[bug-66278] Bug with multiple gradient stops at the exact same location causing a rendering failure (AWT -> not enough colors in gradient). Thanks to Gareth Floodgate. This closes #385

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1904301 13f79535-47bb-0310-9956-ffa450edef68

poi-ooxml/src/test/java/org/apache/poi/xslf/TestXSLFBugs.java

@@ -25,6 +25,11 @@ import static org.junit.jupiter.api.Assertions.*;
 import static org.junit.jupiter.api.Assumptions.assumeFalse;
 
 import java.awt.Color;
+import java.awt.LinearGradientPaint;
+import java.awt.MultipleGradientPaint;
+import java.awt.Paint;
+import java.awt.RadialGradientPaint;
+import java.awt.geom.Point2D;
 import java.awt.geom.Rectangle2D;
 import java.io.File;
 import java.io.FileInputStream;
@@ -1120,4 +1125,97 @@ class TestXSLFBugs {
             }
         }
     }
+
+    @Test
+    void identicalGradientStopsBug() throws IOException {
+
+        final ArrayList<LinearGradientPaint> linearGradients = new ArrayList<>();
+        final ArrayList<RadialGradientPaint> radialGradients = new ArrayList<>();
+        final DummyGraphics2d dgfx = new DummyGraphics2d(new NullPrintStream())
+        {
+            public void setPaint(final Paint paint) {
+                if (paint instanceof LinearGradientPaint) {
+                    linearGradients.add((LinearGradientPaint) paint);
+                }
+                if (paint instanceof RadialGradientPaint) {
+                    radialGradients.add((RadialGradientPaint) paint);
+                }
+            }
+        };
+
+        final List<LinearGradientPaint> expectedLinearGradients = Arrays.asList(
+                new LinearGradientPaint(new Point2D.Double(30.731732283464567, 138.7317322834646),
+                        new Point2D.Double(122.91549846753813, 46.54796609939099),
+                        new float[] { 0.0f, 0.99999994f, 1.0f },
+                        new Color[] { new Color(81, 124, 252, 255),
+                                new Color(81, 124, 252, 255),
+                                new Color(17,21,27, 204) }),
+                new LinearGradientPaint(new Point2D.Double(174.7317322834646, 138.73173228346457),
+                        new Point2D.Double(266.9154984675381, 46.547966099391004),
+                        new float[] { 0.0f, 0.00000005f, 1.0f },
+                        new Color[] { new Color(17,21,27, 204),
+                                new Color(81, 124, 252, 255),
+                                new Color(81, 124, 252, 255) }),
+                new LinearGradientPaint(new Point2D.Double(318.73173228346457, 138.73173228346462),
+                        new Point2D.Double(410.9154984675381, 46.547966099391004),
+                        new float[] { 0.0f, 0.5f, 0.50000006f, 1.0f },
+                        new Color[] { new Color(17,21,27, 204),
+                                new Color(17,21,27, 204),
+                                new Color(81, 124, 252, 255),
+                                new Color(81, 124, 252, 255) })
+        );
+
+        final List<RadialGradientPaint> expectedRadialGradients = Arrays.asList(
+                new RadialGradientPaint(new Point2D.Double(30.731732283464567, 138.7317322834646),
+                        108.0f, new Point2D.Double(122.91549846753813, 46.54796609939099),
+                        new float[] { 0.0f, 0.5f, 0.50000006f, 1.0f },
+                        new Color[] { new Color(17,21,27, 204),
+                                new Color(17,21,27, 204),
+                                new Color(81, 124, 252, 255),
+                                new Color(81, 124, 252, 255)  },
+                        MultipleGradientPaint.CycleMethod.NO_CYCLE),
+                new RadialGradientPaint(new Point2D.Double(228.73173228346457, 226.9755905511811),
+                        108.0f, new Point2D.Double(282.73173228346457, 280.9755905511811),
+                        new float[] { 0.0f, 0.00000005f, 1.0f },
+                        new Color[] { new Color(17,21,27, 204),
+                                new Color(81, 124, 252, 255),
+                                new Color(81, 124, 252, 255)  },
+                        MultipleGradientPaint.CycleMethod.NO_CYCLE),
+                new RadialGradientPaint(new Point2D.Double(84.73173228346457, 226.9755905511811),
+                        108.0f, new Point2D.Double(138.73173228346457, 280.9755905511811),
+                        new float[] { 0.0f, 0.99999994f, 1.0f },
+                        new Color[] { new Color(81, 124, 252, 255),
+                                new Color(81, 124, 252, 255),
+                                new Color(17,21,27, 204) },
+                        MultipleGradientPaint.CycleMethod.NO_CYCLE)
+        );
+
+        try (XMLSlideShow slideShowModel = openSampleDocument("minimal-gradient-fill-issue.pptx")) {
+            // Render the first (and only) slide.
+            slideShowModel.getSlides().get(0).draw(dgfx);
+
+            // Test that the linear gradients have the expected data (stops modified)
+            assertEquals(3, linearGradients.size());
+            for (int i = 0 ; i < expectedLinearGradients.size() ; i++) {
+                final LinearGradientPaint expected = expectedLinearGradients.get(i);
+                final LinearGradientPaint actual = linearGradients.get(i);
+                assertEquals(expected.getStartPoint(), expected.getStartPoint());
+                assertEquals(expected.getEndPoint(), expected.getEndPoint());
+                assertArrayEquals(expected.getFractions(), actual.getFractions());
+                assertArrayEquals(expected.getColors(), actual.getColors());
+            }
+
+            // Test that the radial gradients have the expected data (stops modified)
+            assertEquals(3, radialGradients.size());
+            for (int i = 0 ; i < expectedRadialGradients.size() ; i++) {
+                final RadialGradientPaint expected = expectedRadialGradients.get(i);
+                final RadialGradientPaint actual = radialGradients.get(i);
+                assertEquals(expected.getCenterPoint(), expected.getCenterPoint());
+                assertEquals(expected.getFocusPoint(), expected.getFocusPoint());
+                assertArrayEquals(expected.getFractions(), actual.getFractions());
+                assertArrayEquals(expected.getColors(), actual.getColors());
+            }
+        }
+    }
+
 }

poi/src/main/java/org/apache/poi/sl/draw/DrawPaint.java

@@ -613,7 +613,21 @@ public class DrawPaint {
         // need to remap the fractions, because Java doesn't like repeating fraction values
         Map<Float,Color> m = new TreeMap<>();
         for (float fraction : fill.getGradientFractions()) {
-            m.put(fraction, styles.next());
+            float gradientFraction = fraction;
+
+            // Multiple gradient stops at the same location
+            // can lead to failure when creating AWT gradient, especially
+            // if there are only two stops and they are both on the exact
+            // same location.
+            //   (The example of (only) 2 stops at exactly the same location will cause:
+            //    java.lang.IllegalArgumentException: User must specify at least 2 colors).
+            //
+            // To fix this we nudge the stop a teeny tiny bit.
+            if (m.containsKey(gradientFraction)) {
+                gradientFraction += (gradientFraction == 1.0 ? -1.0 : 1.0) * 0.00000005;
+            }
+
+            m.put(gradientFraction, styles.next());
         }
 
         return init.apply(toArray(m.keySet()), m.values().toArray(new Color[0]));