枚举颜色

通过检索设备的颜色计数并枚举纯色笔的颜色，可以确定设备支持的颜色数量和这些颜色。 若要检索颜色数，请使用具有 NUMCOLORS 值的 GetDeviceCaps 函数。 若要枚举实心笔，请使用 EnumObjects 函数和接收每个笔相关信息的相应回调函数。

// GetTheColors - returns the count and color values of solid colors 
// Returns a pointer to the array containing colors 
// hdc - handle to device context 

COLORREF *GetTheColors(HDC hdc)
{
    int cColors;
    COLORREF *aColors;

    // Get the number of colors. 
    cColors = GetDeviceCaps(hdc, NUMCOLORS);

    // Allocate space for the array. 
    aColors = (COLORREF *)LocalAlloc(LPTR, sizeof(COLORREF) * 
        (cColors+1));

    // Save the count of colors in first element. 
    aColors[0] = (LONG)cColors;

    // Enumerate all pens and save solid colors in the array. 
    EnumObjects(hdc, OBJ_PEN, (GOBJENUMPROC)MyEnumProc, (LONG)aColors);

    // Refresh the count of colors. 
    aColors[0] = (LONG)cColors;

    return aColors;
}

int MyEnumProc(LPVOID lp, LPBYTE lpb)
{
    LPLOGPEN lopn;
    COLORREF *aColors;
    int iColor;

    lopn = (LPLOGPEN)lp;
    aColors = (COLORREF *)lpb;

    if (lopn->lopnStyle==PS_SOLID) 
    {
        // Check for too many colors. 
        if ((iColor = (int)aColors[0]) <= 0)
             return 0;
        aColors[iColor] = lopn->lopnColor;
        aColors[0]--;
    }
    return 1;
}