Question

此刻，我看到的只是一条从JFrame屏幕左上角延伸出来的细黑线。我假设它是我卡的底部边缘，其余部分被阻止查看

当我直接将卡片添加到JFrame时，我可以看到所有这些，所以当我将卡片添加到框架中的JPanel时，我很困惑为什么我只能看到这一行（测量卡片的宽度）。

JFrame代码：

public class WarFrame extends JFrame
{
public WarFrame()
{
    setSize(600, 800);
    setTitle("War");
    setLocationRelativeTo(null);
    setDefaultCloseOperation(EXIT_ON_CLOSE);

    JPanel panel = new JPanel();
    panel.setBackground(Color.GREEN);
    add(panel);
    panel.add(new Card(Rank.ACE));
}

public static void main(String[] args)
{
    WarFrame game = new WarFrame();
    game.setVisible(true);
}
}

卡片代码：

public class Card extends JComponent
{
private final Rank rank;
private boolean faceUp;
private int x;
private int y;
private final int width;
private final int height;
private final int arcWidth;
private final int arcHeight;

public Card(Rank r)
{
    rank = r;
    faceUp = false;
    x = 0;
    y = 0;
    width = 75;
    height = 100;
    arcWidth = 10;
    arcHeight = 10;
}

public Card(Rank r, int x, int y)
{
    rank = r;
    faceUp = false;
    this.x = x;
    this.y = y;
    width = 75;
    height = 100;
    arcWidth = 10;
    arcHeight = 10;
}

@Override
protected void paintComponent(Graphics g)
{
    Graphics2D pen = (Graphics2D) g;
    //this is the black boarder
    pen.fillRoundRect(x, y, width, height, arcWidth, arcHeight);

    //white card body
    pen.setColor(Color.WHITE);
    pen.fillRoundRect(x + 5, y + 5, width - 10, height - 10, arcWidth, arcHeight);

    if (faceUp)
    {
        //draw the card's symbol
        pen.setFont(pen.getFont().deriveFont(50f));
        pen.setColor(Color.RED);
        if (rank == Rank.TEN)
        {
            //10 has 2 digits, so needs to be shifted a bit
            pen.drawString(rank.getSymbol(), x + 5, y + 65);
        }
        else
        {
            pen.drawString(rank.getSymbol(), x + 20, y + 65);
        }
    }
    else
    {
        //draw a blue rectangle as back of card pic
        pen.setColor(Color.BLUE);
        pen.fillRoundRect(x + 10, y + 10, width - 20, height - 20, arcWidth, arcHeight);
    }
}

我还注意到有关将卡直接添加到JFrame的一些有趣内容。如果从0,0

绘制，整张卡片会显示出来

frame.add(new Card(Rank.ACE, 0, 0));

但如果我将其添加到x＆gt; 0，

frame.add(new Card(Rank.ACE, 2, 10));

然后卡片开始在右侧切断。不知何故，当y> 0卡在屏幕下方正确绘制。

所以，任何建议为什么A.将卡片添加到面板只会使一条线可见 B.当直接添加到框架时，为什么只有当x> 1时卡才被切断。 0？

Answer 1

默认情况下，JPanel使用FlowLayout，该getPreferredSize()会考虑添加到其中的任何组件的首选大小。自定义绘制时，JComponent的默认首选大小为（0,0）。

您需要覆盖Card类的Dimension，以便为Card返回正确的{{1}}。

当我将我的卡（JComponent）添加到我的JFrame中时，如何将其完全显示在我的JPanel中？

1 个答案: