DirectX Sample分析：Framework中的控件事件绑定（一）

作者：Junhot
更新时间：2004-12-15
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总的流程描述图：

从具体控件看起，以鼠标点击Button控件的事件为例，Button控件代码包含在dxmutgui.cs文件中：

 

Button的Click事件的原型：

在Button中声明了如下的事件Click及事件触发方法RaiseClickEvent

        public event EventHandler Click;

        protected void RaiseClickEvent(Button sender, bool wasTriggeredByUser)
{
            // Discard events triggered programatically if these types of events haven't been
            // enabled
            if (!Parent.IsUsingNonUserEvents && !wasTriggeredByUser)
                return;

            if (Click != null)
                Click(sender, EventArgs.Empty);
        }
        #endregion

Button内部如何触发Click事件：

HandleMouse这个方法调用RaiseClickEvent方法从而导致Click事件的触发，另外还有如HandleKeyboard方法等，同样也是事件触发的方法之一。

        /// Handle mouse messages from the buttons
        /// </summary>
        public override bool HandleMouse(NativeMethods.WindowMessage msg, System.Drawing.Point pt, IntPtr wParam, IntPtr lParam)
{
            if (!IsEnabled || !IsVisible)
                return false;

            switch(msg)
{
                case NativeMethods.WindowMessage.LeftButtonDoubleClick:
                case NativeMethods.WindowMessage.LeftButtonDown:
{
                    if (ContainsPoint(pt))
{
                        // Pressed while inside the control
                        isPressed = true;
                        NativeMethods.SetCapture(Parent.SampleFramework.Window);
                        if (!hasFocus)
                            Dialog.RequestFocus(this);

                        return true;
                    }
                }
                    break;
                case NativeMethods.WindowMessage.LeftButtonUp:
{
                    if (isPressed)
{
                        isPressed = false;
                        NativeMethods.ReleaseCapture();
                        if (!parentDialog.IsUsingKeyboardInput)
                            Dialog.ClearFocus();

                        // Button click
                        if (ContainsPoint(pt))
                            RaiseClickEvent(this, true);
                    }
                }
                    break;
            }

            return false;
        }

控件如何知道何时该触发Click事件：

在Dialog类中（Dialog类代码同样包含在dxmutgui.cs中）通过MessageProc捕获WindowMessage，然后调用Control的HandleKeyboard或者HandleMouse方法，下面是调用HandleMouse方法的代码：

                // Mouse messages
                case NativeMethods.WindowMessage.MouseMove:
                case NativeMethods.WindowMessage.MouseWheel:
                case NativeMethods.WindowMessage.LeftButtonUp:
                case NativeMethods.WindowMessage.LeftButtonDown:
                case NativeMethods.WindowMessage.LeftButtonDoubleClick:
                case NativeMethods.WindowMessage.RightButtonUp:
                case NativeMethods.WindowMessage.RightButtonDown:
                case NativeMethods.WindowMessage.RightButtonDoubleClick:
                case NativeMethods.WindowMessage.MiddleButtonUp:
                case NativeMethods.WindowMessage.MiddleButtonDown:
                case NativeMethods.WindowMessage.MiddleButtonDoubleClick:
                case NativeMethods.WindowMessage.XButtonUp:
                case NativeMethods.WindowMessage.XButtonDown:
                case NativeMethods.WindowMessage.XButtonDoubleClick:
{
                    // If not accepting mouse input, return false to indicate the message should still 
                    // be handled by the application (usually to move the camera).
                    if (!usingMouseInput)
                        return false;

                    // Current mouse position
                    short mouseX = NativeMethods.LoWord((uint)lParam.ToInt32());
                    short mouseY = NativeMethods.HiWord((uint)lParam.ToInt32());
                    System.Drawing.Point mousePoint = new System.Drawing.Point(mouseX, mouseY);
                    // Offset mouse point
                    mousePoint.X -= dialogX;
                    mousePoint.Y -= dialogY;

                    // If caption is enabled, offset the Y coordinate by the negative of its height.
                    if (hasCaption)
                        mousePoint.Y -= captionHeight;

                    // If a control is in focus, it belongs to this dialog, and it's enabled, then give
                    // it the first chance at handling the message.
                    if (controlFocus != null && 
                        controlFocus.Parent == this && 
                        controlFocus.IsEnabled)
{
                        // If the control MsgProc handles it, then we don't.
                        if (controlFocus.HandleMouse(msg, mousePoint, wParam, lParam))
                            return true;
                    }

                    // Not yet handled, see if the mouse is over any controls
                    Control control = GetControlAtPoint(mousePoint);
                    if ((control != null) && (control.IsEnabled))
{
                        // Let the control handle the mouse if it wants (and return true if it handles it)
                        if (control.HandleMouse(msg, mousePoint, wParam, lParam))
                            return true;
                    }
                    else
{
                        // Mouse not over any controls in this dialog, if there was a control
                        // which had focus it just lost it
                        if (msg == NativeMethods.WindowMessage.LeftButtonDown &&
                            controlFocus != null &&
                            controlFocus.Parent == this)
{
                            controlFocus.OnFocusOut();
                            controlFocus = null;
                        }
                    }