I'm trying to create ListView with fixed width columns in winapi C++ project.
I try use a trick with handling a HDN_BEGINTRACK notification in Dialog Box Procedure just by returning TRUE in it. As I understood from different articles it might work.
Point is, that I catch it, but returning TRUE does not prevent from resizing.
Also tried returning TRUE just after getting WM_NOTIFY - the same effect.
Help me please. Here are some parts of code:
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
hInst = hInstance;
----
hDlg = CreateDialog(hInst,MAKEINTRESOURCE(IDD_DIALOG),
hWnd,(DLGPROC)DlgProc);
INITCOMMONCONTROLSEX icex;
icex.dwICC = ICC_LISTVIEW_CLASSES;
InitCommonControlsEx(&icex);
HWND hWndListView = CreateWindow(
WC_LISTVIEW,
L"",
WS_CHILD | LVS_REPORT |WS_VISIBLE,
0, 0,
382,
200,
hDlg,
(HMENU)IDC_LIST,
hInst,
NULL);
----
//adding columns and items
----
DWORD exStyle = LVS_EX_CHECKBOXES | LVS_EX_FULLROWSELECT | LVS_EX_GRIDLINES;
ListView_SetExtendedListViewStyle(hWndListView,exStyle);
SetWindowTheme(hWndListView, L"Explorer", NULL);
----
return TRUE;
}
BOOL CALLBACK DlgProc(HWND hDlg, UINT Msg, WPARAM wParam, LPARAM lParam)
{
switch (Msg)
{
----
case WM_NOTIFY:
switch(((LPNMHDR)lParam)->code)
{
case HDN_BEGINTRACK:
OutputDebugString(L"HDN_BEGINTRACK\n");
return TRUE;
default:
break;
}
----
}
return FALSE;
}
Thanks in advance!
Returning TRUE from WM_NOTIFY in a dialog procedure only shows you've processed the message. To actually return a result value, you must also set the dialog's DWL_MSGRESULT:
case HDN_BEGINTRACK:
OutputDebugString(L"HDN_BEGINTRACK\n");
SetWindowLong(hDlg, DWL_MSGRESULT, TRUE); // prevent resizing
return TRUE; // message processed; check DWL_MSGRESULT for real result
Related
We've noticed an issue with ScrollWindowEx on our Windows app. Because there are a lot of child windows, if you hold down the scrollbar and move around, it causes a huge stall in DesktopWindowManager.
This is documented here
Why is my MFC application hanging after interacting with both scroll-bars?
So, I've taken the call to ScrollWindowEx out and now I can move my scrollbar with no issues, however the window and all its children only get drawn at the new position when I let go of the scrollbar.
It seems that my entire program stalls and gets stuck in the message loop when the scroll bar is held down. This isnt a problem if we can force the window that the scrollbar is attached to to update. But how do I do that ?
I've tried this
UpdateWindow(pPane);
RedrawWindow(pPane,NULL,NULL,RDW_ALLCHILDREN|RDW_INVALIDATE|RDW_ERASE | RDW_INTERNALPAINT | RDW_UPDATENOW);
And it does update and redraw - you can see the glitching - BUT it redraws it at the position that it was last left at. Not where the new position of the scroll bar would set it.
Im calling
SetScrollInfo(...)
with the correct parameters, otherwise it wouldn't work normally
How can I get it to redraw the window and its children with the correct parameters, whilst the scroll bar is held down?
This is my scroll message handler
case WM_VSCROLL:
{
int iVScrollPos;
SCROLLINFO vsi;
ZeroMemory(&vsi, sizeof(SCROLLINFO));
vsi.cbSize=sizeof(SCROLLINFO);
vsi.fMask=SIF_ALL;
GetScrollInfo(hWnd,SB_VERT,&vsi);
iVScrollPos=vsi.nPos;
switch(LOWORD(wParam))
{
case SB_LINEUP:
if(vsi.nPos>vsi.nMin)
vsi.nPos=vsi.nPos-10;
break;
case SB_PAGEUP:
vsi.nPos = vsi.nPos - vsi.nPage;
break;
case SB_LINEDOWN:
if(vsi.nPos<vsi.nMax)
vsi.nPos=vsi.nPos+10;
break;
case SB_PAGEDOWN:
vsi.nPos = vsi.nPos + vsi.nPage;
break;
case SB_THUMBTRACK:
vsi.nPos=vsi.nTrackPos;
break;
}
vsi.nMin=0;
vsi.nMax=pOW->dialogysize;
vsi.nPage=sy;
SetScrollInfo(hWnd,SB_VERT,&vsi,TRUE);
GetScrollInfo(hWnd, SB_VERT, &vsi);
if(vsi.nPos != iVScrollPos)
{
RedrawWindow(hWnd,NULL,NULL,RDW_ALLCHILDREN|RDW_INVALIDATE|RDW_ERASE | RDW_INTERNALPAINT | RDW_UPDATENOW);
}
The window redraws as you move the scroll bar, but in the same place it was when you held the mouse down on the scrollbar. It onlyupdates position when you let go of the mouse button.
Thanks
Shaun
EDIT - Ive created a sample that reproduces the behaviour. Note we have a separate window class to hold the multiple edit windows. I havent handled the WM_SIZE and WM_MOVE messages in this demo but the code should work with the window as it is.
IF USESCROLL is defined in and you move the scrollbar up and down it casues a lockup in DesktopWindowManager
IF USESCROLL is not commented in, then the trackPos in the structure still gets updated and I call reDrawWindow, but the child edit windows dont move as I scroll the scrollbar.
As I dont want to have the lockup, how can I get them to move please ?
Thanks again
Shaun
#include <windows.h>
#include <stdio.h>
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
LRESULT CALLBACK PaneProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR pCmdLine, int nCmdShow)
{
// Register the window class.
WNDCLASS wc = { };
wc.lpfnWndProc = WindowProc;
wc.hInstance = hInstance;
wc.lpszClassName = "Class";
RegisterClass(&wc);
wc.lpfnWndProc = PaneProc;
wc.hInstance = hInstance;
wc.lpszClassName = "Pane";
RegisterClass(&wc);
// Create the window.
HWND hwnd = CreateWindowEx(
0, // Optional window styles.
(LPCSTR)"Class", // Window class
(LPCSTR)"Test", // Window text
WS_OVERLAPPEDWINDOW| WS_BORDER | WS_CAPTION | WS_CLIPSIBLINGS | WS_THICKFRAME | WS_SYSMENU, // Window style
200,200,400,400,
NULL,NULL,hInstance,NULL);
if (hwnd == NULL)
{
return 0;
}
HWND hwndPane = CreateWindowEx(
0, // Optional window styles.
(LPCSTR)"Pane", // Window class
(LPCSTR)"Test", // Window text
WS_OVERLAPPEDWINDOW|WS_VISIBLE|WS_VSCROLL, // Window style
220,220,400,400,
hwnd,NULL,hInstance,NULL);
if (hwndPane == NULL)
{
return 0;
}
for(int i=0;i<200;i++)
{
HWND eb = CreateWindowEx(WS_EX_CLIENTEDGE, TEXT("Edit"), NULL,ES_AUTOHSCROLL | WS_CHILD| WS_VISIBLE, 16, 16+24*i, 64, 24, hwndPane, (HMENU)i+10000, hInstance, NULL);
char tmp[64];
sprintf(tmp,"%d",i);
SetWindowText(eb,tmp);
}
ShowWindow(hwnd, nCmdShow);
ShowWindow(hwndPane, nCmdShow);
// Run the message loop.
while(1)
{
MSG msg = { };
while (PeekMessage(&msg, NULL, 0,0,PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
Sleep(10);
}
return 0;
}
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg)
{
case WM_DESTROY:
PostQuitMessage(0);
return 0;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
FillRect(hdc, &ps.rcPaint, (HBRUSH) (COLOR_WINDOW+1));
EndPaint(hwnd, &ps);
}
return 0;
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
LRESULT CALLBACK PaneProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg)
{
case WM_CREATE:
int iVScrollPos;
SCROLLINFO vsi;
ZeroMemory(&vsi, sizeof(SCROLLINFO));
vsi.cbSize=sizeof(SCROLLINFO);
vsi.fMask=SIF_ALL;
GetScrollInfo(hwnd,SB_VERT,&vsi);
iVScrollPos=vsi.nPos;
vsi.nMin=0;
vsi.nMax=16+24*200+40;
vsi.nPage=400;
SetScrollInfo(hwnd,SB_VERT,&vsi,TRUE);
GetScrollInfo(hwnd, SB_VERT, &vsi);
break;
case WM_DESTROY:
PostQuitMessage(0);
return 0;
case WM_VSCROLL:
{
int iVScrollPos;
SCROLLINFO vsi;
ZeroMemory(&vsi, sizeof(SCROLLINFO));
vsi.cbSize=sizeof(SCROLLINFO);
vsi.fMask=SIF_ALL;
GetScrollInfo(hwnd,SB_VERT,&vsi);
iVScrollPos=vsi.nPos;
switch(LOWORD(wParam))
{
case SB_THUMBTRACK:
vsi.nPos=vsi.nTrackPos;
break;
}
vsi.nMin=0;
vsi.nMax=16+24*200+40;
vsi.nPage=400;
SetScrollInfo(hwnd,SB_VERT,&vsi,TRUE);
GetScrollInfo(hwnd, SB_VERT, &vsi);
if(vsi.nPos != iVScrollPos)
{
float ScrollAmtY=-(vsi.nPos - iVScrollPos);
#define USESCROLL
#ifdef USESCROLL
int ok=ScrollWindowEx(hwnd ,0,ScrollAmtY,NULL,NULL,NULL,NULL,SW_INVALIDATE|SW_ERASE|SW_SCROLLCHILDREN);
#else
UpdateWindow(hwnd);
RedrawWindow(hwnd,NULL,NULL,RDW_ALLCHILDREN|RDW_INVALIDATE|RDW_ERASE | RDW_INTERNALPAINT | RDW_UPDATENOW);
#endif
}
return 0;
}
break;
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
I'm building a real time graphics application and I've noticed that under certain conditions the operating system will post nonqueued messages that block my program. For example, this will happen during the entire time that a user is resizing the window.
To solve this problem, I would like to put the window on a different thread, but I read that this is a terrible idea because of the way windows messages work. Is it still a problem if I process all messages on the other thread, and never send or receive messages from the main thread? I'm thinking about setting up my own message queue with a mutex so I can pass the data I care about back and forth. If this won't work, are there any other ways to solve this problem?
Here's a simplified version of the code I'm running:
LRESULT CALLBACK WindowCallback(HWND window, UINT message, WPARAM wParam, LPARAM lParam) {
if (message == WM_SIZE) {
// This event gets called a lot
// Handle window resize
return 0;
} else {
return DefWindowProc(window, message, wParam, lParam);
}
}
int APIENTRY WinMain(HINSTANCE instance, HINSTANCE prev, LPSTR cmd, int numCmd) {
WNDCLASSA class = {};
class.style = CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
class.lpfnWndProc = WindowCallback;
class.lpszClassName = "Name";
class.hInstance = instance;
RegisterClassA(&class)l
HWND win = CreateWindowExA(0, class.lpszClassName, "Name",
WS_VISIBLE | WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT, 600, 400,
0, 0, instance, 0);
while(true) {
// Handle Events
MSG msg = {};
while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE) {
if (msg.message == WM_QUIT)
break;
TranslateMessage(&msg);
DispatchMessage(&msg);
}
// Do Updating of State and Graphics Rendering Here
}
}
Thanks in advance!
I am creating a Win32 ComboBox for the first time. And I have a problem here.
When calling CreateWindow for the ComboBox, it calls the WndProc callback function again with the WM_CREATE message, so what happens is the ComboBox makes a child ComboBox, again and again like recursion.
Here is the code:
#include <stdio.h>
#include <conio.h>
#include <Windows.h>
#include <random>
#include <time.h>
#include <string>
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
HINSTANCE g_hInst;
LPCTSTR lpszClass = L"ComboBox";
const WCHAR *items[] = { L"Apple", L"Orange", L"Melon", L"Grape", L"Strawberry" };
HWND hwnd;
enum COMMAND_ID {
COMMAND_ID_CONTROL_COMBO_0
};
int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpszCmdParam, int nCmdShow)
{
srand(time(NULL));
g_hInst = hInstance;
WNDCLASS wndClass;
wndClass.cbClsExtra = 0;
wndClass.cbWndExtra = 0;
wndClass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
wndClass.hCursor = LoadCursor(NULL, IDC_ARROW);
wndClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wndClass.hInstance = hInstance;
wndClass.lpfnWndProc = WndProc;
wndClass.lpszClassName = lpszClass;
wndClass.lpszMenuName = NULL;
wndClass.style = CS_HREDRAW | CS_VREDRAW;
RegisterClass(&wndClass);
hwnd = CreateWindow(
lpszClass,
lpszClass,
WS_CAPTION | WS_SYSMENU | WS_THICKFRAME,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
NULL,
(HMENU)NULL,
hInstance,
NULL);
ShowWindow(hwnd, nCmdShow);
MSG msg;
while (true)
{
GetMessage(&msg, NULL, 0, 0);
if (msg.message == WM_QUIT)
break;
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return (int)msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wparam, LPARAM lparam)
{
static HWND hCombo;
static WCHAR str[128];
switch (msg)
{
case WM_CREATE:
{
hCombo = CreateWindow(
L"combobox",
NULL,
WS_CHILD | WS_VISIBLE | WS_BORDER | CBS_DROPDOWN,
10, 10, 200, 200,
hWnd,
(HMENU)COMMAND_ID_CONTROL_COMBO_0,
g_hInst,
NULL);
for (int i = 0; i < 5; ++i)
{
SendMessage(hCombo, CB_ADDSTRING, 0, (LPARAM)items[i]);
}
SendMessage(hCombo, CB_SETCURSEL, 0, NULL);
}
break;
case WM_COMMAND:
{
switch (LOWORD(wparam))
{
case COMMAND_ID_CONTROL_COMBO_0:
switch (HIWORD(wparam))
{
case CBN_SELCHANGE:
{
int iCurSel = SendMessage(hCombo, CB_GETCURSEL, NULL, NULL);
SendMessage(hCombo, CB_GETLBTEXT, iCurSel, (LPARAM)str);
SetWindowText(hWnd, str);
}
break;
case CBN_EDITCHANGE:
GetWindowText(hCombo, str, 128);
SetWindowText(hWnd, str);
break;
}
break;
default:
break;
}
}
return 0;
}
return DefWindowProc(hWnd, msg, wparam, lparam);
}
And here is the result:
I tried to put some boolean flag to execute WM_CREATE only once, and it works, I mean only creating one ComboBox without any child in it.
But, it just looked like only a white window with a border mark, there's no arrow button or anything to dropdown page that the ComboBox is supposed to have.
This recursive case never happened when I was creating different controls like Buttons, CheckBoxes, ListBoxes, etc.
And the ComboBox created doesn't look like it has the proper shape, too.
Hope I am just missing something simple.
When calling CreateWindow for the ComboBox, it calls the WndProc
callback function again with the WM_CREATE message, so what happens
is the ComboBox makes a child ComboBox, again and again like
recursion.
WM_CREATE message is sent to the window procedure of the new window after the window is created. Your first WM_CREATE message is generated by this line hwnd = CreateWindow(). Then you create another window in first WM_CREATE message, so it will generate second WM_CREATE message. Because you use the same registered class ("ComboBox" / "combobox", it is not case sensitive) to create all these windows, all of them use the same one window procedure. So you receive WM_CREATE message again and again until CreateWindow fail to create a window and return NULL.
But, it just looked like only a white window with a border mark,
there's no arrow button or anything to dropdown page that the ComboBox
is supposed to have.
The root cause is you register a class with the same name as the existing system class: "ComboBox" / "combobox". This new registered class override the existing one. It is just a common window instead of a predefined Combobox control as #RemyLebeau pointed out.
An application can register an application local class having the same
name as a system class. This replaces the system class in the context
of the application but does not prevent other applications from using
the system class.
Refer to "How the System Locates a Window Class".
To make the Combobox display in expected shape, what you need to do is changing the lpszClass to a non-predefined one, for example, like "SimpleComboBoxExample".
It is suggested to use predefined macro of Combobox Class Name: WC_COMBOBOX instead of L"combobox".
More reference: "How to Create a Simple Combo Box".
You are not actually creating a Win32 ComboBox at all. You are registering your own class named "ComboBox", and then creating a window of that class, which creates a window of that class, which creates a window of that class, and so on recursively.
You need to change this line:
LPCTSTR lpszClass = L"ComboBox";
To a different unique name, such as "MyWindowClass".
On a side note, your message loop is structured wrong. It should look like this instead:
MSG msg;
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
And in your WndProc(), the return 0; statement underneath the WM_COMMAND handler is in the wrong place. It needs to be moved inside of the WM_COMMAND handler instead:
case WM_COMMAND:
{
switch (...)
{
...
}
return 0; // <-- moved here
}
//return 0; // <-- from here
I've starting watching the handmade hero videos and I'm trying to make a win32 window but the CreateWindowEx() function keeps failing.
I checked the error code and I get 1407.
Code is below.
Thanks in advance.
#include <Windows.h>
LRESULT CALLBACK WindowProcedure(
HWND hwnd,
UINT uMsg,
WPARAM wParam,
LPARAM lParam
)
{
LRESULT result;
switch (uMsg)
{
case WM_ACTIVATEAPP:
{
OutputDebugStringA("The window is now active");
break;
}
case WM_SIZE:
{
OutputDebugStringA("The window is now being resized");
break;
}
case WM_CREATE:
{
OutputDebugStringA("The window has been created");
break;
}
default:
{
result = DefWindowProc(hwnd, uMsg, wParam, lParam);
break;
}
}
return result;
};
int CALLBACK WinMain(
HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow
)
{
WNDCLASS GameWindow;
GameWindow.style = CS_OWNDC|CS_HREDRAW|CS_VREDRAW;
GameWindow.lpfnWndProc = WindowProcedure;
GameWindow.hInstance = hInstance;
// HICON hIcon;
GameWindow.lpszClassName = "HandmadeHeroWindowClass";
RegisterClass(&GameWindow);
if (HWND GameWindowHandle = CreateWindowEx(
0,
GameWindow.lpszClassName,
"Handmade Hero",
WS_OVERLAPPEDWINDOW | WS_VISIBLE,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
0,
0,
hInstance,
0
))
{
for (;;)
{
MSG message;
BOOL messageResult = GetMessage(&message, GameWindowHandle, 0, 0);
if (messageResult != 0)
{
DispatchMessage(&message);
}
else if (messageResult == 0)
{
break;
}
else
{
// ERROR
}
}
}
else
{
OutputDebugStringA("Couldn't create window");
}
DWORD error = GetLastError();
return 0;
};
Your window procedure returns an uninitialized variable in every path except for default:, this is undefined behavior and failure of window creation is entirely possible.
For WM_CREATE, the documentation says:
If an application processes this message, it should return zero to continue creation of the window.
As Michael noted in the comments, RegisterClass is failing. Same category of mistake, you're passing a WNDCLASS structure leaving most members uninitialized.
Thanks to Remy Lebeau for the answer, the problem was that my WNDCLASS had uninitialized values for all fields except those I changed, this caused the RegisterClass() to fail and consequently the CreateWindowEx() to fail.
I changed WNDCLASS declaration to this:
WNDCLASS GameWindow = {0};
Thanks to everyone who helped.
Here is my code. I'm trying to create an edit control. It's not showing, however. Can some take a look at my code and point out the errors please. I can't figure out where the error is. I feel It might have something to do with the parent child relationship.
#include <cstdlib>
#include <windows.h>
#define MAINWINDOW_CLASS_ID 140;
const char* MAINWINDOW_CLASS_NAME = "Main Window";
const char* TEXTAREA_CLASS_NAME = "EDIT";
using namespace std;
LRESULT CALLBACK WinProc(HWND hwnd, UINT uMsg,
WPARAM wParam, LPARAM lParam);
/*
* Initialize the window class and register it.
*/
BOOL initInstance(HINSTANCE hInstance);
/*
* Create and show the window
*/
HWND initWindow(HINSTANCE hInstance);
HWND createTextArea(HWND hParent);
/*
*
*/
INT WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hprevInstance, LPSTR lpCmdline, INT cmdlShow)
{
if (!initInstance(hInstance))
return 0;
HWND hwndMain = initWindow(hInstance);
ShowWindow(hwndMain, cmdlShow);
MSG msg = {} ;
while (GetMessage(&msg, NULL, 0, 0)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return 0;
}
BOOL initInstance(HINSTANCE hInstance)
{
WNDCLASS wc = {};
wc.lpfnWndProc = WinProc;
wc.hInstance = hInstance,
wc.lpszClassName = MAINWINDOW_CLASS_NAME;
return RegisterClass(&wc);
}
HWND initWindow(HINSTANCE hInstance)
{
HWND hwndMain = CreateWindow(
MAINWINDOW_CLASS_NAME, // The class name
"Text Editor", // The window name
WS_OVERLAPPEDWINDOW,// The window style
CW_USEDEFAULT, // The x pos
CW_USEDEFAULT, // The y pos
CW_USEDEFAULT, // The width
CW_USEDEFAULT, // The height
(HWND) NULL, // Handle to parent
(HMENU) NULL, // Handle to the menu
hInstance, // Handle to the instance
NULL // Window creation data
);
if (!hwndMain) {
return NULL;
}
else {
return hwndMain;
}
}
LRESULT CALLBACK WinProc(HWND hwnd, UINT uMsg,
WPARAM wParam, LPARAM lParam) {
HWND htextArea;
char sztestText[] = "I should be able to see this text.";
switch (uMsg) {
case WM_CREATE:
htextArea = createTextArea(hwnd);
SendMessage(htextArea, WM_SETTEXT, 0, (LPARAM) sztestText);
break;
case WM_PAINT:
break;
case WM_CLOSE:
break;
case WM_SIZE:
RECT rectMainWindow;
GetWindowRect(hwnd, &rectMainWindow);
INT x = rectMainWindow.right - rectMainWindow.left + 50;
INT y = rectMainWindow.bottom - rectMainWindow.top + 50;
MoveWindow(htextArea, 0, 0, x, y, TRUE);
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
/*******************************************************************/
HWND createTextArea(HWND hParent) {
return CreateWindow(
TEXTAREA_CLASS_NAME, // Class control name
NULL, // Title
WS_CHILD | WS_VISIBLE | ES_MULTILINE, // Styles
0, 0, 0, 0, // Sizing and position
hParent,
(HMENU) MAKEINTRESOURCE(100),
(HINSTANCE) GetWindowLong(hParent, GWL_HINSTANCE),
NULL
);
}
You've defined htextArea as a local variable in WinProc and so every time your window procedure is called its value will be uninitialized. You should make it static or move it to global data outside the function.
(The actual problem is that when you get a WM_SIZE message, you've lost the handle to the edit control, and so its size remains as 0,0).