Thread: Draw Program Not Working

This program is supposed to draw a randomly colored dot (connected by a line of the same color) at a random location on the screen when I click "Start", then exit when I click ESCAPE. When I click "Start", though, nothing happens.

Code:

//FILE: main.c

#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include <wingdi.h>
#include <stdlib.h>
#include "resource.h"
#include <stdio.h>
#define WM_START 12342649
HINSTANCE hInst;
void draw(HDC, int, int, int, int);
int x=1, y=1;
HDC me;
WINDOWPLACEMENT wp;
BOOL CALLBACK DialogProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{   
    switch(uMsg)
    {
    case WM_INITDIALOG:
        //SetBkColor(GetDC(NULL), RGB(0,0,0));
        return TRUE;

    case WM_CLOSE:
        EndDialog(hwndDlg, 0);
        return TRUE;

    case WM_COMMAND:
        switch(LOWORD(lParam))
        {
        case 2222:
            MessageBox(hwndDlg, "start", "", MB_OK);
            while(!(GetKeyState(VK_ESCAPE)&0b10000000)) {
                while(((x=rand())<1024)&&(x>1));
                while(((y=rand())<685)&&(x>23));
                draw(me, 10, 10, x, y);
                Sleep(300);
            }
            EndDialog(hwndDlg, 0);
            return TRUE;

        }

    }

    return FALSE;
}


int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
    hInst = hInstance;
    // The user interface is a modal dialog box
    return DialogBox(hInstance, MAKEINTRESOURCE(DLG_MAIN), NULL, (DLGPROC)DialogProc);
}

void draw(HDC dc, int x, int y, int xpos, int ypos)
{
    srand(xpos*ypos);
    //int ca=0, cb=0, cd=0;
    COLORREF color;
    //HPEN pen=CreatePen(PS_SOLID, 20);
    LOGBRUSH mbrush;
    /*while((ca=rand())<=0xFF);
    while((ca=rand())<=0xFF);
    while((ca=rand())<=0xFF);*/
    COLORREF rnd=RGB(rand()&0xFF, rand()&0xFF, rand()&0xFF);
    mbrush.lbStyle=BS_SOLID;
    mbrush.lbColor=rnd;
    mbrush.lbHatch=0;
    HBRUSH brush=CreateBrushIndirect(&mbrush);
    SelectObject(dc, (HGDIOBJ)brush);
    LineTo(dc, xpos, ypos);
    color=rnd;
    //color=RGB(xpos, 0, 0);
    int xx, yy;
    for(xx=0; xx<x; xx++)
    {
        for(yy=0; yy<y; yy++)
        {
            SetPixel(dc, xx+xpos, yy+ypos, color);
        }
    }
}

Code:

//FILE: resource.h
#include <windows.h>

// ID of Main Dialog
#define DLG_MAIN 101

Code:

//FILE: resource.rc
#include "resource.h"

DLG_MAIN DIALOGEX 6, 5, 194, 106

CAPTION ""

STYLE DS_MODALFRAME | DS_SHELLFONT | WS_CAPTION | WS_VISIBLE | WS_POPUP | WS_SYSMENU

BEGIN
 PUSHBUTTON      "Start", 2222/*ID*/, 7, 7, 47, 22
END

What is wrong????? (Probably alot)
NOTE: Some of these functions I have just started using today.

Drawing the dots each paint msg will be very slow, using SetPixel will make it even slower. The drawing will also not remain after the system generates a paint msg (ie another window overlaps your window).

You should create a back buffer, draw the dots to this and when you get a paint msg BitBlt() the back buffer to the screen buffer ('Double Buffer').

I have posted plenty of code before showing exactly how do do this.

PS Make sure your START button ID is the same in the RESOURCE.H file and CALLBACK, better to use the actual ID name [ie IDC_START] (as currently you appear to be using both 12342649 and 2222)

Use the correct CASE ..... BREAK syntax (even if you have a return). It will make your code much more readable and prone to less errors.

Do not call srand() more than once in the whole program. rand is a big list of numbers, srand is the index to start at. If you keep reseting it, you will get exactly the same 'random' number.

Use the modulus function to get a number in the correrct range the first time [int iPercent = (int)(rand() % 100);//return a whole number between 0 and 99 ]