Win32 Colored Emoji Rendering

hello_win32_emojis.md

Win32 Colored Emoji Rendering

Uses DirectWrite and D2D to render Segoe UI Emojis

win32_emojis.cpp

//
// File: win32_emojis.cpp
// Compile with: cl win32_emojis.cpp
//

#define WIN32_LEAN_AND_MEAN
#define NOMINMAX
#include <windows.h>
#include <assert.h>
#include <stdio.h>

#include <d2d1.h>
#include <dwrite.h>

#pragma comment(lib, "gdi32.lib")
#pragma comment(lib, "user32.lib")
#pragma comment(lib, "d2d1.lib")
#pragma comment(lib, "dwrite.lib")

#define WINDOW_CLASS_NAME L"Window Class"

static ID2D1Factory *d2d_factory = NULL;
static IDWriteFactory *dw_factory = NULL;
static ID2D1HwndRenderTarget *render_target = NULL;

static ID2D1SolidColorBrush *brush = NULL;
static IDWriteTextFormat *text_format = NULL;


void win32_fatal(const char *message)
{
    MessageBoxA(NULL, message, "Fatal Error", MB_ICONEXCLAMATION | MB_OK);
    ExitProcess(1);
}

void DrawEmojis(ID2D1HwndRenderTarget *render_target)
{
    render_target->BeginDraw();
    render_target->Clear(D2D1::ColorF(D2D1::ColorF::White));

    WCHAR text[] = L"\U0001F604 \U0001F525 \U0001F422";
    UINT32 count = sizeof(text) / sizeof(WCHAR);
    D2D1_RECT_F rect = D2D1::RectF(50.0f, 50.0f, 200.0f, 200.0f);

    render_target->DrawText(text, count, text_format, rect, brush, D2D1_DRAW_TEXT_OPTIONS_ENABLE_COLOR_FONT);

    render_target->EndDraw();
}

LRESULT CALLBACK win32_window_callback(HWND hwnd, UINT message, WPARAM w_param, LPARAM l_param)
{
    LRESULT result = 0;

    switch (message)
    {
        case WM_CLOSE:
        {
            ExitProcess(0);
        } break;

        case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hwnd, &ps);
            DrawEmojis(render_target);
            EndPaint(hwnd, &ps);
        } break;

        case WM_SIZE:
        {
            UINT width = LOWORD(l_param);
            UINT height = HIWORD(l_param);
            if (render_target)
            {
                render_target->Resize(D2D1_SIZE_U{width, height});
            }
        } break;

        default:
        {
            result = DefWindowProcW(hwnd, message, w_param, l_param);
        } break;
    }

    return result;
}

int APIENTRY WinMain(HINSTANCE instance, HINSTANCE prev_inst, LPSTR argv, int argc)
{
    // NOTE(nick): set DPI awareness
    HMODULE user32 = LoadLibraryA("user32.dll");
    
    // @Incomplete: support older OS versions
    typedef BOOL Win32_SetProcessDpiAwarenessContext(HANDLE);
    Win32_SetProcessDpiAwarenessContext *SetProcessDpiAwarenessContext = (Win32_SetProcessDpiAwarenessContext *) GetProcAddress(user32, "SetProcessDpiAwarenessContext");
    SetProcessDpiAwarenessContext(((HANDLE) -4) /* DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2 */);

    WNDCLASSEXW wc = {};
    wc.cbSize        = sizeof(wc);
    wc.style         = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
    wc.lpfnWndProc   = (WNDPROC)win32_window_callback;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = instance;
    wc.hIcon         = LoadIconA(instance, "APPICON");
    wc.hCursor       = LoadCursorA(0, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = WINDOW_CLASS_NAME;
    wc.hIconSm       = NULL;

    if (!RegisterClassExW(&wc)) {
        win32_fatal("Failed to register window class.\n");
    }

    WCHAR *title16 = L"Win32 Color Emoji Rendering Demo";
    HWND hwnd = CreateWindowW(WINDOW_CLASS_NAME, title16, WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 1280, 720,
        0, 0, instance, 0
    );

    ShowWindow(hwnd, SW_SHOW);

    // NOTE(nick): set up D2D and DirectWrite state
    HRESULT hr = 0;
    hr = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &d2d_factory);
    assert(hr == S_OK);

    D2D1_RENDER_TARGET_PROPERTIES props = D2D1::RenderTargetProperties(D2D1_RENDER_TARGET_TYPE_DEFAULT, D2D1::PixelFormat(DXGI_FORMAT_UNKNOWN, D2D1_ALPHA_MODE_PREMULTIPLIED));
    hr = d2d_factory->CreateHwndRenderTarget(props, D2D1::HwndRenderTargetProperties(hwnd, D2D1_SIZE_U{ (UINT32)(1280), (UINT32)(720) }), &render_target);
    assert(hr == S_OK);

    hr = DWriteCreateFactory(DWRITE_FACTORY_TYPE_SHARED, __uuidof(IDWriteFactory), reinterpret_cast<IUnknown**>(&dw_factory));
    assert(hr == S_OK);

    hr = dw_factory->CreateTextFormat(L"Segoe UI Emoji", NULL, DWRITE_FONT_WEIGHT_NORMAL, DWRITE_FONT_STYLE_NORMAL, DWRITE_FONT_STRETCH_NORMAL, 32.0f, L"", &text_format);
    assert(hr == S_OK);

    hr = render_target->CreateSolidColorBrush(D2D1::ColorF(D2D1::ColorF::Black), &brush);
    assert(hr == S_OK);

    while (true)
    {
        for (;;) {
            MSG msg = {};

            if (!PeekMessageW(&msg, NULL, 0, 0, PM_REMOVE)) {
                break;
            }

            TranslateMessage(&msg);
            DispatchMessageW(&msg);
        }
    }

    return 0;
}