【C#】設定/查詢螢幕背光

　　為了要能用C#控制螢幕背光，跟CreateFile與DeviceIoControl函數奮戰大半天，一直搞不定DeviceIoControl函數使用，後來幸運的在網路上找到有人寫好class可以直接調用，之後有需要用到DeviceIoControl函數功能也能參考這class的做法。

調用方法很簡單：

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LCDBrightness lcd = new LCDBrightness(); lcd.SetBrightness(100); // Set backlight full on LCDBrightness.Brightness value = lcd.GetBrightness(); // Query backlight value

原始class內容為：

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using Microsoft.VisualBasic; using System; using System.Collections; using System.Data; using System.Diagnostics; using System.Drawing; using System.Windows.Forms; using System.Runtime.InteropServices; /// <summary> /// Permet de contrA’ler la luminositAc de l'Accran LCD (sous Windows XP SP2 et ultAcrieur) /// </summary> /// <remarks>Sous rAcserve que le driver de la carte graphique et/ou de l'Accran supporte cette interface</remarks> namespace LCDBrightness { public class LCDBrightness { //Ouvre un fichier ou un pAcriphAcrique [DllImport("kernel32")] private static extern IntPtr CreateFile ( string lpFileName, uint dwDesiredAccess, int dwShareMode, IntPtr lpSecurityAttributes, int dwCreationDisposition, int dwFlagsAndAttributes, IntPtr hTemplateFile); //accA‥s en lecture, partagAc et ouverture uniquement d'un pAcriphAcrique existant private const uint GENERIC_READ = 0x80000000U; private const int SHARE_ALL = 0x7; private const int OPEN_EXISTING = 0x3; //indique l'Acclairage en mode d'alimentation AC ou DC ou les deux private const int DISPLAYPOLICY_AC = 1; private const int DISPLAYPOLICY_DC = 2; private const int DISPLAYPOLICY_BOTH = DISPLAYPOLICY_AC | DISPLAYPOLICY_DC; /// <summary> /// Indique les niveaux d'Acclairage en fonction du mode d'alimentation /// </summary> /// <remarks></remarks> public class Brightness { /// <summary> /// Eclairage en mode Alimentation /// </summary> /// <remarks></remarks> public byte AC; /// <summary> /// Eclairage en mode Batterie /// </summary> /// <remarks></remarks> public byte DC; } /// <summary> /// Contient les donnAces brutes des niveaux d'Acclairage /// </summary> /// <remarks></remarks> private struct DISPLAY_BRIGHTNESS { public byte ucDisplayPolicy; public byte ucACBrightness; public byte ucDCBrightness; } //envoie une requAate A un pAcriphAcrique [DllImport("kernel32")] private static extern bool DeviceIoControl ( IntPtr hDevice, int dwIoControlCode, ref DISPLAY_BRIGHTNESS lpInBuffer, int nInBufferSize, IntPtr lpOutBuffer, int nOutBufferSize, ref int lpBytesReturned, IntPtr lpOverlapped); [DllImport("kernel32")] private static extern bool DeviceIoControl ( IntPtr hDevice, int dwIoControlCode, IntPtr lpInBuffer, int nInBufferSize, ref DISPLAY_BRIGHTNESS lpOutBuffer, int nOutBufferSize, ref int lpBytesReturned, IntPtr lpOverlapped); [DllImport("kernel32")] private static extern bool DeviceIoControl ( IntPtr hDevice, int dwIoControlCode, IntPtr lpInBuffer, int nInBufferSize, [MarshalAs(UnmanagedType.LPArray)] byte[] lpOutBuffer, int nOutBufferSize, ref int lpBytesReturned, IntPtr lpOverlapped); //ferme un fichier ou un pAcriphAcrique [DllImport("kernel32")] private static extern int CloseHandle(IntPtr hObject); #region IOCTL private const int FILE_DEVICE_VIDEO = 0x23; private const int FILE_ANY_ACCESS = 0; private const int FILE_SPECIAL_ACCESS = FILE_ANY_ACCESS; private const int METHOD_BUFFERED = 0; private const int METHOD_NEITHER = 3; private const int ERROR_INSUFFICIENT_BUFFER = 122; /// <summary> /// GA‥re la dAcfinition d'un code de requAate d'un pAcriphAcrique en fonction de ses catAcgories /// </summary> /// <param name="dwDeviceType">Type de pAcriphAcrique</param> /// <param name="dwFunction">RequAate</param> /// <param name="dwMethod">MActhode de la requAate</param> /// <param name="dwAccess">Mode d'accA‥s</param> /// <returns></returns> /// <remarks></remarks> private static int CTL_CODE(int dwDeviceType, int dwFunction, int dwMethod, int dwAccess) { return ((dwDeviceType) << 16) | ((dwAccess) << 14) | ((dwFunction) << 2) | (dwMethod); } //requAate de lecture des niveaux d'Aclcairage supportAcs private static int IOCTL_VIDEO_QUERY_SUPPORTED_BRIGHTNESS = CTL_CODE(FILE_DEVICE_VIDEO, 293, METHOD_BUFFERED, FILE_ANY_ACCESS); //requAate de lecture des niveaux d'Acclairage en cours private static int IOCTL_VIDEO_QUERY_DISPLAY_BRIGHTNESS = CTL_CODE(FILE_DEVICE_VIDEO, 294, METHOD_BUFFERED, FILE_ANY_ACCESS); //requAate de dAcfinition des niveaux d'Acclairage en cours private static int IOCTL_VIDEO_SET_DISPLAY_BRIGHTNESS = CTL_CODE(FILE_DEVICE_VIDEO, 295, METHOD_BUFFERED, FILE_ANY_ACCESS); #endregion /// <summary> /// Ouvre un handle vers le pAcriphAcrique LCD /// </summary> /// <returns></returns> /// <remarks></remarks> private IntPtr OpenLCD() { //ouverture en lecture partagAce return CreateFile("\\\\.\\LCD", GENERIC_READ, SHARE_ALL, IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero); } private byte[] mBrightness = null; /// <summary> /// Renvoie la liste des niveaux d'Acclairage supportAcs /// </summary> /// <value></value> /// <returns></returns> /// <remarks></remarks> public byte[] SupportedBrightness { get { if (mBrightness == null) { int lpRet=0; byte[] ret; //essaie d'ouvrir le LCD IntPtr pDisplay = OpenLCD(); //si erreur, probablement pas un portable if (pDisplay != new IntPtr(-1)) { ret = new byte[256]; //envoie la requAate des niveaux supportAcs if (DeviceIoControl(pDisplay, IOCTL_VIDEO_QUERY_SUPPORTED_BRIGHTNESS, IntPtr.Zero, 0, ret, 256, ref lpRet, IntPtr.Zero)) { //rAccupA‥re un tableau d'octet contenant les niveaux mBrightness = new byte[lpRet]; for (int i = 0; i < lpRet; i++) { mBrightness[i] = ret[i]; } } CloseHandle(pDisplay); } } return mBrightness; } } /// <summary> /// Renvoie l'Acclairage en cours /// </summary> /// <returns>Eclairage en cours par modes d'alimentation</returns> /// <remarks></remarks> public Brightness GetBrightness() { int lpRet=0; Brightness ret = null; //essaie d'ouvrir le LCD IntPtr pDisplay = OpenLCD(); //si erreur, probablement pas un portable if (pDisplay == new IntPtr(-1)) return null; //envoie la requAate de lecture de l'Acclairage en cours DISPLAY_BRIGHTNESS pBrightness = new DISPLAY_BRIGHTNESS(); if (DeviceIoControl(pDisplay, IOCTL_VIDEO_QUERY_DISPLAY_BRIGHTNESS, IntPtr.Zero, 0, ref pBrightness, Marshal.SizeOf(typeof(DISPLAY_BRIGHTNESS)), ref lpRet, IntPtr.Zero)) { //si OK, rAccupA‥re la valeur pour AC/Alimentation et DC/Batterie ret = new Brightness(); ret.AC = pBrightness.ucACBrightness; ret.DC = pBrightness.ucDCBrightness; } CloseHandle(pDisplay); return ret; } /// <summary> /// DAcfinit l'Acclairage A la mAame valeur pour les deux modes d'alimentation /// </summary> /// <param name="brightness">Niveau d'Acclairage</param> /// <returns>true si rAcussi, false sinon</returns> /// <remarks></remarks> public bool SetBrightness(int brightness) { return SetBrightness(brightness, brightness); } /// <summary> /// DAcfinit l'Acclairage par mode d'alimentation /// </summary> /// <param name="acBrightness">Niveau AC/Alimentation</param> /// <param name="dcBrightness">Niveau DC/Batterie</param> /// <returns>true si rAcussi, false sinon</returns> /// <remarks></remarks> public bool SetBrightness(int acBrightness, int dcBrightness) { bool ret; int lpRet=0; //essaie d'ouvrir le LCD IntPtr pDisplay = OpenLCD(); //si erreur, probablement pas un portable if (pDisplay == new IntPtr(-1)) return false; //remplit la structure et informe que l'on dAcfinit les deux valeurs DISPLAY_BRIGHTNESS pBrightness = new DISPLAY_BRIGHTNESS(); pBrightness.ucACBrightness = (byte)(acBrightness & 0xFF); pBrightness.ucDCBrightness = (byte)(dcBrightness & 0xFF); pBrightness.ucDisplayPolicy = DISPLAYPOLICY_BOTH; //envoie la requAate de dAcfinition de l'Acclairage au pAcriphAcrique LCD ret = DeviceIoControl(pDisplay, IOCTL_VIDEO_SET_DISPLAY_BRIGHTNESS, ref pBrightness, Marshal.SizeOf(pBrightness), IntPtr.Zero, 0, ref lpRet, IntPtr.Zero); CloseHandle(pDisplay); return ret; } } }

參考原始出處：http://codes-sources.commentcamarche.net/source/view/53617/1259513#browser

Keyword：C#, Windows, Backlight