Merge pull request #390 from chinapandaman/PPF-387

PPF-387: implement preview method

PyPDFForm/core/constants.py

@@ -22,6 +22,7 @@
 DEFAULT_FONT = "Helvetica"
 DEFAULT_FONT_SIZE = 12
 DEFAULT_FONT_COLOR = (0, 0, 0)
+PREVIEW_FONT_COLOR = (1, 0, 0)
 
 CHECKBOX_TO_DRAW = "\u2713"
 RADIO_TO_DRAW = "\u25CF"

PyPDFForm/core/template.py

@@ -276,6 +276,12 @@ def get_draw_text_coordinates(
 ) -> Tuple[Union[float, int], Union[float, int]]:
     """Returns coordinates to draw text at given a PDF form text element."""
 
+    if element_middleware.preview:
+        return (
+            float(element[constants.ANNOTATION_RECTANGLE_KEY][0]),
+            float(element[constants.ANNOTATION_RECTANGLE_KEY][3]) + 5
+        )
+
     element_value = element_middleware.value or ""
     length = (
         min(len(element_value), element_middleware.max_length)

PyPDFForm/core/utils.py

@@ -154,6 +154,23 @@ def checkbox_radio_to_draw(
     return new_element
 
 
+def preview_element_to_draw(
+    element: ELEMENT_TYPES
+) -> Text:
+    """Converts an element to a preview text element."""
+
+    new_element = Text(
+        element_name=element.name,
+        element_value="{" + f" {element.name} " + "}",
+    )
+    new_element.font = constants.DEFAULT_FONT
+    new_element.font_size = constants.DEFAULT_FONT_SIZE
+    new_element.font_color = constants.PREVIEW_FONT_COLOR
+    new_element.preview = True
+
+    return new_element
+
+
 def remove_all_elements(pdf: bytes) -> bytes:
     """Removes all elements from a pdfrw parsed PDF form."""
 

PyPDFForm/middleware/text.py

@@ -25,6 +25,7 @@ def __init__(
         self.character_paddings = None
         self.text_lines = None
         self.text_line_x_coordinates = None
+        self.preview = False
 
     @property
     def schema_definition(self) -> dict:

PyPDFForm/wrapper.py

@@ -83,6 +83,18 @@ def __add__(self, other: Wrapper) -> Wrapper:
 
         return new_obj
 
+    @property
+    def preview(self) -> bytes:
+        """Inspects all supported elements' names for the PDF form."""
+
+        return filler.fill(
+            self.stream,
+            {
+               key: utils.preview_element_to_draw(value)
+               for key, value in self.elements.items()
+            },
+        )
+
     def fill(
         self,
         data: Dict[str, Union[str, bool, int]],

docs/examples.md

@@ -14,6 +14,30 @@ found [here](https://github.com/chinapandaman/PyPDFForm/raw/master/pdf_samples/s
 It has three text fields `test`, `test_2`, `test_3` and three checkboxes 
 `check`, `check_2`, `check_3` scattered on three pages.
 
+## Preview a PDF form
+
+This example demos how to preview a PDF form. The preview can be used to inspect the elements' names for the PDF form. 
+The generated output will have each element's name labeled on top of it in red.
+
+```python
+import os
+
+from PyPDFForm import PyPDFForm
+
+PATH_TO_DOWNLOADED_SAMPLE_PDF_FORM = os.path.join(
+    os.path.expanduser("~/Downloads"), "sample_template.pdf"
+)  # Change this to where you downloaded the sample PDF form
+
+PATH_TO_FILLED_PDF_FORM = os.path.join(
+    os.path.expanduser("~"), "output.pdf"
+)  # Change this to where you wish to put your filled PDF form
+
+with open(PATH_TO_FILLED_PDF_FORM, "wb+") as output:
+    output.write(
+        PyPDFForm(PATH_TO_DOWNLOADED_SAMPLE_PDF_FORM).preview
+    )
+```
+
 ## Filling a PDF form
 
 This example demos filling a PDF form in the most straight forward way 

tests/test_preview.py

@@ -0,0 +1,75 @@
+# -*- coding: utf-8 -*-
+
+import os
+
+from PyPDFForm import PyPDFForm
+
+
+def test_preview(template_stream, pdf_samples, request):
+    expected_path = os.path.join(pdf_samples, "preview", "test_preview.pdf")
+    with open(expected_path, "rb+") as f:
+        preview = PyPDFForm(template_stream).preview
+
+        request.config.results["expected_path"] = expected_path
+        request.config.results["stream"] = preview
+
+        expected = f.read()
+
+        assert len(preview) == len(expected)
+        assert preview == expected
+
+
+def test_preview_sejda(sejda_template, pdf_samples, request):
+    expected_path = os.path.join(pdf_samples, "preview", "test_preview_sejda.pdf")
+    with open(expected_path, "rb+") as f:
+        preview = PyPDFForm(sejda_template).preview
+
+        request.config.results["expected_path"] = expected_path
+        request.config.results["stream"] = preview
+
+        expected = f.read()
+
+        assert len(preview) == len(expected)
+        assert preview == expected
+
+
+def test_preview_paragraph_complex(sample_template_paragraph_complex, pdf_samples, request):
+    expected_path = os.path.join(pdf_samples, "preview", "test_preview_paragraph_complex.pdf")
+    with open(expected_path, "rb+") as f:
+        preview = PyPDFForm(sample_template_paragraph_complex).preview
+
+        request.config.results["expected_path"] = expected_path
+        request.config.results["stream"] = preview
+
+        expected = f.read()
+
+        assert len(preview) == len(expected)
+        assert preview == expected
+
+
+def test_preview_sejda_complex(sejda_template_complex, pdf_samples, request):
+    expected_path = os.path.join(pdf_samples, "preview", "test_preview_sejda_complex.pdf")
+    with open(expected_path, "rb+") as f:
+        preview = PyPDFForm(sejda_template_complex).preview
+
+        request.config.results["expected_path"] = expected_path
+        request.config.results["stream"] = preview
+
+        expected = f.read()
+
+        assert len(preview) == len(expected)
+        assert preview == expected
+
+
+def test_preview_comb_text_field(sample_template_with_comb_text_field, pdf_samples, request):
+    expected_path = os.path.join(pdf_samples, "preview", "test_preview_comb_text_field.pdf")
+    with open(expected_path, "rb+") as f:
+        preview = PyPDFForm(sample_template_with_comb_text_field).preview
+
+        request.config.results["expected_path"] = expected_path
+        request.config.results["stream"] = preview
+
+        expected = f.read()
+
+        assert len(preview) == len(expected)
+        assert preview == expected