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The DOIView Example Program
The following example, DOIView, demonstrates the use of resources, keyboard accelerators, and pop-up menus. DOIView, short for Declaration of Independence View, displays the United States Declaration of Independence in a window. The text for the program is stored as a series of string resources. DOIView formats the text to fit the application window and uses scroll bars to scroll the text.
Figure 4-3 shows the DOIView window. The keys Ctrl-H and Ctrl-E scroll the document to the start (home) and end of the document. You can also tap on the window to display a short menu that allows you to quickly scroll to the start or end of the document as well as end the program.
Figure 4-3: The DOI View window with the menu displayed
The source for DOIView is shown in Listing 4-2. Notice the inclusion of a third file,
Listing 4-2: The DOIView program
DOIView.rc
//======================================================================
// DOIView - Resource file
//
// Written for the book Programming Windows CE
// Copyright (C) 2003 Douglas Boling
//
//======================================================================
#include "DOIView.h"
//----------------------------------------------------------------------
// Icon
//
ID_ICON ICON "DOIView.ico"
//----------------------------------------------------------------------
// Menu
//
ID_MENU MENU DISCARDABLE
BEGIN
POPUP "&File"
BEGIN
MENUITEM "&Goto Start\tCtrl-H", IDM_HOME
MENUITEM "&Goto End\tCtrl-E", IDM_END
MENUITEM SEPARATOR
MENUITEM "E&xit", IDM_EXIT
END
END
//----------------------------------------------------------------------
// Accelerator table
//
ID_ACCEL ACCELERATORS DISCARDABLE
BEGIN
"H", IDM_HOME, VIRTKEY, CONTROL
"E", IDM_END, VIRTKEY, CONTROL
END
//----------------------------------------------------------------------
// String table
//
STRINGTABLE DISCARDABLE
BEGIN
IDS_DOITEXT, "IN CONGRESS, July 4, 1776.\012The unanimous Declaration of the thirteen united States of America,\012WHEN in the Course of human Events, it becomes necessary for one People to dissolve the Political Bands which have connected them with another, and to assume among the Powers of the Earth, the separate and equal Station to which the Laws of Nature and of Nature''s God entitle them, a decent Respect to the Opinions of Mankind requires that they should declare the causes which impel them to the Separation.\012WE hold these Truths to be self-evident, that all Men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the Pursuit of Happiness -- That to secure these Rights, Governments are instituted among Men, deriving their just Powers from the Consent of the Governed, that whenever any Form of Government becomes destructive of these Ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its Foundation on such Principles, and organizing its Powers in such Form, as to them shall seem most likely to effect their Safety and Happiness. Prudence, indeed, will dictate that Governments long established should not be changed for light and transient Causes; and accordingly all Experience hath shewn, that Mankind are more disposed to suffer, while Evils are sufferable, than to right themselves by abolishing the Forms to which they are accustomed. But when a long Train of Abuses and Usurpations, pursuing invariably the same Object, evinces a Design to reduce them under absolute Despotism, it is their Right, it is their Duty, to throw off such Government, and to provide new Guards for their future Security. Such has been the patient Sufferance of these Colonies; and such is now the Necessity which constrains them to alter their former Systems of Government. The History of the present King of Great Britain is a History of repeated Injuries and Usurpations, all having in direct Object the Establishment of an absolute Tyranny over these States. To prove this, let Facts be submitted to a candid World.\012HE has refused his Assent to Laws, the most wholesome and necessary for the public Good.\012HE has forbidden his Governors to pass Laws of immediate and pressing Importance, unless suspended in their Operation till his Assent should be obtained; and when so suspended, he has utterly neglected to attend to them.\012HE has refused to pass other Laws for the Accommodation of large Districts of People, unless those People would relinquish the Right of Representation in the Legislature, a Right inestimable to them, and formidable to Tyrants only.\012HE has called together Legislative Bodies at Places unusual, uncomfortable, and distant from the Depository of their public Records, for the sole Purpose of fatiguing them into Compliance with his Measures.\012HE has dissolved Representative Houses repeatedly, for opposing with manly Firmness his Invasions on the Rights of the People.\012HE has refused for a long Time, after such Dissolutions, to cause others to be elected; whereby the Legislative Powers, incapable of the Annihilation, have returned to the People at large for their exercise; the State remaining in the mean time exposed to all the Dangers of Invasion from without, and the Convulsions within.\012HE has endeavoured to prevent the Population of these States; for that Purpose obstructing the Laws for Naturalization of Foreigners; refusing to pass others to encourage their Migrations hither, and raising the Conditions of new Appropriations of Lands.\012HE has obstructed the Administration of Justice, by refusing his Assent to Laws for establishing Judiciary Powers.\012HE has made Judges dependent on his Will alone, for the Tenure of their Offices, and the Amount and Payment of their Salaries.\012"
IDS_DOITEXT1, "HE has erected a Multitude of new Offices, and sent hither Swarms of Officers to harrass our People, and eat out their Substance.\012HE has kept among us, in Times of Peace, Standing Armies, without the consent of our Legislatures.\012HE has affected to render the Military independent of and superior to the Civil Power.\012HE has combined with others to subject us to a Jurisdiction foreign to our Constitution, and unacknowledged by our Laws; giving his Assent to their Acts of pretended Legislation:\012FOR quartering large Bodies of Armed Troops among us;\012FOR protecting them, by a mock Trial, from Punishment for any Murders which they should commit on the Inhabitants of these States:\012FOR cutting off our Trade with all Parts of the World:\012FOR imposing Taxes on us without our Consent:\012FOR depriving us, in many Cases, of the Benefits of Trial by Jury:\012FOR transporting us beyond Seas to be tried for pretended Offences:\012FOR abolishing the free System of English Laws in a neighbouring Province, establishing therein an arbitrary Government, and enlarging its Boundaries, so as to render it at once an Example and fit Instrument for introducing the same absolute Rules into these Colonies:\012FOR taking away our Charters, abolishing our most valuable Laws, and altering fundamentally the Forms of our Governments:\012FOR suspending our own Legislatures, and declaring themselves invested with Power to legislate for us in all Cases whatsoever.\012HE has abdicated Government here, by declaring us out of his Protection and waging War against us.\012HE has plundered our Seas, ravaged our Coasts, burnt our Towns, and destroyed the Lives of our People.\012HE is, at this Time, transporting large Armies of foreign Mercenaries to compleat the Works of Death, Desolation, and Tyranny, already begun with circumstances of Cruelty and Perfidy, scarcely paralleled in the most barbarous Ages, and totally unworthy the Head of a civilized Nation.\012HE has constrained our fellow Citizens taken Captive on the high Seas to bear Arms against their Country, to become the Executioners of their Friends and Brethren, or to fall themselves by their Hands.\012HE has excited domestic Insurrections amongst us, and has endeavoured to bring on the Inhabitants of our Frontiers, the merciless Indian Savages, whose known Rule of Warfare, is an undistinguished Destruction, of all Ages, Sexes and Conditions.\012IN every stage of these Oppressions we have Petitioned for Redress in the most humble Terms: Our repeated Petitions have been answered only by repeated Injury. A Prince, whose Character is thus marked by every act which may define a Tyrant, is unfit to be the Ruler of a free People. NOR have we been wanting in Attentions to our Brittish Brethren. We have warned them from Time to Time of Attempts by their Legislature to extend an unwarrantable Jurisdiction over us. We have reminded them of the Circumstances of our Emigration and Settlement here. We have appealed to their native Justice and Magnanimity, and we have conjured them by the Ties of our common Kindred to disavow these Usurpations, which, would inevitably interrupt our Connections and Correspondence. They too have been deaf to the Voice of Justice and of Consanguinity. We must, therefore, acquiesce in the Necessity, which denounces our Separation, and hold them, as we hold the rest of Mankind, Enemies in War, in Peace, Friends.\012"
IDS_DOITEXT2, "WE, therefore, the Representatives of the UNITED STATES OF AMERICA, in GENERAL CONGRESS, Assembled, appealing to the Supreme Judge of the World for the Rectitude of our Intentions, do, in the Name, and by Authority of the good People of these Colonies, solemnly Publish and Declare, That these United Colonies are, and of Right ought to be, FREE AND INDEPENDENT STATES; that they are absolved from all Allegiance to the British Crown, and that all political Connection between them and the State of Great-Britain, is and ought to be totally dissolved; and that as FREE AND INDEPENDENT STATES, they have full Power to levy War, conclude Peace, contract Alliances, establish Commerce, and to do all other Acts and Things which INDEPENDENT STATES may of right do. And for the support of this Declaration, with a firm Reliance on the Protection of divine Providence, we mutually pledge to each other our Lives, our Fortunes, and our sacred Honor."
END
DOIView.h
//======================================================================
// Header file
//
// Written for the book Programming Windows CE
// Copyright (C) 2003 Douglas Boling
//================================================================
// Returns number of elements
#define dim(x) (sizeof(x) / sizeof(x[0]))
//----------------------------------------------------------------------
// Generic defines and data types
//
struct decodeUINT { // Structure associates
UINT Code; // messages
// with a function.
LRESULT (*Fxn)(HWND, UINT, WPARAM, LPARAM);
};
struct decodeCMD { // Structure associates
UINT Code; // menu IDs with a
LRESULT (*Fxn)(HWND, WORD, HWND, WORD); // function
};
#define ID_MENU 10
#define ID_ACCEL 11
#define IDM_HOME 100
#define IDM_END 101
#define IDM_EXIT 102
#define IDS_DOITEXT 1000 // These IDs must be
#define IDS_DOITEXT1 1001 // consecutive
#define IDS_DOITEXT2 1002
//----------------------------------------------------------------------
// Function prototypes
//
LPTSTR WrapString (HDC hdc, LPTSTR pszText, int *pnLen, int nWidth,
BOOL *fEOL);
HWND InitInstance (HINSTANCE, LPWSTR, int);
int TermInstance (HINSTANCE, int);
// Window procedures
LRESULT CALLBACK MainWndProc (HWND, UINT, WPARAM, LPARAM);
// Message handlers
LRESULT DoCreateMain (HWND, UINT, WPARAM, LPARAM);
LRESULT DoSizeMain (HWND, UINT, WPARAM, LPARAM);
LRESULT DoCommandMain (HWND, UINT, WPARAM, LPARAM);
LRESULT DoLButtonDownMain (HWND, UINT, WPARAM, LPARAM);
LRESULT DoRButtonUpMain (HWND, UINT, WPARAM, LPARAM);
LRESULT DoVScrollMain (HWND, UINT, WPARAM, LPARAM);
LRESULT DoPaintMain (HWND, UINT, WPARAM, LPARAM);
LRESULT DoDestroyMain (HWND, UINT, WPARAM, LPARAM);
// Command functions
LPARAM DoMainCommandHome (HWND, WORD, HWND, WORD);
LPARAM DoMainCommandEnd (HWND, WORD, HWND, WORD);
LPARAM DoMainCommandExit (HWND, WORD, HWND, WORD);
DOIView.cpp
//======================================================================
// DOIView - Demonstrates window scroll bars
//
// Written for the book Programming Windows CE
// Copyright (C) 2003 Douglas Boling
//======================================================================
#include <windows.h> // For all that Windows stuff
#include "DOIView.h" // Program-specific stuff
#include <aygshell.h> // Extended shell API
//----------------------------------------------------------------------
// Global data
//
const TCHAR szAppName[] = TEXT("DOIView");
HINSTANCE hInst; // Program instance handle
#define WM_MYMSG (WM_USER + 100)
// Message dispatch table for MainWindowProc
const struct decodeUINT MainMessages[] = {
WM_CREATE, DoCreateMain,
WM_SIZE, DoSizeMain,
WM_LBUTTONDOWN, DoLButtonDownMain,
WM_COMMAND, DoCommandMain,
WM_VSCROLL, DoVScrollMain,
WM_PAINT, DoPaintMain,
WM_DESTROY, DoDestroyMain,
};
// Command Message dispatch for MainWindowProc
const struct decodeCMD MainCommandItems[] = {
IDM_HOME, DoMainCommandHome,
IDM_END, DoMainCommandEnd,
IDM_EXIT, DoMainCommandExit,
};
typedef struct {
LPTSTR pszLine;
int nLen;
} LINEARRAY, *PLINEARRAY;
#define MAXLINES 1000
LINEARRAY laText[MAXLINES];
int nNumLines = 0;
int nFontHeight = 1;
int nLinesPerPage = 1;
LPTSTR pszDeclaration;
HFONT hFont;
int nVPos, nVMax;
BOOL fFirst = TRUE;
//======================================================================
// Program entry point
//
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPWSTR lpCmdLine, int nCmdShow) {
MSG msg;
int rc = 0;
HWND hwndMain;
HACCEL hAccel;
// Initialize this instance.
hwndMain = InitInstance (hInstance, lpCmdLine, nCmdShow);
if (hwndMain == 0) return 0x10;
// Load accelerator table.
hAccel = LoadAccelerators (hInst, MAKEINTRESOURCE (ID_ACCEL));
// Application message loop
while (GetMessage (&msg, NULL, 0, 0)) {
// Translate accelerators
if (!TranslateAccelerator (hwndMain, hAccel, &msg)) {
TranslateMessage (&msg);
DispatchMessage (&msg);
}
}
// Instance cleanup
return TermInstance (hInstance, msg.wParam);
}
//----------------------------------------------------------------------
// InitInstance - Instance initialization
//
HWND InitInstance (HINSTANCE hInstance, LPWSTR lpCmdLine, int nCmdShow) {
WNDCLASS wc;
HWND hWnd;
PBYTE pRes, pBuff;
int nStrLen = 0, i = 0;
// Save program instance handle in global variable.
hInst = hInstance;
#if defined(WIN32_PLATFORM_PSPC)
// If Pocket PC, only allow one instance of the application
hWnd = FindWindow (szAppName, NULL);
if (hWnd) {
SetForegroundWindow ((HWND)(((DWORD)hWnd) | 0x01));
return 0;
}
#endif
// Load text from multiple string resources into one large buffer
pBuff = (PBYTE)LocalAlloc (LPTR, 8);
while (pRes = (PBYTE)LoadString (hInst, IDS_DOITEXT + i++, NULL, 0))
{
// Get the length of the string resource
int nLen = *(PWORD)(pRes-2) * sizeof (TCHAR);
// Resize buffer
pBuff = (PBYTE)LocalReAlloc (pBuff, nStrLen + 8 + nLen,
LMEM_MOVEABLE | LMEM_ZEROINIT);
if (pBuff == NULL) return 0;
// Copy resource into buffer
memcpy (pBuff + nStrLen, pRes, nLen);
nStrLen += nLen;
}
*(TCHAR *)(pBuff + nStrLen) = TEXT (''\0'');
pszDeclaration = (LPTSTR)pBuff;
// Register application main window class.
wc.style = 0; // Window style
wc.lpfnWndProc = MainWndProc; // Callback function
wc.cbClsExtra = 0; // Extra class data
wc.cbWndExtra = 0; // Extra window data
wc.hInstance = hInstance; // Owner handle
wc.hIcon = NULL, // Application icon
wc.hCursor = LoadCursor (NULL, IDC_ARROW);// Default cursor
wc.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wc.lpszMenuName = NULL; // Menu name
wc.lpszClassName = szAppName; // Window class name
if (RegisterClass (&wc) == 0) return 0;
// Create main window.
hWnd = CreateWindowEx (WS_EX_NODRAG, szAppName,
TEXT("The Declaration of Independence"),
WS_VSCROLL | WS_VISIBLE | WS_CAPTION |
WS_SYSMENU, CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT, NULL,
NULL, hInstance, NULL);
if (!IsWindow (hWnd)) return 0; // Fail code if not created.
// Standard show and update calls
ShowWindow (hWnd, nCmdShow);
UpdateWindow (hWnd);
return hWnd;
}
//----------------------------------------------------------------------
// TermInstance - Program cleanup
//
int TermInstance (HINSTANCE hInstance, int nDefRC) {
LocalFree (pszDeclaration);
return nDefRC;
}
//======================================================================
// Message handling procedures for main window
//
//----------------------------------------------------------------------
// MainWndProc - Callback function for application window
//
LRESULT CALLBACK MainWndProc (HWND hWnd, UINT wMsg, WPARAM wParam,
LPARAM lParam) {
int i;
//
// Search message list to see if we need to handle this
// message. If in list, call procedure.
//
for (i = 0; i < dim(MainMessages); i++) {
if (wMsg == MainMessages[i].Code)
return (*MainMessages[i].Fxn)(hWnd, wMsg, wParam, lParam);
}
return DefWindowProc (hWnd, wMsg, wParam, lParam);
}
//----------------------------------------------------------------------
// DoCreateMain - Process WM_CREATE message for window.
//
LRESULT DoCreateMain (HWND hWnd, UINT wMsg, WPARAM wParam,
LPARAM lParam) {
TEXTMETRIC tm;
HDC hdc = GetDC (hWnd);
LOGFONT lf;
HFONT hFontWnd;
hFontWnd = (HFONT)GetStockObject (SYSTEM_FONT);
GetObject (hFontWnd, sizeof (LOGFONT), &lf);
lf.lfHeight = -12 * GetDeviceCaps(hdc, LOGPIXELSY)/ 72;
lf.lfWeight = 0;
hFont = CreateFontIndirect (&lf);
SendMessage (hWnd, WM_SETFONT, (WPARAM)hFont, 0);
// Get the height of the default font.
hFontWnd = (HFONT)SelectObject (hdc, hFont);
GetTextMetrics (hdc, &tm);
nFontHeight = tm.tmHeight + tm.tmExternalLeading;
SelectObject (hdc, hFontWnd);
ReleaseDC (hWnd, hdc);
return 0;
}
//----------------------------------------------------------------------
// DoSizeMain - Process WM_SIZE message for window.
//
LRESULT DoSizeMain (HWND hWnd, UINT wMsg, WPARAM wParam,
LPARAM lParam) {
RECT rect;
HDC hdc = GetDC (hWnd);
GetClientRect (hWnd, &rect);
int i = 0, nChars, nWidth;
LPTSTR pszWndText = pszDeclaration;
SCROLLINFO si;
HFONT hFontWnd;
BOOL fNewLine;
hFontWnd = (HFONT)SelectObject (hdc, hFont);
// Compute the line breaks
nWidth = rect.right - rect.left - 10;
while (i < MAXLINES){
pszWndText = WrapString (hdc, pszWndText, &nChars, nWidth,
&fNewLine);
if (pszWndText == 0)
break;
laText[i].pszLine = pszWndText;
laText[i].nLen = nChars;
i++;
if (fNewLine) {
laText[i].nLen = 0;
i++;
}
pszWndText += nChars;
}
nNumLines = i;
nLinesPerPage = (rect.bottom - rect.top)/nFontHeight;
// Compute lines per window and total lenght
si.cbSize = sizeof (si);
si.nMin = 0;
si.nMax = nNumLines;
si.nPage = nLinesPerPage;
si.nPos = nVPos;
si.fMask = SIF_ALL;
SetScrollInfo (hWnd, SB_VERT, &si, TRUE);
// Clean up
SelectObject (hdc, hFontWnd);
ReleaseDC (hWnd, hdc);
InvalidateRect (hWnd, NULL, TRUE);
return 0;
}
//----------------------------------------------------------------------
// DoCommandMain - Process WM_COMMAND message for window.
//
//
LRESULT DoCommandMain (HWND hWnd, UINT wMsg, WPARAM wParam,
LPARAM lParam) {
WORD idItem, wNotifyCode;
HWND hwndCtl;
int i;
// Parse the parameters.
idItem = (WORD) LOWORD (wParam);
wNotifyCode = (WORD) HIWORD(wParam);
hwndCtl = (HWND) lParam;
// Call routine to handle control message.
for (i = 0; i < dim(MainCommandItems); i++) {
if (idItem == MainCommandItems[i].Code)
return (*MainCommandItems[i].Fxn)(hWnd, idItem, hwndCtl,
wNotifyCode);
}
return 0;
}
//----------------------------------------------------------------------
// DoLButtonDownMain - Process WM_LBUTTONDOWN message for window.
//
LRESULT DoLButtonDownMain (HWND hWnd, UINT wMsg, WPARAM wParam,
LPARAM lParam) {
HMENU hMenuMain, hMenu;
POINT pt;
int rc;
// Display the menu at the point of the tap
pt.x = LOWORD (lParam);
pt.y = HIWORD (lParam);
SHRGINFO sri;
sri.cbSize = sizeof (sri);
sri.dwFlags = 1;
sri.hwndClient = hWnd;
sri.ptDown = pt;
// See if tap and hold
rc = SHRecognizeGesture (&sri);
if (rc == 0) return 0;
// Display the menu at the point of the tap
// First, convert to desktop coordinates
MapWindowPoints (hWnd, HWND_DESKTOP, &pt, 1);
pt.x += 5;
hMenuMain = LoadMenu (hInst, MAKEINTRESOURCE (ID_MENU));
hMenu = GetSubMenu (hMenuMain, 0);
TPMPARAMS tpm;
tpm.cbSize = sizeof (tpm);
GetClientRect (hWnd, &tpm.rcExclude);
TrackPopupMenuEx (hMenu, TPM_LEFTALIGN | TPM_TOPALIGN,
pt.x, pt.y, hWnd, &tpm);
DestroyMenu (hMenuMain);
DestroyMenu (hMenu);
return 0;
}
//----------------------------------------------------------------------
// DoVScrollMain - Process WM_VSCROLL message for window.
//
LRESULT DoVScrollMain (HWND hWnd, UINT wMsg, WPARAM wParam,
LPARAM lParam) {
RECT rect;
SCROLLINFO si;
int sOldPos = nVPos;
GetClientRect (hWnd, &rect);
switch (LOWORD (wParam)) {
case SB_LINEUP:
nVPos -= 1;
break;
case SB_LINEDOWN:
nVPos += 1;
break;
case SB_PAGEUP:
nVPos -= nLinesPerPage;
break;
case SB_PAGEDOWN:
nVPos += nLinesPerPage;
break;
case SB_THUMBTRACK:
case SB_THUMBPOSITION:
nVPos = HIWORD (wParam);
break;
}
// Check range.
if (nVPos < 0)
nVPos = 0;
if (nVPos > nNumLines-1)
nVPos = nNumLines-1;
// If scroll position changed, update scrollbar and
// force redraw of window.
if (nVPos != sOldPos) {
si.cbSize = sizeof (si);
si.nPos = nVPos;
si.fMask = SIF_POS;
SetScrollInfo (hWnd, SB_VERT, &si, TRUE);
InvalidateRect (hWnd, NULL, TRUE);
}
return 0;
}
//----------------------------------------------------------------------
// DoPaintMain - Process WM_PAINT message for window.
//
LRESULT DoPaintMain (HWND hWnd, UINT wMsg, WPARAM wParam,
LPARAM lParam) {
PAINTSTRUCT ps;
HFONT hFontWnd;
RECT rect;
HDC hdc;
int i, y = 5;
hdc = BeginPaint (hWnd, &ps);
GetClientRect (hWnd, &rect);
hFontWnd = (HFONT)SelectObject (hdc, hFont);
// Draw the text
for (i = nVPos; i < nNumLines; i++) {
if (y > rect.bottom - nFontHeight - 10)
break;
if (laText[i].nLen)
ExtTextOut (hdc, 5, y, TRANSPARENT, NULL, laText[i].pszLine,
laText[i].nLen, NULL);
y += nFontHeight;
}
SelectObject (hdc, hFontWnd);
EndPaint (hWnd, &ps);
return 0;
}
//----------------------------------------------------------------------
// DoDestroyMain - Process WM_DESTROY message for window.
//
LRESULT DoDestroyMain (HWND hWnd, UINT wMsg, WPARAM wParam,
LPARAM lParam) {
PostQuitMessage (0);
return 0;
}
//======================================================================
// Command handler routines
//
//----------------------------------------------------------------------
// DoMainCommandHome - Process Program Home command.
//
LPARAM DoMainCommandHome (HWND hWnd, WORD idItem, HWND hwndCtl,
WORD wNotifyCode) {
SCROLLINFO si;
if (nVPos != 0) {
nVPos = 0;
si.cbSize = sizeof (si);
si.nPos = nVPos;
si.fMask = SIF_POS;
SetScrollInfo (hWnd, SB_VERT, &si, TRUE);
InvalidateRect (hWnd, NULL, TRUE);
}
return 0;
}
//----------------------------------------------------------------------
// DoMainCommandEnd - Process End command.
//
LPARAM DoMainCommandEnd (HWND hWnd, WORD idItem, HWND hwndCtl,
WORD wNotifyCode) {
SCROLLINFO si;
int nEndPos = nNumLines - nLinesPerPage + 1;
if (nVPos != nEndPos) {
nVPos = nEndPos;
si.cbSize = sizeof (si);
si.nPos = nVPos;
si.fMask = SIF_POS;
SetScrollInfo (hWnd, SB_VERT, &si, TRUE);
InvalidateRect (hWnd, NULL, TRUE);
}
return 0;
}
//----------------------------------------------------------------------
// DoMainCommandExit - Process Program Exit command.
//
LPARAM DoMainCommandExit (HWND hWnd, WORD idItem, HWND hwndCtl,
WORD wNotifyCode) {
SendMessage (hWnd, WM_CLOSE, 0, 0);
return 0;
}
//----------------------------------------------------------------------
// WrapString - Determine a length that will fit with a width
//
LPTSTR WrapString (HDC hdc, LPTSTR pszText, int *pnLen, int nWidth,
BOOL *fEOL) {
LPTSTR pszStr, pszStart;
SIZE Size;
*fEOL = FALSE;
*pnLen = 0;
// Skip to first non-space char
for (; (*pszText!=TEXT(''\0'')) && (*pszText<=TEXT ('' '')); pszText++);
pszStart = pszText;
if (*pszText == 0)
return 0;
while (1) {
pszStr = pszText;
// Find end of the next word
for (; (*pszText!=TEXT(''\0'')) && *pszText>TEXT ('' '');pszText++);
// Get length of the string
GetTextExtentPoint (hdc, pszStart, pszText - pszStart, &Size);
if (Size.cx > nWidth)
break;
if ((*pszText == TEXT (''\0'')) || (*pszText == TEXT (''\r'')) ||
(*pszText == TEXT (''\n''))) {
*fEOL = TRUE;
pszStr = pszText;
break;
}
// slip past space
pszText++;
}
*pnLen = pszStr - pszStart;
return pszStart;
}
When the program is launched, it reads the string resources into one large buffer. To reduce the memory impact, the string resources are accessed by passing a NULL buffer pointer to the LoadString function. That causes LoadString to return a pointer to the resource in its return value. Note that these strings aren''t zero delimited in this case, so DOIView reads the word before the string to get the number of characters. Because the strings are Unicode, the string length is then multiplied by the size of TCHAR to get the size of the buffer needed for the string.
The main window of DOIView handles a few extra messages. The WM_SIZE handler reformats the text by calling WrapString. This routine measures the length of each line by calling GetTextExtentPoint. If the length is less than the width of the window, the routine then adds another word to the line and remeasures. This continues until the proper number of words is added to the line to fit within the window. The WM_PAINT handler draws the lines of text starting with the top line to be displayed, defined by the current scroll position.
The WM_VSCROLL routine handles the messages from the vertical scroll bar. When the notification is a SB_PAGEUP or SB_PAGEDOWN, the routine subtracts or adds the number of lines displayed in the window to the current scroll position. The WM_LBUTTONDOWN handler loads a menu from a menu resource. The menu has three commands: Home, to scroll to the top of the document; End, to scroll to the bottom; and Exit, which quits the program. DOIView also responds to accelerator keys: Ctrl-H for Home and Ctrl-E for End.
This chapter has covered a huge amount of ground, from basic child windows to controls and on to resources and menus. My goal wasn''t to teach everything there is to know about these topics. Instead, I''ve tried to introduce these program elements, provide a few examples, and point out the subtle differences between the way they''re handled by Windows CE and the desktop versions of Windows.
Although the Windows controls are useful and quite handy, the next chapter covers the common controls. These controls are a far more powerful, and more complex, set of controls, which Windows CE also supports.
