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Resize window when replacing widget

  • I created a Minesweeper application that allows the user to start a game with different numbers of rows, columns, and bombs.

    The first game looks great, and the window fits around game board properly.

    However, when I make the board smaller, the columns get spaced out to fill the space of the window and the rows push to the bottom of the screen.

    How can I make the window resize to the size it should be so the board is not stretched out? Is there anyway to fit to layout without setting the explicit pixel size of the window?

    Here is my window code, and the method where the panel is replaced.

    MainWindow::MainWindow(QWidget *parent)
        : QMainWindow(parent),
          clicksCountLbl(new QLabel),
          layout(new QGridLayout)
        QAction *gamesAction = menuBar()->addAction("Game");
        connect(gamesAction, &QAction::triggered, this, &MainWindow::openGame);
        QWidget *centralWidget = new QWidget;
        int rows = 10;
        int cols = 10;
        numBombs = 8;
        uncoveredSquares = rows*cols - numBombs;
        panel = new MinesweeperPanel(10, 10, 8, this);
        connect(panel, &MinesweeperPanel::bombClicked, this, [=](void){endGame(false);});
        connect(panel, &MinesweeperPanel::click, this, &MainWindow::click);
        connect(panel, &MinesweeperPanel::uncovered, this, &MainWindow::uncovered);
        layout->addWidget(clicksCountLbl, 0, 1);
        layout->addWidget(panel, 1, 0, 1, 2);
    void MainWindow::openGame(){
        GameDialog dialog;
        delete panel;
        panel = new MinesweeperPanel(dialog.height(), dialog.width(), dialog.mines());
        layout->addWidget(panel, 1, 0, 1, 2);

  • Lifetime Qt Champion


    You should also show the implementation of your MinesweeperPanel class.

    From the looks of it, you should make its size fixed based on its content.

  • Panel class is rather long. I'll post it below.

    I figured there may not be a way to fit to contents. I guess I will just have to do a bit of math to figure it out.

    #include "minesweeperpanel.h"
    #include <QGridLayout>
    #include <QRandomGenerator>
    #include <QDebug>
    #include <QMessageBox>
    #include <QApplication>
    int MinesweeperPanel::boxDimensions = 30;
    MinesweeperPanel::MinesweeperPanel(int rows, int cols, int numBombs, QWidget *parent) :
        setStyleSheet("QPushButton{min-width:" + QString::number(boxDimensions) + "px; \
                                    max-width:" + QString::number(boxDimensions) + "px; \
                                    min-height:" + QString::number(boxDimensions) + "px; \
                                    max-height:" + QString::number(boxDimensions) + "px; \
        QGridLayout *layout = new QGridLayout;
        //allocate dynamic arrays of size rows
        board = new MinesweeperButton**[cols];
        bombs = new bool*[cols];
        flags = new bool*[cols];
        revealed = new bool*[cols];
        //set up board and initailize bombs
        for (int i = 0; i < rows; i++) {
            //allocate row
            board[i] = new MinesweeperButton*[cols];
            bombs[i] = new bool[cols];
            flags[i] = new bool[cols];
            revealed[i] = new bool[cols];
            for (int j = 0; j < cols; j++){
                //create button
                board[i][j] = new MinesweeperButton;
                board[i][j]->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
                board[i][j]->setIconSize(QSize(boxDimensions, boxDimensions));
                connect(board[i][j], &QPushButton::clicked, this, [=](void){buttonClicked(i,j);});
                connect(board[i][j], &MinesweeperButton::rightClicked, this, [=](void){buttonRightClicked(i,j);});
                layout->addWidget(board[i][j], i, j);
                //initialize all bomb spots to false
                bombs[i][j] = false;
                flags[i][j] = false;
                revealed[i][j] = false;
            // each i-th pointer is now pointing to dynamic array (size rows) of actual int values
        for (int i=0; i<numBombs; i++){
            int x = static_cast<int>(QRandomGenerator::global()->generateDouble() * (rows-1));
            int y = static_cast<int>(QRandomGenerator::global()->generateDouble() * (cols-1));
            bombs[x][y] = true;
        for (int i=0; i<rows; i++){
            for (int j=0;j<cols; j++){
                delete board[i][j];
        delete this->layout();
     * @brief MinesweeperPanel::buttonClicked
     * Checks for bomb, then starts flood fill from given coordinate
     * @param row
     * @param col
    void MinesweeperPanel::buttonClicked(int row, int col){
        emit click(row, col);
        if (bombs[row][col]){ //bomb clicked
            emit bombClicked();
        floodFill(row, col);
     * @brief MinesweeperPanel::buttonRightClicked
     * Toggles flag on given coordinates
     * @param row
     * @param col
    void MinesweeperPanel::buttonRightClicked(int row, int col){
        flags[row][col] = !flags[row][col]; //flip flag
        emit flagged(row, col, flags[row][col]);
        if (flags[row][col]){
        } else{
     * @brief MinesweeperPanel::isWithinBounds
     * @param x
     * @param y
     * @return square is within bounds of grid
    bool MinesweeperPanel::isWithinBounds(int x, int y){
        return x>=0 && x<rows && y>=0 && y<cols;
     * @brief MinesweeperPanel::floodFill
     * Recursive method that reveals board starting from given coordinates,
     * then checks all neighbors if square has no neighboring bombs.
     * @param x
     * @param y
    void MinesweeperPanel::floodFill(int x, int y){
         if (!isWithinBounds(x,y) //if out of bounds
                || bombs[x][y] //or found bomb
                || revealed[x][y]) //or already visited this square
        revealed[x][y] = true;
        int neighbors = neighboringBombs(x, y);
        board[x][y]->setIcon(QIcon("://images/" + QString::number(neighbors) + ".png"));
        emit uncovered(x,y);
        if (neighbors == 0){
            //search neighbors
            floodFill(x-1, y); //left
            floodFill(x+1, y); //right
            floodFill(x-1, y-1); //left up
            floodFill(x-1, y+1); //left down
            floodFill(x+1, y-1); //right up
            floodFill(x+1, y+1); //right down
            floodFill(x, y+1); //up
            floodFill(x, y-1); //down
     * @brief MinesweeperPanel::isBomb
     * @param x
     * @param y
     * @return square contains bomb
    bool MinesweeperPanel::isBomb(int x, int y){
        return !isWithinBounds(x,y) //within bounds
                && bombs[x][y]; //is bomb
     * @brief MinesweeperPanel::neighboringBombs
     * @param x
     * @param y
     * @return number of neighboring squares that are bombs
    int MinesweeperPanel::neighboringBombs(int x, int y){
        int bombNeighbors=0;
        for (int i=-1; i<=1; i++){
            for (int j=-1; j<=1; j++){
                if (isWithinBounds(x+i, y+j) && //is within bounds
                        !(i==0 && j==0) && //don't check current square
                        bombs[x+i][y+j]) //is bomb
        return bombNeighbors;
     * @brief MinesweeperPanel::revealBoard
     * Uncover all squares in the board
    void MinesweeperPanel::revealBoard(){
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++){
                if (!revealed[i][j]){
                    if (bombs[i][j])
                        board[i][j]->setIcon(QIcon("://images/bomb.png")); //reveal bomb
                        board[i][j]->setIcon(QIcon("://images/" + QString::number(neighboringBombs(i, j)) + ".png")); //reveal # neighbors

  • OMG that's a grid of buttons?! that should be implemented with QTableView/QTableWidget

  • @VRonin
    ... I can hear the hooves of QStyledItemDelegate thundering toward us... ;)

  • @Smeeth
    If there isn't an automatic size policy you can apply to the main window to shrink to contents (I don't know), what about mainWindow->adjustSize() (or resize(minimumSizeHint()))? You may have to call it on a QTimer after the board's dimensions have been changed.

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