c#如何把图片框控件的图片裁剪并保存新的图片，或者在另一个图片控件中显示。

Question

如何实现缩放后图片的中心仍和pictureBox控件的中心重合？

Answer 1

using System.Drawing.Drawing2D;
using System.Drawing.Imaging;

/// <summary>
/// 裁剪图片
/// </summary>
/// <param name="x">相对于图片左上角(0,0)点，x方向的位移</param>
/// <param name="y">相对于图片左上角(0,0)点，y方向的位移</param>
/// <param name="width">裁剪后的图片宽度</param>
/// <param name="height">裁剪后的图片高度</param>
private void CloneImage(float x, float y, float width, float height)
{
if (this.openFileDialog1.ShowDialog() == DialogResult.OK)
{
//获取图像
Bitmap myBitmap = new Bitmap(this.openFileDialog1.FileName);
//设定图像剪切区域
RectangleF cloneRect = new RectangleF(x, y, width, height);
PixelFormat format = myBitmap.PixelFormat;
Bitmap cloneBitmap = myBitmap.Clone(cloneRect, format);

this.pictureBox1.Image = cloneBitmap;

}

}
private void button1_Click(object sender, EventArgs e)
{
//测试
CloneImage(0, 0, 500, 200);
}

追问

谢谢你。测试了一下可以。还想请教你如何实现图片缩放功能，然后再剪切。（发现pictureBox的SizeMode属性必须设置成custom才能实现剪切）。后面给你加分勒，嘿嘿...

追答

下面是图片缩放功能代码，你可试一下。
///
/// 将某个图像生成指定尺寸的图像缩放图
///
/// 原图像
/// 新的图像宽
/// 新的图像高
///
private Image GetThumbnailImage(Bitmap myBitmap, int width, int height)
{

//生成图像的缩放图
Image.GetThumbnailImageAbort myCallback =
new Image.GetThumbnailImageAbort(ThumbnailCallback);

Image myThumbnail = myBitmap.GetThumbnailImage(
width, height, myCallback, IntPtr.Zero);
//this.pictureBox1.Image = myThumbnail;

return myThumbnail;
}
public bool ThumbnailCallback()
{
return false;
}

追问

嗯 谢谢您。测试了可以，再咨询最后一个问题哈。这个程序缩放后的图片位置是以pictureBox控件左上角为原点，不知如何实现缩放后图片的中心仍和pictureBox控件的中心重合，这样更美观一些？

追答

有两种方法，如下所示：
//获取图像
Bitmap myBitmap = new Bitmap(this.openFileDialog1.FileName);
myBitmap = (Bitmap)GetThumbnailImage(myBitmap, 100, 100);
//可以这样
//ShowCenterImage(this.pictureBox1, myBitmap);
//也可以这样
this.pictureBox1.SizeMode = PictureBoxSizeMode.CenterImage;
this.pictureBox1.Image = myBitmap;

//测试代码所下:
private void button5_Click(object sender, EventArgs e)
{
if (this.openFileDialog1.ShowDialog() == DialogResult.OK)
{
//获取图像
Bitmap myBitmap = new Bitmap(this.openFileDialog1.FileName);

myBitmap = (Bitmap)GetThumbnailImage(myBitmap, 100, 100);

//可以这样
//ShowCenterImage(this.pictureBox1, myBitmap);

//也可以这样
this.pictureBox1.SizeMode = PictureBoxSizeMode.CenterImage;
this.pictureBox1.Image = myBitmap;
}
}

///
/// 将图片显示在picturebox中心
///
///
///
private void ShowCenterImage(PictureBox myPictureBox, Image myImage)
{

Graphics g = myPictureBox.CreateGraphics();
g.Clear(Color.White);
//消除锯齿
g.SmoothingMode = SmoothingMode.AntiAlias;
//高质量，低速度绘制
g.CompositingQuality = CompositingQuality.HighQuality;

int x = (myPictureBox.Width - myImage.Width) / 2;
int y = (myPictureBox.Height - myImage.Height) / 2;

g.DrawImage(myImage, new Point(x, y));

}