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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
#include <QtWidgets>
#include <QPrinter>
void examples()
{
{
//! [0]
QGraphicsScene scene;
scene.addText("Hello, world!");
QGraphicsView view(&scene);
view.show();
//! [0]
}
{
QGraphicsItem *someItem;
//! [1]
QGraphicsScene scene;
scene.addItem(someItem);
//...
QPrinter printer(QPrinter::HighResolution);
printer.setPageSize(QPageSize::A4);
QPainter painter(&printer);
scene.render(&painter);
//! [1]
}
{
int depth;
auto sceneRect = []() {return QRectF(); };
//! [2]
QSizeF segmentSize = sceneRect().size() / pow(2, depth - 1);
//! [2]
}
{
//! [3]
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);
//! [3]
}
{
//! [4]
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));
//! [4]
}
}
class TileScene : public QGraphicsScene
{
public:
TileScene(int numTilesH, int numTilesV, int tileWidth, int tileHeight, QObject *parent = nullptr);
QRectF rectForTile(int x, int y) const;
void setTile(int x, int y, const QPixmap &pixmap);
protected:
void drawBackground(QPainter *painter, const QRectF &exposed) override;
private:
int numTilesH;
int numTilesV;
int tileWidth;
int tileHeight;
QVector<QVector<QPixmap>> tiles;
};
//! [5]
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]);
}
}
}
//! [5]