使用JavaFX打印节点

Question

问题就在这里：

我目前必须打印一个a4的横向页面，其中包含当前javaFx场景的“部分”。

我必须打印的部分是BorderPane的部分，我需要打印左侧、中间和底部节点，所以打印的页面应该如下所示：

PrinterJob job = PrinterJob.createPrinterJob();

BorderPane bpToPrint = new BorderPane();
bpToPrint.setLeft(sourceBorderPane.getLeft());
bpToPrint.setCenter(sourceBorderPane.getCenter());
bpToPrint.setBottom(sourceBorderPane.getBottom());

if(job != null && job.showPrintDialog(root.getScene().getWindow())){
    Printer printer = job.getPrinter();
    PageLayout pageLayout = printer.createPageLayout(Paper.A4, PageOrientation.LANDSCAPE, Printer.MarginType.HARDWARE_MINIMUM);

    double scaleX = pageLayout.getPrintableWidth() / bpToPrint.getWidth();
    double scaleY = pageLayout.getPrintableHeight() / bpToPrint.getHeight();

    Scale scale = new Scale(scaleX, scaleY);

    bpToPrint.getTransforms().add(scale);

    boolean success = job.printPage(pageLayout, bpToPrint);
    if(success){
        job.endJob();
    }
}

// Since I did "move" the nodes to the "bpToPrint" borderpane
// I have to put them back to the "source"

sourceBorderPane.setBottom(bpToPrint.getBottom());
sourceBorderPane.setLeft(bpToPrint.getLeft());
sourceBorderPane.setCenter(bpToPrint.getCenter());

// WritableImage myLeft = bPane.getLeft().snapshot(null,null);
// System.out.println("left item width : "+myLeft.getWidth()+" height : "+myLeft.getHeight());
// WritableImage myCenter = bPane.getCenter().snapshot(null,null);
// System.out.println("center item width : "+myCenter.getWidth()+" height : "+myCenter.getHeight());
// WritableImage myBottom = bPane.getBottom().snapshot(null,null);
// System.out.println("Bottom item width : "+myBottom.getWidth()+" height : "+myBottom.getHeight());

我将此作为输出（仅供参考）：

left item width : 112.0 height : 892.0
center item width : 1746.0 height : 892.0
bottom item width : 1858.0 height : 95.0

感谢您的帮助/阅读，感谢您的帮助。

更新01：

PrinterJob job = PrinterJob.createPrinterJob();
Node myLeft = root.getLeft();
Node myCenter = root.getCenter();
Node myBottom = root.getBottom();

//I will use a HBox to put the left & center, and a VBox to put hbox + bottom
VBox vToPrint = new VBox();
HBox hToPrint = new HBox();

hToPrint.getChildren().addAll(myLeft, myCenter);
vToPrint.getChildren().addAll(hToPrint,myBottom);

//Next lines come from the applyCss example               
Group tempRoot = new Group();
Scene tempScene = new Scene(tempRoot);
tempRoot.getChildren().add(vToPrint);

tempRoot.applyCss();
tempRoot.layout();            

if(job != null && job.showPrintDialog(root.getScene().getWindow())){
    Printer printer = job.getPrinter();
    PageLayout pageLayout = printer.createPageLayout(Paper.A4, PageOrientation.LANDSCAPE, Printer.MarginType.HARDWARE_MINIMUM);

    double width = vToPrint.getWidth();
    System.out.println("WIDTH : "+width);
    //Output : 852.0

    double height = vToPrint.getHeight();
    System.out.println("HEIGHT : "+height);
    //Output : 803.0

    PrintResolution resolution = job.getJobSettings().getPrintResolution();

    System.out.println("FEEDRESOLUTION : "+resolution.getFeedResolution());
    //Output : 600

    System.out.println("CROSSFEEDRESOLUTION : "+resolution.getCrossFeedResolution());
    //Output : 600


    width /= resolution.getFeedResolution();
    System.out.println("NEW WIDTH : "+width);
    //Output : 1.42

    height /= resolution.getCrossFeedResolution();
    System.out.println("NEW HEIGHT : "+height);
    //Output : 1.3383333333333334

    double scaleX = pageLayout.getPrintableWidth() / 72 / width;
    System.out.println("SCALE X : "+scaleX);
    //Output : 8.01056338028169

    double scaleY = pageLayout.getPrintableHeight() / 72 / height;
    System.out.println("SCALE Y : "+scaleY);
    //Output : 5.935252677755962

    Scale scale = new Scale(scaleX, scaleY);

    vToPrint.getTransforms().add(scale);

    boolean success = job.printPage(pageLayout, vToPrint);

    if(success){
        job.endJob();
    }
}
root.setLeft(myLeft);
root.setCenter(myCenter);
root.setBottom(myBottom);

left item width : 112.0 height : 892.0
center item width : 1746.0 height : 892.0
bottom item width : 1858.0 height : 95.0

这真是让人摸不着头脑...

更新02：

使用快照和imageViews进行新尝试：

PrinterJob job = PrinterJob.createPrinterJob();
WritableImage myLeftImg = root.getLeft().snapshot(null, null);
WritableImage myCenterImg = root.getCenter().snapshot(null, null);
WritableImage myBottomImg = root.getBottom().snapshot(null, null);

ImageView myLeftImgView = new ImageView();
ImageView myCenterImgView = new ImageView();
ImageView myBottomImgView = new ImageView();

myLeftImgView.setImage(myLeftImg);
myCenterImgView.setImage(myCenterImg);
myBottomImgView.setImage(myBottomImg);

VBox vToPrint = new VBox();
HBox hToPrint = new HBox();
hToPrint.getChildren().addAll(myLeftImgView, myCenterImgView);
vToPrint.getChildren().addAll(hToPrint, myBottomImgView);

Group myRoot = new Group();
Scene myScene = new Scene(myRoot);
myRoot.getChildren().add(vToPrint);                

myRoot.applyCss();
myRoot.layout();

if(job != null && job.showPrintDialog(root.getScene().getWindow())){
    Printer printer = job.getPrinter();
    PageLayout pageLayout = printer.createPageLayout(Paper.A4, PageOrientation.LANDSCAPE, Printer.MarginType.HARDWARE_MINIMUM);
    boolean success = job.printPage(pageLayout, vToPrint);
    if(success){
        job.endJob();
    }
}

double scaleX = pageLayout.getPrintableWidth() / 72 / width;

我把它除以600（就像Resolution.GetFeedResolution）...但这可能是错误的，因为我之前已经把它和600分了...：

width /= resolution.getFeedResolution();
// ... 
double scaleX = pageLayout.getPrintableWidth() / width / 600;

结果将“Vtoprint”vbox打印在a4景观页面上，但分辨率真的，真的，真的，……糟糕！整件事都像素化了。文本是可读的，但现在打印分辨率出了问题。

我还尝试制作要打印的节点的快照，因此我构建了vToPrint VBox，然后对其进行快照，并将快照保存到.png文件中。这很好，分辨率很好。所以现在问题出在打印部分...

Answer 1

点是距离的度量（1/72英寸），而像素仍然是绝对值。该API可以为您的屏幕获取每英寸的像素（点）量。将每英寸72个点除以检索到的每英寸像素量，就会得到所需的系数：

double scaleX = 72.0/(Screen.getPrimary().getDpi());
double scaleY = scaleX;

如果添加一个Scale-instance来“get transforms（）”（如问题中所做），这就足够了。如果您将该刻度应用为：

bp.setScaleX(scaleX);

还需要进行一次修正,因为该方法从中心缩放：

bp.setTranslateX(bp.getTranslateX() - bp.getBoundsInParent().getMinX());