Fix clipped line renderer.

Fix for a nasty corner case where supposedly clipped pixel were
still rasterized (see polytest.cxx:implTestPolyDrawClip for what
failed previously).

Added much more unit tests while at it, clippedlinerenderer.hxx
should now have 100% coverage.

1 files changed, 100 insertions, 5 deletions

diff --git a/basebmp/test/polytest.cxx b/basebmp/test/polytest.cxx
index 8cc51d4921ee..63485000b7f9 100644
--- a/basebmp/test/polytest.cxx
+++ b/basebmp/test/polytest.cxx
@@ -65,7 +65,6 @@ private:
         const Color aBgCol(0);
         rDevice->clear(aBgCol);
         basegfx::B2DPolyPolygon aPoly;
-        ::rtl::OUString aSvg;
 
         basegfx::tools::importFromSvgD(
             aPoly,
@@ -100,7 +99,6 @@ private:
         const Color aBgCol(0);
         rDevice->clear(aBgCol);
         basegfx::B2DPolyPolygon aPoly;
-        ::rtl::OUString aSvg;
 
         basegfx::tools::importFromSvgD(
             aPoly,
@@ -150,7 +148,6 @@ private:
         const Color aBgCol(0);
         rDevice->clear(aBgCol);
         basegfx::B2DPolyPolygon aPoly;
-        ::rtl::OUString aSvg;
 
         basegfx::tools::importFromSvgD( aPoly,
                                         ::rtl::OUString(RTL_CONSTASCII_USTRINGPARAM(
@@ -170,7 +167,6 @@ private:
         const Color aBgCol(0);
         rDevice->clear(aBgCol);
         basegfx::B2DPolyPolygon aPoly;
-        ::rtl::OUString aSvg;
 
         basegfx::tools::importFromSvgD( aPoly,
                                         ::rtl::OUString(RTL_CONSTASCII_USTRINGPARAM(
@@ -204,13 +200,98 @@ private:
                                countPixel( rDevice, aCol ) == 7);
     }
 
+    void implTestLineDrawClip(const BitmapDeviceSharedPtr& rDevice)
+    {
+        const Color aCol(0xFFFFFFFF);
+        const Color aBgCol(0);
+        rDevice->clear(aBgCol);
+
+        // create rectangular subset, such that we can 'see' extra
+        // pixel outside
+        BitmapDeviceSharedPtr pClippedDevice=(
+            subsetBitmapDevice( rDevice,
+                                basegfx::B2IBox(3,3,5,9) ));
+
+        // trigger "alternate bresenham" case in
+        // clippedlinerenderer.hxx, first point not clipped
+        const basegfx::B2IPoint aPt1(3,3);
+        const basegfx::B2IPoint aPt2(4,2);
+        pClippedDevice->drawLine( aPt1, aPt2, aCol, DrawMode_PAINT );
+
+        CPPUNIT_ASSERT_MESSAGE("number of rendered pixel is not 1",
+                               countPixel( rDevice, aCol ) == 1);
+
+        // trigger "alternate bresenham" case in
+        // clippedlinerenderer.hxx, both start and endpoint clipped
+        const basegfx::B2IPoint aPt3(0,4);
+        pClippedDevice->drawLine( aPt3, aPt2, aCol, DrawMode_XOR );
+
+        CPPUNIT_ASSERT_MESSAGE("number of rendered pixel is not 0",
+                               countPixel( rDevice, aCol ) == 0);
+
+        // trigger "standard bresenham" case in
+        // clippedlinerenderer.hxx, first point not clipped
+        const basegfx::B2IPoint aPt4(6,2);
+        pClippedDevice->drawLine( aPt1, aPt4, aCol, DrawMode_PAINT );
+
+        CPPUNIT_ASSERT_MESSAGE("number of rendered pixel is not 2",
+                               countPixel( rDevice, aCol ) == 2);
+
+        // trigger "clipCode1 & aMinFlag/bMinFlag" cases in
+        // clippedlinerenderer.hxx (note1: needs forcing end point to
+        // be clipped as well, otherwise optimisation kicks in. note2:
+        // needs forcing end point to clip on two edges, not only on
+        // one, otherwise swap kicks in)
+        const basegfx::B2IPoint aPt5(1,1);
+        const basegfx::B2IPoint aPt6(6,10);
+        pClippedDevice->drawLine( aPt5, aPt6, aCol, DrawMode_XOR );
+
+        CPPUNIT_ASSERT_MESSAGE("number of rendered pixel is not 6",
+                               countPixel( rDevice, aCol ) == 6);
+
+        // trigger "clipCode1 & (aMinFlag|aMaxFlag)" case in
+        // clippedlinerenderer.hxx that was not taken for the test
+        // above
+        pClippedDevice->drawLine( aPt3, aPt6, aCol, DrawMode_XOR );
+
+        CPPUNIT_ASSERT_MESSAGE("number of rendered pixel is not 8",
+                               countPixel( rDevice, aCol ) == 8);
+
+    }
+
+    void implTestPolyDrawClip(const BitmapDeviceSharedPtr& rDevice)
+    {
+        const Color aCol(0xFFFFFFFF);
+        const Color aBgCol(0);
+        rDevice->clear(aBgCol);
+        basegfx::B2DPolyPolygon aPoly;
+
+        // test all corner-touching lines of our clip rect. note that
+        // *all* of the four two-pixel lines in that polygon do *not*
+        // generate a single pixel, due to the rasterization effect.
+        basegfx::tools::importFromSvgD( aPoly,
+                                        ::rtl::OUString(RTL_CONSTASCII_USTRINGPARAM(
+                                            "M2 3 l1 -1 M4 2 l1 1 M2 8 l1 1 M5 8 l-1 1 M2 5 h4 M3 0 v10" )) );
+        BitmapDeviceSharedPtr pClippedDevice=(
+            subsetBitmapDevice( rDevice,
+                                basegfx::B2IBox(3,3,5,9) ));
+
+        for( unsigned int i=0; i<aPoly.count(); ++i )
+            pClippedDevice->drawPolygon(
+                aPoly.getB2DPolygon(i),
+                aCol,
+                DrawMode_PAINT );
+
+        CPPUNIT_ASSERT_MESSAGE("number of rendered pixel is not 7",
+                               countPixel( rDevice, aCol ) == 7);
+    }
+
     void implTestPolyPolyCrissCross(const BitmapDeviceSharedPtr& rDevice)
     {
         const Color aCol(0xFFFFFFFF);
         const Color aBgCol(0);
         rDevice->clear(aBgCol);
         basegfx::B2DPolyPolygon aPoly;
-        ::rtl::OUString aSvg;
 
         basegfx::tools::importFromSvgD( aPoly,
                                         ::rtl::OUString(RTL_CONSTASCII_USTRINGPARAM(
@@ -264,6 +345,18 @@ public:
         implTestPolyPolyClip(mpDevice32bpp);
     }
 
+    void testLineDrawClip()
+    {
+        implTestLineDrawClip(mpDevice1bpp);
+        implTestLineDrawClip(mpDevice32bpp);
+    }
+
+    void testPolyDrawClip()
+    {
+        implTestPolyDrawClip(mpDevice1bpp);
+        implTestPolyDrawClip(mpDevice32bpp);
+    }
+
     void testPolyPolyCrissCross()
     {
         implTestPolyPolyCrissCross(mpDevice1bpp);
@@ -279,6 +372,8 @@ public:
     CPPUNIT_TEST(testHairline);
     CPPUNIT_TEST(testPolyPoly);
     CPPUNIT_TEST(testPolyPolyClip);
+    CPPUNIT_TEST(testLineDrawClip);
+    CPPUNIT_TEST(testPolyDrawClip);
     CPPUNIT_TEST(testPolyPolyCrissCross);
     CPPUNIT_TEST_SUITE_END();
 };