Background paintiing

[Shrek]

--Global
User32Library = Library.Load("user32.dll");
Gdi32Library = Library.Load("Gdi32.dll");
BOOL = INT
HDC = INT
RECT = MemoryEx.DefineStruct{
	LONG 		"left";
	LONG 		"top";
	LONG 		"right";
    LONG 		"bottom";
};
PAINTSTRUCT = MemoryEx.DefineStruct{
  HDC  "hdc";
  BOOL "fErase";
  RECT "rcPaint";
  BOOL "fRestore";
  BOOL "fIncUpdate";
  BYTE "rgbReserved";
}
HostWindow = {}
HostWindow.CreateHost = function(x,y,w,h)
  local WS_EX_CLIENTEDGE = 0x00000200;
  local hWnd = Application.GetWndHandle();
  local WS_CHILD = 0x40000000;
  local WS_VISIBLE = 0x10000000;
  local nstyle = WS_CHILD + WS_VISIBLE;
  local bhdl = User32Library.CreateWindowExA(WS_EX_CLIENTEDGE,32770,"",nstyle,x,y,w,h,hWnd,0,0,0)
  if bhdl and (type(bhdl) ~= "number") then
   return false, "Can't create container"
  end
  HostWindow.HostHandle = bhdl
  local s = Subclass.Create(HostWindow.HostHandle, function(hWnd, uMsg, wParam, lParam)
   if(uMsg == 0x0014)then--WM_ERASEBKGND
     local lpBuff = MemoryEx.Allocate(MemoryEx.StructSize(PAINTSTRUCT) + 100);
     if not lpBuff then
      return 0
     end
     local hStruct = MemoryEx.AssignStruct(lpBuff + 50, PAINTSTRUCT);
      if not hStruct then
      return 0
     end
     local x = User32Library.BeginPaint(hWnd,hStruct:GetPointer())
     if (x ~= nil and x > 0) then
      local x = User32Library.FillRect(wParam,hStruct.rcPaint:GetPointer(),HostWindow.BrushHandle)
      User32Library.EndPaint(hWnd,hStruct:GetPointer())
      hStruct:Close();
      MemoryEx.Free(lpBuff);
      return 0
     else
      hStruct:Close();
      MemoryEx.Free(lpBuff);
      return 0
     end
   end
  return Subclass.OldWinProc(hWnd, uMsg, wParam, lParam);
  end)
  local x,y = HostWindow.CreateBrush()
  if not x then
   return false, "Can't create brush"
  else
   HostWindow.BrushHandle = y
  end
   HostWindow.BringToTop(HostWindow.HostHandle)
  return true, "OK"
end;
HostWindow.BringToTop = function(SWnd)
  if tonumber(User32Library.BringWindowToTop(SWnd)) == 0 then
   return false, "Can't bring to top"
  else
   return true, "OK"
  end
end;
HostWindow.CreateBrush = function()
 local hBrush = Gdi32Library.CreateSolidBrush(16777215)
 if hBrush and (type(hBrush) ~= "number") then
  return false, "Can't create brush"
 else
  return true, hBrush
 end
end;

--Button / On Show

HostWindow.CreateHost(10,10,400,300)

--Maximize then window shows window mirror, minimize then restore and background works

Anyone have any idea why this is not working as planed? its supposed to simply paint the window background colour white but it fails to update without the main window being re-sized but if you maximize then it draws an image of the main window within the created window yet if you minimize then restore it looks like it works as it should do.

[reteset]

Hi

WM_ERASEBKGND is not right event to do drawing
you should use WM_PAINT

WM_ERASEBKGND means that the window's background is being erased/redrawed
this event expects a brush to use to draw background , in general you will not need to handle this event , Windows will use default theme color to draw window background

you should use WM_PAINT to draw content over this

[Shrek]

Cheers, WM_PAINT kind of does the trick but occasionally the background becomes the default window colour again on resizing or on creation, what I'm trying to do is create a host window for a combo-box and a couple of inputs without using the shape plugin as a background, 32770 is the dialog class window that seems to be the best type for the job as there is no carrot but by default the background color is grey and I want white lol

[reteset]

InvalidateRect() function should be called in some cases WM_SIZE event gets called whenever window size changes
so you should call that function in WM_SIZE event , and after window is created

you can use NULL as lpRect parameter

in addition , use STATIC as window class when you will use it as a dummy window

STATIC class is recomended for host windows or custom controls

[Shrek]

Cheers mate, WM_SIZE seems to have caught the odd occasion t would not paint.

[reteset]

in addition , if you are going to follow my advise and will use STATIC then
you should also handle WM_GETTEXTLENGTH and invalidate client area

otherwise , you might find yourself while asking 'where did my drawings go again'

[Shrek]

I did indeed swap it to static, you know AMS makes things real easy as a simple thing like this is a mission