图形对象的PictureBox缩放模式效果

Question

当您将图像加载到PictureBox中时，会对图像位置进行缩放，如何使用图形对象实现同样的效果？

Answer 1

我想你的意思是，你想在Rectangle中自己绘制一些Image，并使用一些Graphics对象，就像PictureBox在Zoom模式中渲染其图像一样。请尝试以下代码。我想你想在窗体上绘制Image，绘制代码应该添加到窗体的Paint事件处理程序中：

//The Rectangle (corresponds to the PictureBox.ClientRectangle)
//we use here is the Form.ClientRectangle
//Here is the Paint event handler of your Form1
private void Form1_Paint(object sender, EventArgs e){
  ZoomDrawImage(e.Graphics, yourImage, ClientRectangle);
}
//use this method to draw the image like as the zooming feature of PictureBox
private void ZoomDrawImage(Graphics g, Image img, Rectangle bounds){
  decimal r1 = (decimal) img.Width/img.Height;
  decimal r2 = (decimal) bounds.Width/bounds.Height;
  int w = bounds.Width;
  int h = bounds.Height;
  if(r1 > r2){
    w = bounds.Width;
    h = (int) (w / r1);
  } else if(r1 < r2){
    h = bounds.Height;
    w = (int) (r1 * h);
  }
  int x = (bounds.Width - w)/2;
  int y = (bounds.Height - h)/2;
  g.DrawImage(img, new Rectangle(x,y,w,h));
}

为了在表单上完美地测试它，您还必须设置ResizeRedraw = true并启用DoubleBuffered:

public Form1(){
  InitializeComponent();
  ResizeRedraw = true;
  DoubleBuffered = true;
}