sw_engine: fixed incorrect image blending operations

The anti-aliased outline color was incorrectly blended
at the multiply option.

The fix can be observed in the example:
'examples/lottie/resourcesguitar.json'

in order to do this, RenderMehthod::blend() method introduced
`bool direct` for figuring out the intermediate composition.

src/renderer/gl_engine/tvgGlRenderer.cpp

@@ -913,11 +913,10 @@ const Surface* GlRenderer::mainSurface()
 }
 
 
-bool GlRenderer::blend(TVG_UNUSED BlendMethod method)
+bool GlRenderer::blend(TVG_UNUSED BlendMethod method, TVG_UNUSED bool direct)
 {
-    if (method != BlendMethod::Normal) {
+    if (method != BlendMethod::Normal) return true;
-        return true;
+
-    }
     //TODO:
     return false;
 }

src/renderer/gl_engine/tvgGlRenderer.h

@@ -63,7 +63,7 @@ public:
     RenderRegion region(RenderData data) override;
     RenderRegion viewport() override;
     bool viewport(const RenderRegion& vp) override;
-    bool blend(BlendMethod method) override;
+    bool blend(BlendMethod method, bool direct) override;
     ColorSpace colorSpace() override;
     const Surface* mainSurface() override;
 

src/renderer/sw_engine/tvgSwCommon.h

@@ -363,7 +363,7 @@ static inline uint32_t opBlendSrcOver(uint32_t s, TVG_UNUSED uint32_t d, TVG_UNU
 }
 
 //TODO: BlendMethod could remove the alpha parameter.
-static inline uint32_t opBlendDifference(uint32_t s, uint32_t d, TVG_UNUSED uint8_t a)
+static inline uint32_t opBlendDifference(uint32_t s, uint32_t d, uint8_t a)
 {
     //if (s > d) => s - d
     //else => d - s
@@ -400,8 +400,7 @@ static inline uint32_t opBlendScreen(uint32_t s, uint32_t d, TVG_UNUSED uint8_t
     return JOIN(255, c1, c2, c3);
 }
 
-
+static inline uint32_t opBlendDirectMultiply(uint32_t s, uint32_t d, uint8_t a)
-static inline uint32_t opBlendMultiply(uint32_t s, uint32_t d, TVG_UNUSED uint8_t a)
 {
     // s * d
     auto c1 = MULTIPLY(C1(s), C1(d));
@@ -410,6 +409,10 @@ static inline uint32_t opBlendMultiply(uint32_t s, uint32_t d, TVG_UNUSED uint8_
     return JOIN(255, c1, c2, c3);
 }
 
+static inline uint32_t opBlendMultiply(uint32_t s, uint32_t d, uint8_t a)
+{
+    return opBlendDirectMultiply(s, d, a) + ALPHA_BLEND(d, IA(s));
+}
 
 static inline uint32_t opBlendOverlay(uint32_t s, uint32_t d, TVG_UNUSED uint8_t a)
 {

src/renderer/sw_engine/tvgSwRaster.cpp

@@ -1383,7 +1383,7 @@ static bool _rasterDirectBlendingImage(SwSurface* surface, const SwImage* image,
                 *dst = INTERPOLATE(tmp, *dst, A(*src));
             }
         } else {
-            for (auto x = region.min.x; x < region.max.x; ++x, ++dst, ++src) {
+            for (auto x = region.min.x; x < region.max.x; x++, dst++, src++) {
                 auto tmp = ALPHA_BLEND(*src, opacity);
                 auto tmp2 = surface->blender(tmp, *dst, 255);
                 *dst = INTERPOLATE(tmp2, *dst, A(tmp));

src/renderer/sw_engine/tvgSwRenderer.cpp

@@ -100,7 +100,6 @@ struct SwShapeTask : SwTask
         return (width * sqrt(transform.e11 * transform.e11 + transform.e12 * transform.e12));
     }
 
-
     bool clip(SwRle* target) override
     {
         if (shape.fastTrack) rleClipRect(target, &bbox);
@@ -442,7 +441,7 @@ bool SwRenderer::renderShape(RenderData data)
 }
 
 
-bool SwRenderer::blend(BlendMethod method)
+bool SwRenderer::blend(BlendMethod method, bool direct)
 {
     if (surface->blendMethod == method) return true;
     surface->blendMethod = method;
@@ -455,7 +454,7 @@ bool SwRenderer::blend(BlendMethod method)
             surface->blender = opBlendScreen;
             break;
         case BlendMethod::Multiply:
-            surface->blender = opBlendMultiply;
+            surface->blender = direct ? opBlendDirectMultiply : opBlendMultiply;
             break;
         case BlendMethod::Overlay:
             surface->blender = opBlendOverlay;

src/renderer/sw_engine/tvgSwRenderer.h

@@ -46,7 +46,7 @@ public:
     RenderRegion region(RenderData data) override;
     RenderRegion viewport() override;
     bool viewport(const RenderRegion& vp) override;
-    bool blend(BlendMethod method) override;
+    bool blend(BlendMethod method, bool direct) override;
     ColorSpace colorSpace() override;
     const Surface* mainSurface() override;
 

src/renderer/tvgPaint.cpp

@@ -225,8 +225,6 @@ bool Paint::Impl::render(RenderMethod* renderer)
 
     if (cmp) renderer->beginComposite(cmp, compData->method, compData->target->pImpl->opacity);
 
-    renderer->blend(blendMethod);
-
     bool ret;
     PAINT_METHOD(ret, render(renderer));
 

src/renderer/tvgPicture.cpp

@@ -73,6 +73,8 @@ bool Picture::Impl::needComposition(uint8_t opacity)
 bool Picture::Impl::render(RenderMethod* renderer)
 {
     bool ret = false;
+    renderer->blend(picture->blend(), true);
+
     if (surface) return renderer->renderImage(rd);
     else if (paint) {
         Compositor* cmp = nullptr;

src/renderer/tvgRender.h

@@ -294,7 +294,7 @@ public:
     virtual RenderRegion region(RenderData data) = 0;
     virtual RenderRegion viewport() = 0;
     virtual bool viewport(const RenderRegion& vp) = 0;
-    virtual bool blend(BlendMethod method) = 0;
+    virtual bool blend(BlendMethod method, bool direct = false) = 0;
     virtual ColorSpace colorSpace() = 0;
     virtual const Surface* mainSurface() = 0;
 

src/renderer/tvgScene.h

@@ -120,6 +120,8 @@ struct Scene::Impl
         Compositor* cmp = nullptr;
         auto ret = true;
 
+        renderer->blend(scene->blend());
+
         if (needComp) {
             cmp = renderer->target(bounds(renderer), renderer->colorSpace());
             renderer->beginComposite(cmp, CompositeMethod::None, opacity);

src/renderer/tvgShape.h

@@ -54,10 +54,13 @@ struct Shape::Impl
         Compositor* cmp = nullptr;
         bool ret;
 
+        renderer->blend(shape->blend(), !needComp);
+
         if (needComp) {
             cmp = renderer->target(bounds(renderer), renderer->colorSpace());
             renderer->beginComposite(cmp, CompositeMethod::None, opacity);
         }
+
         ret = renderer->renderShape(rd);
         if (cmp) renderer->endComposite(cmp);
         return ret;

src/renderer/tvgText.h

@@ -89,6 +89,7 @@ struct Text::Impl
 
     bool render(RenderMethod* renderer)
     {
+        renderer->blend(paint->blend(), true);
         return PP(shape)->render(renderer);
     }
 

src/renderer/wg_engine/tvgWgRenderer.cpp

@@ -218,7 +218,7 @@ bool WgRenderer::viewport(const RenderRegion& vp)
 }
 
 
-bool WgRenderer::blend(BlendMethod method)
+bool WgRenderer::blend(BlendMethod method, TVG_UNUSED bool direct)
 {
     mBlendMethod = method;
     return false;

src/renderer/wg_engine/tvgWgRenderer.h

@@ -38,7 +38,7 @@ public:
     RenderRegion region(RenderData data) override;
     RenderRegion viewport() override;
     bool viewport(const RenderRegion& vp) override;
-    bool blend(BlendMethod method) override;
+    bool blend(BlendMethod method, bool direct) override;
     ColorSpace colorSpace() override;
     const Surface* mainSurface() override;