为什么在更改 WinAPI 控件的大小后不调用WM_NCCALSIZE?

我有一个丰富的编辑控件，创建后其大小会更改。

我想自定义控件的外观，因此每次更改控件的大小时，都需要重新计算其工作区的大小。想法是在每次组件收到消息时更改工作区的大小WM_NCCALCSIZE因为 MSDN 文档WM_NCCALCSIZE指出：

在必须计算窗口工作区的大小和位置时发送。通过处理此消息，应用程序可以在窗口的大小或位置更改时控制窗口工作区的内容。

问题是在更改控件大小后不调用WM_NCCALCSIZE(仅在创建控件时调用一次(。

此行为并非特定于丰富的编辑控件。同样的情况也是如此，例如按钮控件。在组件显示在屏幕上之前还是之后更改大小也无关紧要。

#include <windows.h>
#include <commctrl.h>
#include <richedit.h>
#include <string>
#pragma comment(lib, "comctl32.lib")
#pragma comment(linker,""/manifestdependency:type='win32' 
name='Microsoft.Windows.Common-Controls' version='6.0.0.0' 
processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*'"")
LRESULT CALLBACK WindowProc(HWND, UINT, WPARAM, LPARAM);
LRESULT CALLBACK RichEditProc(HWND, UINT, WPARAM, LPARAM);
WNDPROC richEditOrigProc;
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
LoadLibrary(TEXT("msftedit.dll"));
WNDCLASSEX mainwcex;
mainwcex.cbSize = sizeof(WNDCLASSEX);
mainwcex.style = CS_HREDRAW | CS_VREDRAW;
mainwcex.lpfnWndProc = WindowProc;
mainwcex.cbClsExtra = 0;
mainwcex.cbWndExtra = 0;
mainwcex.hInstance = hInstance;
mainwcex.hIcon = NULL;
mainwcex.hCursor = (HICON)LoadCursor(NULL, IDC_ARROW);
mainwcex.hbrBackground = GetSysColorBrush(COLOR_MENU);
mainwcex.lpszMenuName = NULL;
mainwcex.lpszClassName = "mainwindow";
mainwcex.hIconSm = NULL;
RegisterClassEx(&mainwcex);
HWND mainWindow = CreateWindowEx(
NULL,
"mainwindow",
NULL,
WS_OVERLAPPEDWINDOW,
100,
100,
600,
400,
NULL,
NULL,
hInstance,
NULL);
HWND richEditControl = CreateWindowEx(
NULL,
"RICHEDIT50W",
"Rich Edit",
WS_CHILD | WS_VISIBLE | WS_BORDER | WS_TABSTOP,
50,
50,
100,
25,
mainWindow,
NULL,
hInstance,
NULL);
richEditOrigProc = (WNDPROC) SetWindowLongPtr(richEditControl, GWLP_WNDPROC, (LONG_PTR) RichEditProc);
// Changes the width of rich edit control from 100 px to 400 px.
SetWindowPos(richEditControl, NULL, 0, 0, 400, 25,
SWP_NOMOVE | SWP_NOZORDER | SWP_NOOWNERZORDER | SWP_NOACTIVATE);
ShowWindow(mainWindow, nCmdShow);
MSG msg;
while (GetMessage(&msg, NULL, 0, 0)) {
if (!IsDialogMessage(mainWindow, &msg)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return static_cast<int>(msg.wParam);
}
LRESULT CALLBACK WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg) {
case WM_DESTROY:
{
PostQuitMessage(0);
return 0;
}
}
return DefWindowProc(hWnd, uMsg, wParam, lParam);
}
LRESULT CALLBACK RichEditProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg) {
case WM_NCCALCSIZE:
{
RECT newClientRect;
GetWindowRect(hWnd, &newClientRect);
MapWindowPoints(HWND_DESKTOP, GetParent(hWnd), reinterpret_cast<POINT*>(&newClientRect), 2);
InflateRect(&newClientRect, -3, -3);
int width = newClientRect.right - newClientRect.left;
int height = newClientRect.bottom - newClientRect.top;
if (wParam) {
NCCALCSIZE_PARAMS* ncParams = reinterpret_cast<NCCALCSIZE_PARAMS*>(lParam);
ncParams->rgrc[0].left = newClientRect.left;
ncParams->rgrc[0].top = newClientRect.top;
ncParams->rgrc[0].right = newClientRect.right;
ncParams->rgrc[0].bottom = newClientRect.bottom;
return WVR_HREDRAW;
}
return 0;
}
}
return CallWindowProc(richEditOrigProc, hWnd, uMsg, wParam, lParam);
}

在此示例中，很明显，虽然丰富编辑控件的总大小发生了更改，但它的工作区不会重新计算，而是对应于其初始大小。

调整自定义控件工作区大小以反映其总大小变化的正确方法是什么。