SVGIO: tdf#97383: Keep ratio in embedded images...

... when height and width are different

SVG specifies embedded graphics to keep their aspect ratio (thanks to Regina for pointing out).
To implement this for Office SVG import, I had to correctly set the graphic data unit dimensions to make the existing SvgAspectRatio mapping work.
All together this now simplifies this method and packs all in clean linear transformations in the created stack of drwainglayer primitives.

Change-Id: Id80c2f74ffb148085085b2c9627bc31bc15bdee5
Reviewed-on: https://gerrit.libreoffice.org/21830
Reviewed-by: Armin Le Grand <Armin.Le.Grand@cib.de>
Tested-by: Armin Le Grand <Armin.Le.Grand@cib.de>

2 files changed, 59 insertions, 45 deletions

diff --git a/svgio/source/svgreader/svgimagenode.cxx b/svgio/source/svgreader/svgimagenode.cxx
index a53798a45d24..d58dd716b8cd 100644
--- a/svgio/source/svgreader/svgimagenode.cxx
+++ b/svgio/source/svgreader/svgimagenode.cxx
@@ -271,16 +271,45 @@ namespace svgio
                         }
                     }
 
-                    if(!aBitmapEx.IsEmpty())
+                    if(!aBitmapEx.IsEmpty() && 0 != aBitmapEx.GetSizePixel().Width()  && 0 != aBitmapEx.GetSizePixel().Height())
                     {
-                        // create content from created bitmap
+                        // calculate centered unit size
+                        const double fAspectRatio = (double)aBitmapEx.GetSizePixel().Width() / (double)aBitmapEx.GetSizePixel().Height();
+
+                        if(basegfx::fTools::equal(fAspectRatio, 0.0))
+                        {
+                            // use unit range
+                            aViewBox = basegfx::B2DRange(0.0, 0.0, 1.0, 1.0);
+                        }
+                        else if(basegfx::fTools::more(fAspectRatio, 0.0))
+                        {
+                            // width bigger height
+                            const double fHalfHeight((1.0 / fAspectRatio) * 0.5);
+                            aViewBox = basegfx::B2DRange(
+                                0.0,
+                                0.5 - fHalfHeight,
+                                1.0,
+                                0.5 + fHalfHeight);
+                        }
+                        else
+                        {
+                            // height bigger width
+                            const double fHalfWidth(fAspectRatio * 0.5);
+                            aViewBox = basegfx::B2DRange(
+                                0.5 - fHalfWidth,
+                                0.0,
+                                0.5 + fHalfWidth,
+                                1.0);
+                        }
+
+                        // create content from created bitmap, use calculated unit range size
+                        // as transformation to map the picture data correctly
                         aNewTarget.resize(1);
                         aNewTarget[0] = new drawinglayer::primitive2d::BitmapPrimitive2D(
                             aBitmapEx,
-                            basegfx::B2DHomMatrix());
-
-                        // fill aViewBox. No size set yet, use unit size
-                        aViewBox = basegfx::B2DRange(0.0, 0.0, 1.0, 1.0);
+                            basegfx::tools::createScaleTranslateB2DHomMatrix(
+                                aViewBox.getRange(),
+                                aViewBox.getMinimum()));
                     }
 
                     if(!aNewTarget.empty())
@@ -295,47 +324,30 @@ namespace svgio
                             // create mapping
                             const SvgAspectRatio& rRatio = getSvgAspectRatio();
 
-                            if(rRatio.isSet())
+                            // even when ratio is not set, use the defaults
+                            // let mapping be created from SvgAspectRatio
+                            const basegfx::B2DHomMatrix aEmbeddingTransform(rRatio.createMapping(aTarget, aViewBox));
+
+                            if(!aEmbeddingTransform.isIdentity())
                             {
-                                // let mapping be created from SvgAspectRatio
-                                const basegfx::B2DHomMatrix aEmbeddingTransform(rRatio.createMapping(aTarget, aViewBox));
-
-                                if(!aEmbeddingTransform.isIdentity())
-                                {
-                                    const drawinglayer::primitive2d::Primitive2DReference xRef(
-                                        new drawinglayer::primitive2d::TransformPrimitive2D(
-                                            aEmbeddingTransform,
-                                            aNewTarget));
-
-                                    aNewTarget = drawinglayer::primitive2d::Primitive2DContainer { xRef };
-                                }
-
-                                if(!rRatio.isMeetOrSlice())
-                                {
-                                    // need to embed in MaskPrimitive2D to ensure clipping
-                                    const drawinglayer::primitive2d::Primitive2DReference xMask(
-                                        new drawinglayer::primitive2d::MaskPrimitive2D(
-                                            basegfx::B2DPolyPolygon(
-                                                basegfx::tools::createPolygonFromRect(aTarget)),
-                                            aNewTarget));
-
-                                    aNewTarget = drawinglayer::primitive2d::Primitive2DContainer { xMask };
-                                }
+                                const drawinglayer::primitive2d::Primitive2DReference xRef(
+                                    new drawinglayer::primitive2d::TransformPrimitive2D(
+                                        aEmbeddingTransform,
+                                        aNewTarget));
+
+                                aNewTarget = drawinglayer::primitive2d::Primitive2DContainer { xRef };
                             }
-                            else
+
+                            if(!rRatio.isMeetOrSlice())
                             {
-                                // choose default mapping
-                                const basegfx::B2DHomMatrix aEmbeddingTransform(SvgAspectRatio::createLinearMapping(aTarget, aViewBox));
-
-                                if(!aEmbeddingTransform.isIdentity())
-                                {
-                                    const drawinglayer::primitive2d::Primitive2DReference xRef(
-                                        new drawinglayer::primitive2d::TransformPrimitive2D(
-                                            aEmbeddingTransform,
-                                            aNewTarget));
-
-                                    aNewTarget = drawinglayer::primitive2d::Primitive2DContainer { xRef };
-                                }
+                                // need to embed in MaskPrimitive2D to ensure clipping
+                                const drawinglayer::primitive2d::Primitive2DReference xMask(
+                                    new drawinglayer::primitive2d::MaskPrimitive2D(
+                                        basegfx::B2DPolyPolygon(
+                                            basegfx::tools::createPolygonFromRect(aTarget)),
+                                        aNewTarget));
+
+                                aNewTarget = drawinglayer::primitive2d::Primitive2DContainer { xMask };
                             }
 
                             // embed and add to rTarget, take local extra-transform into account
diff --git a/svgio/source/svgreader/svgtools.cxx b/svgio/source/svgreader/svgtools.cxx
index 349fd292f595..ff74d63061aa 100644
--- a/svgio/source/svgreader/svgtools.cxx
+++ b/svgio/source/svgreader/svgtools.cxx
@@ -67,7 +67,9 @@ namespace svgio
 
         basegfx::B2DHomMatrix SvgAspectRatio::createMapping(const basegfx::B2DRange& rTarget, const basegfx::B2DRange& rSource) const
         {
-            if(!isSet() || Align_none == getSvgAlign())
+            // removed !isSet() from below. Due to correct defaults in the constructor an instance
+            // of this class is perfectly useful without being set by any importer
+            if(Align_none == getSvgAlign())
             {
                 // create linear mapping (default)
                 return createLinearMapping(rTarget, rSource);