本節討論下列主題。
建立游標
下列範例會建立兩個游標句柄：一個用於標準沙漏游標，另一個用於應用程式資源定義文件中作為資源所包含的自定義游標。
HCURSOR hCurs1 = LoadCursor(NULL, IDC_WAIT);
HCURSOR hCurs2 = LoadCursor(hInstance, MAKEINTRESOURCE(IDC_MYICON));
應用程式應實作自定義數據指標作為資源，並使用 LoadCursor、LoadCursorFromFile或 LoadImage，而不是在運行時間建立數據指標。 使用數據指標資源可避免裝置依賴、簡化當地語系化，並讓應用程式共用數據指標設計。
下列範例會使用 CreateCursor 函式，在執行時建立自定義單色游標。 此處包含範例，以說明系統如何解譯游標遮罩。
游標映射中的每個像素由單一字元表示：
| Symbol | AND 位元 | XOR 位元 | 顯示 |
|---|---|---|---|
|
1 | 0 | Transparent |
X |
1 | 1 | 倒置螢幕 |
o |
0 | 1 | 白 |
+ |
0 | 0 | 黑 |
#define CURSOR_SIZE 32
// Symbol encoding: ' '=transparent 'o'=white '+'=black
static const char *const yin_cursor[CURSOR_SIZE] = {
" ++++ ",
" ++++oooo+ ",
" ++oooooo++ ",
" +ooooooo+ ",
" +oooooooo+ ",
" +oooooooo+ ",
" +oooooooo+ ",
" +oooooooo+ ",
" +ooooooooo+ ",
" +oooooooo+ ",
" +ooooooooo+ ",
" +ooooooooo+ ",
" +oooooooooo+ ",
"+ooooooooooo+ ",
"+oooooooooooo+ ",
"+ooooooooooooo++ ",
"+ooooooooooooooo+ ",
"+oooooooooooooooo++ ",
"+oooooooooooooooooo+ ",
" +ooooooooooooooooo+ ",
" +oooooooo+++ooooooo+ ",
" +ooooooo+++++oooooo+ ",
" +oooooo+++++oooooo+ ",
" +oooooo+++++ooooo+ ",
" +oooooo+++oooooo+ ",
" +ooooooooooooo+ ",
" +ooooooooooooo+ ",
" ++oooooooooo+ ",
" +oooooooo+ ",
" ++oooo++ ",
" ++++ ",
" ",
};
// Pack an XPM-style cursor map into separate 1bpp AND and XOR bit planes.
// Output buffers must be sized: ((w + 15) / 16) * 2 * h bytes.
static void PackCursorMasks(const char *const rows[], int w, int h,
BYTE *pbAnd, BYTE *pbXor)
{
int stride = ((w + 15) / 16) * 2; // WORD-aligned row stride, per CreateCursor contract
ZeroMemory(pbAnd, stride * h);
ZeroMemory(pbXor, stride * h);
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
BYTE bit = (BYTE)(0x80 >> (x % 8));
int idx = y * stride + x / 8;
char sym = rows[y][x];
if (sym == ' ' || sym == 'X') pbAnd[idx] |= bit;
if (sym == 'o' || sym == 'X') pbXor[idx] |= bit;
}
}
}
// Row stride for a 32-pixel-wide 1bpp mask: ((32 + 15) / 16) * 2 = 4 bytes.
BYTE abAnd[CURSOR_SIZE * 4];
BYTE abXor[CURSOR_SIZE * 4];
PackCursorMasks(yin_cursor, CURSOR_SIZE, CURSOR_SIZE, abAnd, abXor);
// hInstance is the application's HINSTANCE from WinMain.
// Call DestroyCursor when the cursor is no longer needed.
HCURSOR hCurs3 = CreateCursor(
hInstance, // application instance
19, // hot spot x
2, // hot spot y
CURSOR_SIZE,
CURSOR_SIZE,
abAnd,
abXor);
如需詳細資訊，請參閱 位陣圖。
使用游標函數創建捕鼠器
以下範例使用 SetCursorPos、 GetCursorPos、 CreateCursor、 CreateIcon、 SetCursor 和 DrawIconEx 函式來建立一個簡單的捕鼠器。 視窗中央繪有一個陽形圖示。 如果游標3秒內未移動，會跳到陽圖示並變為陰型。 移動滑鼠會重置陷阱。
// PackCursorMasks, yin_cursor, and CURSOR_SIZE are defined in the preceding example.
#define ICON_SIZE 32
#define YIN_HOT_X 19
#define YIN_HOT_Y 2
#define IDT_CURSOR 1
#define TRAP_DELAY 3000 // ms of inactivity before the cursor snaps to the icon
// Symbol encoding: ' '=transparent 'o'=white '+'=black
static const char *const yang_icon[ICON_SIZE] = {
" ",
" ++++ ",
" ++++++++ ",
" ++++++++++ ",
" +++++++++++++ ",
" +++++++++++++++ ",
" +++++++++++++++ ",
" ++++++ooo++++++++ ",
" +++++ooooo++++++++ ",
" ++++++ooooo++++++++ ",
" ++++++ooooo+++++++++ ",
" +++++++ooo++++++++++ ",
" +++++++++++++++++++ ",
" ++++++++++++++++++++",
" +++++++++++++++++++",
" ++++++++++++++++++",
" ++++++++++++++++",
" +++++++++++++++",
" +++++++++++++",
" ++++++++++++ ",
" +++++++++++ ",
" +++++++++++ ",
" ++++++++++ ",
" +++++++++++ ",
" ++++++++++ ",
" ++++++++++ ",
" ++++++++++ ",
" ++++++++++ ",
" +++++++++ ",
" ++++++++++ ",
" +++++++++ ",
" ++++ ",
};
static HICON hYang;
static HCURSOR hYin;
static POINT ptLast;
static BOOL bTrapped;
LRESULT CALLBACK MainWndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg)
{
case WM_CREATE:
{
HINSTANCE hInstance = ((LPCREATESTRUCT)lParam)->hInstance;
BYTE abAndIcon[ICON_SIZE * 4];
BYTE abXorIcon[ICON_SIZE * 4];
PackCursorMasks(yang_icon, ICON_SIZE, ICON_SIZE, abAndIcon, abXorIcon);
hYang = CreateIcon(hInstance, ICON_SIZE, ICON_SIZE, 1, 1,
abAndIcon, abXorIcon);
BYTE abAndCursor[CURSOR_SIZE * 4];
BYTE abXorCursor[CURSOR_SIZE * 4];
PackCursorMasks(yin_cursor, CURSOR_SIZE, CURSOR_SIZE, abAndCursor, abXorCursor);
hYin = CreateCursor(hInstance, YIN_HOT_X, YIN_HOT_Y, CURSOR_SIZE, CURSOR_SIZE,
abAndCursor, abXorCursor);
GetCursorPos(&ptLast);
SetTimer(hWnd, IDT_CURSOR, TRAP_DELAY, (TIMERPROC)NULL);
return 0;
}
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hDC = BeginPaint(hWnd, &ps);
RECT rc;
GetClientRect(hWnd, &rc);
DrawIconEx(hDC,
(rc.right - ICON_SIZE) / 2,
(rc.bottom - ICON_SIZE) / 2,
hYang, ICON_SIZE, ICON_SIZE, 0, NULL, DI_NORMAL);
EndPaint(hWnd, &ps);
return 0;
}
case WM_MOUSEMOVE:
{
POINT ptNow;
GetCursorPos(&ptNow);
if (ptNow.x != ptLast.x || ptNow.y != ptLast.y)
{
ptLast = ptNow;
bTrapped = FALSE;
SetTimer(hWnd, IDT_CURSOR, TRAP_DELAY, (TIMERPROC)NULL);
}
break;
}
case WM_TIMER:
{
POINT ptNow;
GetCursorPos(&ptNow);
if (ptNow.x == ptLast.x && ptNow.y == ptLast.y)
{
RECT rc;
GetClientRect(hWnd, &rc);
POINT ptTarget = {
(rc.right - ICON_SIZE) / 2 + YIN_HOT_X,
(rc.bottom - ICON_SIZE) / 2 + YIN_HOT_Y
};
ClientToScreen(hWnd, &ptTarget);
SetCursorPos(ptTarget.x, ptTarget.y);
// Ignore the mouse-move notification generated by this repositioning.
GetCursorPos(&ptLast);
SetCursor(hYin);
bTrapped = TRUE;
KillTimer(hWnd, IDT_CURSOR);
}
else
{
// Movement outside this window does not generate WM_MOUSEMOVE here.
ptLast = ptNow;
}
return 0;
}
case WM_SETCURSOR:
if (bTrapped)
{
SetCursor(hYin);
return TRUE;
}
break;
case WM_DESTROY:
KillTimer(hWnd, IDT_CURSOR);
DestroyCursor(hYin);
DestroyIcon(hYang);
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hWnd, uMsg, wParam, lParam);
}
建立Alpha混合游標
請遵循下列步驟，在運行時間建立 Alpha 混合游標或圖示：
- 填寫一個用於由上而下 DIB 的 BITMAPINFOHEADER（
biBitCount=32、biCompression=BI_RGB、biHeight為負值），並呼叫 CreateDIBSection 以取得彩色點陣圖。 重複使用相同的標頭，並搭配biBitCount=1來建立 1bpp AND 遮罩。 - 將游標影像繪入彩色 DIB 區段，並設定每個像素的 alpha 位元組。
- 填入 AND 遮罩：在
alpha > 0的位置，將每個位元設為 0（不透明）；在alpha == 0的位置，將其設為 1（透明）。 - 將 DIB 區段填入 ICONINFO
hbmColor結構，將 AND 遮罩填入hbmMask。 - 呼叫 CreateIconIndirect 來建立游標或圖示。
下列程式代碼示範如何建立Alpha混合游標。
DrawRGBCircles 直接寫入三個重疊的 R/G/B 半透明圓圈到像素緩衝區：它會用 AC_SRC_OVER 公式解析合成這些圓圈，並儲存預先乘法的 RGB 通道，alpha 為 rgbReserved。 游標大小是從 GetSystemMetrics 讀取，以匹配系統游標大小設定。 改 fIcon 成 來 TRUE 建立圖示。
#define WIDTHBYTES(bits) ((DWORD)(((bits) + 31) & ~31) / 8)
// Fill pixels (top-down, cx-cy) with three overlapping R/G/B circles, each alpha=128.
// Composites with AC_SRC_OVER and preserves premultiplied RGB channels.
static void DrawRGBCircles(RGBQUAD *pixels, int cx, int cy)
{
// r = cx/3: each center is r px from its nearest edge, so the circle touches exactly.
const int r = cx / 3;
struct { int x, y; RGBQUAD color; } circles[3] = {
// B G R A
{ cx / 2, r, { 0, 0, 255, 128 } }, // red, top-center
{ r, cy - r, { 0, 255, 0, 128 } }, // green, bottom-left
{ cx - r, cy - r, {255, 0, 0, 128 } }, // blue, bottom-right
};
for (int y = 0; y < cy; y++) {
for (int x = 0; x < cx; x++) {
DWORD R = 0, G = 0, B = 0, A = 0;
for (int i = 0; i < 3; i++) {
int dx = x - circles[i].x, dy = y - circles[i].y;
if (dx*dx + dy*dy > r*r) continue;
DWORD a = circles[i].color.rgbReserved, inv = 255 - a;
// AC_SRC_OVER (premultiplied): dst = src + dst * (1 - src_a/255)
R = circles[i].color.rgbRed * a / 255 + R * inv / 255;
G = circles[i].color.rgbGreen * a / 255 + G * inv / 255;
B = circles[i].color.rgbBlue * a / 255 + B * inv / 255;
A = a + A * inv / 255;
}
RGBQUAD *p = &pixels[y * cx + x];
p->rgbReserved = (BYTE)A;
p->rgbRed = (BYTE)R;
p->rgbGreen = (BYTE)G;
p->rgbBlue = (BYTE)B;
}
}
}
HCURSOR CreateAlphaCursor(void)
{
int cx = GetSystemMetrics(SM_CXCURSOR);
int cy = GetSystemMetrics(SM_CYCURSOR);
// Extra RGBQUAD at the end for the 1bpp colour table (index 1 = white).
BYTE bmiBuffer[sizeof(BITMAPINFO) + sizeof(RGBQUAD)] = {0};
BITMAPINFO *pBmi = (BITMAPINFO *)bmiBuffer;
pBmi->bmiHeader.biSize = sizeof(pBmi->bmiHeader);
pBmi->bmiHeader.biWidth = cx;
pBmi->bmiHeader.biHeight = -cy; // negative = top-down
pBmi->bmiHeader.biPlanes = 1;
pBmi->bmiHeader.biCompression = BI_RGB;
// Create a top-down 32bpp DIB section for the color (XOR) image.
pBmi->bmiHeader.biBitCount = 32;
RGBQUAD *lpBits;
HBITMAP hBitmap = CreateDIBSection(NULL, pBmi, DIB_RGB_COLORS, (void **)&lpBits, NULL, 0);
DrawRGBCircles(lpBits, cx, cy);
// Reuse the same header for the 1bpp AND mask; switch biBitCount and set the colour table.
pBmi->bmiHeader.biBitCount = 1;
pBmi->bmiColors[0].rgbRed = pBmi->bmiColors[0].rgbGreen = pBmi->bmiColors[0].rgbBlue = 0;
pBmi->bmiColors[1].rgbRed = pBmi->bmiColors[1].rgbGreen = pBmi->bmiColors[1].rgbBlue = 255;
BYTE *andBits;
HBITMAP hMaskBitmap = CreateDIBSection(NULL, pBmi, DIB_RGB_COLORS, (void **)&andBits, NULL, 0);
// Set AND mask: bit=1 (transparent) wherever no circle was drawn.
int maskStride = WIDTHBYTES(cx * 1);
for (int y = 0; y < cy; y++) {
for (int x = 0; x < cx; x++) {
if (lpBits[y * cx + x].rgbReserved == 0)
andBits[y * maskStride + x / 8] |= (BYTE)(0x80 >> (x % 8));
}
}
ICONINFO ii = {0};
ii.fIcon = FALSE;
ii.xHotspot = cx / 2;
ii.yHotspot = cy / 2;
ii.hbmMask = hMaskBitmap;
ii.hbmColor = hBitmap;
HCURSOR hCursor = (HCURSOR)CreateIconIndirect(&ii);
DeleteObject(hBitmap);
DeleteObject(hMaskBitmap);
return hCursor;
}
在關閉之前，您必須使用 DestroyCursor 函式來銷毀您使用 CreateCursor 或 CreateIconIndirect所建立的任意游標。 不需要刪除其他函式所建立的游標。
取得游標大小
以下範例從游標的握把取得游標或圖示的尺寸：
BOOL GetCursorDimensions(_In_ HCURSOR hcur, _Out_ SIZE *psiz)
{
ICONINFO ii;
BOOL fResult = GetIconInfo(hcur, &ii);
if (fResult) {
BITMAP bm;
fResult = GetObject(ii.hbmMask, sizeof(bm), &bm) == sizeof(bm);
if (fResult) {
psiz->cx = bm.bmWidth;
psiz->cy = ii.hbmColor ? bm.bmHeight : bm.bmHeight / 2;
}
DeleteObject(ii.hbmMask);
if (ii.hbmColor) DeleteObject(ii.hbmColor);
}
return fResult;
}
顯示游標
系統會自動顯示類別游標（該游標與游標指向的視窗相關聯）。 您可以在註冊視窗類別時指派類別游標。 藉由將游標句柄指派給由 wc 參數所識別的 WNDCLASS 結構的 hCursor 成員，下列範例說明了這一點。
WNDCLASS wc = {0};
wc.lpfnWndProc = MainWndProc;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wc.hCursor = LoadCursor(hInstance, MAKEINTRESOURCE(IDC_MYICON));
wc.hbrBackground = GetStockObject(WHITE_BRUSH);
wc.lpszMenuName = TEXT("GenericMenu");
wc.lpszClassName = TEXT("GenericWClass");
return RegisterClass(&wc);
當視窗類別被註冊時，應用程式資源定義檔案中所識別的 IDC_MYICON 游標即為所有視窗的預設游標。
您的應用程式可以使用 SetCursor 函式，並指定不同的游標句柄，來變更游標的設計。 然而，當游標移動時，系統會在新的位置重繪類別游標。 若要防止類別游標被重新繪製，您必須處理 WM_SETCURSOR 訊息。 每次未擷取游標移動和滑鼠輸入時，系統都會將此訊息傳送至游標移動所在的視窗。
處理 WM_SETCURSOR時，您可以針對不同情況指定不同的游標。 檢查 LOWORD(lParam)，以區分用戶端區域與非用戶端區域（例如調整大小控點）；將非用戶端點擊傳遞給 DefWindowProc，讓系統在該處設定適當的系統游標。
case WM_SETCURSOR:
if (LOWORD(lParam) == HTCLIENT)
{
SetCursor(hCurs3);
return TRUE;
}
return DefWindowProc(hWnd, uMsg, wParam, lParam);
回傳 TRUE 會阻止 DefWindowProc 將游標重設到職業游標。 將非客戶端的點擊傳給 DefWindowProc 會保留系統的調整大小與移動游標。
你可以用 SetClassLongPtr 函式替換類別游標。 此函式會變更指定類別之所有視窗的預設窗口設定。 下列範例會將現有的類別游標替換為 hCurs2 游標。
SetClassLongPtr(hWnd, GCLP_HCURSOR, (LONG_PTR)hCurs2);
限制游標
下列範例會將游標限制在應用程式的視窗，然後將游標還原至其上一個視窗。 此範例會使用 GetClipCursor 函式來記錄游標可以移動的區域，以及 ClipCursor 函式來限制和還原游標。
RECT rcOldClip;
GetClipCursor(&rcOldClip);
RECT rcClip;
GetWindowRect(hWnd, &rcClip);
ClipCursor(&rcClip);
// ... process input from the confined cursor ...
ClipCursor(&rcOldClip);
因為系統中一次只有一個游標可用，因此限制游標的應用程式必須先恢復游標，再將控制權轉交給另一個視窗。
使用鍵盤移動游標
由於系統不需要滑鼠，因此應用程式應該能夠使用鍵盤模擬滑鼠動作。 下列範例示範如何使用 GetCursorPos 和 SetCursorPos 函式，以及處理箭頭鍵的輸入，來達成此目的。
static int nRepeat = 1;
switch (uMsg)
{
case WM_KEYDOWN:
{
int dx = 0, dy = 0;
switch (wParam)
{
case VK_LEFT: dx = -nRepeat; break;
case VK_RIGHT: dx = +nRepeat; break;
case VK_UP: dy = -nRepeat; break;
case VK_DOWN: dy = +nRepeat; break;
default: return DefWindowProc(hWnd, uMsg, wParam, lParam);
}
POINT pt;
GetCursorPos(&pt);
ScreenToClient(hWnd, &pt);
pt.x += dx;
pt.y += dy;
RECT rc;
GetClientRect(hWnd, &rc);
if (pt.x < rc.left) pt.x = rc.left;
else if (pt.x >= rc.right) pt.x = rc.right - 1;
if (pt.y < rc.top) pt.y = rc.top;
else if (pt.y >= rc.bottom) pt.y = rc.bottom - 1;
ClientToScreen(hWnd, &pt);
SetCursorPos(pt.x, pt.y);
if (nRepeat < 32) nRepeat++;
return 0;
}
case WM_KEYUP:
nRepeat = 1;
return 0;
}