src_gui_graphicsview_qgraphicsscene.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
 
QGraphicsScene scene;
scene.addText("Hello, world!");
 
QGraphicsView view(&scene);
view.show();
 
 
QGraphicsScene scene;
scene.addItem(...
...
QPrinter printer(QPrinter::HighResolution);
printer.setPaperSize(QPrinter::A4);
 
QPainter painter(&printer);
scene.render(&painter);
 
 
QSizeF segmentSize = sceneRect().size() / pow(2, depth - 1);
 
 
QGraphicsScene scene;
QGraphicsView view(&scene);
view.show();
 
// a blue background
scene.setBackgroundBrush(Qt::blue);
 
// a gradient background
QRadialGradient gradient(0, 0, 10);
gradient.setSpread(QGradient::RepeatSpread);
scene.setBackgroundBrush(gradient);
 
 
QGraphicsScene scene;
QGraphicsView view(&scene);
view.show();
 
// a white semi-transparent foreground
scene.setForegroundBrush(QColor(255, 255, 255, 127));
 
// a grid foreground
scene.setForegroundBrush(QBrush(Qt::lightGray, Qt::CrossPattern));
 
 
QRectF TileScene::rectForTile(int x, int y) const
{
    // Return the rectangle for the tile at position (x, y).
    return QRectF(x * tileWidth, y * tileHeight, tileWidth, tileHeight);
}
 
void TileScene::setTile(int x, int y, const QPixmap &pixmap)
{
    // Sets or replaces the tile at position (x, y) with pixmap.
    if (x >= 0 && x < numTilesH && y >= 0 && y < numTilesV) {
        tiles[y][x] = pixmap;
        invalidate(rectForTile(x, y), BackgroundLayer);
    }
}
 
void TileScene::drawBackground(QPainter *painter, const QRectF &exposed)
{
    // Draws all tiles that intersect the exposed area.
    for (int y = 0; y < numTilesV; ++y) {
        for (int x = 0; x < numTilesH; ++x) {
            QRectF rect = rectForTile(x, y);
            if (exposed.intersects(rect))
                painter->drawPixmap(rect.topLeft(), tiles[y][x]);
        }
    }
}