问题
I am new to iText and faced with a real interesting case about adding external images to a paragraph. Here is the thing:
Document document = new Document();
PdfWriter.getInstance(document, new FileOutputStream("out2.pdf"));
document.open();
Paragraph p = new Paragraph();
Image img = Image.getInstance("blablabla.jpg");
img.setAlignment(Image.LEFT| Image.TEXTWRAP);
// Notice the image added to the Paragraph through a Chunk
p.add(new Chunk(img2, 0, 0, true));
document.add(p);
Paragraph p2 = new Paragraph("Hello Worlddd!");
document.add(p2);
gives me the picture and "Hello Worlddd!" string below. However,
Document document = new Document();
PdfWriter.getInstance(document, new FileOutputStream("out2.pdf"));
document.open();
Paragraph p = new Paragraph();
Image img = Image.getInstance("blablabla.jpg");
img.setAlignment(Image.LEFT| Image.TEXTWRAP);
// Notice the image added directly to the Paragraph
p.add(img);
document.add(p);
Paragraph p2 = new Paragraph("Hello Worlddd!");
document.add(p2);
gives me the picture and string "Hello worlddd!" located on the right hand side of the picture and one line above it.
What is the logic behind that difference?
回答1:
The behaviour you described is because in the second code snippet the Paragraph doesn't adjust its leading, but adjust its width. If in the second snippet you add the line
p.add("Hello world 1")
just before
p.add(img)
you'll see the string "Hello world 1" on the left and a little bit above the string "Hello Worlddd!". If you output the leading of p (System.out.println(p.getLeading()) you can see it's a low number (typically 16) and not the height of the image.
In the first example you use the chunk constructor with 4 arguments
new Chunk(img, 0, 0, true)
with the last (true) saying to adjust the leading, so it print as you expected.
回答2:
If you add an image directly, its alignment properties (set with setAlignment()) are taken into account. So the image is on the left (Image.LEFT) and the text is wrapped around (Image.TEXTWRAP).
If you wrap the image in a Chunk it is handled as if it were a chunk of text. So the alignment properties, specific to images, are lost. This results in the text being below the image.
If you try Image.RIGHT, this becomes more apparent. Nothing changes in the first example: the image is still on the left. In the second example, the image is aligned to the right and the text is wrapped left of it.
来源：https://stackoverflow.com/questions/11118224/itext-adding-external-image-using-chunk