IText图像集绝对位置

Question

我需要使用iText库将图像放在PDF中，位置与Adobe Acrobat下面的屏幕截图所示的位置完全相同。我需要将哪些值传递给图像setabsolute位置，如下所示：

        Image image = Image.getInstance(stream.toByteArray());
        image.scaleAbsolute(150f, 150f);
        image.setAbsolutePosition(???f, ???f);

        PdfContentByte overContent = stamper.getOverContent(1);
        overContent.addImage(image);
        stamper.setFormFlattening(true);
        stamper.close();

我正在尝试所有的值，图像在输出文件中跳转arround。我应该使用什么价值？我还包括了获取Field Position（）输出的截图。

Answer 1

如果你有问题，你无法弄清楚pt到x，y位置的转换，也许这会有所帮助：

要从Pixels转到Em，只需除以16

使用Reed Design的表格，其中列出从Points到Pixels到Em到％的转换。这是一个近似值，取决于字体，浏览器和操作系统，但它是一个很好的起点。

https://answers.yahoo.com/question/index?qid=20070723201114AAzsYjC

否则，我会为图像执行类似于yo的操作：

    /**
     * Adds an image to the PDF
     * @param imageData The data for the image to add
     * @param page The page number of where to add the photo
     * @param xPos The x coordinate of where to put the image. Note that 0 is the left of the page
     * @param yPos The y coordinate of where to put the image. Note that 0 is the top of the page. This is
     * different than the addText function for some reason.
     * @param layer
     * @throws Exception If there was an error adding the image to the PDF
     */
    public void addImageToPDF(float xPos, float yPos, byte[] imageData, int page,  Layer layer) throws Exception
    {
        PdfContentByte content = getPdfContentByte(page, layer);
        Image img = Image.getInstance(imageData);
        img.setAbsolutePosition(xPos, yPos);
        content.addImage(img);
    }


    /**
     * Gets a PdfContentByte. This is used to make changes to the PDF
     * @param page The page number that is to be modified
     * @param layer The layer that is to be modified
     * @return A PdfContentByte that can be used to modify the PDF
     */
    private PdfContentByte getPdfContentByte(int page, Layer layer)
    {
        return layer == Layer.OVER ? stamper.getOverContent(page) : stamper.getUnderContent(page);
    }

Layer是一个简单的枚举，用于确定应该采用哪些PDF层：

    /**
     * Represents a layer of the PDF relative to the original file. For example,
     * if an operation requires a Layer argument, OVER will make the changes ontop
     * of the original PDF. UNDER will make the changes under the original PDF. So
     * if there is text in the original PDF and you choose UNDER, the changes you make
     * may be covered up by the original text. If you choose OVER, you changes will be
     * ontop of whatever was in the original PDF
     */
    public enum Layer{
        /**
         * Represents ontop of the original PDF
         */
        OVER,

        /**
         * Represents under the original PDF
         */
        UNDER
    }