Fixed the ID2D1RenderTarget::GetSize() madness a *SECOND* time. Urgh. Also removed a now-irrelevant TODO.

ui.h

@@ -280,7 +280,6 @@ typedef struct uiDrawContext uiDrawContext;
 struct uiAreaHandler {
 	void (*Draw)(uiAreaHandler *, uiArea *, uiAreaDrawParams *);
 	// TODO document that resizes cause a full redraw for non-scrolling areas; implementation-defined for scrolling areas
-	// TODO if the scrollbars disappear the histogram example won't recognize points in the correct spot until the area is resized
 	void (*MouseEvent)(uiAreaHandler *, uiArea *, uiAreaMouseEvent *);
 	// TODO document that on first show if the mouse is already in the uiArea then one gets sent with left=0
 	// TODO what about when the area is hidden and then shown again?

windows/area.c

@@ -7,6 +7,22 @@ uiWindowsDefineControl(
 	uiAreaType							// type function
 )
 
+// I love COM interfaces that actually only work on C++
+// ID2D1RenderTarget::GetSize is defined as returninig a structure
+// with stdcall, this means it's an extra last argument
+// the compiler tries to return it directly, and crashes
+// I originally thought this was a bug in MinGW-w64, but it turns out it also affects MSVC! https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64384
+// So we have to work around it.
+// TODO is the return type correct? or should we just use C++?
+void renderTargetGetSize(ID2D1RenderTarget *rt, D2D1_SIZE_F *size)
+{
+	typedef void (STDMETHODCALLTYPE *fptr)(ID2D1RenderTarget *, D2D1_SIZE_F *);
+	fptr f;
+
+	f = (fptr) (rt->lpVtbl->GetSize);
+	(*f)(rt, size);
+}
+
 static LRESULT CALLBACK areaWndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
 {
 	uiArea *a;

windows/area.h

@@ -24,6 +24,9 @@ struct uiArea {
 	ID2D1HwndRenderTarget *rt;
 };
 
+// area.c
+extern void renderTargetGetSize(ID2D1RenderTarget *rt, D2D1_SIZE_F *size);
+
 // areadraw.h
 extern BOOL areaDoDraw(uiArea *a, UINT uMsg, WPARAM wParam, LPARAM lParam, LRESULT *lResult);
 extern void areaDrawOnResize(uiArea *, RECT *);

windows/areadraw.c

@@ -15,7 +15,7 @@ static HRESULT doPaint(uiArea *a, ID2D1RenderTarget *rt, RECT *clip)
 	dp.AreaWidth = 0;
 	dp.AreaHeight = 0;
 	if (!a->scrolling) {
-		size = ID2D1RenderTarget_GetSize(rt);
+		renderTargetGetSize(rt, &size);
 		dp.AreaWidth = size.width;
 		dp.AreaHeight = size.height;
 	}

windows/areaevents.c

@@ -41,7 +41,7 @@ static void areaMouseEvent(uiArea *a, uintmax_t down, uintmax_t  up, WPARAM wPar
 	me.AreaWidth = 0;
 	me.AreaHeight = 0;
 	if (!a->scrolling) {
-		size = ID2D1HwndRenderTarget_GetSize(a->rt);
+		renderTargetGetSize((ID2D1RenderTarget *) (a->rt), &size);
 		me.AreaWidth = size.width;
 		me.AreaHeight = size.height;
 	}