GDI Documentation

Introduction

The Windows Graphics Device Interface (GDI) provides a set of functions for drawing graphics, formatting text, and managing fonts and palettes. This documentation covers the core concepts, functions, structures, and best practices for using GDI in native Windows applications.

Key Concepts

• Device Context (DC) – the fundamental drawing surface.
• Handles – GDI objects such as pens, brushes, fonts, and bitmaps are referenced via handles.
• Coordinate Systems – logical vs. device units.
• Clipping – limit drawing to specific regions.

Quick Start

#include <windows.h>

int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrev, LPSTR cmd, int nShow){
    HWND hwnd = CreateWindowEx(0, L"STATIC", L"GDI Demo",
                               WS_OVERLAPPEDWINDOW | WS_VISIBLE,
                               100,100,400,300, NULL, NULL, hInst, NULL);
    HDC hdc = GetDC(hwnd);
    HPEN hPen = CreatePen(PS_SOLID, 2, RGB(0,0,255));
    SelectObject(hdc, hPen);
    MoveToEx(hdc, 50,50,NULL);
    LineTo(hdc, 200,200);
    DeleteObject(hPen);
    ReleaseDC(hwnd, hdc);
    MSG msg;
    while(GetMessage(&msg,NULL,0,0)){
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return 0;
}

Search Functions

• CreateCompatibleDC
• DeleteDC
• GetDeviceCaps
• MoveToEx
• LineTo
• Rectangle
• Ellipse
• TextOut
• SetBkMode
• SetTextColor