C#软件开发实例.个人定制自己的屏幕抓图工具（八）加入了截图功能键盘

        /// <summary>
        /// 处理键盘按下事件
        /// 用于实现下面功能：
        /// 当用户按下Esc键时,退出截图过程；
        /// Shift + Enter 開始截图的功能；
        /// 使用键盘的上下左右键调整截图位置的功能。
        /// Shift + 上下左右键调整截图区域大小的功能；
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Escape)
            {
                ExitCutImage(true);
                // 假设不加这一句。热键仅仅能在窗体隐藏后使用一次，之后就不起作用了。
                //RegisterHotKey(Handle, 100, 2 | 1, Keys.A);
            }
            if (e.Shift && e.KeyCode == Keys.Enter)
            {
                if (!this.lbl_CutImage.Visible)
                {
                    this.isCuting = true;
                    this.beginPoint = MousePosition;
                    this.endPoint = MousePosition;
                    SaveCutImageSize(MousePosition, MousePosition);
                    UpdateCutInfoLabel(UpdateUIMode.ShowInfoBox | UpdateUIMode.ShowCutImage);
                }
            }
            if (e.KeyCode == Keys.Left)
            {
                if (this.lbl_CutImage.Visible)
                {
                    if (e.Shift)
                    {
                        if (this.cutImageRect.Width > 1)
                        {
                            this.cutImageRect.Width -= 1;
                            Cursor.Position = new Point(Cursor.Position.X - 1, Cursor.Position.Y);
                            UpdateCutInfoLabel(UpdateUIMode.None);
                        }
                    }
                    else
                    {
                        if (this.cutImageRect.Left > -1)
                        {
                            this.cutImageRect.X -= 1;
                            UpdateCutInfoLabel(UpdateUIMode.None);
                        }
                    }
                }
                else
                {
                    if (Cursor.Position.X > -1)
                    {
                        Cursor.Position = new Point(Cursor.Position.X - 1, Cursor.Position.Y);
                    }
                }
            }
            if (e.KeyCode == Keys.Right)
            {
                if (this.lbl_CutImage.Visible)
                {
                    if (e.Shift)
                    {
                        if (this.cutImageRect.Right < this.Width + 1)
                        {
                            this.cutImageRect.Width += 1;
                            Cursor.Position = new Point(Cursor.Position.X + 1, Cursor.Position.Y);
                            UpdateCutInfoLabel(UpdateUIMode.None);
                        }
                    }
                    else
                    {
                        if (this.cutImageRect.Right < this.Width + 1)
                        {
                            this.cutImageRect.X += 1;
                            UpdateCutInfoLabel(UpdateUIMode.None);
                        }
                    }
                }
                else
                {
                    if (Cursor.Position.X < this.Width + 1)
                    {
                        Cursor.Position = new Point(Cursor.Position.X + 1, Cursor.Position.Y);
                    }
                }
            }

            if (e.KeyCode == Keys.Up)
            {
                if (this.lbl_CutImage.Visible)
                {
                    if (e.Shift)
                    {
                        if (this.cutImageRect.Height > 1)
                        {
                            this.cutImageRect.Height -= 1;
                            Cursor.Position = new Point(Cursor.Position.X, Cursor.Position.Y - 1);
                            UpdateCutInfoLabel(UpdateUIMode.None);
                        }
                    }
                    else
                    {
                        if (this.cutImageRect.Top > -1)
                        {
                            this.cutImageRect.Y -= 1;
                            UpdateCutInfoLabel(UpdateUIMode.None);
                        }
                    }
                }
                else
                {
                    if (Cursor.Position.Y > -1)
                    {
                        Cursor.Position = new Point(Cursor.Position.X, Cursor.Position.Y - 1);
                    }
                }
            }
            if (e.KeyCode == Keys.Down)
            {
                if (this.lbl_CutImage.Visible)
                {
                    if (e.Shift)
                    {
                        if (this.cutImageRect.Bottom < this.Height + 1)
                        {
                            this.cutImageRect.Height += 1;
                            Cursor.Position = new Point(Cursor.Position.X, Cursor.Position.Y + 1);
                            UpdateCutInfoLabel(UpdateUIMode.None);
                        }
                    }
                    else
                    {
                        if (this.cutImageRect.Bottom < this.Height + 1)
                        {
                            this.cutImageRect.Y += 1;
                            UpdateCutInfoLabel(UpdateUIMode.None);
                        }
                    }
                }
                else
                {
                    if (Cursor.Position.Y < this.Height + 1)
                    {
                        Cursor.Position = new Point(Cursor.Position.X, Cursor.Position.Y + 1);
                    }
                }
            }
        }

        /// <summary>
        /// 处理键盘抬起事件
        /// Shift + Enter 開始截图。当松开Shitf键后。
        /// 停止截图区域大小的设置。不然的话鼠标移动还会改变截取区域的大小；
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Form1_KeyUp(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.ShiftKey)
            {
                if (this.isCuting)
                {
                    this.isCuting = false;
                    this.pictureBox_zoom.Hide();

                    this.lastMouseMoveTime = 0;
                    UpdateCutInfoLabel(UpdateUIMode.None);
                }
            }
        }