环境配置 :MinGW + QT 5.12 |
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这种自定义拖拽样式的灵感来自于Chrome浏览器的书签栏。文章中所使用的自定义QListWidget来自于:自定义QListWidget实现item被hover时改变图标样式(模仿网易云音乐选项列表)(方法二)中的TestListWidget类的拓展(在之前的基础上加入了拖拽的代码)。本文中拖拽的特点是:拖拽即选中。
实现的功能及方法:
- 拖拽功能实现:继承QListWidget(重写drag事件)
- item在release时被选中:继承QListWidget(重写mousePressEvent和mouseReleaseEvent)
- item在被hover时改变图标样式:继承QListWigetItem + 继承QStyledItemDelegate
- 绘制dropIndicator:继承QListWidget(使用update()进行控制) + 继承QStyledItemDelegate (使用画笔进行绘制)
拖拽时缩略图thumbnail类:
推荐其它关于拖拽的文章:
- 拖拽之路(原生之初一):自定义QListWidget实现美观的拖拽样式
- 拖拽之路(原生之初二):自定义QListView实现美观的拖拽样式
- 拖拽之路(一):自定义QListWidget实现美观的拖拽样式(拖拽即选中)
- 拖拽之路(二):自定义QListWidget实现美观的拖拽样式(拖拽不影响选中)
- 拖拽之路(三):自定义QListView实现美观的拖拽样式(拖拽即选中)
- 拖拽之路(四):自定义QListView实现美观的拖拽样式(拖拽不影响选中)
- 拖拽之路(五):自定义QListWidget实现美观的拖拽样式(拖拽不影响选中 + doAutoScroll)
这里需要说明一下:QListWidget是鼠标press时item就会被选中,自定义的TestListWidget类重写了mousePressEvent和mouseReleaseEvent使得item在鼠标release时才会被选中。至于为什么这样做,是因为Chrome浏览器的书签栏以及网易云音乐的选项列表都是在鼠标release时才会触发选中…
正是由于item在鼠标release时才会被选中,所以才会出现 拖拽即选中 和 拖拽不影响选中 两种情况,而QListWidget是鼠标press时item就会被选中,所以只能是 拖拽即选中(拖拽的条件是press,导致item在触发拖拽时就被选中)。
(0)TestListWidgetItem类继承自QListWidgetItem
- TestListWidgetItem.h文件:
class TestListWidgetItem : public QListWidgetItem
{
//Q_OBJECT //由于QListWidgetItem没有QObject属性,所以Q_OBJECT需要注释掉
public:
explicit TestListWidgetItem(QListWidget *view = nullptr);
void setUpIcon(const QIcon &icon, const QIcon &icon_hover);
QIcon Img;
QIcon Img_hover;
};
- TestListWidgetItem.c文件:
TestListWidgetItem::TestListWidgetItem(QListWidget *view) :
QListWidgetItem(view)
{
}
void TestListWidgetItem::setUpIcon(const QIcon &icon, const QIcon &icon_hover)
{
Img = icon;
Img_hover = icon_hover;
setIcon(Img);
}
(1)TestListWidget类继承自QListWidget
- TestListWidget.h文件:
class TestListWidget : public QListWidget
{
Q_OBJECT
public:
explicit TestListWidget(QWidget *parent = nullptr);
bool isDraging() const {return IsDraging;}
int offset() const {return 19;}
int highlightedRow() const {return theHighlightedRow;}
int dragRow() const {return theDragRow;}
static QString myMimeType() { return QStringLiteral("TestListWidget/text-icon-icon_hover"); }
protected:
void mousePressEvent(QMouseEvent *event) override;
void mouseReleaseEvent(QMouseEvent *event) override;
void mouseMoveEvent(QMouseEvent *event) override;
void dragEnterEvent(QDragEnterEvent *event) override;
void dragLeaveEvent(QDragLeaveEvent *event) override;
void dragMoveEvent(QDragMoveEvent *event) override;
void dropEvent(QDropEvent *event) override;
private:
QPoint startPos;
bool IsDraging = false;
QRect oldHighlightedRect;
QRect theHighlightedRect;
int theHighlightedRow = -2;
int theDragRow = -1;
const QRect targetRect(const QPoint &position) const;
};
- TestListWidget.c文件:
TestListWidget::TestListWidget(QWidget *parent) :
QListWidget(parent)
{
//setMouseTracking(true); //注释与否没有影响
//setDragEnabled(true); //注释与否没有影响
setAcceptDrops(true);
//setDropIndicatorShown(false); //注释与否没有影响
//setDefaultDropAction(Qt::MoveAction); //注释与否没有影响
}
//拖拽起点
void TestListWidget::mousePressEvent(QMouseEvent *event)
{
if(event->buttons() & Qt::LeftButton){
startPos = event->pos();
}
}
void TestListWidget::mouseReleaseEvent(QMouseEvent *event)
{
if((event->pos() - startPos).manhattanLength() > 5) return;
TestListWidgetItem *item = static_cast<TestListWidgetItem *>(itemAt(event->pos()));
setCurrentItem(item);
}
void TestListWidget::mouseMoveEvent(QMouseEvent *event)
{
if(event->buttons() & Qt::LeftButton){
//[1]超过规定距离才会触发拖拽,防止手滑...
if((event->pos() - startPos).manhattanLength() < QApplication::startDragDistance()) return;
//[1]
TestListWidgetItem *theDragItem = static_cast<TestListWidgetItem *>(itemAt(startPos));
setCurrentItem(theDragItem); //拖拽即选中
theDragRow = row(theDragItem);
//[2]这部分是把拖拽的数据放在QMimeData容器中(参考Qt例程puzzle,使用QByteArray和QDataStream感觉很方便)
QString text = theDragItem->text();
QIcon icon = theDragItem->Img;
QIcon icon_hover = theDragItem->Img_hover;
QByteArray itemData;
QDataStream dataStream(&itemData, QIODevice::WriteOnly);
dataStream << text << icon << icon_hover;
QMimeData *mimeData = new QMimeData;
mimeData->setData(myMimeType(), itemData);
//[2]
//[3]设置拖拽时的缩略图,thumbnail类(找机会我会写一篇单独的文章介绍)是继承自QWidget的类椭圆形半透明窗口,使用grab()将QWidget变成QPixmap。
thumbnail *DragImage = new thumbnail(this);
DragImage->setupthumbnail(icon_hover, text);
//DragImage->setIconSize(18); //default:20
QPixmap pixmap = DragImage->grab();
QDrag *drag = new QDrag(this);
drag->setMimeData(mimeData);
//设置缩略图
drag->setPixmap(pixmap);
//设置鼠标在缩略图上的位置
drag->setHotSpot(QPoint(pixmap.width()/2, pixmap.height()/2));
//[3]
//拖拽开始!
if(drag->exec(Qt::MoveAction) == Qt::MoveAction){
}
}
}
void TestListWidget::dragEnterEvent(QDragEnterEvent *event)
{
TestListWidget *source = qobject_cast<TestListWidget *>(event->source());
if (source && source == this) {
//IsDraging(标志位)判断是否正在拖拽
IsDraging = true;
event->setDropAction(Qt::MoveAction);
event->accept();
}
}
//当拖拽离开QListWidget时,需要update以保证DropIndicator消失
void TestListWidget::dragLeaveEvent(QDragLeaveEvent *event)
{
theHighlightedRow = -2;
update(theHighlightedRect);
//IsDraging(标志位)判断是否正在拖拽
IsDraging = false;
event->accept();
}
//拖拽移动时刷新以更新DropIndicator
void TestListWidget::dragMoveEvent(QDragMoveEvent *event)
{
TestListWidget *source = qobject_cast<TestListWidget *>(event->source());
if (source && source == this) {
oldHighlightedRect = theHighlightedRect;
theHighlightedRect = targetRect(event->pos());
//offset() = 19(这个数值是我调用父类的dropEvent(event)一次一次试出来的,我觉得公式应该是19 = 40 / 2 - 1, 其中40是item行高)
if(event-o>pos().y() >= offset()){
theHighlightedRow = row(itemAt(event->pos() - QPoint(0, offset())));
if(oldHighlightedRect != theHighlightedRect){
update(oldHighlightedRect); //刷新旧区域使DropIndicator消失
update(theHighlightedRect); //刷新新区域使DropIndicator显示
}else
update(theHighlightedRect);
}else{
theHighlightedRow = -1;
update(QRect(0, 0, width(), 80)); //仅刷新第一行
}
event->setDropAction(Qt::MoveAction);
event->accept();
}
}
void TestListWidget::dropEvent(QDropEvent *event)
{
TestListWidget *source = qobject_cast<TestListWidget *>(event->source());
if (source && source == this){
IsDraging = false; //拖拽完成
theHighlightedRow = -2;
update(theHighlightedRect); //拖拽完成,刷新以使DropIndicator消失
QListWidget::dropEvent(event); //因为是拖拽即选中,所以可以直接调用父类的dropEvent(event)
event->setDropAction(Qt::MoveAction);
event->accept();
}
}
const QRect TestListWidget::targetRect(const QPoint &position) const
{
//40是item的行高
if(position.y() >= offset())
return QRect(0, (position.y() - offset()) / 40 * 40, width(), 2 * 40);
else
return QRect(0, 0, width(), 40);
}
(2)TestItemDelegate类继承自QStyledItemDelegate,主要是为了绘制dropIndicator。图示为dropIndicator组成:
- TestItemDelegate.h文件:
#define POLYGON 4 //等腰三角形直角边长
#define WIDTH 1 //分隔符粗细的一半
class TestItemDelegate : public QStyledItemDelegate
{
Q_OBJECT
public:
TestItemDelegate(QObject *parent = nullptr);
protected:
void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const;
};
- TestItemDelegate.c文件:
TestItemDelegate::TestItemDelegate(QObject *parent)
: QStyledItemDelegate(parent)
{
}
void TestItemDelegate::paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const
{
TestListWidget *dragWidget = qobject_cast<TestListWidget *>(option.styleObject);
bool isDraging = dragWidget->isDraging();
QRect rect = option.rect;
painter->setRenderHint(QPainter::Antialiasing, true);
painter->setPen(Qt::NoPen);
if(option.state & (QStyle::State_MouseOver | QStyle::State_Selected)){
TestListWidgetItem *item = static_cast<TestListWidgetItem *>(dragWidget->item(index.row()));
item->setIcon(item->Img_hover);
if(option.state & QStyle::State_MouseOver){
}
if(option.state & QStyle::State_Selected){
painter->setBrush(QColor(180, 0, 0));
painter->drawRect(rect.topLeft().x(), rect.topLeft().y(), 4, rect.height());
painter->setBrush(QColor(230, 231, 234));
painter->drawRect(rect.topLeft().x() + 4, rect.topLeft().y(), rect.width() - 4, rect.height());
}
}else{
TestListWidgetItem *item = static_cast<TestListWidgetItem *>(dragWidget->item(index.row()));
item->setIcon(item->Img);
}
//begin drag
if(isDraging){
int theDragRow = dragWidget->dragRow();
int UpRow = dragWidget->highlightedRow();
int DownRow = UpRow + 1;
int rowCount = dragWidget->count() - 1;
//绘制DropIndicator
if(index.row() == UpRow && index.row() != theDragRow - 1 && index.row() != theDragRow){
painter->setBrush(QColor(66, 133, 244));
if(UpRow == rowCount){
//到达尾部,三角形向上移动一个WIDTH的距离,以使分隔符宽度*2
QPolygon trianglePolygon_bottomLeft;
trianglePolygon_bottomLeft << QPoint(rect.bottomLeft().x(), rect.bottomLeft().y() - (POLYGON + WIDTH) + 1 - WIDTH);
trianglePolygon_bottomLeft << QPoint(rect.bottomLeft().x(), rect.bottomLeft().y() - WIDTH + 1 - WIDTH);
trianglePolygon_bottomLeft << QPoint(rect.bottomLeft().x() + POLYGON, rect.bottomLeft().y() - WIDTH + 1 - WIDTH);
QPolygon trianglePolygon_bottomRight;
trianglePolygon_bottomRight << QPoint(rect.bottomRight().x() + 1, rect.bottomRight().y() - (POLYGON + WIDTH) + 1 - WIDTH);
trianglePolygon_bottomRight << QPoint(rect.bottomRight().x() + 1, rect.bottomRight().y() - WIDTH + 1 - WIDTH);
trianglePolygon_bottomRight << QPoint(rect.bottomRight().x() - POLYGON + 1, rect.bottomRight().y() - WIDTH + 1 - WIDTH);
painter->drawRect(rect.bottomLeft().x(), rect.bottomLeft().y() - 2 * WIDTH + 1, rect.width(), 2 * WIDTH); //rect
painter->drawPolygon(trianglePolygon_bottomLeft);
painter->drawPolygon(trianglePolygon_bottomRight);
}
else {
//正常情况,组成上半部分(+1是根据实际情况修正)
QPolygon trianglePolygon_bottomLeft;
trianglePolygon_bottomLeft << QPoint(rect.bottomLeft().x(), rect.bottomLeft().y() - (POLYGON + WIDTH) + 1);
trianglePolygon_bottomLeft << QPoint(rect.bottomLeft().x(), rect.bottomLeft().y() - WIDTH + 1);
trianglePolygon_bottomLeft << QPoint(rect.bottomLeft().x() + POLYGON, rect.bottomLeft().y() - WIDTH + 1);
QPolygon trianglePolygon_bottomRight;
trianglePolygon_bottomRight << QPoint(rect.bottomRight().x() + 1, rect.bottomRight().y() - (POLYGON + WIDTH) + 1);
trianglePolygon_bottomRight << QPoint(rect.bottomRight().x() + 1, rect.bottomRight().y() - WIDTH + 1);
trianglePolygon_bottomRight << QPoint(rect.bottomRight().x() - POLYGON + 1, rect.bottomRight().y() - WIDTH + 1);
painter->drawRect(rect.bottomLeft().x(), rect.bottomLeft().y() - WIDTH + 1, rect.width(), WIDTH); //rect
painter->drawPolygon(trianglePolygon_bottomLeft);
painter->drawPolygon(trianglePolygon_bottomRight);
}
}
else if(index.row() == DownRow && index.row() != theDragRow + 1 && index.row() != theDragRow){
painter->setBrush(QColor(66, 133, 244));
if(DownRow == 0){
//到达头部,三角形向下移动一个WIDTH的距离,以使分隔符宽度*2
QPolygon trianglePolygon_topLeft;
trianglePolygon_topLeft << QPoint(rect.topLeft().x(), rect.topLeft().y() + (POLYGON + WIDTH) + WIDTH);
trianglePolygon_topLeft << QPoint(rect.topLeft().x(), rect.topLeft().y() + WIDTH + WIDTH);
trianglePolygon_topLeft << QPoint(rect.topLeft().x() + POLYGON, rect.topLeft().y() + WIDTH + WIDTH);
QPolygon trianglePolygon_topRight;
trianglePolygon_topRight << QPoint(rect.topRight().x() + 1, rect.topRight().y() + (POLYGON + WIDTH) + WIDTH);
trianglePolygon_topRight << QPoint(rect.topRight().x() + 1, rect.topRight().y() + WIDTH + WIDTH);
trianglePolygon_topRight << QPoint(rect.topRight().x() - POLYGON + 1, rect.topRight().y() + WIDTH + WIDTH);
painter->drawRect(rect.topLeft().x(), rect.topLeft().y(), rect.width(), 2 * WIDTH); //rect
painter->drawPolygon(trianglePolygon_topLeft);
painter->drawPolygon(trianglePolygon_topRight);
}
else{
//正常情况,组成下半部分(+1是根据实际情况修正)
QPolygon trianglePolygon_topLeft;
trianglePolygon_topLeft << QPoint(rect.topLeft().x(), rect.topLeft().y() + (POLYGON + WIDTH));
trianglePolygon_topLeft << QPoint(rect.topLeft().x(), rect.topLeft().y() + WIDTH);
trianglePolygon_topLeft << QPoint(rect.topLeft().x() + POLYGON, rect.topLeft().y() + WIDTH);
QPolygon trianglePolygon_topRight;
trianglePolygon_topRight << QPoint(rect.topRight().x() + 1, rect.topRight().y() + (POLYGON + WIDTH));
trianglePolygon_topRight << QPoint(rect.topRight().x() + 1, rect.topRight().y() + WIDTH);
trianglePolygon_topRight << QPoint(rect.topRight().x() - POLYGON + 1, rect.topRight().y() + WIDTH);
painter->drawRect(rect.topLeft().x(), rect.topLeft().y(), rect.width(), WIDTH); //rect
painter->drawPolygon(trianglePolygon_topLeft);
painter->drawPolygon(trianglePolygon_topRight);
}
}
QStyledItemDelegate::paint(painter, option, index);
return;
}
//end drag
QStyledItemDelegate::paint(painter, option, index);
}
(3)使用TestListWidgetItem和TestItemDelegate
- 主窗口.h文件:
class test : public QWidget
{
Q_OBJECT
public:
explicit test(QWidget *parent = nullptr);
private:
void initUi();
};
- 主窗口.c文件:
test::test(QWidget *parent) : QWidget(parent)
{
initUi();
}
void test::initUi()
{
setFixedSize(250, 600);
TestListWidget *listwidget = new TestListWidget(this);
listwidget->setIconSize(QSize(25, 25));
listwidget->setFocusPolicy(Qt::NoFocus); //这样可禁用tab键和上下方向键并且除去复选框
listwidget->setFixedHeight(320);
listwidget->setFont(QFont("宋体", 10, QFont::DemiBold));
listwidget->setStyleSheet(
//"*{outline:0px;}" //除去复选框
"QListWidget{background:rgb(245, 245, 247); border:0px; margin:0px 0px 0px 0px;}"
"QListWidget::Item{height:40px; border:0px; padding-left:14px; color:rgba(200, 40, 40, 255);}"
"QListWidget::Item:hover{color:rgba(40, 40, 200, 255); padding-left:14px;}"
"QListWidget::Item:selected{color:rgba(40, 40, 200, 255); padding-left:15px;}"
);
TestItemDelegate *delegate = new TestItemDelegate();
listwidget->setItemDelegate(delegate);
TestListWidgetItem *item1 = new TestListWidgetItem(listwidget);
item1->setUpIcon(QIcon(":/listBar_Icon/1.png"), QIcon(":/listBar_Icon/1_hover.png"));
item1->setText("发现音乐");
TestListWidgetItem *item2 = new TestListWidgetItem(listwidget);
item2->setUpIcon(QIcon(":/listBar_Icon/2.png"), QIcon(":/listBar_Icon/2_hover.png"));
item2->setText("私人FM");
TestListWidgetItem *item3 = new TestListWidgetItem(listwidget);
item3->setUpIcon(QIcon(":/listBar_Icon/3.png"), QIcon(":/listBar_Icon/3_hover.png"));
item3->setText("朋友");
TestListWidgetItem *item4 = new TestListWidgetItem(listwidget);
item4->setUpIcon(QIcon(":/listBar_Icon/4.png"), QIcon(":/listBar_Icon/4_hover.png"));
item4->setText("MV");
TestListWidgetItem *item5 = new TestListWidgetItem(listwidget);
item5->setUpIcon(QIcon(":/listBar_Icon/5.png"), QIcon(":/listBar_Icon/5_hover.png"));
item5->setText("本地音乐");
TestListWidgetItem *item6 = new TestListWidgetItem(listwidget);
item6->setUpIcon(QIcon(":/listBar_Icon/6.png"), QIcon(":/listBar_Icon/6_hover.png"));
item6->setText("下载管理");
TestListWidgetItem *item7 = new TestListWidgetItem(listwidget);
item7->setUpIcon(QIcon(":/listBar_Icon/7.png"), QIcon(":/listBar_Icon/7_hover.png"));
item7->setText("我的音乐云盘");
TestListWidgetItem *item8 = new TestListWidgetItem(listwidget);
item8->setUpIcon(QIcon(":/listBar_Icon/8.png"), QIcon(":/listBar_Icon/8_hover.png"));
item8->setText("我的收藏");
QVBoxLayout *layout = new QVBoxLayout(this);
layout->setSpacing(0);
layout->addWidget(listwidget);
layout->setContentsMargins(0, 0, 0, 0);
setLayout(layout);
}
如果想要接触更多关于拖拽的代码,在Qt例程中搜索“drag”。推荐看一下例程puzzle的两种实现方法(一种是继承QListWidget,另一种是QListView + 继承QAbstractListModel)。
环境配置 :MinGW + QT 5.12 |