如何理解 pdf 表单标志？
How to understand pdf forms flags?
我使用 pdfbox 阅读 pdf 结构，但我无法从流中找到一些数据：
1 g
0 0 18 18 re
f
0.5 0.5 17 17 re
s
q
1 1 16 16 re
W
n
0 g
BT
/ZaDb 14.532 Tf
2.853 4.081 Td
13.9943 TL
(4) Tj
ET
Q
是checkbox的流信息，但是那个字母是什么意思？
任何人都可以向我解释，或者如果你可以与我分享我可以在哪里阅读它会更好吗？
1 g --- select DeviceGray WHITE as non-stroking color
0 0 18 18 re --- define a 18×18 rectangular path, lower left at 0,0
f --- fill the path with the non-stroking color
0.5 0.5 17 17 re --- define a 17×17 rectangular path, lower left at 0.5,0.5
s --- stroke the path with the stroking color
q --- save graphics state
1 1 16 16 re --- define a 16×16 rectangular path, lower left at 1,1
W --- intersect the current clip path with the just defined path
n --- don't draw the path
0 g --- select DeviceGray BLACK as non-stroking color
BT --- begin text object
/ZaDb 14.532 Tf --- select font with name ZaDb at size 14.532
2.853 4.081 Td --- move text insertion point by 2.853,4.081
13.9943 TL --- set leading to 13.9943
(4) Tj --- draw the string with one character with character code 0x34 (what you display as "4" is the byte 0x34)
ET --- end text object
Q --- restore graphics state
哪个字符的字符代码为0x34，取决于ZaDb是如何定义的。你应该可以在你关注的窗体XObject的字体资源中找到它的定义。
不过，ZaDb 很有可能是采用 ZapfDingbats 编码的 ZapfDingbats 字体，请参阅 ISO 32000-2 附件 D.6。在这种情况下，字符代码 0x34 对应于 ✔.
换句话说，您的窗体 XObject 绘制了一个黑边内白的正方形，然后在该正方形内绘制了一个黑色勾号。
我使用 pdfbox 阅读 pdf 结构，但我无法从流中找到一些数据：
1 g
0 0 18 18 re
f
0.5 0.5 17 17 re
s
q
1 1 16 16 re
W
n
0 g
BT
/ZaDb 14.532 Tf
2.853 4.081 Td
13.9943 TL
(4) Tj
ET
Q
是checkbox的流信息，但是那个字母是什么意思？
任何人都可以向我解释，或者如果你可以与我分享我可以在哪里阅读它会更好吗？
1 g --- select DeviceGray WHITE as non-stroking color
0 0 18 18 re --- define a 18×18 rectangular path, lower left at 0,0
f --- fill the path with the non-stroking color
0.5 0.5 17 17 re --- define a 17×17 rectangular path, lower left at 0.5,0.5
s --- stroke the path with the stroking color
q --- save graphics state
1 1 16 16 re --- define a 16×16 rectangular path, lower left at 1,1
W --- intersect the current clip path with the just defined path
n --- don't draw the path
0 g --- select DeviceGray BLACK as non-stroking color
BT --- begin text object
/ZaDb 14.532 Tf --- select font with name ZaDb at size 14.532
2.853 4.081 Td --- move text insertion point by 2.853,4.081
13.9943 TL --- set leading to 13.9943
(4) Tj --- draw the string with one character with character code 0x34 (what you display as "4" is the byte 0x34)
ET --- end text object
Q --- restore graphics state
哪个字符的字符代码为0x34，取决于ZaDb是如何定义的。你应该可以在你关注的窗体XObject的字体资源中找到它的定义。
不过，ZaDb 很有可能是采用 ZapfDingbats 编码的 ZapfDingbats 字体，请参阅 ISO 32000-2 附件 D.6。在这种情况下，字符代码 0x34 对应于 ✔.
换句话说，您的窗体 XObject 绘制了一个黑边内白的正方形，然后在该正方形内绘制了一个黑色勾号。