Merge pull request #36 from jonmccracken-wf/fixRotatedStrokeWidth

Fix stroke width in for lines in rotated transform spaces

graphics2d/src/main/java/de/rototor/pdfbox/graphics2d/PdfBoxGraphics2D.java

@@ -49,6 +49,7 @@
 import java.awt.geom.Line2D;
 import java.awt.geom.NoninvertibleTransformException;
 import java.awt.geom.Path2D;
+import java.awt.geom.Point2D;
 import java.awt.geom.PathIterator;
 import java.awt.geom.Rectangle2D;
 import java.awt.geom.RoundRectangle2D;
@@ -287,7 +288,7 @@ public PDResources getResources()
 
 	/**
 	 * *AFTER* you have disposed() this Graphics2D you can access the XForm
-	 * 
+	 *
 	 * @return the PDFormXObject which resulted in this graphics
 	 */
     @SuppressWarnings("WeakerAccess")
@@ -530,16 +531,18 @@ private void applyStroke(Stroke strokeToApply) throws IOException
             }
 
             AffineTransform tf = getCurrentEffectiveTransform();
+            float lineWidth = calculateTransformedLength(basicStroke.getLineWidth(), tf);
+
+            contentStream.setLineWidth(lineWidth);
 
-            double scaleX = tf.getScaleX();
-            contentStream.setLineWidth((float) Math.abs(basicStroke.getLineWidth() * scaleX));
             float[] dashArray = basicStroke.getDashArray();
             if (dashArray != null)
             {
                 for (int i = 0; i < dashArray.length; i++)
-                    dashArray[i] = (float) Math.abs(dashArray[i] * scaleX);
+                    dashArray[i] = calculateTransformedLength(dashArray[i], tf);
+
                 contentStream.setLineDashPattern(dashArray,
-                        (float) Math.abs(basicStroke.getDashPhase() * scaleX));
+                    calculateTransformedLength(basicStroke.getDashPhase(), tf));
             }
         }
         else if (strokeToApply != null)
@@ -549,6 +552,15 @@ else if (strokeToApply != null)
         }
     }
 
+    private float calculateTransformedLength(float length, AffineTransform tf) {
+        // Represent stroke width as a horizontal line from origin to basicStroke.LineWidth.
+        Point2D.Float lengthVector = new Point2D.Float(length, 0);
+        // Apply the current transform to the horizontal line.
+        tf.deltaTransform(lengthVector, lengthVector);
+        // Calculate the length of the transformed line. This is the new, adjusted length.
+        return (float) Math.sqrt(lengthVector.x * lengthVector.x + lengthVector.y * lengthVector.y);
+    }
+
     private AffineTransform getCurrentEffectiveTransform()
     {
         AffineTransform tf = new AffineTransform();

graphics2d/src/test/java/de/rototor/pdfbox/graphics2d/RenderSVGsTest.java

@@ -38,6 +38,13 @@ public void testSVGs() throws IOException
         renderSVG("watermark.svg", 0.4);
     }
 
+    @Test
+    public void testRotatedStrokes() throws IOException
+    {
+        renderSVG("strokeRotation.svg", 0.55);
+        renderSVG("dashedStrokeRotation.svg", 0.55);
+    }
+
     @Test
     public void renderFailureCases() throws IOException
     {