How do I get rid of flicker with STM_SETIMAGE - winapi

Question

We have updated our windows code to use Styles and since then we get a flicker in various parts of the code when using STM_SETIMAGE to update a bitmap on a window.
I have created a minimal reproducible example here. Can anyone tell me what I need to do to get rid of the flicker please ?
The code simply redraws a bitmap every 1/100 second and calls the windows function to set the image onto the window. It worked without a flicker before we added Windows Styles.
Thanks
Shaun
#include <windows.h>
#include <CommCtrl.h>
#include <math.h>
#include <objbase.h>
#pragma comment(linker,"\"/manifestdependency:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*'\"")
//--------------------------------------
#ifndef HINST_THISCOMPONENT
EXTERN_C IMAGE_DOS_HEADER __ImageBase;
#define HINST_THISCOMPONENT ((HINSTANCE)&__ImageBase)
#endif
//--------------------------------------
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
return DefWindowProc(hwnd, message, wParam, lParam);
}
//--------------------------------------
HWND logo;
HWND m_hwnd;
HBITMAP testBitmap;
int counter=0;
typedef unsigned char u8;
typedef unsigned int u32;
//--------------------------------------
HRESULT App_Initialize()
{
HRESULT hr;
// Register the window class.
WNDCLASSEX wcex = { sizeof(WNDCLASSEX) };
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = sizeof(LONG_PTR);
wcex.hInstance = HINST_THISCOMPONENT;
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);;
wcex.lpszMenuName = NULL;
wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
wcex.lpszClassName = TEXT("myApp");
RegisterClassEx(&wcex);
int dpiX = 0;
int dpiY = 0;
HDC hdc = GetDC(NULL);
if (hdc)
{
dpiX = GetDeviceCaps(hdc, LOGPIXELSX);
dpiY = GetDeviceCaps(hdc, LOGPIXELSY);
ReleaseDC(NULL, hdc);
}
m_hwnd = CreateWindow( TEXT("myApp"), TEXT("Simple Set image Example"), WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN, CW_USEDEFAULT, CW_USEDEFAULT, 640, 640, NULL,NULL,HINST_THISCOMPONENT,0);
hr = m_hwnd ? S_OK : E_FAIL;
if (SUCCEEDED(hr))
{
ShowWindow(m_hwnd, SW_SHOWNORMAL);
UpdateWindow(m_hwnd);
}
logo = CreateWindow("Static", NULL, SS_BITMAP | WS_CHILD | WS_VISIBLE, 40, 40,512,512, m_hwnd, NULL, NULL, NULL);
return hr;
}
//----------------------------------------------
void Redraw()
{
DeleteObject(testBitmap);
testBitmap=0;
u8 * RenderImageData=(u8*)malloc(512*512*4);
u32 * p=(u32*)RenderImageData;
for(int i=0;i<512;i++)
{
p[i+counter*512]=0xff000000;
p[i*512+counter]=0xff000000;
}
testBitmap = CreateBitmap(512,512, 4, 8, RenderImageData);
SendMessage(logo,STM_SETIMAGE, IMAGE_BITMAP, (LPARAM) testBitmap);
free(RenderImageData);
counter=(counter+1)&511;
}
//----------------------------------------------
int WINAPI WinMain(HINSTANCE hInstance ,HINSTANCE hPrevInstance ,LPSTR lpCmdLine ,int nCmdShow)
{
if (SUCCEEDED(CoInitialize(NULL)))
{
if (SUCCEEDED(App_Initialize()))
{
MSG msg;
while(1)
{
while (PeekMessage(&msg, NULL, 0,0,PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
Sleep(10);
Redraw();
}
}
CoUninitialize();
}
return 0;
}
//----------------------------------------------

Answer 1

I found this code which seems to work.
Instead of
HBITMAP hbm=(HBITMAP)SendMessage(hWndPic,STM_SETIMAGE, IMAGE_BITMAP, (LPARAM) pD->hbitmap);
I call
GDI_SetImageX(pD->hbitmap,hWndPic, xs, ys);
void GDI_SetImageX( HBITMAP hBM, HWND hCtrl , int w, int h)
{
HDC hdcSrc=CreateCompatibleDC(0);
HDC hdcDst=GetDC(hCtrl);
HGDIOBJ hbmOld=SelectObject(hdcSrc,hBM);
HGDIOBJ hbmNew=CreateBitmap(w,h,4,8,0);
HGDIOBJ hbmOld2=SelectObject(hdcDst,hbmNew);
BitBlt(hdcDst,0,0,w,h,hdcSrc,0,0,0x00cc0020);
SelectObject(hdcSrc,hbmOld);
DeleteDC(hdcSrc);
ReleaseDC(hCtrl,hdcDst);
SendMessage(hCtrl,0x0b,0,0);
LRESULT oBM=SendMessage(hCtrl,STM_SETIMAGE, IMAGE_BITMAP, (LPARAM) hBM);
SendMessage(hCtrl,0x0b,1,0);
DeleteObject(hBM);
}