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#include <stdio.h>
#include <stdlib.h>
#include <windows.h>

LRESULT CALLBACK window_process (HWND, UINT, WPARAM, LPARAM);
void error(char * from);
void notify(char * message); // Notify user via a message box

LPSTR app_name = "cdump";

int WINAPI WinMain(HINSTANCE instance, HINSTANCE prev_instance,
    PSTR cmd_line, int cmd_show){
    HWND hwnd;
    MSG window_msg;
    WNDCLASS mainwnd;
    
    memset(&mainwnd, 0, sizeof(WNDCLASS));
    mainwnd.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
    mainwnd.lpfnWndProc = &window_process;
    mainwnd.cbClsExtra = 0;
    mainwnd.cbWndExtra = 0;
    mainwnd.hInstance = instance;
    mainwnd.hIcon = LoadIcon(instance, "ICON_OPEN");
    mainwnd.hCursor = LoadCursor (NULL, IDC_ARROW); // default IDC_ARROW
    mainwnd.hbrBackground = CreateSolidBrush(RGB(100, 100, 100));
    mainwnd.lpszClassName = app_name;
    mainwnd.lpszMenuName  = NULL; 
    if(!RegisterClass(&mainwnd)){
        error("RegisterClass");
    }

    hwnd = CreateWindow(app_name, app_name, WS_OVERLAPPEDWINDOW    , 
        CW_USEDEFAULT, CW_USEDEFAULT, 500, 255, NULL, NULL, instance, NULL);
    if(!hwnd){
        error("from:CreateWindow");
    }

    ShowWindow (hwnd, cmd_show);
    UpdateWindow(hwnd);
    while(GetMessage (&window_msg, NULL, 0, 0)){
        TranslateMessage(&window_msg);
        DispatchMessage(&window_msg);
    }
    return window_msg.wParam;
}

LRESULT CALLBACK window_process (HWND hwnd, UINT message, WPARAM
    wParam, LPARAM lParam){
    HDC hdc;
    PAINTSTRUCT paint_class;
    
    char text_out[512];
    memset(text_out, 512, 0);

    int ypos = 0;
    int counter = 0;
    static int x = 1;
    static int y = 1;
    if(message == WM_PAINT){
        hdc = BeginPaint(hwnd, &paint_class);
        SetTextColor(hdc, RGB(1,250,50));
        SetBkMode(hdc, TRANSPARENT);
        EndPaint (hwnd, &paint_class);
    }
    else if(message == WM_KEYDOWN){
        hdc = GetDC(hwnd);
        switch(wParam){
            case VK_RIGHT:
                x++;
                break;
            case VK_DOWN:
                y++;
                break;
            case VK_LEFT:
                x--;
                break;
            case VK_UP:
                y--;
                break;
        }
        SetPixel (hdc, x, y, RGB(255, 255, 255)) ;
        ReleaseDC(hwnd, hdc);
    }
    else if(message == WM_DESTROY){
        PostQuitMessage(0);
        return 0;
    }
    else if(message == WM_CLOSE){
        DestroyWindow(hwnd);
    }
    return DefWindowProc(hwnd, message, wParam, lParam);
}

void error(char * error){
    char message[530];
    memset(message, 0, 530);
    if(!strncmp(error, "from:", 5)){
        error += 5;
        char formulated[513];
        memset(formulated, 0, 513);
        FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, 0, GetLastError(), 0,
            formulated, 512, NULL);
        sprintf(message, "%s: %s", error, formulated);
    }
    else{
        sprintf(message, "%s", error);
    }
    MessageBox (NULL, message, app_name, MB_ICONERROR);
    exit(1);
}

void notify(char * message){
    MessageBox (NULL, message, app_name, MB_ICONINFORMATION);
}