使用图形对象的PictureBox缩放模式效果 [英] PictureBox Zoom Mode Effect With Graphics Object

问题描述

当您将图片加载到图片框中时，图片放置位置会缩放，我如何通过图片对象实现同样的效果？

解决方案 a Rectangle 并使用一些 Graphics 对象，如 PictureBox 将其图像渲染到 Zoom 模式。尝试下面的代码。我想你想在一个Form上绘制 Image ，绘图代码应该添加到 Paint 事件处理程序中你的表单：

  //矩形（对应于PictureBox.ClientRectangle）
 //我们在这里使用的是Form.ClientRectangle 
 //这里是Form1的Paint事件处理程序
 private void Form1_Paint（object sender，EventArgs e）{
 ZoomDrawImage（e.Graphics，yourImage，ClientRectangle）; 
} 
 //使用此方法绘制图像，如同PictureBox的缩放功能一样
 private void ZoomDrawImage（Graphics g，Image img，Rectangle bounds）{
 decimal r1 = （十进制）img.Width / img.Height; 
十进制r2 =（十进制）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  h = bounds.Height; 
 w =（int）（r1 * h）; 
} 
 int x =（bounds.Width  -  w）/ 2; 
 int y =（bounds.Height  -  h）/ 2; 
 gDrawImage（img，new Rectangle（x，y，w，h））; 
} 
  

为了完美地测试你的表单，你还必须设置 ResizeRedraw = true 并启用 DoubleBuffered ：

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

When you load an image into a PictureBox there is a zoom for the image placement, how do I achieve that same effect with a graphics object?

解决方案

I think you mean you want to draw some Image yourself in a Rectangle and using some Graphics object like as the PictureBox renders its Image in Zoom mode. Try the following code. I suppose you want to draw the Image on a Form, the drawing code should be added in a Paint event handler of your form:

//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));
}

To test it on your form perfectly, you should also have to set ResizeRedraw = true and enable DoubleBuffered:

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

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