#include <windows.h>

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

#define LINES 27
static char *abc[] = {
"anteater",
"bear",
"cougar",
"dingo",
"elephant",
"frog",
"gazelle",
"hyena",
"iguana",
"jackal",
"kangaroo",
"llama",
"moose",
"newt",
"octopus",
"penguin",
"quail",
"rat",
"squid",
"tortoise",
"urus",
"vole",
"walrus",
"xylophone",
"yak",
"zebra",
"This line contains many words, but no character. Go figure."
};

LRESULT CALLBACK MainWndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam )
{
HDC hdc;
PAINTSTRUCT ps;
TEXTMETRIC tm;
SCROLLINFO si;

/* These variables are required to display text. */

static int xClient; /* width of client area */
static int yClient; /* height of client area */
static int xClientMax; /* maximum width of client area */

static int xChar; /* horizontal scrolling unit */
static int yChar; /* vertical scrolling unit */

static int xUpper; /* average width of uppercase letters */

static int xPos; /* current horizontal scrolling position */
static int yPos; /* current vertical scrolling position */

static int xMax; /* maximum horiz. scrolling position */
static int yMax; /* maximum vert. scrolling position */

int xInc; /* horizontal scrolling increment */
int yInc; /* vertical scrolling increment */

int i; /* loop counter */
int x, y; /* horiz. and vert. printing coords */

int FirstLine; /* first line in the invalidated area */
int LastLine; /* last line in the invalidated area */

RECT rect;

switch (msg) {
case WM_CREATE :

/* Get the handle of the client area's device context. */

hdc = GetDC (hwnd);

/* Extract font dimensions from the text metrics. */

GetTextMetrics (hdc, &tm);

xChar = tm.tmAveCharWidth;
xUpper = (tm.tmPitchAndFamily & 1 ? 3 : 2) * xChar/2;
yChar = tm.tmHeight + tm.tmExternalLeading;

/* Free the device context. */

ReleaseDC (hwnd, hdc);

/*
* Set an arbitrary maximum width for client area.
* (xClientMax is the sum of the widths of 48 average
* lowercase letters and 12 uppercase letters.)
*/

xClientMax = 48 * xChar + 12 * xUpper;

return 0;

case WM_SIZE:

/* Retrieve the dimensions of the client area. */

yClient = HIWORD (lParam);
xClient = LOWORD (lParam);

/*
* Determine the maximum vertical scrolling position.
* The two is added for extra space below the lines
* of text.
*/

yMax = max (0, LINES + 2 - yClient/yChar);

/*
* Make sure the current vertical scrolling position
* does not exceed the maximum.
*/

yPos = min(yPos, yMax);

/*
* Adjust the vertical scrolling range and scroll box
* position to reflect the new yMax and yPos values.
*/

si.cbSize = sizeof(si);
si.fMask = SIF_RANGE | SIF_PAGE | SIF_POS;
si.nMin = 0;
si.nMax = yMax;
si.nPage = yClient / yChar;
si.nPos = yPos;
SetScrollInfo(hwnd, SB_VERT, &si, TRUE);

/*
* Determine the maximum horizontal scrolling position.
* The two is added for extra space to the right of the
* lines of text.
*/

xMax = max (0, 2 + (xClientMax - xClient)/xChar);

/*
* Make sure the current horizontal scrolling position
* does not exceed the maximum.
*/

xPos = min (xPos, xMax);

/*
* Adjust the horizontal scrolling range and scroll box
* position to reflect the new xMax and xPos values.
*/

si.cbSize = sizeof(si);
si.fMask = SIF_RANGE | SIF_PAGE | SIF_POS;
si.nMin = 0;
si.nMax = xMax;
si.nPage = xClient / xChar;
si.nPos = xPos;
SetScrollInfo(hwnd, SB_HORZ, &si, TRUE);

return 0;

case WM_PAINT:

/* Prepare the window for painting. */

hdc = BeginPaint(hwnd, &ps);

(void) GetClientRect(hwnd, &rect);
FillRect(hdc, &rect, GetStockObject(LTGRAY_BRUSH));

/*
* Use the current vertical scrolling position and
* coordinates of the invalid rectangle to determine
* the range of new lines that should be drawn in the
* client area.
*/

FirstLine = max (0, yPos + ps.rcPaint.top/yChar - 1);
LastLine = min (LINES, yPos + ps.rcPaint.bottom/yChar);

/* Display these lines. */

for (i = FirstLine;i < LastLine;i++) {
x = xChar * (1 - xPos);
y = yChar * (1 - yPos + i);
TextOut (hdc, x, y, abc[i], lstrlen(abc[i]));
}

/* Indicate that painting is finished. */

EndPaint(hwnd, &ps);
break;

case WM_HSCROLL:
switch(LOWORD (wParam)) {

/* User clicked shaft left of the scroll box. */

case SB_PAGEUP:
xInc = -8;
break;

/* User clicked shaft right of the scroll box. */

case SB_PAGEDOWN:
xInc = 8;
break;

/* User clicked the left arrow. */

case SB_LINEUP:
xInc = -1;
break;

/* User clicked the right arrow. */

case SB_LINEDOWN:
xInc = 1;
break;

/* User dragged the scroll box. */

case SB_THUMBTRACK:
xInc = HIWORD(wParam) - xPos;
break;

default:
xInc = 0;
}

/*
* If applying the horizontal scrolling increment does not
* take the scrolling position out of the scrolling range,
* increment the scrolling position, adjust the position
* of the scroll box, and update the window.
*/

if (xInc = max (-xPos, min (xInc, xMax - xPos))) {
xPos += xInc;

ScrollWindowEx (hwnd, -xChar * xInc, 0,
(CONST RECT *) NULL, (CONST RECT *) NULL,
(HRGN) NULL, (LPRECT) NULL, SW_INVALIDATE);
si.cbSize = sizeof(si);
si.fMask = SIF_POS;
si.nPos = xPos;
SetScrollInfo(hwnd, SB_HORZ, &si, TRUE);
UpdateWindow (hwnd);
}

return 0;

case WM_VSCROLL:
switch(LOWORD (wParam)) {

/* User clicked the shaft above the scroll box. */

case SB_PAGEUP:
yInc = min(-1, -yClient / yChar);
break;

/* User clicked the shaft below the scroll box. */

case SB_PAGEDOWN:
yInc = max(1, yClient / yChar);
break;

/* User clicked the top arrow. */

case SB_LINEUP:
yInc = -1;
break;

/* User clicked the bottom arrow. */

case SB_LINEDOWN:
yInc = 1;
break;

/* User dragged the scroll box. */

case SB_THUMBTRACK:
yInc = HIWORD(wParam) - yPos;
break;

default:
yInc = 0;
}

/*
* If applying the vertical scrolling increment does not
* take the scrolling position out of the scrolling range,
* increment the scrolling position, adjust the position
* of the scroll box, and update the window. UpdateWindow
* sends the WM_PAINT message.
*/
if (yInc = max(-yPos, min(yInc, yMax - yPos))) {
yPos += yInc;
ScrollWindowEx(hwnd, 0, -yChar * yInc,
(CONST RECT *) NULL, (CONST RECT *) NULL,
(HRGN) NULL, (LPRECT) NULL, SW_INVALIDATE);
si.cbSize = sizeof(si);
si.fMask = SIF_POS;
si.nPos = yPos;

SetScrollInfo(hwnd, SB_VERT, &si, TRUE);
UpdateWindow (hwnd);
}

return 0;

case WM_DESTROY:
PostQuitMessage( 0 );
break;

default:
return(DefWindowProc(hwnd, msg, wParam, lParam));
}

return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
WNDCLASS wc;
MSG msg;
HWND hwnd;

if(! hPrevInstance) {
memset(&wc,0,sizeof(WNDCLASS));
wc.lpszClassName = "MyAppClass";
wc.lpfnWndProc = MainWndProc;
wc.style = CS_VREDRAW | CS_HREDRAW;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(NULL, IDI_APPLICATION );
wc.hCursor = LoadCursor(NULL, IDC_ARROW );
wc.hbrBackground = (HBRUSH)(COLOR_WINDOW);
wc.lpszMenuName = NULL;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
RegisterClass(&wc);
}

hwnd = CreateWindowEx(
0L,
"MyAppClass",
"Scroll Bar Application",
WS_OVERLAPPEDWINDOW | WS_HSCROLL | WS_VSCROLL,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
(HWND)NULL,
(HMENU)NULL,
hInstance,
(LPVOID)NULL
);

ShowWindow(hwnd, nCmdShow);

while (GetMessage(&msg, NULL, 0, 0 )) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}

return msg.wParam;
}