Freestyle layout policy. More...
Public Member Functions | |
| MFreestyleLayoutPolicy (MLayout *layout) | |
| virtual | ~MFreestyleLayoutPolicy () |
| virtual void | addItem (QGraphicsLayoutItem *item) |
| void | addItemAtGeometry (QGraphicsLayoutItem *item, const QRectF &geom) |
| void | moveItemTo (QGraphicsLayoutItem *item, const QRectF &geom) |
Protected Member Functions | |
| virtual void | relayout () |
Detailed Description
Freestyle layout policy.
This policy arranges the items as much as possible according to the user's wishes but avoids any overlap. The height is computed as needed.
The following example adds items to the freestyle layout policy in a circle shape:
/* Create a MLayout that we set the policy for */ MLayout *layout = new MLayout; MFreestyleLayoutPolicy *policy = new MFreestyleLayoutPolicy(layout); policy->setSpacing(10); MApplicationWindow window; MApplicationPage page; /* Attach the layout to the page */ page.centralWidget()->setLayout(layout); page.appear(&window); window.show(); int n = 20; for (int i = 0; i < n; ++i) { MLabel *label = new MLabel(QString("Item %1").arg(i + 1)); label->setObjectName("item"); //Place the items in an ellipse with the width and height of the page int center_x = label->preferredWidth() / 2 + (page.geometry().width() - label->preferredWidth()) / 2 * (1 - cos(2 * 3.13 * i / n)); int center_y = 25 + (page.geometry().height() - 50) / 3 * (1 - sin(2 * 3.13 * i / n)); policy->addItemAtGeometry(label, QRect(center_x - label->preferredWidth() / 2, center_y - label->preferredHeight() / 2, label->preferredWidth(), label->preferredHeight())); label->setAlignment(Qt::AlignCenter); }
The result, with appropriate CSS styling, looks like:
- See also:
- MFreestyleLayoutPolicy Example
Definition at line 46 of file corelib/layout/mfreestylelayoutpolicy.h.
Constructor & Destructor Documentation
| MFreestyleLayoutPolicy::MFreestyleLayoutPolicy | ( | MLayout * | layout | ) | [explicit] |
Constructs a freestyle layout policy.
Definition at line 23 of file mfreestylelayoutpolicy.cpp.
:
MAbstractLayoutPolicy(*(new MFreestyleLayoutPolicyPrivate(layout)))
{ }
| MFreestyleLayoutPolicy::~MFreestyleLayoutPolicy | ( | ) | [virtual] |
Member Function Documentation
| void MFreestyleLayoutPolicy::addItem | ( | QGraphicsLayoutItem * | item | ) | [virtual] |
Add an item to the top left hand corner in the freestyle layout.
If the new item overlaps any existing items, the existing items will be moved out of the way.
The item will be given its preferredSize.
- Parameters:
-
item The item to add.
Reimplemented from MAbstractLayoutPolicy.
Definition at line 30 of file mfreestylelayoutpolicy.cpp.
{
addItemAtGeometry(item, QRectF(contentsArea().topLeft(), item->effectiveSizeHint(Qt::PreferredSize)));
}
| void MFreestyleLayoutPolicy::addItemAtGeometry | ( | QGraphicsLayoutItem * | item, | |
| const QRectF & | geom | |||
| ) |
Add an item at a specific geometry in the freestyle layout.
If the new item overlaps any existing items, the existing items will be moved out of the way.
- Parameters:
-
item The item to add. geom The geometry where to add the item.
Definition at line 35 of file mfreestylelayoutpolicy.cpp.
{
Q_D(MFreestyleLayoutPolicy);
MAbstractLayoutPolicy::addItem(item);
QPointF topLeft = contentsArea().topLeft();
//set the item's geometry to geom, bounded by the item's minimum and maximum
//size.
QSizeF maximum = item->effectiveSizeHint(Qt::MaximumSize);
QSizeF minimum = item->effectiveSizeHint(Qt::MinimumSize);
QRectF new_geometry = QRectF(geom.topLeft(), geom.size().boundedTo(maximum).expandedTo(minimum));
QList<QRectF> new_geometries;
const int size = count();
for (int i = 0; i < size - 1; ++i)
new_geometries << itemGeometry(i);
//Add the new item to the list of geometries and place it
new_geometries << new_geometry;
d->placeItem(size - 1, new_geometries, topLeft, contentsArea().width());
for (int i = 0; i < size; ++i)
setItemGeometry(i, new_geometries.at(i));
updateGeometry();
}
| void MFreestyleLayoutPolicy::moveItemTo | ( | QGraphicsLayoutItem * | item, | |
| const QRectF & | geom | |||
| ) |
Move an item to the given geometry.
The given item will be animated to the given geometry, if possible, moving any overlapping items out of the way, if possible.
Definition at line 64 of file mfreestylelayoutpolicy.cpp.
{
Q_D(MFreestyleLayoutPolicy);
int index = indexOf(item);
if (index < 0)
return; //Item not found
QPointF topLeft = contentsArea().topLeft();
QList<QRectF> new_geometries;
const int size = count();
for (int i = 0; i < size; ++i)
new_geometries << itemGeometry(i);
new_geometries[index] = geom;
d->placeItem(index, new_geometries, topLeft, contentsArea().width());
for (int i = 0; i < size; ++i)
setItemGeometry(i, new_geometries.at(i));
updateGeometry();
}
| void MFreestyleLayoutPolicy::relayout | ( | ) | [protected, virtual] |
Callback triggered when a relayout is required.
This method is triggered whenever complete relayout is required (e.g. when the layout itself is resized).
All affected items are computed and the layout is triggered to update the information.
You must override this method in your custom policies.
Implements MAbstractLayoutPolicy.
Definition at line 88 of file mfreestylelayoutpolicy.cpp.
{
Q_D(MFreestyleLayoutPolicy);
QPointF topLeft = contentsArea().topLeft();
QList<QRectF> new_geometries;
const int size = count();
for (int i = 0; i < size; ++i) {
new_geometries << itemGeometry(i);
d->placeItem(i, new_geometries, topLeft, contentsArea().width());
}
QRectF area = contentsArea();
for (int i = 0; i < size; ++i) {
area = area.united(new_geometries.at(i));
setItemGeometry(i, new_geometries.at(i));
}
//if we have moved items outside of the bounding box, we need to invalidate the layout
//causing another relayout, but we have to be careful that we don't end up in an
//infinite loop because of this.
if (area.isValid() && !contentsArea().adjusted(-0.0000001, -0.0000001, 0.0000001, 0.0000001).contains(area)) //adjust for rounding errors
updateGeometry();
}
