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前文链接：QGraphicsView实现简易地图10『自适应窗口大小』
提供一个地图初始化函数，指定地图显示的中心点和地图缩放层级
能够让地图显示某一层级的瓦片，并将中心点坐标显示在视图中心。
1、动态演示效果
7级地图-大连-老虎滩 定位到 8级地图-台湾-台北

2、指定层级-定位坐标的代码

注：WHMapView继承自MapView

void WHMapView::centerAndZoom(const GeoCoord&geoCenter, int zoom)
{m_geoCoord = geoCenter;m_curLevel = zoom - 1;MapDataManager::instance()->setMapLevel(m_curLevel);double len = MapUtility::sceneSize(m_curLevel);setSceneRect(QRect(0, 0, len, len));// 经纬度坐标转场景坐标、视图定位到中心点QPointF offsetPos = QPointF(viewport()->width() / 2.0, viewport()->height() / 2.0);QPointF scenePos = MapUtility::sceneCoordFromGeoCoord(m_geoCoord, m_curLevel);horizontalScrollBar()->setValue(scenePos.x() - offsetPos.x());verticalScrollBar()->setValue(scenePos.y() - offsetPos.y());scaleScene();updateOtherItemPos();
}void MapView::scaleScene()
{// 前面省略与计算无关的代码...// 视口宽度和高度int w = viewport()->width();int h = viewport()->height();// 瓦片像素点坐标、视口坐标QPointF scenePos = MapUtility::sceneCoordFromGeoCoord(m_geoCoord, m_curLevel);QPointF pixelPos = MapUtility::tilePixelCoordFromScene(scenePos, m_curLevel);QPoint viewportPos = mapFromScene(scenePos);// 鼠标所在瓦片的四边 与 视口四边的距离int lPixel = viewportPos.x() - pixelPos.x();int rPixel = w - (viewportPos.x() + PIXMAP_SIZE - pixelPos.x());int tPixel = viewportPos.y() - pixelPos.y();int bPixel = h - (viewportPos.y() + PIXMAP_SIZE - pixelPos.y());// 计算鼠标所在瓦片的四边应该填充的完整图片数量、是否存在剩余像素int leftPixmapCount = lPixel / PIXMAP_SIZE;bool remainLeftPixel = lPixel % PIXMAP_SIZE;int rightPixmapCount = rPixel / PIXMAP_SIZE;bool remainRightPixel = rPixel % PIXMAP_SIZE;int topPixmapCount = tPixel / PIXMAP_SIZE;bool remainTopPixel = tPixel % PIXMAP_SIZE;int bottomPixmapCount = bPixel / PIXMAP_SIZE;bool remainBottomPixel = bPixel % PIXMAP_SIZE;// 计算呈现的瓦片地图左上角的瓦片坐标m_curTileCoord = MapUtility::tileCoordFromGeoCoord(m_geoCoord, m_curLevel);m_topLeftTileCoord.x = qMax(m_curTileCoord.x - leftPixmapCount, 0);m_topLeftTileCoord.y = qMax(m_curTileCoord.y - topPixmapCount, 0);if (remainLeftPixel && m_topLeftTileCoord.x > 0)m_topLeftTileCoord.x -= 1;if (remainTopPixel && m_topLeftTileCoord.y > 0)m_topLeftTileCoord.y -= 1;// 计算呈现的瓦片地图右下角的瓦片坐标int mapSideCount = MapUtility::mapSideCount(m_curLevel);m_bottomRightTileCoord.x = qMin(m_curTileCoord.x + rightPixmapCount, mapSideCount - 1);m_bottomRightTileCoord.y = qMin(m_curTileCoord.y + bottomPixmapCount, mapSideCount - 1);if (remainRightPixel && m_bottomRightTileCoord.x < mapSideCount - 1)m_bottomRightTileCoord.x += 1;if (remainBottomPixel && m_bottomRightTileCoord.y < mapSideCount - 1)m_bottomRightTileCoord.y += 1;// 计算瓦片集合，视口最小瓦片集合+周边瓦片集合vector<TileCoord> vecTileCoord;m_viewAndAroundTileRect = CommonUtility::getViewAndAroundTileCoords(m_topLeftTileCoord.y, m_topLeftTileCoord.x, m_bottomRightTileCoord.y, m_bottomRightTileCoord.x, m_curLevel, vecTileCoord);//showTileCoord();showGraticules();// 上方即为计算瓦片索引的核心代码，省略下方加载瓦片的代码...// 加载瓦片代码...
}