打印时如何在JTable中添加背景图像? [英] How to add background image in JTable when printing?

问题描述

我要打印带有背景图像或水印的JTable.我的代码是:

I want to print a JTable with background image or water mark. My code is:

public void actionPerformed(ActionEvent ae)
{
    boolean status=false;

    MessageFormat header = null;
    header = new MessageFormat("Header");
    MessageFormat footer = null;
    footer = new MessageFormat("Page");

    boolean fitWidth = true;
    boolean showPrintDialog = true;
    boolean interactive = true;

    /* determine the print mode */
    JTable.PrintMode mode = fitWidth ? JTable.PrintMode.FIT_WIDTH
                                     : JTable.PrintMode.NORMAL;

    try
    {
        status = jt.print(mode, header, footer,showPrintDialog,null,interactive);

        if(status ==true)
        {
            frame.dispose();
        }
    }
    catch(Exception ee)
    {
        System.out.println(ee.getMessage());
    }
}

如何通过此方法传递或设置背景图像?

How can I pass or set the background image in this method?

推荐答案

问题有两个部分

每页
• 打印一张图片
• 确保图像透视"表

• print an image an each page
• be sure the image "shines-through" the table

第二个问题由@mKorbel解决(尽管由于没有很好的解决方案，所以并未真正解决:-)

the second is addressed by @mKorbel (though not really solved because there is no nice solution :-)

要解决第一个问题，我将选择自定义Printable和子类JTable来返回它，例如

To solve the first, I would go for a custom Printable and subclass JTable to return it, something like

public class BackgroundPrintable implements Printable {

    Printable tablePrintable;
    JTable table;
    MessageFormat header; 
    MessageFormat footer;
    BufferedImage background;

    public BackgroundPrintable(MessageFormat header, MessageFormat footer) {
        this.header = header;
        this.footer = footer;
    }

    public void setTablePrintable(JTable table, Printable printable) {
        tablePrintable = printable;        
        this.table = table;
    }

    @Override
    public int print(Graphics graphics, PageFormat pageFormat, 
            int pageIndex) throws PrinterException {
        printImage(graphics, pageFormat, pageIndex);
        int exists = tablePrintable.print(graphics, pageFormat, pageIndex);
        if (exists != PAGE_EXISTS) {
            return exists;
        }
        return PAGE_EXISTS;        
    }

    private void printImage(Graphics graphics, PageFormat pageFormat,
            int pageIndex) {
        // grab an untainted graphics
        Graphics2D g2d = (Graphics2D)graphics.create();
        // do the image painting 
        ....
        // cleanup  
        g2d.dispose();
    }

}

// use in JTable subclass
@Override
public Printable getPrintable(PrintMode printMode,
        MessageFormat headerFormat, MessageFormat footerFormat) {
    Printable printable = super.getPrintable(printMode, null, null);
    BackgroundPrintable custom = new BackgroundPrintable(headerFormat, footerFormat);
    custom.setTablePrintable(this, printable);
    return custom;
}

要实现第二个目标，JTable及其呈现器都必须是透明的.棘手的，因为:

To achieve the second, both the JTable and its renderers must be transparent. Tricky, because:

• 可能仅在打印时使用-否则它们应该具有通常的不透明性
• 所有渲染器必须透明，并且没有完全安全的方式来保存所有渲染器

• probably only if printing - otherwise they should have their usual opacity
• all of the renderers must be transparent, and there is no completely safe way to get hold of them all

自定义JTable可以通过在prepareRenderer中强制呈现组件的不透明度来尝试实现这一目标:

A custom JTable could try to achieve that by forcing the rendering component's opacity in its prepareRenderer:

  @Override
   public Component prepareRenderer(TableCellRenderer renderer,
            int row, int column) {
        JComponent comp = (JComponent) super.prepareRenderer(renderer, row, column);
        if (isPaintingForPrint()) {
            comp.setOpaque(false);
        } else {
            comp.setOpaque(true);
        }   
        return comp;
   }

实际上，这并不完全有效:else块中的代码对于自然透明的组件而言可能是错误的做法.恐怕没有真正可靠的解决方案.

Actually, that's not entirely valid: the code in the else block might be the wrong-thing-to-do for naturally transparent components. No really reliable solution available, I'm afraid.

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