(setVisZoom()));



	QHBoxLayout *layout1 = new QHBoxLayout;

	layout1->addWidget(spinBox1);

	layout1->addWidget(slider1);

	SubWidget1->setLayout(layout1);



	QSpinBox *spinBox2 = new QSpinBox;

	QSlider *slider2 = new QSlider(Qt::Horizontal);

	spinBox2->setRange(0, 130);

	spinBox2->setValue(25);

	slider2->setRange(0, 130);

	QObject::connect(spinBox2, SIGNAL(valueChanged(int)),

		slider2, SLOT(setValue(int)));

	QObject::connect(slider2, SIGNAL(valueChanged(int)),

		spinBox2, SLOT(setValue(int)));



	QHBoxLayout *layout2 = new QHBoxLayout;

	layout2->addWidget(spinBox2);

	layout2->addWidget(slider2);

	SubWidget2->setLayout(layout2);



	WidgetRight->addWidget(SubWidget1);

	WidgetRight->addWidget(SubWidget2);



	MainSplitter->addWidget(view);

	MainSplitter->addWidget(WidgetRight);



	view->setDragMode(QGraphicsView::RubberBandDrag);// 选择多个节点方式：1.按ctrl；2.设置橡皮筋方式

	view->setRenderHints(QPainter::Antialiasing

		| QPainter::TextAntialiasing);

	view->setContextMenuPolicy(Qt::ActionsContextMenu);// 右键菜单

	setCentralWidget(MainSplitter);



	scene = new QGraphicsScene(0, 0, Xmax*VisZoom, Ymax*VisZoom);// 创建场景，起始点为(0,0), 宽600，高500

	view->setScene(scene);// 显示场景

	view->setStyleSheet("background-color:gray");



	minZ = 0;

	maxZ = 0;

	seqNumber = 0;

	createActions();

	createMenus();

	createToolBars();

	connect(scene, SIGNAL(selectionChanged()),

		this, SLOT(updateActions()));

	setWindowTitle(tr("Diagram"));

	updateActions();

}





// 增加一个节点

void iItems::addNode1()

{

	Node *node = new Node;

	node->setText(tr("Node %1").arg(seqNumber + 1));

	setupNode1(node);

}



void iItems::setupNode1(Node *node)

{

	node->setPos(QPoint(80 + (100 * (seqNumber % 5)),



		80 + (50 * ((seqNumber / 5) % 7))));

	scene->addItem(node);

	++seqNumber;

	scene->clearSelection();

	node->setSelected(true);

	bringToFront();

}



void iItems::bringToFront()

{

	++maxZ;

	setZValue(maxZ);

}

void iItems::sendToBack()

{

	--minZ;

	setZValue(minZ);

}

void iItems::setZValue(int z)

{

	Node *node = selectedNode();

	if (node)

		node->setZValue(z);

}



Node *iItems::selectedNode() const

{

	QList<QGraphicsItem *> items = scene->selectedItems();

	if (items.count() == 1) {

		return dynamic_cast<Node *>(items.first());

	} else {

		return 0;

	}

}



void iItems::addLink()

{

	NodePair nodes = selectedNodePair();

	if (nodes == NodePair())

		return;

	Link *link = new Link(nodes.first, nodes.second);

	scene->addItem(link);

}
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superwavelet 2010-11-15
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接ls的代码






iItems::NodePair iItems::selectedNodePair() const

{

	QList<QGraphicsItem *> items = scene->selectedItems();

	if (items.count() == 2) {

		Node *first = dynamic_cast<Node *>(items.first());

		Node *second = dynamic_cast<Node *>(items.last());

		if (first && second)

			return NodePair(first, second);

	}

	return NodePair();

}

// 删除选择的图元：首先删除连线，然后删除节点，以防止多次删除同一个连线

void iItems::del()

{

	QList<QGraphicsItem *> items = scene->selectedItems();

	QMutableListIterator<QGraphicsItem *> i(items);

	while (i.hasNext()) {

		Link *link = dynamic_cast<Link *>(i.next());

		if (link) {

			delete link;

			i.remove();

		}

	}

	qDeleteAll(items);

}



void iItems::properties()

{

	Node *node = selectedNode();

	Link *link = selectedLink();

	if (node) {

		PropertiesDialog dialog(node, this);

		dialog.exec();

	} else if (link) {

		QColor color = QColorDialog::getColor(link->color(), this);

		if (color.isValid())

			link->setColor(color);

	}

}



// 剪切操作：先复制，后删除

void iItems::cut()

{

	Node *node = selectedNode();

	if (!node)

		return;

	copy();

	delete node;

}

// 拷贝操作：值得研究！！！

void iItems::copy()

{

	Node *node = selectedNode();

	if (!node)

		return;

	QString str = QString("Node %1 %2 %3 %4")

		.arg(node->textColor().name())

		.arg(node->outlineColor().name())

		.arg(node->backgroundColor().name())

		.arg(node->text());



		QApplication::clipboard()->setText(str);

}



void iItems::paste()

{

	QString str = QApplication::clipboard()->text();

	QStringList parts = str.split(" ");

	if (parts.count() >= 5 && parts.first() == "Node") {

		Node *node = new Node;

		node->setText(QStringList(parts.mid(4)).join(" "));// 连接字符串列表

		node->setTextColor(QColor(parts[1]));

		node->setOutlineColor(QColor(parts[2]));

		node->setBackgroundColor(QColor(parts[3]));

		setupNode1(node);

	}

}







// 更新动作使能



void iItems::updateActions()

{

	bool hasSelection = !scene->selectedItems().isEmpty();

	bool isNode = (selectedNode() != 0);

	bool isNodePair = (selectedNodePair() != NodePair());

	cutAction->setEnabled(isNode);

	copyAction->setEnabled(isNode);

	addLinkAction->setEnabled(isNodePair);

	deleteAction->setEnabled(hasSelection);

	bringToFrontAction->setEnabled(isNode);

	sendToBackAction->setEnabled(isNode);

	propertiesAction->setEnabled(isNode);

	foreach (QAction *action, view->actions())

		view->removeAction(action);  // 删除右键菜单



	foreach (QAction *action, editMenu->actions()) {

		if (action->isEnabled())

			view->addAction(action);  // 增加右键菜单

	}

}





void iItems::createActions()

{

	exitAction = new QAction(tr("E&xit"), this);

	exitAction->setShortcut(tr("Ctrl+Q"));

	connect(exitAction, SIGNAL(triggered()), this, SLOT(close()));



    openAction = new QAction(tr("&Open Data"),this);

	connect(openAction, SIGNAL(triggered()), this, SLOT(openFile()));



	addNodeAction = new QAction(tr("Add &Node"), this);

	addNodeAction->setIcon(QIcon(":/images/node.png"));

	addNodeAction->setShortcut(tr("Ctrl+N"));

	connect(addNodeAction, SIGNAL(triggered()), this, SLOT(addNode1()));



	addLinkAction = new QAction(tr("Add &Link"), this);

	addLinkAction->setIcon(QIcon(":/images/link.png"));

	addLinkAction->setShortcut(tr("Ctrl+L"));

	connect(addLinkAction, SIGNAL(triggered()), this, SLOT(addLink()));



	deleteAction = new QAction(tr("&Delete"), this);

	deleteAction->setIcon(QIcon(":/images/delete.png"));

	deleteAction->setShortcut(tr("Del"));

	connect(deleteAction, SIGNAL(triggered()), this, SLOT(del()));



	cutAction = new QAction(tr("Cu&t"), this);

	cutAction->setIcon(QIcon(":/images/cut.png"));

	cutAction->setShortcut(tr("Ctrl+X"));

	connect(cutAction, SIGNAL(triggered()), this, SLOT(cut()));



	copyAction = new QAction(tr("©"), this);

	copyAction->setIcon(QIcon(":/images/copy.png"));

	copyAction->setShortcut(tr("Ctrl+C"));

	connect(copyAction, SIGNAL(triggered()), this, SLOT(copy()));



	pasteAction = new QAction(tr("&Paste"), this);

	pasteAction->setIcon(QIcon(":/images/paste.png"));

	pasteAction->setShortcut(tr("Ctrl+V"));

	connect(pasteAction, SIGNAL(triggered()), this, SLOT(paste()));



	bringToFrontAction = new QAction(tr("Bring to &Front"), this);

	bringToFrontAction->setIcon(QIcon(":/images/bringtofront.png"));

	connect(bringToFrontAction, SIGNAL(triggered()),

		this, SLOT(bringToFront()));



	sendToBackAction = new QAction(tr("&Send to Back"), this);

	sendToBackAction->setIcon(QIcon(":/images/sendtoback.png"));

	connect(sendToBackAction, SIGNAL(triggered()),

		this, SLOT(sendToBack()));



	propertiesAction = new QAction(tr("P&roperties..."), this);

	connect(propertiesAction, SIGNAL(triggered()),

		this, SLOT(properties()));

}



void iItems::createMenus()

{

	fileMenu = menuBar()->addMenu(tr("&File"));

	fileMenu->addAction(exitAction);

	fileMenu->addAction(openAction);

	editMenu = menuBar()->addMenu(tr("&Edit"));

	editMenu->addAction(addNodeAction);

	editMenu->addAction(addLinkAction);

	editMenu->addAction(deleteAction);

	editMenu->addSeparator();

	editMenu->addAction(cutAction);

	editMenu->addAction(copyAction);

	editMenu->addAction(pasteAction);

	editMenu->addSeparator();

	editMenu->addAction(bringToFrontAction);

	editMenu->addAction(sendToBackAction);

	editMenu->addSeparator();

	editMenu->addAction(propertiesAction);

}



void iItems::createToolBars()

{

	editToolBar = addToolBar(tr("Edit"));

	editToolBar->addAction(addNodeAction);

	editToolBar->addAction(addLinkAction);

	editToolBar->addAction(deleteAction);

	editToolBar->addSeparator();

	editToolBar->addAction(cutAction);

	editToolBar->addAction(copyAction);

	editToolBar->addAction(pasteAction);

	editToolBar->addSeparator();

	editToolBar->addAction(bringToFrontAction);

	editToolBar->addAction(sendToBackAction);

}



Link *iItems::selectedLink() const

{

	QList<QGraphicsItem *> items = scene->selectedItems();

	if (items.count() == 1) {

		return dynamic_cast<Link *>(items.first());

	} else {

		return 0;

	}

}

void iItems::openFile(const QString &path)

{

	QString fileName;

	if (path.isNull())

		fileName = QFileDialog::getOpenFileName(this, tr("Open Data File"),

		currentPath, "*.plain");

	else

		fileName = path;



	if (!fileName.isEmpty()) {

		this->openFile(fileName);

		if (!fileName.startsWith(":/")) {

			currentPath = fileName;

			setWindowTitle(tr("%1 - iItem").arg(currentPath));

		}

	}

}



void iItems::setupNode2(Node *node)

{

	node->setScale(0.3);

	scene->addItem(node);

    

	scene->clearSelection();

	node->setSelected(true);

}

void iItems::setVisZoom()

{

    view->scale(spinBox1->value()/SpinBoxValue1,spinBox1->value()/SpinBoxValue1);

	SpinBoxValue1=spinBox1->value();

}
superwavelet 2010-11-15
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我知道怎么回事啦，是整型四舍五入了
libinfei8848 2010-11-15
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达到一定的比例尺了，很多设备汇聚在一个像素点这样展示没有意义，就直接控制不显示了
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