renderer: ++stabilization

This introduces a managed condition to precisely control the
canvas updates. This prevents a crash when the target is
changed and drawn without any update calls.

issue: https://github.com/thorvg/thorvg/issues/2484

src/renderer/tvgCanvas.h

@@ -26,7 +26,7 @@
 #include "tvgPaint.h"
 
 
-enum Status : uint8_t {Synced = 0, Updating, Drawing};
+enum Status : uint8_t {Synced = 0, Updating, Drawing, Damanged};
 
 struct Canvas::Impl
 {
@@ -35,8 +35,6 @@ struct Canvas::Impl
     RenderRegion vport = {0, 0, INT32_MAX, INT32_MAX};
     Status status = Status::Synced;
 
-    bool refresh = false;   //if all paints should be updated by force.
-
     Impl(RenderMethod* pRenderer) : renderer(pRenderer)
     {
         renderer->ref();
@@ -87,18 +85,13 @@ struct Canvas::Impl
         return Result::Success;
     }
 
-    void needRefresh()
-    {
-        refresh = true;
-    }
-
     Result update(Paint* paint, bool force)
     {
         if (paints.empty() || status == Status::Drawing) return Result::InsufficientCondition;
 
         Array<RenderData> clips;
         auto flag = RenderUpdateFlag::None;
-        if (refresh || force) flag = RenderUpdateFlag::All;
+        if (status == Status::Damanged || force) flag = RenderUpdateFlag::All;
 
         if (paint) {
             paint->pImpl->update(renderer, nullptr, clips, 255, flag);
@@ -106,7 +99,6 @@ struct Canvas::Impl
             for (auto paint : paints) {
                 paint->pImpl->update(renderer, nullptr, clips, 255, flag);
             }
-            refresh = false;
         }
         status = Status::Updating;
         return Result::Success;
@@ -114,6 +106,7 @@ struct Canvas::Impl
 
     Result draw()
     {
+        if (status == Status::Damanged) update(nullptr, false);
         if (status == Status::Drawing || paints.empty() || !renderer->preRender()) return Result::InsufficientCondition;
 
         bool rendered = false;
@@ -129,7 +122,7 @@ struct Canvas::Impl
 
     Result sync()
     {
-        if (status == Status::Synced) return Result::InsufficientCondition;
+        if (status == Status::Synced || status == Status::Damanged) return Result::InsufficientCondition;
 
         if (renderer->sync()) {
             status = Status::Synced;
@@ -141,7 +134,8 @@ struct Canvas::Impl
 
     Result viewport(int32_t x, int32_t y, int32_t w, int32_t h)
     {
-        if (status != Status::Synced) return Result::InsufficientCondition;
+        if (status != Status::Damanged && status != Status::Synced) return Result::InsufficientCondition;
+
         RenderRegion val = {x, y, w, h};
         //intersect if the target buffer is already set.
         auto surface = renderer->mainSurface();
@@ -151,7 +145,7 @@ struct Canvas::Impl
         if (vport == val) return Result::Success;
         renderer->viewport(val);
         vport = val;
-        needRefresh();
+        status = Status::Damanged;
         return Result::Success;
     }
 };

src/renderer/tvgGlCanvas.cpp

@@ -62,7 +62,9 @@ GlCanvas::~GlCanvas()
 Result GlCanvas::target(int32_t id, uint32_t w, uint32_t h) noexcept
 {
 #ifdef THORVG_GL_RASTER_SUPPORT
-    if (Canvas::pImpl->status != Status::Synced) return Result::InsufficientCondition;
+    if (Canvas::pImpl->status != Status::Damanged && Canvas::pImpl->status != Status::Synced) {
+        return Result::InsufficientCondition;
+    }
 
     //We know renderer type, avoid dynamic_cast for performance.
     auto renderer = static_cast<GlRenderer*>(Canvas::pImpl->renderer);
@@ -73,7 +75,7 @@ Result GlCanvas::target(int32_t id, uint32_t w, uint32_t h) noexcept
     renderer->viewport(Canvas::pImpl->vport);
 
     //Paints must be updated again with this new target.
-    Canvas::pImpl->needRefresh();
+    Canvas::pImpl->status = Status::Damanged;
 
     return Result::Success;
 #endif

src/renderer/tvgSwCanvas.cpp

@@ -82,7 +82,9 @@ Result SwCanvas::mempool(MempoolPolicy policy) noexcept
 Result SwCanvas::target(uint32_t* buffer, uint32_t stride, uint32_t w, uint32_t h, Colorspace cs) noexcept
 {
 #ifdef THORVG_SW_RASTER_SUPPORT
-    if (Canvas::pImpl->status != Status::Synced) return Result::InsufficientCondition;
+    if (Canvas::pImpl->status != Status::Damanged && Canvas::pImpl->status != Status::Synced) {
+        return Result::InsufficientCondition;
+    }
 
     //We know renderer type, avoid dynamic_cast for performance.
     auto renderer = static_cast<SwRenderer*>(Canvas::pImpl->renderer);
@@ -92,12 +94,12 @@ Result SwCanvas::target(uint32_t* buffer, uint32_t stride, uint32_t w, uint32_t
     Canvas::pImpl->vport = {0, 0, (int32_t)w, (int32_t)h};
     renderer->viewport(Canvas::pImpl->vport);
 
-    //Paints must be updated again with this new target.
-    Canvas::pImpl->needRefresh();
-
     //FIXME: The value must be associated with an individual canvas instance.
     ImageLoader::cs = static_cast<ColorSpace>(cs);
 
+    //Paints must be updated again with this new target.
+    Canvas::pImpl->status = Status::Damanged;
+
     return Result::Success;
 #endif
     return Result::NonSupport;

src/renderer/tvgWgCanvas.cpp

@@ -57,7 +57,9 @@ WgCanvas::~WgCanvas()
 Result WgCanvas::target(void* instance, void* surface, uint32_t w, uint32_t h) noexcept
 {
 #ifdef THORVG_WG_RASTER_SUPPORT
-    if (Canvas::pImpl->status != Status::Synced) return Result::InsufficientCondition;
+    if (Canvas::pImpl->status != Status::Damanged && Canvas::pImpl->status != Status::Synced) {
+        return Result::InsufficientCondition;
+    }
 
     if (!instance || !surface || (w == 0) || (h == 0)) return Result::InvalidArguments;
 
@@ -70,7 +72,7 @@ Result WgCanvas::target(void* instance, void* surface, uint32_t w, uint32_t h) n
     renderer->viewport(Canvas::pImpl->vport);
 
     //Paints must be updated again with this new target.
-    Canvas::pImpl->needRefresh();
+    Canvas::pImpl->status = Status::Damanged;
 
     return Result::Success;
 #endif