QGraphicsItem交互式调整大小 [英] QGraphicsItem interactive resizing
问题描述
我分叉了项目 https://github.com/cesarbs/sizegripitem 交互QGraphicsItem的大小调整为8个处理程序，问题是如果我将主QGraphicsItem设置为Selectable，则当我拖动处理程序时，主QGraphicsItem会移动而不是重新调整大小，下面是SizeGripItem.cpp
i've forked the project https://github.com/cesarbs/sizegripitem that is a intercative QGraphicsItem resizing with 8 handlers, the problem is that if i set my main QGraphicsItem to be Selectable, when i drag the handlers, the main QGraphicsItem moves rather then being resized, bellow is the source for SizeGripItem.cpp
/*
* SizeGripItem - A size grip QGraphicsItem for interactive resizing.
*
* Copyright (c) 2011 Cesar L. B. Silveira
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <QBrush>
#include "SizeGripItem.h"
SizeGripItem::HandleItem::HandleItem(int positionFlags, SizeGripItem* parent)
: QGraphicsRectItem(-4, -4, 8, 8, parent),
positionFlags_(positionFlags),
parent_(parent)
{
setBrush(QBrush(Qt::lightGray));
setFlag(ItemIsMovable);
setFlag(ItemSendsGeometryChanges);
}
int SizeGripItem::HandleItem::positionFlags() const
{
return positionFlags_;
}
QVariant SizeGripItem::HandleItem::itemChange(GraphicsItemChange change,
const QVariant &value)
{
QVariant retVal = value;
if (change == ItemPositionChange)
{
retVal = restrictPosition(value.toPointF());
}
else if (change == ItemPositionHasChanged)
{
QPointF pos = value.toPointF();
switch (positionFlags_)
{
case TopLeft:
parent_->setTopLeft(pos);
break;
case Top:
parent_->setTop(pos.y());
break;
case TopRight:
parent_->setTopRight(pos);
break;
case Right:
parent_->setRight(pos.x());
break;
case BottomRight:
parent_->setBottomRight(pos);
break;
case Bottom:
parent_->setBottom(pos.y());
break;
case BottomLeft:
parent_->setBottomLeft(pos);
break;
case Left:
parent_->setLeft(pos.x());
break;
}
}
return retVal;
}
QPointF SizeGripItem::HandleItem::restrictPosition(const QPointF& newPos)
{
QPointF retVal = pos();
if (positionFlags_ & Top || positionFlags_ & Bottom)
retVal.setY(newPos.y());
if (positionFlags_ & Left || positionFlags_ & Right)
retVal.setX(newPos.x());
if (positionFlags_ & Top && retVal.y() > parent_->rect_.bottom())
retVal.setY(parent_->rect_.bottom());
else if (positionFlags_ & Bottom && retVal.y() < parent_->rect_.top())
retVal.setY(parent_->rect_.top());
if (positionFlags_ & Left && retVal.x() > parent_->rect_.right())
retVal.setX(parent_->rect_.right());
else if (positionFlags_ & Right && retVal.x() < parent_->rect_.left())
retVal.setX(parent_->rect_.left());
return retVal;
}
SizeGripItem::SizeGripItem(Resizer* resizer, QGraphicsItem* parent)
: QGraphicsItem(parent),
resizer_(resizer)
{
if (parentItem())
rect_ = parentItem()->boundingRect();
handleItems_.append(new HandleItem(TopLeft, this));
handleItems_.append(new HandleItem(Top, this));
handleItems_.append(new HandleItem(TopRight, this));
handleItems_.append(new HandleItem(Right, this));
handleItems_.append(new HandleItem(BottomRight, this));
handleItems_.append(new HandleItem(Bottom, this));
handleItems_.append(new HandleItem(BottomLeft, this));
handleItems_.append(new HandleItem(Left, this));
updateHandleItemPositions();
}
SizeGripItem::~SizeGripItem()
{
if (resizer_)
delete resizer_;
}
QRectF SizeGripItem::boundingRect() const
{
return rect_;
}
void SizeGripItem::paint(QPainter* painter,
const QStyleOptionGraphicsItem* option,
QWidget* widget)
{
}
#define IMPL_SET_FN(TYPE, POS) \
void SizeGripItem::set ## POS (TYPE v) \
{ \
rect_.set ## POS (v); \
doResize(); \
}
IMPL_SET_FN(qreal, Top)
IMPL_SET_FN(qreal, Right)
IMPL_SET_FN(qreal, Bottom)
IMPL_SET_FN(qreal, Left)
IMPL_SET_FN(const QPointF&, TopLeft)
IMPL_SET_FN(const QPointF&, TopRight)
IMPL_SET_FN(const QPointF&, BottomRight)
IMPL_SET_FN(const QPointF&, BottomLeft)
void SizeGripItem::doResize()
{
if (resizer_)
{
(*resizer_)(parentItem(), rect_);
updateHandleItemPositions();
}
}
void SizeGripItem::updateHandleItemPositions()
{
foreach (HandleItem* item, handleItems_)
{
item->setFlag(ItemSendsGeometryChanges, false);
switch (item->positionFlags())
{
case TopLeft:
item->setPos(rect_.topLeft());
break;
case Top:
item->setPos(rect_.left() + rect_.width() / 2 - 1,
rect_.top());
break;
case TopRight:
item->setPos(rect_.topRight());
break;
case Right:
item->setPos(rect_.right(),
rect_.top() + rect_.height() / 2 - 1);
break;
case BottomRight:
item->setPos(rect_.bottomRight());
break;
case Bottom:
item->setPos(rect_.left() + rect_.width() / 2 - 1,
rect_.bottom());
break;
case BottomLeft:
item->setPos(rect_.bottomLeft());
break;
case Left:
item->setPos(rect_.left(),
rect_.top() + rect_.height() / 2 - 1);
break;
}
item->setFlag(ItemSendsGeometryChanges, true);
}
}
推荐答案
在SizeGripItem :: HandleItem :: itemChange中设置父位置在这里看起来很奇怪.我认为itemChange函数可能不应该设置父项的位置.它应该只调整坐标并返回一个值.
Setting the parent positions in SizeGripItem::HandleItem::itemChange looks odd here. I think that the itemChange function probably should not be setting the position of the parent item. It should only adjust coordinates and return a value.
过去，我的做法有所不同.首先，删除HandleItem中的ItemSendsGeometryChanges标志.
In the past, I've done this a little differently. Firstly, remove the ItemSendsGeometryChanges flag in the HandleItem.
然后为HandleItem实现mousePressEvent，mouseMoveEvent和mouseReleaseEvent.在mouseMoveEvent中，随着手柄的移动，更新父对象的边界矩形.
Then implement mousePressEvent, mouseMoveEvent and mouseReleaseEvent for HandleItem. In mouseMoveEvent, update the parent's bounding rect as the handle is moved.
这允许同时将主GraphicsItem及其句柄设置为可选和可移动.
This allows both the main GraphicsItem and its handles to be set as selectable and moveable.
这篇关于QGraphicsItem交互式调整大小的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
