问题
I am creating web application where I am displaying images/ pdf in thumbnail format. Onclicking respective image/ pdf it get open in new window.
For PDF, I have (this is code of the new window)
<iframe src="images/testes.pdf" width="800" height="200" />
Using this I can see all PDF in web browser. However for thumbnail purpose, I want to display only first page of PDF as an Image.
I tried
<h:graphicImage value="images/testes.pdf" width="800" height="200" />
however it is not working. Any idea how to get this done?
Update 1
I am providing path of pdf file for example purpose. However I have images in Database. In actual I have code as below.
<iframe src="#{PersonalInformationDataBean.myAttachmentString}" width="800" height="200" />
Update 2
For sake of thumbnail, what I am using is
<h:graphicImage height=200 width=200 value="....">
however I need to achieve same for PDF also.
Hope I am clear what I am expecting...
回答1:
I'm not sure if all browsers display your embedded PDF (done via <h:graphicImage value="some.pdf" ... />
) equally well.
Extracting 1st Page as PDF
If you insist on using PDF, I'd recommend one of these 2 commandline tools to extract the first page of any PDF:
pdftk- Ghostscript
Both are available for Linux, Mac OS X and Windows.
pdftk command
pdftk input.pdf cat 1 output page-1-of-input.pdf
Ghostscript command
gs -o page-1-of-input.pdf -sDEVICE=pdfwrite -dPDFLastPage=1 input.pdf
(On Windows use gswin32c.exe or gswin64c.exe instead of gs.)
pdftk is slightly faster than Ghostscript when it comes to page extraction, but for a single page that difference is probably neglectable.
Converting 1st Page to JPEG
If you want to be sure that even older browsers can display your 1st page well, then convert it to JPEG. Ghostscript is your friend here (ImageMagick cannot do it by itself, it needs the help of Ghostscript anyway):
gs -o page-1-of-input-PDF.jpeg -sDEVICE=jpeg -dLastPage=1 input.pdf
Should you need page 33, you can do it like this:
gs -o page-33-of-input-PDF.jpeg -sDEVICE=jpeg -dFirstPage=33 -dLastPage33 input.pdf
If you need a range of PDFs, like pages 17-23, try this:
gs -o page-16+%03d-of-input-PDF.jpeg -sDEVICE=jpeg -dFirstPage=17 -dLastPage23 input.pdf
Note, that the %03d notation increments with each page processed, starting with 1. So your first JPEG's name would be page-16+001-of-input-PDF.jpeg.
Maybe PNG is better?
Be aware that JPEG isn't a format suited well for images containing high black+white contrast and sharp edges like text pages. PNG is much better for this.
To create a PNG from the 1st PDF pages with Ghostscript is easy:
gs -o page-1-of-input-PDF.png -sDEVICE=pngalpha -dLastPage=1 input.pdf
The analog options as with JPEGs are true when it comes to extract ranges of pages.
回答2:
Warning: Don't use Ma9ic's script (posted in another answer) unless you want to...
- ...make the PDF->JPEG conversion consume much more time + resources than it should be
- ...give up your own control over the PDF->JPEG conversion process altogether.
While it may work well for you there are so many problems in these 8 little lines of Bash.
First,
it uses identify to extract the number of pages from the input PDF. However, identify (part of ImageMagick) is completely unable to process PDFs all by itself. It has to run Ghostscript as a 'delegate' to handle PDF input. It would be much more efficient to use Ghostscript directly instead of running it indirectly, via ImageMagick.
Second,
it uses convert to PDF->JPEG conversion. Same remark as above: it uses Ghostscript anyway, so why not run it directly?
Third,
it loops over the pages and runs a different convert process for every single page of the PDF, that is 100 converts for a 100 page PDF file. That means: it also runs 100 Ghostscript commands to produce 100 JPEGs.
Fourth,
Fahim Parkar's question was to get a thumbnail from the first page of the PDF, not from all of them.
The script does run at least 201 different commands for a 100 page PDF, when it could all be done in just 1 command. If you Ghostscript directly...
- ...not only will it run faster and more efficiently,
- ...but also it will give you more fine-grained and better control over the JPEGs' quality settings.
Use the right tool for the job, and use it correctly!
Update:
Since I was asked, here is my alternative implementation to Ma9ic's script.
#!/bin/bash
infile=${1}
gs -q -o $(basename "${infile}")_p%04d.jpeg -sDEVICE=jpeg "${infile}"
# To get thumbnail JPEGs with a width 200 pixel use the following command:
# gs -q -o name_200px_p%04d.jpg -sDEVICE=jpeg -dPDFFitPage -g200x400 "${infile}"
# To get higher quality JPEGs (but also bigger-in-size ones) with a
# resolution of 300 dpi use the following command:
# gs -q -o name_300dpi_p%04d.jpg -sDEVICE=jpeg -dJPEGQ=100 -r300 "${infile}"
echo "Done"
I've even run a benchmark on it. I converted the 756-page PDF-1.7 specification to JPEGs with both scripts:
- Ma9ic's version needs 1413 seconds generate the 756 JPEGs.
- My version saves 93% of that time and takes 91 seconds.
- Moreover, Ma9ic's script produces on my system mostly black JPEG images, mine are Ok.
回答3:
This is what I used
Document document = new Document();
try {
document.setFile(myProjectPath);
System.out.println("Parsed successfully...");
} catch (PDFException ex) {
System.out.println("Error parsing PDF document " + ex);
} catch (PDFSecurityException ex) {
System.out.println("Error encryption not supported " + ex);
} catch (FileNotFoundException ex) {
System.out.println("Error file not found " + ex);
} catch (IOException ex) {
System.out.println("Error handling PDF document " + ex);
}
// save page caputres to file.
float scale = 1.0f;
float rotation = 0f;
System.out.println("scale == " + scale);
// Paint each pages content to an image and write the image to file
InputStream fis2 = null;
File file = null;
for (int i = 0; i < 1; i++) {
BufferedImage image = (BufferedImage) document.getPageImage(i,
GraphicsRenderingHints.SCREEN,
Page.BOUNDARY_CROPBOX, rotation, scale);
RenderedImage rendImage = image;
// capture the page image to file
try {
System.out.println("\t capturing page " + i);
file = new File(myProjectActualPath + "myImage.png");
ImageIO.write(rendImage, "png", file);
fis2 = new BufferedInputStream(new FileInputStream(myProjectActualPath + "myImage.png"));
} catch (IOException ioe) {
System.out.println("IOException :: " + ioe);
} catch (Exception e) {
System.out.println("Exception :: " + e);
}
image.flush();
}
来源：https://stackoverflow.com/questions/11828528/display-first-page-of-pdf-as-image