求助。关于重绘的问题

[小猪飞剑]

我做了个小东西

private void button2_Click(object sender, EventArgs e)
{
Bitmap bmp = new Bitmap(this.pictureBox1.ClientRectangle.Width, this.pictureBox1.ClientRectangle.Height);
Graphics g = Graphics.FromImage(bmp);
g.Clear(Color.Black);
g.DrawRectangle(new Pen(Color.Red), 10, 10, 40, 20);
g.Dispose();
this.pictureBox1.Image = bmp;
｝
类似的吧。。。
然后呢。我想在pictureBox里先添加个图片再进行操作。
但是，执行上面的代码后，出现原来的图片没了，只有上面的操作了。去解决方法

[orochiheart]

this.pictureBox1有clear方法么 最后一行执行前加上clear试试有没有效果

[mfkuyg61]

你将原来的清除了,试试下面的
private void button1_Click(object sender, EventArgs e)
{
Bitmap bmp = new Bitmap(pictureBox1.Image);
Graphics g = Graphics.FromImage(bmp);
g.DrawRectangle(new Pen(Color.Red), 10, 10, 40, 20);
g.Dispose();
this.pictureBox1.Image = bmp;
}

[aa6103848252]

private void button2_Click(object sender, EventArgs e)
{
Graphics g = Graphics.FromImage(pictureBox1.Image);
g.DrawRectangle(new Pen(Color.Red), 10, 10, 40, 20);
g.Dispose();
｝