C++: Draw Bitmap in more than one instance using Firebreath

Question

I'm struggling with this,

I want to draw a Bitmap into a PluginWindowWin (Firebreath) using GDI+; for that I have a timer, simulating the wm_paint message for now, and this code inside:

using namespace Gdiplus;
Graphics graphics(hwnd);
graphics.DrawImage(image, 0, 0, 400, 400);

image is a Gdiplus::Image, it works fine, BUT if I create 2 instances of the plugin (two different HWND) it will ONLY draw in one of them.

Is that the expected behavior?, I mean, GDI+ will draw only in one context created from an HWND?

Thanks!

Answer 1

Basically, each (toplevel) window must have its own thread. If you put either window in its own thread, you should be able to draw in parallel by sending the message to both windows/threads having their own message dispatcher.

Edit: Threading with shared GDI- objects is a risky task. Resource management must be thread safe.