Java 将图像放入打印区域
我需要用Java打印图像。所以我实现了Java 将图像放入打印区域,java,printing,jpanel,Java,Printing,Jpanel,我需要用Java打印图像。所以我实现了print()方法的Printable接口。但打印机总是只打印一些原始图像。如何使图像适合打印区域(A4),使打印机能够打印整个图像,而不是其中的一部分?现在,我的代码如下所示: public int print(Graphics graphics, PageFormat pageFormat, int pageIndex) throws PrinterException { if (pageIndex >= images.size())
print()
方法的Printable
接口。但打印机总是只打印一些原始图像。如何使图像适合打印区域(A4),使打印机能够打印整个图像,而不是其中的一部分?现在,我的代码如下所示:
public int print(Graphics graphics, PageFormat pageFormat, int pageIndex) throws PrinterException {
if (pageIndex >= images.size()) {
return Printable.NO_SUCH_PAGE;
}
RenderedImage image;
Graphics2D graphics2D = (Graphics2D) graphics;
image = new NullOpImage((RenderedImage) images.get(pageIndex), null, null, OpImage.OP_IO_BOUND);
double x = (pageFormat.getImageableWidth() - image.getWidth())/2 + pageFormat.getImageableX();
double y = (pageFormat.getImageableHeight() - image.getHeight())/2 + pageFormat.getImageableY();
graphics2D.drawRenderedImage(image, AffineTransform.getTranslateInstance(x, y));
return PAGE_EXISTS;
}
您需要缩小图像以适应可用区域
private int currentPage = -1;
private Image cachedScaledImage = null;
public double getScaleFactor(int iMasterSize, int iTargetSize) {
double dScale = 1;
if (iMasterSize > iTargetSize) {
dScale = (double) iTargetSize / (double) iMasterSize;
} else {
dScale = (double) iTargetSize / (double) iMasterSize;
}
return dScale;
}
public double getScaleFactorToFit(BufferedImage img, Dimension size) {
double dScale = 1;
if (img != null) {
int imageWidth = img.getWidth();
int imageHeight = img.getHeight();
dScale = getScaleFactorToFit(new Dimension(imageWidth, imageHeight), size);
}
return dScale;
}
public double getScaleFactorToFit(Dimension original, Dimension toFit) {
double dScale = 1d;
if (original != null && toFit != null) {
double dScaleWidth = getScaleFactor(original.width, toFit.width);
double dScaleHeight = getScaleFactor(original.height, toFit.height);
dScale = Math.min(dScaleHeight, dScaleWidth);
}
return dScale;
}
public int print(Graphics graphics, PageFormat pageFormat, int pageIndex) throws PrinterException {
if (pageIndex >= images.size()) {
return Printable.NO_SUCH_PAGE;
}
RenderedImage image;
Graphics2D graphics2D = (Graphics2D) graphics;
int width = (int)Math.round(pageFormat.getImageableWidth());
int height = (int)Math.round(pageFormat.getImageableHeight());
if (currentPage != pageIndex || cachedScaledImage == null) {
currentPage = pageIndx;
image = new NullOpImage((RenderedImage) images.get(pageIndex), null, null, OpImage.OP_IO_BOUND);
BufferedImage imageCopy = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = imageCopy.createGraphics();
g2d.drawImage(imageCopy, 0, 0, null);
g2d.dispose();
double scaleFactor = getScaleFactorToFit(new Dimension(image.getWidth(), image.getHeight()), new Dimension(width, height));
int imageWidth = (int)Math.round(image.getWidth() * scaleFactor);
int imageHeight = (int)Math.round(image.getHeight() * scaleFactor);
double x = ((pageFormat.getImageableWidth() - imageWidth) / 2) + pageFormat.getImageableX();
double y = ((pageFormat.getImageableHeight() - imageHeight) / 2) + pageFormat.getImageableY();
cachedScaledImage = imageCopy.getScaledInstance(imageWidth, imageHeight, Image.SCALE_SMOOTH);
}
graphics2D.drawRenderedImage(cachedScaledImage, AffineTransform.getTranslateInstance(x, y));
return PAGE_EXISTS;
}
谢谢但是我得到了:
ClassCastExcepion
这里:graphics2D.drawrenteredimage(scaledImage,AffineTransform.getTranslateInstance(x,y))代码>我(通过更改方法)将其修复为drawImage(…)
。但是现在我得到了Java.lang.OutOfMemoryError:Java堆空间
,这并不奇怪。系统多次请求渲染特定页面,这意味着每次我们都要创建图像的新副本和缩放实例。您应该考虑创建一个缓存,该缓存允许您缓存缩放的实例并引用该实例,直到页码发生更改,我读取到JAI ImageIO工具可能会导致类似这样的错误。需要我NullOpImage
?或者我可以通过另一个类来更改它?我已经更新了我的代码,以演示如何使用缩放图像的缓存版本。我不确定您试图从NullOpImage
中实现什么,因此我不能在那里提出任何建议。我不需要使用NullOpImage
,我从示例中获得它。。。当我将NullOpImage
更改为simplejava.awt.Image
时,我不再得到类似OutOfMemoryError
的错误。所以我认为我不应该使用NullOpImage
。但是如果我使用Image
,像getWidth
和getHeight
这样的方法需要额外的参数(ImageObserver
),当我将null
作为打印空页的参数传递时,不是实际的图像。。。