- Fixed issue #11640: Polygon size reducement failes for very thin four edged

  polygones

4 files changed, 66 insertions, 12 deletions

diff --git a/ChangeLog b/ChangeLog
index 6b8e820..98b10a5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,8 @@
 1.2 - [RELEASEDATE]
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+- Fixed issue #11640: Polygon size reducement failes for very thin four edged
+  polygones
 - Fixed issue #11511: Line thickness wan't used for rendering
 - Fixed issue #11509: Typo in line chart option
 - Implemented feature #10978: Add support for stacked bar charts
diff --git a/src/interfaces/driver.php b/src/interfaces/driver.php
index dfd8e1a..5eb6f03 100644
--- a/src/interfaces/driver.php
+++ b/src/interfaces/driver.php
@@ -105,6 +105,7 @@ abstract class ezcGraphDriver
 
         // Build normalized vectors between polygon edge points
         $vectors = array();
+        $vectorLength = array();
         for ( $i = 0; $i < $pointCount; ++$i )
         {
             $nextPoint = ( $i + 1 ) % $pointCount;
@@ -112,7 +113,8 @@ abstract class ezcGraphDriver
                             ->sub( $points[$i] );
 
             // Throw exception if polygon is too small to reduce
-            if ( $vectors[$i]->length() < $size )
+            $vectorLength[$i] = $vectors[$i]->length();
+            if ( $vectorLength[$i] < $size )
             {
                 throw new ezcGraphReducementFailedException();
             }
@@ -215,17 +217,32 @@ abstract class ezcGraphDriver
             // point and the size as distance to move.
             // point + v + size / tan( angle / 2 ) * startVector
             $newPoint = clone $vectors[$next];
-            $newPoints[$next] = 
-                $v  ->add( 
-                        $newPoint
-                            ->scalar( 
-                                $size / 
-                                tan( 
-                                    $lastVector->angle( $vectors[$next] ) / 2
-                                ) 
-                            ) 
-                    )
-                    ->add( $points[$next] );
+            $v  ->add( 
+                $newPoint
+                    ->scalar( 
+                        $size / 
+                        tan( 
+                            $lastVector->angle( $vectors[$next] ) / 2
+                        ) 
+                    ) 
+            );
+
+            // A fast guess: If the movement of the point exceeds the length of
+            // the surrounding edge vectors the angle was to small to perform a
+            // valid size reducement. In this case we just fall back to the
+            // original point array.
+            //
+            // The correct way to check would be a test, if the calculated
+            // point is still in the original polygon, but a test for a point
+            // in a polygon is too expensive.
+            $movement = $v->length();
+            if ( ( $movement > $vectorLength[$last] ) &&
+                 ( $movement > $vectorLength[$next] ) )
+            {
+                $v->unify()->scalar( min( $vectorLength[$last], $vectorLength[$next] ) );
+            }
+
+            $newPoints[$next] = $v->add( $points[$next] );
         }
 
         return $newPoints;
diff --git a/tests/data/compare/ezcGraphSvgDriverTest_testDrawPolygonFourPointsNotFilledBorderSizeReducement.svg b/tests/data/compare/ezcGraphSvgDriverTest_testDrawPolygonFourPointsNotFilledBorderSizeReducement.svg
new file mode 100644
index 0000000..c3c5d82
--- /dev/null
+++ b/tests/data/compare/ezcGraphSvgDriverTest_testDrawPolygonFourPointsNotFilledBorderSizeReducement.svg
@@ -0,0 +1,2 @@
+<?xml version="1.0"?>
+<svg xmlns="http://www.w3.org/2000/svg" width="200" height="100" version="1.0" id="ezcGraph"><defs/><g id="ezcGraphChart" color-rendering="optimizeQuality" shape-rendering="geometricPrecision" text-rendering="optimizeLegibility"><path d=" M 24.4367,27.7272 L 24.6906,27.9766 L 30.5106,22.4890 L 30.2567,22.2397 L 24.4367,27.7272 z " style="fill: none; stroke: #3465a4; stroke-width: 1; stroke-opacity: 0.50; stroke-linecap: round; stroke-linejoin: round;" id="ezcGraphPolygon_1"/><path d=" M 43.6544,8.6381 L 24.7929,28.0781 L 11.2929,41.5781 L 30.1544,22.1381 L 43.6544,8.6381 z " style="fill: #3465a4; fill-opacity: 0.50; stroke: none;" id="ezcGraphPolygon_2"/></g></svg>
diff --git a/tests/driver_svg_test.php b/tests/driver_svg_test.php
index 75233e4..16dedff 100644
--- a/tests/driver_svg_test.php
+++ b/tests/driver_svg_test.php
@@ -151,6 +151,39 @@ class ezcGraphSvgDriverTest extends ezcGraphTestCase
         );
     }
 
+    public function testDrawPolygonFourPointsNotFilledBorderSizeReducement()
+    {
+        $filename = $this->tempDir . __FUNCTION__ . '.svg';
+
+        $this->driver->drawPolygon(
+            array( 
+                new ezcGraphCoordinate( 24.79289, 28.078128 ),
+                new ezcGraphCoordinate( 11.29289, 41.578128 ),
+                new ezcGraphCoordinate( 30.15439, 22.13813 ),
+                new ezcGraphCoordinate( 43.65439, 8.63813 ),
+            ),
+            ezcGraphColor::fromHex( '#3465A480' ),
+            false
+        );
+
+        $this->driver->drawPolygon(
+            array( 
+                new ezcGraphCoordinate( 24.79289, 28.078128 ),
+                new ezcGraphCoordinate( 11.29289, 41.578128 ),
+                new ezcGraphCoordinate( 30.15439, 22.13813 ),
+                new ezcGraphCoordinate( 43.65439, 8.63813 ),
+            ),
+            ezcGraphColor::fromHex( '#3465A480' )
+        );
+
+        $this->driver->render( $filename );
+
+        $this->compare( 
+            $filename,
+            $this->basePath . 'compare/' . __CLASS__ . '_' . __FUNCTION__ . '.svg'
+        );
+    }
+
     public function testDrawPolygonThreePointsNotFilledReverse()
     {
         $filename = $this->tempDir . __FUNCTION__ . '.svg';