win32 gui: replace D2D renderer with D3d11 shader

src/win32/win32ext.zig

@@ -0,0 +1,32 @@
+const std = @import("std");
+const win32 = @import("win32").everything;
+
+// todo: these should be available in zigwin32
+fn xFromLparam(lparam: win32.LPARAM) i16 {
+    return @bitCast(win32.loword(lparam));
+}
+fn yFromLparam(lparam: win32.LPARAM) i16 {
+    return @bitCast(win32.hiword(lparam));
+}
+pub fn pointFromLparam(lparam: win32.LPARAM) win32.POINT {
+    return win32.POINT{ .x = xFromLparam(lparam), .y = yFromLparam(lparam) };
+}
+
+// TODO: update zigwin32 with a way to get the corresponding IID for any COM interface
+pub fn queryInterface(obj: anytype, comptime Interface: type) *Interface {
+    const obj_basename_start: usize = comptime if (std.mem.lastIndexOfScalar(u8, @typeName(@TypeOf(obj)), '.')) |i| (i + 1) else 0;
+    const obj_basename = @typeName(@TypeOf(obj))[obj_basename_start..];
+    const iface_basename_start: usize = comptime if (std.mem.lastIndexOfScalar(u8, @typeName(Interface), '.')) |i| (i + 1) else 0;
+    const iface_basename = @typeName(Interface)[iface_basename_start..];
+
+    const iid_name = "IID_" ++ iface_basename;
+    const iid = @field(win32, iid_name);
+
+    var iface: *Interface = undefined;
+    const hr = obj.IUnknown.QueryInterface(iid, @ptrCast(&iface));
+    if (hr < 0) std.debug.panic(
+        "QueryInferface on " ++ obj_basename ++ " as " ++ iface_basename ++ " failed, hresult={}",
+        .{@as(u32, @bitCast(hr))},
+    );
+    return iface;
+}