C#中pictureBox改变图片大小

如何使用鼠标滚轮仅改变图片的大小,而不改变pictureBox的大小

推荐一个完整范例

在pictureBox的鼠标滚轮事件里面重绘图片就行
private Image myBitmap;
private float h;
private float w;
private float x;
private float y;
private void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
{
Graphics g = this.pictureBox1.CreateGraphics();
//消除锯齿
g.SmoothingMode = SmoothingMode.AntiAlias;
//高质量,低速度绘制
g.CompositingQuality = CompositingQuality.HighQuality;

            g.Clear(Color.White);
            h = h + e.Delta;
            w = w + e.Delta;
            x = this.pictureBox1.Width / 2 - w / 2;
            y = this.pictureBox1.Height / 2 - h / 2;
            RectangleF rt =new RectangleF(x,y,w,h);
            g.DrawImage(myBitmap, rt);
    }

    private void Form9_Load(object sender, EventArgs e)
    {
         myBitmap = System.Drawing.Image.FromFile(@"d:\aa.png");
         h = myBitmap.Height;
         w = myBitmap.Width;
         pictureBox1.Image = myBitmap;
    }

private Image myBitmap;
private float h;
private float w;
private float x;
private float y;
private void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
{
Graphics g = this.pictureBox1.CreateGraphics();
//消除锯齿
g.SmoothingMode = SmoothingMode.AntiAlias;
//高质量,低速度绘制
g.CompositingQuality = CompositingQuality.HighQuality;

            g.Clear(Color.White);
            h = h + e.Delta;
            w = w + e.Delta;
            x = this.pictureBox1.Width / 2 - w / 2;
            y = this.pictureBox1.Height / 2 - h / 2;
            RectangleF rt =new RectangleF(x,y,w,h);
            g.DrawImage(myBitmap, rt);
    }

    private void Form9_Load(object sender, EventArgs e)
    {
         myBitmap = System.Drawing.Image.FromFile(@"d:\aa.png");
         h = myBitmap.Height;
         w = myBitmap.Width;
         pictureBox1.Image = myBitmap;
    }