Cómo: Usar una clase auxiliar para las invocaciones de la plataforma
Actualización: noviembre 2007
Este programa de ejemplo encapsula las estructuras, las declaraciones de invocación de la plataforma y el delegado para llamar a los procedimientos de ventana nativos. Los temas siguientes utilizan esta clase:
Cómo: Crear subclases de un control TreeView mediante devoluciones de llamada nativas
Cómo: Crear subclases de un botón mediante devoluciones de llamada nativas
Este programa de ejemplo se describe con detalle en Crear subclases de controles con un procedimiento de ventana administrado.
Ejemplo
using System;
using System.Drawing;
using System.Runtime.InteropServices;
// Contains managed wrappers and implementations of Win32
// structures, delegates, constants and platform invokes
// used by the GradientFill and Subclassing samples.
public sealed class Win32
{
public struct TRIVERTEX
{
public int x;
public int y;
public ushort Red;
public ushort Green;
public ushort Blue;
public ushort Alpha;
public TRIVERTEX(int x, int y, Color color)
: this(x, y, color.R, color.G, color.B, color.A)
{
}
public TRIVERTEX(
int x, int y,
ushort red, ushort green, ushort blue,
ushort alpha)
{
this.x = x;
this.y = y;
this.Red = (ushort)(red << 8);
this.Green = (ushort)(green << 8);
this.Blue = (ushort)(blue << 8);
this.Alpha = (ushort)(alpha << 8);
}
}
public struct GRADIENT_RECT
{
public uint UpperLeft;
public uint LowerRight;
public GRADIENT_RECT(uint ul, uint lr)
{
this.UpperLeft = ul;
this.LowerRight = lr;
}
}
public struct GRADIENT_TRIANGLE
{
public uint Vertex1;
public uint Vertex2;
public uint Vertex3;
public GRADIENT_TRIANGLE(uint v1, uint v2, uint v3)
{
this.Vertex1 = v1;
this.Vertex2 = v2;
this.Vertex3 = v3;
}
}
// WM_NOTIFY notification message header.
[System.Runtime.InteropServices.StructLayout(LayoutKind.Sequential)]
public class NMHDR
{
private IntPtr hwndFrom;
public uint idFrom;
public uint code;
}
//[System.Runtime.InteropServices.StructLayout(LayoutKind.Sequential)]
public struct TVITEM
{
public int mask;
private IntPtr hItem;
public int state;
public int stateMask;
private IntPtr pszText;
public int cchTextMax;
public int iImage;
public int iSelectedImage;
public int cChildren;
private IntPtr lParam;
}
// Native representation of a point.
public struct POINT
{
public int X;
public int Y;
}
public struct TVHITTESTINFO
{
public POINT pt;
public uint flags;
private IntPtr hItem;
}
// A callback to a Win32 window procedure (wndproc):
// Parameters:
// hwnd - The handle of the window receiving a message.
// msg - The message
// wParam - The message's parameters (part 1).
// lParam - The message's parameters (part 2).
// Returns an integer as described for the given message in MSDN.
public delegate int WndProc(IntPtr hwnd, uint msg, uint wParam, int lParam);
[DllImport("coredll.dll", SetLastError = true, EntryPoint = "GradientFill")]
public extern static bool GradientFill(
IntPtr hdc,
TRIVERTEX[] pVertex,
uint dwNumVertex,
GRADIENT_RECT[] pMesh,
uint dwNumMesh,
uint dwMode);
public const int GRADIENT_FILL_RECT_H = 0x00000000;
public const int GRADIENT_FILL_RECT_V = 0x00000001;
// Not supported on Windows CE:
public const int GRADIENT_FILL_TRIANGLE = 0x00000002;
[DllImport("coredll.dll")]
public extern static IntPtr SetWindowLong(
IntPtr hwnd, int nIndex, IntPtr dwNewLong);
public const int GWL_WNDPROC = -4;
[DllImport("coredll.dll")]
public extern static int CallWindowProc(
IntPtr lpPrevWndFunc, IntPtr hwnd, uint msg, uint wParam, int lParam);
[DllImport("coredll.dll")]
public extern static int DefWindowProc(
IntPtr hwnd, uint msg, uint wParam, int lParam);
[DllImport("coredll.dll")]
public extern static int SendMessage(
IntPtr hwnd, uint msg, uint wParam, ref TVHITTESTINFO lParam);
[DllImport("coredll.dll", SetLastError = true)]
public extern static int SendMessage(
IntPtr hwnd, uint msg, uint wParam, ref TVITEM lParam);
[DllImport("coredll.dll")]
public extern static uint GetMessagePos();
[DllImport("coredll.dll")]
public extern static IntPtr BeginPaint(IntPtr hwnd, ref PAINTSTRUCT ps);
[DllImport("coredll.dll")]
public extern static bool EndPaint(IntPtr hwnd, ref PAINTSTRUCT ps);
public struct PAINTSTRUCT
{
private IntPtr hdc;
public bool fErase;
public Rectangle rcPaint;
public bool fRestore;
public bool fIncUpdate;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
public byte[] rgbReserved;
}
[DllImport("coredll.dll")]
public extern static IntPtr GetDC(IntPtr hwnd);
[DllImport("coredll.dll")]
public extern static bool ReleaseDC(IntPtr hwnd, IntPtr hdc);
// Helper function to convert a Windows lParam into a Point.
// lParam - The parameter to convert.
// Returns a Point where X is the low 16 bits and Y is the
// high 16 bits of the value passed in.
public static Point LParamToPoint(int lParam)
{
uint ulParam = (uint)lParam;
return new Point(
(int)(ulParam & 0x0000ffff),
(int)((ulParam & 0xffff0000) >> 16));
}
// Windows messages
public const uint WM_PAINT = 0x000F;
public const uint WM_ERASEBKGND = 0x0014;
public const uint WM_KEYDOWN = 0x0100;
public const uint WM_KEYUP = 0x0101;
public const uint WM_MOUSEMOVE = 0x0200;
public const uint WM_LBUTTONDOWN = 0x0201;
public const uint WM_LBUTTONUP = 0x0202;
public const uint WM_NOTIFY = 0x4E;
// Notifications
public const uint NM_CLICK = 0xFFFFFFFE;
public const uint NM_DBLCLK = 0xFFFFFFFD;
public const uint NM_RCLICK = 0xFFFFFFFB;
public const uint NM_RDBLCLK = 0xFFFFFFFA;
// Key
public const uint VK_SPACE = 0x20;
public const uint VK_RETURN = 0x0D;
// Treeview
public const uint TV_FIRST = 0x1100;
public const uint TVM_HITTEST = TV_FIRST + 17;
public const uint TVHT_NOWHERE = 0x0001;
public const uint TVHT_ONITEMICON = 0x0002;
public const uint TVHT_ONITEMLABEL = 0x0004;
public const uint TVHT_ONITEM = (TVHT_ONITEMICON | TVHT_ONITEMLABEL | TVHT_ONITEMSTATEICON);
public const uint TVHT_ONITEMINDENT = 0x0008;
public const uint TVHT_ONITEMBUTTON = 0x0010;
public const uint TVHT_ONITEMRIGHT = 0x0020;
public const uint TVHT_ONITEMSTATEICON = 0x0040;
public const uint TVHT_ABOVE = 0x0100;
public const uint TVHT_BELOW = 0x0200;
public const uint TVHT_TORIGHT = 0x0400;
public const uint TVHT_TOLEFT = 0x0800;
public const uint TVM_GETITEM = TV_FIRST + 62; //TVM_GETITEMW
public const uint TVIF_TEXT = 0x0001;
public const uint TVIF_IMAGE = 0x0002;
public const uint TVIF_PARAM = 0x0004;
public const uint TVIF_STATE = 0x0008;
public const uint TVIF_HANDLE = 0x0010;
public const uint TVIF_SELECTEDIMAGE = 0x0020;
public const uint TVIF_CHILDREN = 0x0040;
public const uint TVIF_DI_SETITEM = 0x1000;
}
Vea también
Tareas
Cómo: Utilizar una clase para enlazar procedimientos de Windows
Cómo: Crear subclases de un control TreeView mediante devoluciones de llamada nativas
Cómo: Crear subclases de un botón mediante devoluciones de llamada nativas
Conceptos
Crear subclases de controles con un procedimiento de ventana administrado
.Temas "Cómo..." de .NET Compact Framework