为什么在使用Android中的iText库将图像转换为PDF时图像会被裁剪 [英] Why are images getting cropped while converting Images to PDF using iText library in android
问题描述
在我的应用程序中，我想将用户选择的图像转换为单个PDF文件。
我正在使用许多人建议的iText库。
用户选择多个图像，并使用它创建一个pdf，其中每个图像为1 pdf页。
In my application i want to convert the images selected by the user into one single PDF file. I am using iText library as suggested by many people. The user selects multiple images and one pdf is created with it where each image is 1 pdf page.
我正在使用的代码如下所示
The Code i am using is give as below
Document document = new Document(PageSize.A4);
try {
String path = Environment.getExternalStorageDirectory()+"/PDFile.pdf";
File file= new File(path);
if(file.exists())
{
}
else
{
file.createNewFile();
}
PdfWriter.getInstance(document,new FileOutputStream(path));
document.open();
for(int i =0; i<pdfImage.size();i++)
{
Image image = Image.getInstance(pdfImage.get(i));
image.scaleAbsolute(PageSize.A4);
image.setAbsolutePosition(0, 0);
document.add(image);
}
document.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
生成pdf但图片被裁剪。只有一半的图像是可见的其余部分被裁剪。
The pdf is getting generated but the image is cropped. Only half of the image is visible rest of it is cropped.
我是否必须为pdf设置采用图像大小的任何内容？
Do i have to set anything for the pdf to adopt to the image size ??
或者我是必须更改或调整图像大小以采用pdf页面大小??
Or do i have to change or resize the image to adopt to pdf page size??
请帮助!!我不知道如何解决这个问题???
Please help!! I have no idea how to resolve this???
推荐答案
当你这样做时：
Document document = new Document();
然后，您隐式创建一个页面大小称为A4的文档。即：宽度为595，高度为842个用户单位。
Then you implicitly create a document of which the pages have a page size known as A4. That is: a width of 595 and a height 842 user units.
如果添加较小的图像，则不会裁剪它们。如果添加更大的图像。图像将被裁剪...
If you add images that are smaller, they won't be cropped. If you add images that are bigger. The images will be cropped...
如果您希望图像完全适合页面，您有两种选择：
If you want an image to fit a page exactly, you have two options:
- 调整页面大小，或
- 调整图像大小。
这两个选项都是等价的，因为iText不会改变图像的分辨率：每个像素都会被保留。
Both options are equivalent, as iText will not change the resolution of the images: every pixel will be preserved.
选项1：
请参阅我对问题的回答：在iText Java上添加地图
See my answer to the question: Adding maps at iText Java
在这个问题中，我这样做：
In this question, I do this:
Image img = Image.getInstance(IMG);
Document document = new Document(img);
PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(dest));
document.open();
img.setAbsolutePosition(0, 0);
document.add(img);
document.close();
文档对象接受 Rectangle 作为参数。此矩形以用户单位定义页面大小。由于 Image 类是 Rectangle 类的子类，我可以使用 Image instance作为创建 Document 实例的参数。
The Document object accepts a Rectangle as parameter. This Rectangle defines the page size in user units. As the Image class is a subclass of the Rectangle class, I can use the Image instance as a parameter to create the Document instance.
另一种选择是做这个：
Rectangle pagesize = new Rectangle(img.getScaledWidth(), img.getScaledHeight());
Document document = new Document(pagesize);
如果您的文档有不同的页面，则必须使用 setPageSize（）方法在触发新页面之前。
If your document has different pages, you must use the setPageSize() method before triggering a new page.
选项2：
See my answer to the question: Backgroundimage in landscape and cover whole pdf with iTextSharp
代码看起来像这样（嗯，实际代码有点不同，但这样会也工作）：
The code looks like this (well, the actual code is a tad different, but this will work too):
Document document = new Document(PageSize.A4.rotate());
PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(dest));
document.open();
Image image = Image.getInstance(IMAGE);
image.scaleAbsolute(PageSize.A4.rotate());
image.setAbsolutePosition(0, 0);
document.add(image);
document.close();
这里我有横向A4尺寸的页面，我缩放图像以使其适合页面完全。这是危险，因为这会改变图像的宽高比。这可能导致图像失真。用 scaleToFit（）替换 scaleAbsolute（）将避免这个问题，但如果方面你会有一些白色边距 - 图像的比例与页面的宽高比不同。
Here I have pages with size A4 in landscape, and I scale the image so that it fits the page completely. That is dangerous because this changes the aspect-ratio of the image. This can result in distorted images. Replacing scaleAbsolute() by scaleToFit() will avoid that problem, but you'll have some white margins if the aspect-ratio of the image is different from the aspect-ratio of the page.
重要：请注意，我使用了两种情况下都有setAbsolutePosition（0,0）; 。我正在介绍此行，以便图像的左下角与页面的左下角重合。如果你不这样做，你会看到底部和左边的边距，你的图像将被剪裁到顶部和右边。
Important: Note that I used setAbsolutePosition(0, 0); in both cases. I am introducing this line so that the lower-left corner of the image coincides with the lower-left corner of the page. If you don't do this, you will see a margin to the bottom and to the left, and your image will be clipped to the top and the right.
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