[lua] Add Image.context property (fix #4330)

src/app/script/graphics_context.h

@@ -32,7 +32,16 @@ private:
 
 public:
   GraphicsContext(const os::SurfaceRef& surface, int uiscale) : m_surface(surface), m_uiscale(uiscale) { }
-  GraphicsContext(GraphicsContext&& gc) {
+  GraphicsContext(const GraphicsContext& gc) {
+    m_surface = gc.m_surface;
+    m_font = gc.m_font;
+    m_paint = gc.m_paint;
+    m_palette = gc.m_palette;
+    m_path = gc.m_path;
+    m_saved = gc.m_saved;
+    m_uiscale = gc.m_uiscale;
+  }
+  GraphicsContext(GraphicsContext&& gc) noexcept {
     std::swap(m_surface, gc.m_surface);
     std::swap(m_paint, gc.m_paint);
     std::swap(m_font, gc.m_font);

src/app/script/image_class.cpp

@@ -20,12 +20,14 @@
 #include "app/script/blend_mode.h"
 #include "app/script/docobj.h"
 #include "app/script/engine.h"
+#include "app/script/graphics_context.h"
 #include "app/script/luacpp.h"
 #include "app/script/security.h"
 #include "app/site.h"
 #include "app/tx.h"
 #include "app/util/autocrop.h"
 #include "app/util/resize_image.h"
+#include "app/util/shader_helpers.h"
 #include "base/fs.h"
 #include "doc/algorithm/flip_image.h"
 #include "doc/algorithm/flip_type.h"
@@ -37,6 +39,7 @@
 #include "doc/primitives.h"
 #include "doc/sprite.h"
 #include "render/render.h"
+#include "ui/scale.h"
 
 #include <algorithm>
 #include <cstring>
@@ -54,6 +57,11 @@ struct ImageObj {
   doc::ObjectId celId = 0;
   doc::ObjectId tilesetId = 0;
   doc::tile_index ti = 0;
+
+#if LAF_SKIA
+  std::unique_ptr<GraphicsContext> context = nullptr;
+#endif
+
   ImageObj(doc::Image* image)
     : imageId(image->id()) {
   }
@@ -742,6 +750,23 @@ int Image_get_cel(lua_State* L)
   return 1;
 }
 
+int Image_get_context(lua_State* L)
+{
+#if LAF_SKIA
+  auto* obj = get_obj<ImageObj>(L, 1);
+
+  if (!obj->context) {
+    auto surface = wrap_docimage_in_surface(obj->image(L));
+    obj->context = std::make_unique<GraphicsContext>(surface, ui::guiscale());
+  }
+
+  push_obj(L, *obj->context);
+  return 1;
+#else
+  return 0;
+#endif
+}
+
 const luaL_Reg Image_methods[] = {
   { "clone", Image_clone },
   { "clear", Image_clear },
@@ -774,6 +799,7 @@ const Property Image_properties[] = {
   { "colorMode", Image_get_colorMode, nullptr },
   { "spec", Image_get_spec, nullptr },
   { "cel", Image_get_cel, nullptr },
+  { "context", Image_get_context, nullptr },
   { nullptr, nullptr, nullptr }
 };
 

src/app/util/shader_helpers.cpp

@@ -16,6 +16,8 @@
 
 #if LAF_SKIA
 
+#include "os/skia/skia_surface.h"
+
 #include "include/core/SkSurface.h"
 #if SK_ENABLE_SKSL
   #include "src/core/SkRuntimeEffectPriv.h"
@@ -110,6 +112,11 @@ sk_sp<SkSurface> wrap_docimage_in_sksurface(const doc::Image* img)
     img->rowBytes());
 }
 
+os::SurfaceRef wrap_docimage_in_surface(const doc::Image* img)
+{
+  return os::SurfaceRef(new os::SkiaSurface(wrap_docimage_in_sksurface(img)));
+}
+
 } // namespace app
 
 #endif // LAF_SKIA

src/app/util/shader_helpers.h

@@ -12,6 +12,7 @@
 
 #include "app/color.h"
 #include "gfx/color.h"
+#include "os/surface.h"
 
 #include "include/core/SkCanvas.h"
 #include "include/core/SkImage.h"
@@ -94,6 +95,7 @@ SkImageInfo get_skimageinfo_for_docimage(const doc::Image* img);
 sk_sp<SkImage> make_skimage_for_docimage(const doc::Image* img);
 std::unique_ptr<SkCanvas> make_skcanvas_for_docimage(const doc::Image* img);
 sk_sp<SkSurface> wrap_docimage_in_sksurface(const doc::Image* img);
+os::SurfaceRef wrap_docimage_in_surface(const doc::Image* img);
 
 } // namespace app