loader/svg: support the focal property in the radial gradient.

@Issue: https://github.com/thorvg/thorvg/issues/1555

src/loaders/svg/tvgSvgLoader.cpp

@@ -2100,6 +2100,12 @@ static void _handleRadialFyAttr(SvgLoaderData* loader, SvgRadialGradient* radial
 }
 
 
+static void _handleRadialFrAttr(SvgLoaderData* loader, SvgRadialGradient* radial, const char* value)
+{
+    radial->fr = _gradientToFloat(loader->svgParse, value, radial->isFrPercentage);
+}
+
+
 static void _handleRadialRAttr(SvgLoaderData* loader, SvgRadialGradient* radial, const char* value)
 {
     radial->r = _gradientToFloat(loader->svgParse, value, radial->isRPercentage);
@@ -2130,6 +2136,13 @@ static void _recalcRadialFyAttr(SvgLoaderData* loader, SvgRadialGradient* radial
 }
 
 
+static void _recalcRadialFrAttr(SvgLoaderData* loader, SvgRadialGradient* radial, bool userSpace)
+{
+    // scaling factor based on the Units paragraph from : https://www.w3.org/TR/2015/WD-SVG2-20150915/coords.html
+    if (userSpace && !radial->isFrPercentage) radial->fr = radial->fr / (sqrtf(powf(loader->svgParse->global.h, 2) + powf(loader->svgParse->global.w, 2)) / sqrtf(2.0));
+}
+
+
 static void _recalcRadialRAttr(SvgLoaderData* loader, SvgRadialGradient* radial, bool userSpace)
 {
     // scaling factor based on the Units paragraph from : https://www.w3.org/TR/2015/WD-SVG2-20150915/coords.html
@@ -2173,6 +2186,15 @@ static void _recalcInheritedRadialFyAttr(SvgLoaderData* loader, SvgRadialGradien
 }
 
 
+static void _recalcInheritedRadialFrAttr(SvgLoaderData* loader, SvgRadialGradient* radial, bool userSpace)
+{
+    if (!radial->isFrPercentage) {
+        if (userSpace) radial->fr /= sqrtf(powf(loader->svgParse->global.h, 2) + powf(loader->svgParse->global.w, 2)) / sqrtf(2.0);
+        else radial->fr *= sqrtf(powf(loader->svgParse->global.h, 2) + powf(loader->svgParse->global.w, 2)) / sqrtf(2.0);
+    }
+}
+
+
 static void _recalcInheritedRadialRAttr(SvgLoaderData* loader, SvgRadialGradient* radial, bool userSpace)
 {
     if (!radial->isRPercentage) {
@@ -2214,6 +2236,14 @@ static void _inheritRadialFyAttr(SvgStyleGradient* to, SvgStyleGradient* from)
 }
 
 
+static void _inheritRadialFrAttr(SvgStyleGradient* to, SvgStyleGradient* from)
+{
+    to->radial->fr = from->radial->fr;
+    to->radial->isFrPercentage = from->radial->isFrPercentage;
+    to->flags = (to->flags | SvgGradientFlags::Fr);
+}
+
+
 static void _inheritRadialRAttr(SvgStyleGradient* to, SvgStyleGradient* from)
 {
     to->radial->r = from->radial->r;
@@ -2247,7 +2277,8 @@ static constexpr struct
     RADIAL_DEF(cy, Cy, SvgGradientFlags::Cy),
     RADIAL_DEF(fx, Fx, SvgGradientFlags::Fx),
     RADIAL_DEF(fy, Fy, SvgGradientFlags::Fy),
-    RADIAL_DEF(r, R, SvgGradientFlags::R)
+    RADIAL_DEF(r, R, SvgGradientFlags::R),
+    RADIAL_DEF(fr, Fr, SvgGradientFlags::Fr)
 };
 
 
@@ -2315,6 +2346,7 @@ static SvgStyleGradient* _createRadialGradient(SvgLoaderData* loader, const char
     grad->radial->isFxPercentage = true;
     grad->radial->isFyPercentage = true;
     grad->radial->isRPercentage = true;
+    grad->radial->isFrPercentage = true;
 
     loader->svgParse->gradient.parsedFx = false;
     loader->svgParse->gradient.parsedFy = false;

src/loaders/svg/tvgSvgLoaderCommon.h

@@ -184,7 +184,8 @@ enum class SvgGradientFlags
     Cy = 0x80,
     R = 0x100,
     Fx = 0x200,
-    Fy = 0x400
+    Fy = 0x400,
+    Fr = 0x800
 };
 
 constexpr bool operator &(SvgGradientFlags a, SvgGradientFlags b)
@@ -392,11 +393,13 @@ struct SvgRadialGradient
     float fx;
     float fy;
     float r;
+    float fr;
     bool isCxPercentage;
     bool isCyPercentage;
     bool isFxPercentage;
     bool isFyPercentage;
     bool isRPercentage;
+    bool isFrPercentage;
 };
 
 struct SvgComposite

src/loaders/svg/tvgSvgSceneBuilder.cpp

@@ -26,11 +26,12 @@
 #include "tvgShapeImpl.h"
 #include "tvgCompressor.h"
 #include "tvgPaint.h"
+#include "tvgFill.h"
+#include "tvgStr.h"
 #include "tvgSvgLoaderCommon.h"
 #include "tvgSvgSceneBuilder.h"
 #include "tvgSvgPath.h"
 #include "tvgSvgUtil.h"
-#include "tvgStr.h"
 
 /************************************************************************/
 /* Internal Class Implementation                                        */
@@ -151,6 +152,7 @@ static unique_ptr<RadialGradient> _applyRadialGradientProperty(SvgStyleGradient*
         g->radial->r = g->radial->r * sqrtf(powf(vBox.w, 2.0f) + powf(vBox.h, 2.0f)) / sqrtf(2.0f);
         g->radial->fx = g->radial->fx * vBox.w;
         g->radial->fy = g->radial->fy * vBox.h;
+        g->radial->fr = g->radial->fr * sqrtf(powf(vBox.w, 2.0f) + powf(vBox.h, 2.0f)) / sqrtf(2.0f);
     } else {
         Matrix m = {vBox.w, 0, vBox.x, 0, vBox.h, vBox.y, 0, 0, 1};
         if (isTransform) _transformMultiply(&m, &finalTransform);
@@ -162,11 +164,7 @@ static unique_ptr<RadialGradient> _applyRadialGradientProperty(SvgStyleGradient*
 
     if (isTransform) fillGrad->transform(finalTransform);
 
-    //TODO: Tvg is not support to focal
+    P(fillGrad)->radial(g->radial->cx, g->radial->cy, g->radial->r, g->radial->fx, g->radial->fy, g->radial->fr);
-    //if (g->radial->fx != 0 && g->radial->fy != 0) {
-    //    fillGrad->radial(g->radial->fx, g->radial->fy, g->radial->r);
-    //}
-    fillGrad->radial(g->radial->cx, g->radial->cy, g->radial->r);
     fillGrad->spread(g->spread);
 
     //Update the stops