Function InitializeWindowViewport

src/viewport.cpp:218–273

* Initialize viewport of the window for use. * @param w Window to use/display the viewport in * @param x Offset of left edge of viewport with respect to left edge window \a w * @param y Offset of top edge of viewport with respect to top edge window \a w * @param width Width of the viewport * @param height Height of the viewport * @param focus Either the tile index or vehicle ID to focus. *

 * @param zoom Zoomlevel to display
 */
void InitializeWindowViewport(Window *w, int x, int y,
	int width, int height, std::variant<TileIndex, VehicleID> focus, ZoomLevel zoom)
{
	assert(w->viewport == nullptr);

	auto vp = std::make_unique<ViewportData>();

	vp->left = x + w->left;
	vp->top = y + w->top;
	vp->width = width;
	vp->height = height;

	vp->zoom = Clamp(zoom, _settings_client.gui.zoom_min, _settings_client.gui.zoom_max);

	vp->virtual_width = ScaleByZoom(width, zoom);
	vp->virtual_height = ScaleByZoom(height, zoom);

	Point pt;

	if (std::holds_alternative<VehicleID>(focus)) {
		const Vehicle *veh;

		vp->follow_vehicle = std::get<VehicleID>(focus);
		veh = Vehicle::Get(vp->follow_vehicle);
		pt = MapXYZToViewport(*vp, veh->x_pos, veh->y_pos, veh->z_pos);
	} else {
		TileIndex tile = std::get<TileIndex>(focus);
		if (tile == INVALID_TILE) {
			/* No tile? Use center of main viewport. */
			const Window *mw = GetMainWindow();

			/* center on same place as main window (zoom is maximum, no adjustment needed) */
			pt.x = mw->viewport->scrollpos_x + mw->viewport->virtual_width / 2;
			pt.x -= vp->virtual_width / 2;
			pt.y = mw->viewport->scrollpos_y + mw->viewport->virtual_height / 2;
			pt.y -= vp->virtual_height / 2;
		} else {
			x = TileX(tile) * TILE_SIZE;
			y = TileY(tile) * TILE_SIZE;
			pt = MapXYZToViewport(*vp, x, y, GetSlopePixelZ(x, y));
		}
		vp->follow_vehicle = VehicleID::Invalid();
	}

	vp->scrollpos_x = pt.x;
	vp->scrollpos_y = pt.y;
	vp->dest_scrollpos_x = pt.x;
	vp->dest_scrollpos_y = pt.y;

	vp->overlay = nullptr;

	vp->virtual_left = 0;
	vp->virtual_top = 0;

	w->viewport = std::move(vp);
}

static Point _vp_move_offs;