grid_view Class Reference

Scrollable grid of stream thumbnails. More...

#include <frontend/include/widgets/grid_view.hpp>

Inheritance diagram for grid_view:

Collaboration diagram for grid_view:

Signals
void	stream_closed (const QString &name)
	Emitted after a stream cell was closed and removed.
void	stream_enlarge (const QString &name)
	Emitted when a stream cell requests focus/enlargement.

Public Member Functions
	grid_view (QWidget *parent=nullptr)
	Construct an empty grid view.
bool	has_stream (const QString &name) const
	Check whether a stream with given name exists in the grid.
QStringList	stream_names () const
	Get names of all streams currently in the grid.
void	add_stream (const QString &name)
	Add a new stream cell to the grid.
void	remove_stream (const QString &name)
	Remove a stream cell from the grid.
stream_cell *	take_stream_cell (const QString &name)
	Detach a stream cell from the grid without deleting it.
void	put_stream_cell (stream_cell *cell)
	Return a previously taken cell back into the grid.
stream_cell *	peek_stream_cell (const QString &name) const
	Get a pointer to a cell without removing it.

Private Member Functions
void	rebuild_layout ()
	Recompute and rebuild the grid layout.
void	close_requested (const QString &name)
	Internal handler for stream_cell::request_close.
void	enlarge_requested (const QString &name)
	Internal handler for stream_cell::request_focus.

Private Attributes
QScrollArea *	scroll
	Scroll area wrapping the grid container.
QWidget *	grid_container
	Widget that owns the grid layout and all tiles.
QGridLayout *	grid_layout
	Grid layout arranging tiles.
QMap< QString, stream_cell * >	tiles
	Map of stream name to corresponding tile widget.

Detailed Description

Scrollable grid of stream thumbnails.

Responsibilities:

• Own and display a collection of stream_cell widgets in a grid.
• Rebuild the layout when the set changes, choosing a roughly square grid.
• Forward user intents from individual cells via signals:
  • close requests -> stream_closed
  • focus/enlarge requests -> stream_enlarge

Ownership model:

• grid_view owns all cells currently present in the grid.
• take_stream_cell transfers a cell out of the grid without deleting it (caller is expected to reparent/place it elsewhere).
• put_stream_cell returns a cell back into the grid.

Threading:

• UI class; all methods are expected to be called from the Qt GUI thread.

Definition at line 44 of file grid_view.hpp.

Constructor & Destructor Documentation

grid_view()

grid_view::grid_view ( QWidget * parent = nullptr )

explicit

Construct an empty grid view.

Creates an internal QScrollArea with a container widget holding a QGridLayout. The scroll area is configured for horizontal scrolling when needed and no vertical scrollbar (layout expands horizontally).

Parameters

parent

Optional parent widget.

Definition at line 13 of file grid_view.cpp.

    : QWidget(parent)
    , scroll(new QScrollArea(this))
    , grid_container(new QWidget(scroll))
    , grid_layout(new QGridLayout(grid_container)) {
    grid_layout->setContentsMargins(6, 6, 6, 6);
    grid_layout->setSpacing(6);
 
    grid_container->setLayout(grid_layout);
 
    scroll->setWidgetResizable(true);
    scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAsNeeded);
    scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    scroll->setWidget(grid_container);
 
    auto* outer = new QVBoxLayout(this);
    outer->setContentsMargins(0, 0, 0, 0);
    outer->addWidget(scroll);
    setLayout(outer);
}

References grid_layout, and scroll.

Referenced by controller::setup_grid_connections().

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Member Function Documentation

add_stream()

void grid_view::add_stream

(

const QString &

name

)

Add a new stream cell to the grid.

If name is empty or already present, the call is ignored. The created cell is connected to internal handlers and the layout is rebuilt.

Parameters

name	Logical stream name.

Definition at line 40 of file grid_view.cpp.

                                              {
    if (name.isEmpty() || tiles.contains(name)) {
        return;
    }
 
    auto* tile = new stream_cell(name, grid_container);
    tile->setMinimumSize(kMinTileW, kMinTileH);
    tile->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);
 
    connect(
        tile, &stream_cell::request_close, this, &grid_view::close_requested
    );
    connect(
        tile, &stream_cell::request_focus, this, &grid_view::enlarge_requested
    );
 
    tiles.insert(name, tile);
    rebuild_layout();
}

References kMinTileH, kMinTileW, and rebuild_layout().

Referenced by controller::handle_show_stream_changed().

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close_requested()

void grid_view::close_requested ( const QString & name )

private

Internal handler for stream_cell::request_close.

Removes the stream and emits stream_closed.

Parameters

name	Stream name.

Definition at line 116 of file grid_view.cpp.

                                                   {
    remove_stream(name);
    emit stream_closed(name);
}

enlarge_requested()

void grid_view::enlarge_requested ( const QString & name )

private

Internal handler for stream_cell::request_focus.

Emits stream_enlarge.

Parameters

name	Stream name.

Definition at line 121 of file grid_view.cpp.

                                                     {
    emit stream_enlarge(name);
}

has_stream()

bool grid_view::has_stream

(

const QString &

name

)

const

Check whether a stream with given name exists in the grid.

Parameters

name	Stream name.

Returns

true if a cell with that name is present.

Definition at line 34 of file grid_view.cpp.

                                                    {
    return tiles.contains(name);
}

peek_stream_cell()

stream_cell * grid_view::peek_stream_cell

(

const QString &

name

)

const

Get a pointer to a cell without removing it.

Parameters

name	Stream name.

Returns

Pointer to the cell, or nullptr if not found.

Definition at line 108 of file grid_view.cpp.

                                                                  {
    const auto it = tiles.find(name);
    if (it == tiles.end()) {
        return nullptr;
    }
    return it.value();
}

Referenced by controller::handle_show_stream_changed(), and controller::tile_for_stream_name().

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put_stream_cell()

void grid_view::put_stream_cell

(

stream_cell *

cell

)

Return a previously taken cell back into the grid.

The cell is reparented to the grid container, inserted by its name, shown, and the layout is rebuilt. If a cell with the same name already exists, the call is ignored.

Parameters

cell	Cell to put back.

Definition at line 91 of file grid_view.cpp.

                                                 {
    if (!cell) {
        return;
    }
 
    const QString name = cell->get_name();
    if (tiles.contains(name)) {
        return;
    }
 
    cell->setParent(grid_container);
    tiles.insert(name, cell);
    cell->show();
 
    rebuild_layout();
}

References rebuild_layout().

Referenced by board::clear_active(), and board::set_active_stream().

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rebuild_layout()

void grid_view::rebuild_layout ( )

private

Recompute and rebuild the grid layout.

Clears existing layout items, hides widgets during rebuild, and places all current tiles into a grid with approximately sqrt(n) columns, stretched equally.

If there are no tiles, the widget hides itself.

Definition at line 127 of file grid_view.cpp.

                               {
    // todo fix layout
    while (grid_layout->count() > 0) {
        auto* item = grid_layout->takeAt(0);
        if (item->widget()) {
            item->widget()->hide();
        }
        delete item;
    }
 
    const int n = static_cast<int>(tiles.size());
    if (n == 0) {
        this->hide();
        updateGeometry();
        return;
    }
    this->show();
 
    const int cols = qCeil(qSqrt(static_cast<double>(n)));
    const int rows = ceil_div(n, cols);
 
    for (int c = 0; c < cols; ++c) {
        grid_layout->setColumnStretch(c, 1);
    }
    for (int r = 0; r < rows; ++r) {
        grid_layout->setRowStretch(r, 1);
    }
 
    int idx = 0;
    for (auto it = tiles.cbegin(); it != tiles.cend(); ++it, ++idx) {
        const int r = idx / cols;
        const int c = idx % cols;
        auto* tile = it.value();
        tile->show();
        grid_layout->addWidget(tile, r, c);
    }
 
    grid_container->updateGeometry();
}

References ceil_div(), and grid_layout.

Referenced by add_stream(), put_stream_cell(), remove_stream(), and take_stream_cell().

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remove_stream()

void grid_view::remove_stream

(

const QString &

name

)

Remove a stream cell from the grid.

If no such stream exists, this is a no-op. Otherwise the cell is removed from the layout and scheduled for deletion with deleteLater().

Parameters

name	Logical stream name.

Definition at line 60 of file grid_view.cpp.

                                                 {
    const auto it = tiles.find(name);
    if (it == tiles.end()) {
        return;
    }
 
    auto* tile = it.value();
    tiles.erase(it);
 
    grid_layout->removeWidget(tile);
    tile->deleteLater();
 
    rebuild_layout();
}

References grid_layout, and rebuild_layout().

Referenced by controller::handle_show_stream_changed().

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stream_closed

void grid_view::stream_closed ( const QString & name )

signal

Emitted after a stream cell was closed and removed.

Triggered by the close button in a cell.

Parameters

name	Name of the closed stream.

stream_enlarge

void grid_view::stream_enlarge ( const QString & name )

signal

Emitted when a stream cell requests focus/enlargement.

Triggered by the focus/enlarge button in a cell.

Parameters

name	Name of the stream to enlarge.

Referenced by controller::setup_grid_connections().

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stream_names()

QStringList grid_view::stream_names

(

)

const

Get names of all streams currently in the grid.

Returns

List of stream names in insertion/order of the internal map.

Definition at line 38 of file grid_view.cpp.

{ return tiles.keys(); }

take_stream_cell()

stream_cell * grid_view::take_stream_cell

(

const QString &

name

)

Detach a stream cell from the grid without deleting it.

This is used when a stream becomes "active" elsewhere. The cell is:

• removed from internal map,
• removed from the layout,
• hidden,
• returned to the caller.

Layout is rebuilt afterwards.

Parameters

name	Stream name to take.

Returns

Pointer to the detached cell, or nullptr if not found.

Definition at line 75 of file grid_view.cpp.

                                                            {
    auto it = tiles.find(name);
    if (it == tiles.end()) {
        return nullptr;
    }
 
    stream_cell* cell = it.value();
 
    tiles.erase(it);
    grid_layout->removeWidget(cell);
    cell->hide();
 
    rebuild_layout();
    return cell;
}

References grid_layout, and rebuild_layout().

Referenced by board::set_active_stream().

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Member Data Documentation

grid_container

QWidget* grid_view::grid_container

private

Widget that owns the grid layout and all tiles.

Definition at line 183 of file grid_view.hpp.

grid_layout

QGridLayout* grid_view::grid_layout

private

Grid layout arranging tiles.

Definition at line 186 of file grid_view.hpp.

Referenced by grid_view(), rebuild_layout(), remove_stream(), and take_stream_cell().

scroll

QScrollArea* grid_view::scroll

private

Scroll area wrapping the grid container.

Definition at line 180 of file grid_view.hpp.

Referenced by grid_view().

tiles

QMap<QString, stream_cell*> grid_view::tiles

private

Map of stream name to corresponding tile widget.

Definition at line 189 of file grid_view.hpp.

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The documentation for this class was generated from the following files:

• grid_view.hpp
• grid_view.cpp