JPanel 与图像背景

发布于 2024-09-29 22:36:49 字数 269 浏览 5 评论 0原文

如何在JPANEL上添加图像背景？

JPanel pDraw = new JPanel(new GridLayout(ROWS,COLS,2,2)); 
pDraw.setPreferredSize(new Dimension(600,600)); //size of the JPanel
pDraw.setBackground(Color.RED); //How can I change the background from red color to image?

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How to put image background on JPANEL?

JPanel pDraw = new JPanel(new GridLayout(ROWS,COLS,2,2)); 
pDraw.setPreferredSize(new Dimension(600,600)); //size of the JPanel
pDraw.setBackground(Color.RED); //How can I change the background from red color to image?

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禾厶谷欠 2024-10-06 22:36:49

将 Image 加载到 ImageIcon 中并将其显示在 JLabel 中可能是最简单的方法，但是：
要将图像直接“绘制”到 JPanel，请重写 JPanel 的 paintComponent(Graphics) 方法，如下所示：

public void paintComponent(Graphics page)
{
    super.paintComponent(page);
    page.drawImage(img, 0, 0, null);
}

其中 img 是 Image > （可能通过 ImageIO.read() 调用加载）。

Graphics#drawImage 是一个重载的命令，它允许您高度具体地指定如何、多少以及在何处将图像绘制到组件。

您还可以使用 Image#getScaledInstance 方法来获得“奇特”的效果并将图像缩放到您满意的程度。这将为 width 或 height 参数取 -1，以保持图像的纵横比相同。

用更奇特的方式来说：

public void paintComponent(Graphics page)
{
    super.paintComponent(page);

    int h = img.getHeight(null);
    int w = img.getWidth(null);

    // Scale Horizontally:
    if ( w > this.getWidth() )
    {
        img = img.getScaledInstance( getWidth(), -1, Image.SCALE_DEFAULT );
        h = img.getHeight(null);
    }

    // Scale Vertically:
    if ( h > this.getHeight() )
    {
        img = img.getScaledInstance( -1, getHeight(), Image.SCALE_DEFAULT );
    }

    // Center Images
    int x = (getWidth() - img.getWidth(null)) / 2;
    int y = (getHeight() - img.getHeight(null)) / 2;

    // Draw it
    page.drawImage( img, x, y, null );
}

It is probably easiest to load the Image into an ImageIcon and display it in a JLabel, however:
To directly 'draw' the image to the JPanel, override the JPanel's paintComponent(Graphics) method to something like the following:

public void paintComponent(Graphics page)
{
    super.paintComponent(page);
    page.drawImage(img, 0, 0, null);
}

where img is an Image (possibly loaded through the ImageIO.read() call).

Graphics#drawImage is a heavily overloaded command which will allow you to be highly specific in how, how much, and where you paint the image to the component.

You can also get 'fancy' and scale the image to your pleasing using the Image#getScaledInstance method. This will take a -1 for either the width or the height parameter in order to keep the aspect ratio of the image the same.

Putting it in a more fancy way:

public void paintComponent(Graphics page)
{
    super.paintComponent(page);

    int h = img.getHeight(null);
    int w = img.getWidth(null);

    // Scale Horizontally:
    if ( w > this.getWidth() )
    {
        img = img.getScaledInstance( getWidth(), -1, Image.SCALE_DEFAULT );
        h = img.getHeight(null);
    }

    // Scale Vertically:
    if ( h > this.getHeight() )
    {
        img = img.getScaledInstance( -1, getHeight(), Image.SCALE_DEFAULT );
    }

    // Center Images
    int x = (getWidth() - img.getWidth(null)) / 2;
    int y = (getHeight() - img.getHeight(null)) / 2;

    // Draw it
    page.drawImage( img, x, y, null );
}

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