java PrinterJob无法打印以适合纸张

Question

我目前在使用默认打印机打印jpeg文件时陷入困境。在我的程序中，当我从文件夹中选择图像时，我需要使用打印机默认设置（纸张尺寸，边距，方向）进行打印。

目前我得到这个：

PrintService printService = PrintServiceLookup.lookupDefaultPrintService();
final BufferedImage image = ImageIO.read(new File("car.jpg"));

PrinterJob printJob = PrinterJob.getPrinterJob();
printJob.setPrintService(printService);
printJob.setPrintable(new Printable(){
  @Override
  public int print(Graphics graphics, PageFormat pageFormat, int pageIndex) throws PrinterException{
      if (pageIndex == 0) {
          graphics.drawImage(image, 0, 0, (int)pageFormat.getWidth(), (int)pageFormat.getHeight(), null);
          return PAGE_EXISTS;
      else return NO_SUCH_PAGE;
  }
}

printJob.print();

现在，我的打印机的默认大小设置为：10 x 15厘米（4 x 6英寸），但是当我将程序设置为打印给定图像时，它仅显示一小部分纸张。

请帮帮我。

Answer 1

首先，请确保您将Graphics上下文翻译成适合可成像的区域…

g2d.translate((int) pageFormat.getImageableX(),
              (int) pageFormat.getImageableY());

接下来，请确保您使用的是imageableWidth和imageableHeight的PageFormat

double width = pageFormat.getImageableWidth();
double height = pageFormat.getImageableHeight();

而不是width/ height属性。其中许多东西都是从不同的上下文中翻译过来的…

graphics.drawImage(image, 0, 0, (int)width, (int)height, null);

该getImageableWidth/Height页面方向的范围内返回页面大小

打印几乎都假设dpi为72（不要强调，打印API可以处理更高的分辨率，但是核心API假设72dpi）

这意味着10x15cm的页面应转换为283.46456664x425.19684996像素。您可以通过使用System.out.println并转储结果getImageableWidth/Height到控制台来验证此信息。

如果您获得不同的设置，则可能是Java覆盖了默认页面属性

你有两个选择

显示PrintDialog并确保选择了正确的页面设置

PrintRequestAttributeSet aset = new HashPrintRequestAttributeSet();
aset.add(new PrinterResolution(300, 300, PrinterResolution.DPI));
aset.add(new MediaPrintableArea(0, 0, 150, 100, MediaPrintableArea.MM));

PrinterJob pj = PrinterJob.getPrinterJob();
pj.setPrintable(new PrintTask()); // You Printable here

if (pj.printDialog(aset)) {
    try {
        pj.print(aset);
    } catch (PrinterException ex) {
        ex.printStackTrace();
    }
}

或者你可以…

只需手动设置纸张/页面值…

public static void main(String[] args) {
    PrinterJob pj = PrinterJob.getPrinterJob();
    PageFormat pf = pj.defaultPage();
    Paper paper = pf.getPaper();
    // 10x15mm
    double width = cmsToPixel(10, 72);
    double height = cmsToPixel(15, 72);
    paper.setSize(width, height);
    // 10 mm border...
    paper.setImageableArea(
                    cmsToPixel(0.1, 72),
                    cmsToPixel(0.1, 72),
                    width - cmsToPixel(0.1, 72),
                    height - cmsToPixel(0.1, 72));
    // Orientation
    pf.setOrientation(PageFormat.PORTRAIT);
    pf.setPaper(paper);
    PageFormat validatePage = pj.validatePage(pf);
    pj.setPrintable(new Printable() {
        @Override
        public int print(Graphics graphics, PageFormat pageFormat, int pageIndex) throws PrinterException {
            // Your code here
            return NO_SUCH_PAGE;
        }

    },  validatePage);
    try {
        pj.print();
    } catch (PrinterException ex) {
        ex.printStackTrace();
    }
}

// The number of CMs per Inch
public static final double CM_PER_INCH = 0.393700787d;
// The number of Inches per CMs
public static final double INCH_PER_CM = 2.545d;
// The number of Inches per mm's
public static final double INCH_PER_MM = 25.45d;

/**
 * Converts the given pixels to cm's based on the supplied DPI
 *
 * @param pixels
 * @param dpi
 * @return
 */
public static double pixelsToCms(double pixels, double dpi) {
    return inchesToCms(pixels / dpi);
}

/**
 * Converts the given cm's to pixels based on the supplied DPI
 *
 * @param cms
 * @param dpi
 * @return
 */
public static double cmsToPixel(double cms, double dpi) {
    return cmToInches(cms) * dpi;
}

/**
 * Converts the given cm's to inches
 *
 * @param cms
 * @return
 */
public static double cmToInches(double cms) {
    return cms * CM_PER_INCH;
}

/**
 * Converts the given inches to cm's
 *
 * @param inch
 * @return
 */
public static double inchesToCms(double inch) {
    return inch * INCH_PER_CM;
}