common paint: fix invalid memory access in unit test

casting the paint to shape is not allowed if the compositor target
is not shape, here it concretely checking the the type before casting....

diff --git a/src/lib/tvgPaint.cpp b/src/lib/tvgPaint.cpp
index a8f6e5e..f20c920 100644 (file)
--- a/src/lib/tvgPaint.cpp
+++ b/src/lib/tvgPaint.cpp
@@ -206,7 +206,7 @@ void* Paint::Impl::update(RenderMethod& renderer, const RenderTransform* pTransf
            we can avoid regular ClipPath / AlphaMasking sequence but use viewport for performance */
         auto tryFastTrack = false;
         if (cmpMethod == CompositeMethod::ClipPath) tryFastTrack = true;
-        else if (cmpMethod == CompositeMethod::AlphaMask) {
+        else if (cmpMethod == CompositeMethod::AlphaMask && cmpTarget->identifier() == TVG_CLASS_ID_SHAPE) {
             auto shape = static_cast<Shape*>(cmpTarget);
             uint8_t a;
             shape->fillColor(nullptr, nullptr, nullptr, &a);