Making Transparent Label c++ WINAPI - c++

Question

Having a window with gif and some elements c++ winapi(Non-MFC) using gdi+. SO I want to make transparent elements(Edit,Static,Button). I want to make transparent gray background of elements.
I have tried to handle WM_CTLCOLORSTATIC and adding style WS_EX_TRANSPARENT and m. but it didn't give correct result. But when I handle WM_CTLCOLORSTATIC with code:
hdcStatic = (HDC) wParam;
SetTextColor(hdcStatic, RGB(0,0,0));
SetBkMode (hdcStatic, TRANSPARENT);
return (LRESULT)GetStockObject(NULL_BRUSH);
And it showed STATIC styles transparent, but I could see background of Windows 10.
Minimum code is:
#include <memory>
#include "Resource.h"
#include <vector>
#include "TESTING.h"
#include "framework.h"
#include <algorithm>
#include <windows.h>
#include <objidl.h>
#include <GdiPlus.h>
#include <gdiplusimaging.h>
#include <shlwapi.h>
#include<CommCtrl.h>
using namespace Gdiplus;
#pragma comment (lib,"Gdiplus.lib")
#pragma comment (lib,"shlwapi.lib")
#pragma comment (lib,"Comctl32.lib")
#define TIMER_ID 101
static HFONT s_hFont = NULL;
static HWND hWnd;
static HWND hwndText;
static HWND hwndButton;
static HWND hwndLabel;
static HWND hwndCode;
static HWND hwndCode2;
static HWND hwndTime;
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
LRESULT CALLBACK SubWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam, UINT_PTR, DWORD_PTR);
int WINAPI _WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow)
{
ULONG_PTR m_gdiplusToken;
GdiplusStartupInput gdiplusStartupInput;
GdiplusStartup(&m_gdiplusToken, &gdiplusStartupInput, NULL);
HMODULE hMod = GetModuleHandle(NULL);
HRSRC hRes = FindResource(hMod, MAKEINTRESOURCEW(MY_GIF_ID), RT_RCDATA);
if (!hRes) MessageBox(NULL, L"hRes!!", L"ERROR", 0);
HGLOBAL hGlobal = LoadResource(hMod, hRes);
if (!hGlobal)MessageBox(NULL, L"hGlobal!!", L"ERROR", 0);
void* pResData = LockResource(hGlobal);
if (!pResData) MessageBox(NULL, L"pResData!!", L"ERROR", 0);
DWORD dwResData = SizeofResource(hMod, hRes);
IStream* pStream = SHCreateMemStream((BYTE*)pResData, dwResData);
if (!pStream) MessageBox(NULL, L"pStream!!", L"ERROR", 0);
Image gif(pStream);
pStream->Release();
MSG msg = { 0 };
WNDCLASS wc = { 0 };
wc.lpfnWndProc = WndProc;
wc.hInstance = hInstance;
wc.hbrBackground = NULL; // <= Do not provide a background brush.
wc.lpszClassName = L"anim_gif_player";
if (!RegisterClass(&wc))
return -1;
hWnd = CreateWindow(wc.lpszClassName,
L"",
WS_EX_TOPMOST | WS_CLIPCHILDREN & ~WS_CAPTION & ~WS_SYSMENU,
0, 0, 640, 480, 0, 0, hInstance, &gif);
if (!hWnd) {
MessageBox(0, L"SSSSSSSSSSSSSSSSSSS", L"kkkkkkkkkkkkkkkkkkkkkk", 0);
return -2;
}
hwndLabel = CreateWindowEx(WS_EX_TRANSPARENT,L"STATIC",
NULL,
WS_CHILD | WS_VISIBLE | WS_TABSTOP | WS_CLIPSIBLINGS,
325, 90, 440, 45,
hWnd,
NULL,
NULL,
NULL);
SetWindowSubclass(hwndLabel, SubWndProc, 0, 0);
const TCHAR* fontName = TEXT("Croobie");
const long nFontSize = 24;
HDC hdc = GetDC(hwndLabel);
LOGFONT logFont = { 0 };
logFont.lfHeight = -MulDiv(nFontSize, GetDeviceCaps(hdc, LOGPIXELSY), 72);
logFont.lfWeight = FW_BOLD;
wcscpy_s(logFont.lfFaceName, fontName);
s_hFont = CreateFontIndirect(&logFont);
SendMessage(hwndLabel, WM_SETFONT, (WPARAM)s_hFont, (LPARAM)MAKELONG(TRUE, 0));
ShowWindow(hWnd, SW_SHOWMAXIMIZED);
UpdateWindow(hWnd);
while (GetMessage(&msg, NULL, 0, 0) > 0) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
//DeleteObject(wc.hbrBackground);
return msg.wParam;
}
std::vector<unsigned int> LoadGifFrameInfo(Image* image)
{
// I think animated gifs will always only have 1 frame dimension...
// the "dimension" being the frame count, but I could be wrong about this
int count = image->GetFrameDimensionsCount();
if (count != 1)
return std::vector<unsigned int>();
GUID guid;
if (image->GetFrameDimensionsList(&guid, 1) != 0)
return std::vector<unsigned int>();
int frame_count = image->GetFrameCount(&guid);
auto sz = image->GetPropertyItemSize(PropertyTagFrameDelay);
if (sz == 0)
return std::vector<unsigned int>();
// copy the frame delay property into the buffer backing an std::vector
// of bytes and then get a pointer to its value, which will be an array of
// unsigned ints
std::vector<unsigned char> buffer(sz);
PropertyItem* property_item = reinterpret_cast<PropertyItem*>(&buffer[0]);
image->GetPropertyItem(PropertyTagFrameDelay, sz, property_item);
unsigned int* frame_delay_array = (unsigned int*)property_item[0].value;
// copy the delay values into an std::vector while converting to milliseconds.
std::vector<unsigned int> frame_delays(frame_count);
std::transform(frame_delay_array, frame_delay_array + frame_count, frame_delays.begin(),
[](unsigned int n) {return n * 10; }
);
return frame_delays;
}
void GenerateFrame(Bitmap* bmp, Image* gif)
{
Graphics dest(bmp);
SolidBrush white(Color::White);
dest.FillRectangle(&white, 0, 0, bmp->GetWidth(), bmp->GetHeight());
if (gif)
dest.DrawImage(gif, 0, 0);
}
std::unique_ptr<Bitmap> CreateBackBuffer(HWND hWnd)
{
RECT r;
GetClientRect(hWnd, &r);
return std::make_unique<Bitmap>(r.right - r.left, r.bottom - r.top);
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static Image* animated_gif;
static std::unique_ptr<Bitmap> back_buffer;
static std::vector<unsigned int> frame_delays;
static int current_frame;
switch (message) {
case WM_CREATE: {
animated_gif = reinterpret_cast<Image*>(
reinterpret_cast<CREATESTRUCT*>(lParam)->lpCreateParams
);
if (!animated_gif || animated_gif->GetLastStatus() != 0) {
MessageBox(hWnd, L"Unable to load animated gif", L"error", MB_ICONERROR);
return 0;
}
// Create a bitmap the size of the window's clent area
back_buffer = CreateBackBuffer(hWnd);
// get the frame delays and thereby test that this is really an animated gif
frame_delays = LoadGifFrameInfo(animated_gif);
if (frame_delays.empty()) {
MessageBox(hWnd, L"Invalid gif or not an animated gif", L"error", MB_ICONERROR);
return 0;
}
current_frame = 0;
animated_gif->SelectActiveFrame(&FrameDimensionTime, current_frame);
GenerateFrame(back_buffer.get(), animated_gif);
SetTimer(hWnd, TIMER_ID, frame_delays[0], nullptr);
InvalidateRect(hWnd, nullptr, FALSE);
}
break;
case WM_TIMER: {
KillTimer(hWnd, TIMER_ID);
current_frame = (current_frame + 1) % frame_delays.size();
animated_gif->SelectActiveFrame(&FrameDimensionTime, current_frame);
GenerateFrame(back_buffer.get(), animated_gif);
SetTimer(hWnd, TIMER_ID, frame_delays[current_frame], nullptr);
InvalidateRect(hWnd, nullptr, FALSE);
} break;
case WM_PAINT: {
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
Graphics g(hdc);
g.DrawImage(back_buffer.get(), 0, 0);
EndPaint(hWnd, &ps);
} break;
case WM_SIZE: {
back_buffer = CreateBackBuffer(hWnd);
GenerateFrame(back_buffer.get(), animated_gif);
} break;
case WM_CLOSE:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
LRESULT CALLBACK SubWndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam, UINT_PTR, DWORD_PTR) {
switch (msg) {
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
RECT rc; GetClientRect(hwnd, &rc);
SetTextColor(hdc, Color::Yellow);
SetBkMode(hdc, TRANSPARENT);
wchar_t buf[256] = { 0 };
GetWindowTextW(hwnd, buf, sizeof(buf) / sizeof(*buf));
DrawTextW(hdc, buf, wcslen(buf), &rc, DT_LEFT | DT_TOP);
EndPaint(hwnd, &ps);
return 0;
}
case WM_NCDESTROY://safely remove subclass
RemoveWindowSubclass(hwnd, SubWndProc, 0);
return DefSubclassProc(hwnd, msg, wParam, lParam);
}
return DefSubclassProc(hwnd, msg, wParam, lParam);
}

Answer 1

The WS_EX_TRANSPARENT style doesn’t mean “transparent”; it means
“paint over siblings.”
The style is called “transparent” not because it makes the window
transparent but because it makes transparency possible.
Please refer: Why isn't my transparent static control transparent?
The only way I've found to do this reliably is to sub-class the static control and paint the background manually.
You can catch the WM_ERASEBKGND message and paint the appropriate portion of the underlying bitmap.
Please refer:
Is it possible to make a Static control transparent?
C++ Win32 Static Control Transparent Background
Also, if you want remove grey background, you can change static control background and make it transparent.
Demon of custom static control:
#include "stdafx.h"
#include "Test_WM_CTLCOLORSTATIC.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
HWND hWndStatic;
// Forward declarations of functions included in this code module:
ATOM MyRegisterClass(HINSTANCE hInstance);
BOOL InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
LRESULT CALLBACK WndProcPanel(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM);
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_TESTWMCTLCOLORSTATIC, szWindowClass, MAX_LOADSTRING);
MyRegisterClass(hInstance);
// Perform application initialization:
if (!InitInstance (hInstance, nCmdShow))
{
return FALSE;
}
HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_TESTWMCTLCOLORSTATIC));
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;
}
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_TESTWMCTLCOLORSTATIC));
wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = MAKEINTRESOURCEW(IDC_TESTWMCTLCOLORSTATIC);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
return RegisterClassExW(&wcex);
}
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
hInst = hInstance; // Store instance handle in our global variable
HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);
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
//
//
WNDPROC StaticWndProc = NULL;
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_CREATE:
{ LRESULT lRes = DefWindowProc(hWnd, message, wParam, lParam);
hWndStatic = CreateWindowEx(0, L"Static", NULL, WS_CHILD | WS_VISIBLE | SS_LEFT, 10, 130, 200, 40, hWnd, NULL, hInst, NULL); //v2 deleted HWND
StaticWndProc = (WNDPROC)SetWindowLong(hWndStatic, GWL_WNDPROC, (LPARAM)WndProcPanel);
return lRes;
}
break;
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_ERASEBKGND:
{
HBRUSH brush;
RECT rect;
brush = CreateSolidBrush(RGB(0, 255, 0));
SelectObject((HDC)wParam, brush);
GetClientRect(hWnd, &rect);
Rectangle((HDC)wParam, rect.left, rect.top, rect.right, rect.bottom);
}
break;
case WM_DESTROY:
SetWindowLong(hWndStatic, GWL_WNDPROC, (LPARAM)StaticWndProc);
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;
}
TCHAR szText[] = _T("TestString");;
LRESULT CALLBACK WndProcPanel(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_PAINT)
{
RECT rc;
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
GetClientRect(hWnd, &rc);
SetBkMode(hdc, TRANSPARENT);
DrawText(hdc, szText, _tcslen(szText), &rc, DT_CENTER | DT_VCENTER);
EndPaint(hWnd, &ps);
return 0;
}
return CallWindowProc(StaticWndProc, hWnd, message, wParam, lParam);
}
thx #IInspectable's remind, the best way to subclass controls is to use SetWindowsSubclass, see Subclassing Controls
I'll update the new code later, and I'm sorry for my shallow knowledge.
Updated:
case WM_TIMER: {
KillTimer(hWnd, TIMER_ID);
current_frame = (current_frame + 1) % frame_delays.size();
animated_gif->SelectActiveFrame(&FrameDimensionTime, current_frame);
GenerateFrame(back_buffer.get(), animated_gif);
SetTimer(hWnd, TIMER_ID, frame_delays[current_frame], nullptr);
InvalidateRect(hWnd, nullptr, FALSE);
InvalidateRect(hwndLabel, nullptr, FALSE); //Here add new code
}
Debug Result: