Add FPDF.bezier() method exposing PaintedPath.curve_to (py-pdf#1174)

* Began implementation of bezier method. * Focus on cubic Bezier curves for now, added to doc page on shapes, and added one test. * Image for shapes doc page * Remove code paste comment from writing Bezier test * FPDF.bezier(): Remove unused variable, add extra space following * Mention new Cubic bezier method in CHANGELOG.md * Make Bezier curves as open paths by default * Quadratic or cubic curves with bezier(), Draw Bezier curves as open paths by default * Error handling in FPDF.bezier() and adding closed paths to tests * Accept style in .bezier(), convert it to PathPaintRule * Fix style errors reported by pylint * Fix accidentally calling boolean attribute as if it were function * Show styles functionality in Bezier curve testing * Test that line width and dash pattern are updated from FPDF object; Remove generate=True from Bezier tests; clean up point drawing function for bezier tests. * Update template PDFs for Bezier test. * Remove debug_stream param from fdpf.bezier(), Ran black * Do not mention removed parameter in docstring for fpdf.bezier() * Fix merge conflict in and mention Bezier curves in CHANGELOG.md
andersonhc · May 30, 2024 · f0bd468 · f0bd468
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -20,7 +20,7 @@ This can also be enabled programmatically with `warnings.simplefilter('default',
 ### Added
 * [`Templates`](https://py-pdf.github.io/fpdf2/fpdf/Templates.html) can now be also defined in JSON files.
 * support to optionally set `wrapmode` in templates (default `"WORD"` can optionally be set to `"CHAR"` to support wrapping on characters for scripts like Chinese or Japanese) - _cf._ [#1159](https://github.com/py-pdf/fpdf2/issues/1159)
-
+* support for quadratic and cubic Bézier curves with [`FPDF.bezier()`](https://py-pdf.github.io/fpdf2/fpdf/Shapes.html#fpdf.fpdf.FPDF.bezier)
 ### Fixed
 * [`fpdf.drawing.DeviceCMYK`](https://py-pdf.github.io/fpdf2/fpdf/drawing.html#fpdf.drawing.DeviceCMYK) objects can now be passed to [`FPDF.set_draw_color()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.set_draw_color), [`FPDF.set_fill_color()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.set_fill_color) and [`FPDF.set_text_color()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.set_text_color) without raising a `ValueError`: [documentation](https://py-pdf.github.io/fpdf2/Text.html#text-formatting).
 * individual `/Resources` directories are now properly created for each document page. This change ensures better compliance with the PDF specification but results in a slight increase in the size of PDF documents. You can still use the old behavior by setting `FPDF().single_resources_object = True`.
@@ -666,4 +666,4 @@ prevented strings passed first to the text-rendering methods to be displayed.
 ### Modified
 * turned `accept_page_break` into a property
 * unit tests now use the standard `unittest` lib
-* massive code cleanup using `flake8`
+* massive code cleanup using `flake8`
diff --git a/docs/Shapes.md b/docs/Shapes.md
@@ -161,6 +161,19 @@ pdf.output("solid_arc.pdf")
 ```
 ![](solid_arc.png)
 
+## Bezier Curve ##
+Using [`bezier()`](fpdf/fpdf.html#fpdf.fpdf.FPDF.bezier) to create a cubic Bezier curve:
+```python
+from fpdf import FPDF
+pdf = FPDF()
+pdf.add_page()
+pdf.set_fill_color(r=255, g=0, b=255)
+pdf.bezier([(20, 80), (40, 20), (60, 80)])
+pdf.output("bezier.pdf")
+```
+
+![](bezier.png)
+
 ## Regular Polygon ##
 
 Using [`regular_polygon()`](fpdf/fpdf.html#fpdf.fpdf.FPDF.regular_polygon):

diff --git a/docs/bezier.png b/docs/bezier.png
diff --git a/fpdf/fpdf.py b/fpdf/fpdf.py
@@ -1828,6 +1828,74 @@ def solid_arc(
             style,
         )
 
+    def bezier(self, point_list, closed=False, style=None):
+        """
+        Outputs a quadratic or cubic Bézier curve, defined by three or four coordinates.
+
+        Args:
+            point_list (list of tuples): List of Abscissa and Ordinate of
+                                        segments that should be drawn. Should be
+                                        three or four tuples. The first and last
+                                        points are the start and end point. The
+                                        middle point(s) are the control point(s).
+            closed (bool): True to draw the curve as a closed path, False (default)
+                                        for it to be drawn as an open path.
+            style (fpdf.enums.RenderStyle, str): Optional style of rendering. Allowed values are:
+            * `D` or None: draw border. This is the default value.
+            * `F`: fill
+            * `DF` or `FD`: draw and fill
+        """
+        points = len(point_list)
+        if points not in (3, 4):
+            raise ValueError(
+                "point_list should contain 3 tuples for a quadratic curve"
+                "or 4 tuples for a cubic curve."
+            )
+
+        if style is None:
+            style = RenderStyle.DF
+        else:
+            style = RenderStyle.coerce(style)
+
+        # QuadraticBezierCurve and BezierCurve make use of `initial_point` when instantiated.
+        # If we want to define all 3 (quad.) or 4 (cubic) points, we can set `initial_point`
+        # to be the first point given in `point_list` by creating a separate dummy path at that pos.
+        with self.drawing_context() as ctxt:
+            p1 = point_list[0]
+            x1, y1 = p1[0], p1[1]
+
+            dummy_path = PaintedPath(x1, y1)
+            ctxt.add_item(dummy_path)
+
+            p2 = point_list[1]
+            x2, y2 = p2[0], p2[1]
+
+            p3 = point_list[2]
+            x3, y3 = p3[0], p3[1]
+
+            if points == 4:
+                p4 = point_list[3]
+                x4, y4 = p4[0], p4[1]
+
+            path = PaintedPath(x1, y1)
+
+            # Translate enum style (RenderStyle) into rule (PathPaintRule)
+            rule = PathPaintRule.STROKE_FILL_NONZERO
+            if style.is_draw and not style.is_fill:
+                rule = PathPaintRule.STROKE
+            elif style.is_fill and not style.is_draw:
+                rule = PathPaintRule.FILL_NONZERO
+
+            path.style.paint_rule = rule
+            path.style.auto_close = closed
+
+            if points == 4:
+                path.curve_to(x2, y2, x3, y3, x4, y4)
+            elif points == 3:
+                path.curve_to(x2, y2, x2, y2, x3, y3)
+
+            ctxt.add_item(path)
+
     def add_font(self, family=None, style="", fname=None, uni="DEPRECATED"):
         """
         Imports a TrueType or OpenType font and makes it available

diff --git a/test/shapes/bezier_curve_line_settings.pdf b/test/shapes/bezier_curve_line_settings.pdf
diff --git a/test/shapes/cubic_bezier_curve.pdf b/test/shapes/cubic_bezier_curve.pdf
diff --git a/test/shapes/quadratic_bezier_curve.pdf b/test/shapes/quadratic_bezier_curve.pdf
diff --git a/test/shapes/test_bezier.py b/test/shapes/test_bezier.py
@@ -0,0 +1,86 @@
+from pathlib import Path
+
+import fpdf
+from test.conftest import assert_pdf_equal
+
+
+HERE = Path(__file__).resolve().parent
+
+
+def draw_points(pdf, point_lists):
+    for pl in point_lists:
+        for p in pl:
+            pdf.circle(x=p[0], y=p[1], r=1, style="FD")
+
+
+def test_quadratic_beziers(tmp_path):
+    pdf = fpdf.FPDF(unit="mm")
+    pdf.add_page()
+
+    pl1 = [(20, 40), (40, 20), (60, 40)]
+    pl2 = [(20, 80), (50, 100), (60, 80)]
+    pl3 = [(20, 120), (40, 110), (60, 120)]
+    pl4 = [(20, 170), (40, 160), (60, 170)]
+    pl5 = [[20, 230], (40, 280), (60, 250)]
+
+    pdf.set_fill_color(r=255, g=0, b=0)
+    pdf.bezier(pl1)
+    pdf.set_fill_color(r=0, g=255, b=0)
+    pdf.bezier(pl2)
+    pdf.set_fill_color(r=0, g=0, b=255)
+    pdf.bezier(pl3, closed=True)
+    pdf.bezier(pl4, style="F")
+    pdf.bezier(pl5, style="D")
+
+    draw_points(pdf, [pl1, pl2, pl3, pl4, pl5])
+
+    assert_pdf_equal(pdf, HERE / "quadratic_bezier_curve.pdf", tmp_path)
+
+
+def test_cubic_beziers(tmp_path):
+    pdf = fpdf.FPDF(unit="mm")
+    pdf.add_page()
+
+    pl1 = [(120, 40), (140, 30), (160, 49), (180, 50)]
+    pl2 = [(120, 80), (150, 100), (160, 80), (180, 80)]
+    pl3 = [(120, 120), (140, 130), (160, 140), (180, 120)]
+    pl4 = [(20, 20), (40, 10), (60, 20)]
+    pl5 = [[20, 80], (40, 90), (60, 80)]
+
+    pdf.set_fill_color(r=255, g=0, b=0)
+    pdf.bezier(pl1)
+    pdf.set_fill_color(r=0, g=255, b=0)
+    pdf.bezier(pl2)
+    pdf.set_fill_color(r=0, g=0, b=255)
+    pdf.bezier(pl3, closed=True)
+    pdf.bezier(pl4, style="F")
+    pdf.bezier(pl5, style="D")
+
+    draw_points(pdf, [pl1, pl2, pl3, pl4, pl5])
+
+    assert_pdf_equal(pdf, HERE / "cubic_bezier_curve.pdf", tmp_path)
+
+
+def test_bezier_line_settings(tmp_path):
+    pdf = fpdf.FPDF(unit="mm")
+    pdf.add_page()
+
+    pl1 = [(120, 40), (140, 30), (160, 49), (180, 50)]
+    pl2 = [(20, 80), (50, 100), (60, 80)]
+
+    pdf.set_fill_color(r=255, g=0, b=0)
+    pdf.set_dash_pattern(dash=2, gap=3)
+    pdf.bezier(pl1)
+
+    pdf.set_fill_color(r=0, g=255, b=0)
+    pdf.set_dash_pattern(dash=4, gap=6)
+    pdf.set_line_width(2)
+    pdf.bezier(pl2)
+
+    # Reset for drawing points
+    pdf.set_line_width(0.2)
+    pdf.set_dash_pattern(0, 0, 0)
+
+    draw_points(pdf, [pl1, pl2])
+
+    assert_pdf_equal(pdf, HERE / "bezier_curve_line_settings.pdf", tmp_path)