时间戳

首页 > 解决方案 > 如何使用 apache poi 将背景图像设置为居中

java - 如何使用 apache poi 将背景图像设置为居中

问题描述

例如：

幻灯片尺寸：950 x 510

图像尺寸：500 x 4620

这是我的代码

XSLFPictureData idx = ppt.addPicture(file, pictureType);
CTBackgroundProperties bgPr = this.slide.getXmlObject().getCSld().addNewBg().addNewBgPr();
CTBlipFillProperties blipPr = bgPr.addNewBlipFill();
CTBlip blib = blipPr.addNewBlip();
CTRelativeRect ctRelativeRect = blipPr.addNewStretch().addNewFillRect();

double imgHeight =  idx.getImageDimensionInPixels().getHeight();
double imgWidth  =  idx.getImageDimensionInPixels().getWidth();
double pptHeight =  ppt.getPageSize().getHeight();
double pptWidth  =  ppt.getPageSize().getWidth();

if (pptHeight - imgHeight < 0) {
    //How to calculate the offset above and below the image
    ctRelativeRect.setT(?);
    ctRelativeRect.setB(?);
}else if(pptWidth - imgWidth < 0) {
    //
    ctRelativeRect.setR(?);
    ctRelativeRect.setL(?);
}

RelationPart rp = slide.addRelation(null, XSLFRelation.IMAGES, idx);
blib.setEmbed(rp.getRelationship().getId());

我不知道如何计算图像的偏移量，可以使它居中。请给我一些建议。

这是图像： 在此处输入图像描述

这是我想要的效果： 在此处输入图像描述

标签： javaimageapacheapache-poi

解决方案

之所以CTRelativeRect命名为相对，是因为它的尺寸是幻灯片高度和幻灯片宽度的百分比。您的长图像将被拉伸或压缩到这些百分比尺寸。此外，左、右、顶部和底部的所有偏移量都以幻灯片高度和幻灯片宽度的百分比表示。

根据您显示的所需效果，图像应填充整个幻灯片宽度。所以图片宽度将从500px拉伸到950px。这是 950/500 的比率。以相同的比例，高度也会被拉伸。

知道了这一点，我们需要计算图片尺寸从像素到幻灯片尺寸的百分比。知道这一点后，我们可以将顶部偏移量计算为 (100% - 图片高度，以 % 为单位) / 2。如果设置了相同的底部偏移量，则长图片的确切中间将显示在幻灯片背景中。如果顶部偏移量是 (100% - 图片高度，%) / 2) - 100%，底部偏移量是 (100% - 图片高度，%) / 2 + 100%，则幻灯片背景显示长中间以下 1 个幻灯片高度图片。

除此之外，Microsoft总是会考虑到它自己奇怪的测量单位。由于避免了百分比的浮点数，因此此处的测量单位为千分之一。

例子：

import java.io.FileOutputStream;
import java.io.FileInputStream;

import org.apache.poi.xslf.usermodel.*;
import org.apache.poi.sl.usermodel.*;

import org.openxmlformats.schemas.presentationml.x2006.main.*;
import org.openxmlformats.schemas.drawingml.x2006.main.*;

import java.awt.Dimension;

public class CreatePPTXSheetsBackgroundPicture {

 public static void main(String[] args) throws Exception {

  XMLSlideShow slideShow = new XMLSlideShow();
  XSLFPictureData pictureData = slideShow.addPicture(new FileInputStream("2hGsR.jpg"), PictureData.PictureType.JPEG);
  slideShow.setPageSize(new Dimension(950, 510));

  double imgHeight =  pictureData.getImageDimensionInPixels().getHeight();
  double imgWidth  =  pictureData.getImageDimensionInPixels().getWidth();
  double sildeHeight =  slideShow.getPageSize().getHeight();
  double slideWidth  =  slideShow.getPageSize().getWidth();

  //How to calculate the offset above and below the image
  // imgWidth stretched to slideWidth => ratio = slideWidth / imgWidth
  double ratio = slideWidth / imgWidth;
  // sildeHeight% = 100%
  // imgHeight% = (imgHeight * ratio) * 100% / sildeHeight
  double imgHeightPerCent = (imgHeight * ratio) * 100 / sildeHeight;
  // topMiddle% = (100% - imgHeight%) / 2
  // bottomMiddle% = (100% - imgHeight%) / 2
  // topMiddle+1slideHeight% = (100% - imgHeight%) / 2) - 100%
  // bottomMiddle+1slideHeight% = (100% - imgHeight%) / 2 + 100%
  // topMiddle-1slideHeight% = (100% - imgHeight%) / 2) + 100%
  // bottomMiddle-1slideHeight% = (100% - imgHeight%) / 2 - 100%

  // first slide
  XSLFSlide slide = slideShow.createSlide();
  CTBackgroundProperties backgroundProperties = slide.getXmlObject().getCSld().addNewBg().addNewBgPr();
  CTBlipFillProperties blipFillProperties = backgroundProperties.addNewBlipFill();
  CTRelativeRect ctRelativeRect = blipFillProperties.addNewStretch().addNewFillRect();

  // first slide shows 1 slide above middle of long picture
  // measurement unit is thousandth => percent * 1000
  int top = (int)Math.round(((100 - imgHeightPerCent) / 2 + 100) * 1000);
  int bottom = (int)Math.round(((100 - imgHeightPerCent) / 2 -100) * 1000);
  ctRelativeRect.setT(top);
  ctRelativeRect.setB(bottom);

  String idx = slide.addRelation(null, XSLFRelation.IMAGES, pictureData).getRelationship().getId();
  CTBlip blib = blipFillProperties.addNewBlip();
  blib.setEmbed(idx);

  // second slide
  slide = slideShow.createSlide();
  backgroundProperties = slide.getXmlObject().getCSld().addNewBg().addNewBgPr();
  blipFillProperties = backgroundProperties.addNewBlipFill();
  ctRelativeRect = blipFillProperties.addNewStretch().addNewFillRect();

  // second slide shows middle of long picture
  top = (int)Math.round(((100 - imgHeightPerCent) / 2) * 1000);
  bottom = (int)Math.round(((100 - imgHeightPerCent) / 2) * 1000);
  ctRelativeRect.setT(top);
  ctRelativeRect.setB(bottom);

  idx = slide.addRelation(null, XSLFRelation.IMAGES, pictureData).getRelationship().getId();
  blib = blipFillProperties.addNewBlip();
  blib.setEmbed(idx);

  // third slide
  slide = slideShow.createSlide();
  backgroundProperties = slide.getXmlObject().getCSld().addNewBg().addNewBgPr();
  blipFillProperties = backgroundProperties.addNewBlipFill();
  ctRelativeRect = blipFillProperties.addNewStretch().addNewFillRect();

  // third slide shows 1 slide below middle of long picture
  top = (int)Math.round(((100 - imgHeightPerCent) / 2 - 100) * 1000);
  bottom = (int)Math.round(((100 - imgHeightPerCent) / 2 + 100) * 1000);
  ctRelativeRect.setT(top);
  ctRelativeRect.setB(bottom);

  idx = slide.addRelation(null, XSLFRelation.IMAGES, pictureData).getRelationship().getId();
  blib = blipFillProperties.addNewBlip();
  blib.setEmbed(idx);


  FileOutputStream out = new FileOutputStream("CreatePPTXSheetsBackgroundPicture.pptx");
  slideShow.write(out);
  out.close();
 }
}

第二张幻灯片显示了您的长图的中间，如您想要的效果所述。

暗示：

整个效果只能使用查看PowerPoint。Impress无法显示该效果。并且PowerPoint 2007可以使用小于 0% 和/或大于 100% 的偏移量来显示效果，但不能设置小于 0% 和/或大于 100% 的偏移量。

推荐阅读