C#图像显示实现拖拽、锚点缩放功能【转】

1.图像拖拽

核心步骤:

①新建Point类型全局变量mouseDownPoint,记录拖拽过程中鼠标位置;

②MouseDown事件记录Cursor位置;

③MouseMove事件计算移动矢量,并更新pictureBox1.Location。

代码:
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                mouseDownPoint.X = Cursor.Position.X;   //记录鼠标左键按下时位置
                mouseDownPoint.Y = Cursor.Position.Y;                
                isMove = true;
                pictureBox1.Focus();    //鼠标滚轮事件(缩放时)需要picturebox有焦点
            }
        }

        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                isMove = false;                
            }
        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            pictureBox1.Focus();    //鼠标在picturebox上时才有焦点,此时可以缩放
            if (isMove)
            {
                int x, y;           //新的pictureBox1.Location(x,y)
                int moveX, moveY;   //X方向,Y方向移动大小。
                moveX = Cursor.Position.X - mouseDownPoint.X;
                moveY = Cursor.Position.Y - mouseDownPoint.Y;
                x = pictureBox1.Location.X + moveX;
                y = pictureBox1.Location.Y + moveY;                
                pictureBox1.Location = new Point(x, y);
                mouseDownPoint.X = Cursor.Position.X;
                mouseDownPoint.Y = Cursor.Position.Y;                
            }
        }
        
        private void panel2_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                mouseDownPoint.X = Cursor.Position.X;   //记录鼠标左键按下时位置
                mouseDownPoint.Y = Cursor.Position.Y;
                isMove = true;
            }
        }

        private void panel2_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                isMove = false;
            }
        }

        private void panel2_MouseMove(object sender, MouseEventArgs e)
        {
            panel2.Focus();  //鼠标不在picturebox上时焦点给别的控件,此时无法缩放            
            if (isMove)
            {
                int x, y;           //新的pictureBox1.Location(x,y)
                int moveX, moveY;   //X方向,Y方向移动大小。
                moveX = Cursor.Position.X - mouseDownPoint.X;
                moveY = Cursor.Position.Y - mouseDownPoint.Y;
                x = pictureBox1.Location.X + moveX;
                y = pictureBox1.Location.Y + moveY;
                pictureBox1.Location = new Point(x, y);
                mouseDownPoint.X = Cursor.Position.X;
                mouseDownPoint.Y = Cursor.Position.Y;
            }
        }
2.图像缩放
核心思想:利用picturebox的zoom模式,根据图像显示大小更改picturebox大小,记录鼠标位置补偿缩放位移,实现锚点缩放,即以鼠标位置为中心进行缩放。
代码:
//实现锚点缩放(以鼠标所指位置为中心缩放);
        //步骤:
        //①先改picturebox长宽,长宽改变量一样;
        //②获取缩放后picturebox中实际显示图像的长宽,这里长宽是不一样的;
        //③将picturebox的长宽设置为显示图像的长宽;
        //④补偿picturebox因缩放产生的位移,实现锚点缩放。
        //  注释:为啥要②③步?由于zoom模式的机制,把picturebox背景设为黑就知道为啥了。
        //这里需要获取zoom模式下picturebox所显示图像的大小信息,添加 using System.Reflection;
        //pictureBox1_MouseWheel事件没找到。。。手动添加,别忘在Form1.Designer.cs的“Windows 窗体设计器生成的代码”里加入:        
        //this.pictureBox1.MouseWheel += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseWheel)。
        private void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
        {
            int x = e.Location.X;
            int y = e.Location.Y;
            int ow = pictureBox1.Width;
            int oh = pictureBox1.Height;            
            int VX, VY;     //因缩放产生的位移矢量
            if (e.Delta > 0)    //放大
            {
                //第①步
                pictureBox1.Width += zoomStep;
                pictureBox1.Height += zoomStep;
                //第②步
                PropertyInfo pInfo = pictureBox1.GetType().GetProperty("ImageRectangle", BindingFlags.Instance |
                    BindingFlags.NonPublic);
                Rectangle rect = (Rectangle)pInfo.GetValue(pictureBox1, null);
                //第③步
                pictureBox1.Width = rect.Width;
                pictureBox1.Height = rect.Height;
            }
            if (e.Delta < 0)    //缩小
            {
                //防止一直缩成负值
                if (pictureBox1.Width < myBmp.Width / 10)
                    return;
                
                pictureBox1.Width -= zoomStep;
                pictureBox1.Height -= zoomStep;
                PropertyInfo pInfo = pictureBox1.GetType().GetProperty("ImageRectangle", BindingFlags.Instance |
                    BindingFlags.NonPublic);
                Rectangle rect = (Rectangle)pInfo.GetValue(pictureBox1, null);
                pictureBox1.Width = rect.Width;
                pictureBox1.Height = rect.Height;
            }
            //第④步,求因缩放产生的位移,进行补偿,实现锚点缩放的效果
            VX = (int)((double)x * (ow - pictureBox1.Width) / ow);
            VY = (int)((double)y * (oh - pictureBox1.Height) / oh);
            pictureBox1.Location = new Point(pictureBox1.Location.X + VX, pictureBox1.Location.Y + VY);
        }

 

posted @ 2015-09-16 10:14  Simmy.卧龙先生  阅读(2402)  评论(0编辑  收藏  举报