Win32 Prevent being transparent the borders of the Window [duplicate] - c++

Question

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Is it possible to create a winapi window with only borders
(1 answer)
Closed 2 years ago.
I am dealing with win32. I have created a window. What I want is a transparent window for clicked area but nontransparent for border. Additionaly with no title bar. It should seem like an empty rectangle. When I add the following code I, my whole window becomes transparent (borders are also tranparent.)
SetWindowLong(hwnd, GWL_EXSTYLE, GetWindowLong(hwnd, GWL_EXSTYLE) | WS_EX_LAYERED);
SetLayeredWindowAttributes(hwnd, RGB(0, 0, 0), 75, LWA_ALPHA);
SetWindowLong(hwnd, GWL_STYLE, 0);
The output of my code by adding the above code is like following:
When opacity value is 255:
When opacity value is 75
As you can see that the borders also transparent. How can I prevent becoming transparent border, but obtain transparent clicked area like a rectange?
Thanks...

Answer 1

It looks like you want to make part of the window transparent.For this, you need to create two windows to complete.
Use SetWindowRgn to create a window with a hole
Use the WS_EX_LAYERED and WS_EX_TRANSPARENT style to place
another transparent window in the hole.
Like this:
The whole code:
// Test_transparent.cpp : Defines the entry point for the application.
//
#include "framework.h"
#include "Test_transparent.h"
#define MAX_LOADSTRING 100
// Global Variables:
HINSTANCE hInst; // current instance
WCHAR szTitle[MAX_LOADSTRING]; // The title bar text
WCHAR szWindowClass[MAX_LOADSTRING]; // the main window class name
// Forward declarations of functions included in this code module:
ATOM MyRegisterClass(HINSTANCE hInstance);
BOOL InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM);
HWND hWnd;
HWND child;
int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
_In_opt_ HINSTANCE hPrevInstance,
_In_ LPWSTR lpCmdLine,
_In_ int nCmdShow)
{
UNREFERENCED_PARAMETER(hPrevInstance);
UNREFERENCED_PARAMETER(lpCmdLine);
// TODO: Place code here.
// Initialize global strings
LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
LoadStringW(hInstance, IDC_TESTTRANSPARENT, szWindowClass, MAX_LOADSTRING);
MyRegisterClass(hInstance);
// Perform application initialization:
if (!InitInstance (hInstance, nCmdShow))
{
return FALSE;
}
HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_TESTTRANSPARENT));
MSG msg;
// Main message loop:
while (GetMessage(&msg, nullptr, 0, 0))
{
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return (int) msg.wParam;
}
//
// FUNCTION: MyRegisterClass()
//
// PURPOSE: Registers the window class.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
WNDCLASSEXW wcex;
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_TESTTRANSPARENT));
wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = MAKEINTRESOURCEW(IDC_TESTTRANSPARENT);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
return RegisterClassExW(&wcex);
}
//
// FUNCTION: InitInstance(HINSTANCE, int)
//
// PURPOSE: Saves instance handle and creates main window
//
// COMMENTS:
//
// In this function, we save the instance handle in a global variable and
// create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
hWnd = CreateWindowEx(0, szWindowClass, L" ", WS_POPUP, 100, 100, 800, 600, NULL, NULL, hInst, 0);
child = CreateWindowEx(WS_EX_LAYERED, szWindowClass, szTitle, WS_POPUP | WS_VISIBLE | WS_CHILD, 300, 300, 200, 200, hWnd, NULL, hInst, 0);
SetLayeredWindowAttributes(child, 0, 50, LWA_ALPHA);
if (!hWnd)
{
return FALSE;
}
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
return TRUE;
}
//
// FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
// PURPOSE: Processes messages for the main window.
//
// WM_COMMAND - process the application menu
// WM_PAINT - Paint the main window
// WM_DESTROY - post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
RECT rect;
RECT rc;
COLORREF brColor;
static HRGN hRgnWnd;
static HRGN hRgnWnd1;
static HBRUSH hBr;
switch (message)
{
case WM_COMMAND:
{
int wmId = LOWORD(wParam);
// Parse the menu selections:
switch (wmId)
{
case IDM_ABOUT:
DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
break;
case IDM_EXIT:
DestroyWindow(hWnd);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
}
break;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
// TODO: Add any drawing code that uses hdc here...
brColor = RGB(51, 143, 178);
hBr = CreateSolidBrush(brColor);
GetClientRect(hWnd, &rect);
rc.left = 200;
rc.top = 200;
rc.right = 400;
rc.bottom = 400;
hRgnWnd = CreateRectRgn(rect.left, rect.top, rect.right, rect.bottom);
hRgnWnd1 = CreateRectRgn(rc.left, rc.top, rc.right, rc.bottom);
CombineRgn(hRgnWnd1, hRgnWnd1, hRgnWnd, RGN_XOR);
SetWindowRgn(hWnd, hRgnWnd1, true);
FillRect(hdc, &rect, hBr);
EndPaint(hWnd, &ps);
}
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
// Message handler for about box.
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
UNREFERENCED_PARAMETER(lParam);
switch (message)
{
case WM_INITDIALOG:
return (INT_PTR)TRUE;
case WM_COMMAND:
if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
{
EndDialog(hDlg, LOWORD(wParam));
return (INT_PTR)TRUE;
}
break;
}
return (INT_PTR)FALSE;
}
To get a borderless window, you need to comment the MENU code in the .rc file.
.rc cpp
//Microsoft Visual C++ generated resource script.
//
#include "resource.h"
#define APSTUDIO_READONLY_SYMBOLS
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE resource.
//
#ifndef APSTUDIO_INVOKED
#include "targetver.h"
#endif
#define APSTUDIO_HIDDEN_SYMBOLS
#include "windows.h"
#undef APSTUDIO_HIDDEN_SYMBOLS
/////////////////////////////////////////////////////////////////////////////
#undef APSTUDIO_READONLY_SYMBOLS
#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_ENU)
LANGUAGE 9, 1
/////////////////////////////////////////////////////////////////////////////
//
// Icon
//
// Icon with lowest ID value placed first to ensure application icon
// remains consistent on all systems.
IDI_TESTTRANSPARENT ICON "Test_transparent.ico"
IDI_SMALL ICON "small.ico"
/////////////////////////////////////////////////////////////////////////////
//
// Menu
//
//
//IDC_TESTTRANSPARENT MENU
//BEGIN
// POPUP "&File"
// BEGIN
// MENUITEM "E&xit", IDM_EXIT
// END
// POPUP "&Help"
// BEGIN
// MENUITEM "&About ...", IDM_ABOUT
// END
//END
/////////////////////////////////////////////////////////////////////////////
//
// Accelerator
//
IDC_TESTTRANSPARENT ACCELERATORS
BEGIN
"?", IDM_ABOUT, ASCII, ALT
"/", IDM_ABOUT, ASCII, ALT
END
/////////////////////////////////////////////////////////////////////////////
//
// Dialog
//
IDD_ABOUTBOX DIALOGEX 0, 0, 170, 62
STYLE DS_SETFONT | DS_MODALFRAME | DS_FIXEDSYS | WS_POPUP | WS_CAPTION | WS_SYSMENU
CAPTION "About Test_transparent"
FONT 8, "MS Shell Dlg"
BEGIN
ICON IDR_MAINFRAME,IDC_STATIC,14,14,21,20
LTEXT "Test_transparent, Version 1.0",IDC_STATIC,42,14,114,8,SS_NOPREFIX
LTEXT "Copyright (c) 2020",IDC_STATIC,42,26,114,8
DEFPUSHBUTTON "OK",IDOK,113,41,50,14,WS_GROUP
END
/////////////////////////////////////////////////////////////////////////////
//
// DESIGNINFO
//
#ifdef APSTUDIO_INVOKED
GUIDELINES DESIGNINFO
BEGIN
IDD_ABOUTBOX, DIALOG
BEGIN
LEFTMARGIN, 7
RIGHTMARGIN, 163
TOPMARGIN, 7
BOTTOMMARGIN, 55
END
END
#endif // APSTUDIO_INVOKED
#ifdef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// TEXTINCLUDE
//
1 TEXTINCLUDE
BEGIN
"resource.h\0"
END
2 TEXTINCLUDE
BEGIN
"#ifndef APSTUDIO_INVOKED\r\n"
"#include ""targetver.h""\r\n"
"#endif\r\n"
"#define APSTUDIO_HIDDEN_SYMBOLS\r\n"
"#include ""windows.h""\r\n"
"#undef APSTUDIO_HIDDEN_SYMBOLS\r\n"
"\0"
END
3 TEXTINCLUDE
BEGIN
"\r\n"
"\0"
END
#endif // APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// String Table
//
STRINGTABLE
BEGIN
IDC_TESTTRANSPARENT "TESTTRANSPARENT"
IDS_APP_TITLE "Test_transparent"
END
#endif
/////////////////////////////////////////////////////////////////////////////
#ifndef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE resource.
//
/////////////////////////////////////////////////////////////////////////////
#endif // not APSTUDIO_INVOKED