使用矩形在图像上创建搜索区域

Question

我有一个显示图像的图像查看器。我想用鼠标在图像上绘制一个矩形，得到矩形（X1，X2，Y1和Y2）的x和y坐标。我将使用这些坐标来创建一个搜索区域，并找到一个数组中的最大值和最小值，这些值的精确像素数与两个坐标轴中的图像一致。
任何人都可以引导我开始一个方向吗？

Answer 1

您应该使用画布来显示图像并在其上绘制矩形。

例子：

MainWindow.xaml：

<Window x:Class="CanvasRectangleSample.MainWindow" 
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     Title="MainWindow"> 
    <Grid> 
     <Canvas x:Name="SampleImageCanvas" 
       MouseMove="SampleImageCanvas_MouseMove" 
       MouseDown="SampleImageCanvas_MouseDown" 
       Width="512" Height="389"> 
      <Canvas.Background> 
       <!--Here you set the image to display -> You probably want to bind it to something. --> 
       <ImageBrush x:Name="SampleImage" Stretch="Uniform" ImageSource="C:\Users\Public\Pictures\Sample Pictures\Koala.jpg"> 
       </ImageBrush> 
      </Canvas.Background> 
      <!-- Here you draw whatever you want on the canvas. --> 
      <!-- You'll probably want to bind its width and height to something too. --> 
      <Rectangle x:Name="ROI" Stroke="#FFF1133E" Width="50" Height="50"/> 
     </Canvas> 
    </Grid> 
</Window> 

MainWindow.xaml.cs：

using System.Windows; 
using System.Windows.Input; 
using System.Windows.Controls; 
namespace CanvasRectangleSample 
{ 
    /// <summary> 
    /// Interaction logic for MainWindow.xaml 
    /// </summary> 
    public partial class MainWindow : Window 
    { 
     public MainWindow() 
     { 
      this.DataContext = this; 
      InitializeComponent(); 
     } 

     // Handling the redrawing of the rectangle according to mouse location 
     private void SampleImageCanvas_MouseMove(object sender, MouseEventArgs e) 
     { 
      //get mouse location relative to the canvas 
      Point pt = e.MouseDevice.GetPosition(sender as Canvas); 

      //here you set the rectangle loction relative to the canvas 
      Canvas.SetLeft(ROI, pt.X - (int)(ROI.Width/2)); 
      Canvas.SetTop(ROI, pt.Y - (int)(ROI.Height/2)); 
     } 


     private void SampleImageCanvas_MouseDown(object sender, MouseButtonEventArgs e) 
     { 
      //Here you should handle saving the rectangle location 

      //don't forget to calculate the proportion between Canvas's size and real Image's size. 

     } 
    } 

} 

如果你愿意，你可以限制矩形搬迁到画布区域使用if表情检查画布区域是否包含鼠标位置

Answer 2

感谢这个指针ters和帮助： 这是我完成的代码，它的工作原理。将鼠标放在画布上的任意位置，按住鼠标并拖动以创建矩形。它可以使用更多的改进来在任何方向拖拽和创建矩形。

XAML：

<Canvas Name="ImageCanvas" 
      MouseMove="ImageCanvas_MouseMove" 
       MouseDown="ImageCanvas_MouseDown" 
      Height="240" Width="320" 
      HorizontalAlignment="Left" 
      Margin="87,514,0,0" VerticalAlignment="Top" MouseLeftButtonUp="ImageCanvas_MouseLeftButtonUp"> 
      <Canvas.Background> 
      <ImageBrush x:Name="Image" Stretch="Uniform" ImageSource="C:\image.bmp"> 
      </ImageBrush> 
      </Canvas.Background> 
      <Rectangle x:Name="ROI" Stroke="#FFF1133E" Width="20" Height="20" Canvas.Left="155" Canvas.Top="115" /> 

     </Canvas> 

代码：

double topLeftX = 0; 
double topLeftY = 0; 
double bottomRightX = 0; 
double bottomrigthY = 0; 
bool setRect = false; 

private void ImageCanvas_MouseDown(object sender, MouseButtonEventArgs e) 
{ 
    topLeftY = topLeftX = bottomrigthY = bottomRightX = 0; 
    setRect = true; 
    System.Windows.Point pt = e.MouseDevice.GetPosition(sender as Canvas); 
    topLeftX = pt.X; topLeftY = pt.Y; 
} 

private void ImageCanvas_MouseMove(object sender, System.Windows.Input.MouseEventArgs e) 
{ 
    if (setRect == true) 
    { 
     //get mouse location relative to the canvas 
     System.Windows.Point pt = e.MouseDevice.GetPosition(sender as Canvas); 
     Canvas.SetLeft(ROI, topLeftX); 
     Canvas.SetTop(ROI, topLeftY); 
     ROI.Width = System.Math.Abs((int)(pt.X - topLeftX)); 
     ROI.Height = System.Math.Abs((int)(pt.Y - topLeftY)); 
     commandReturnTB.Text = (Convert.ToString(pt.X) + "," + Convert.ToString(pt.Y))+"\n"; 
    } 
} 

private void ImageCanvas_MouseLeftButtonUp(object sender, MouseButtonEventArgs e) 
{ 
    System.Windows.Point pt = e.MouseDevice.GetPosition(sender as Canvas); 
    bottomRightX = pt.X; 
    bottomrigthY = pt.Y; 
    ROI.Width = System.Math.Abs((int)(bottomRightX - topLeftX)); 
    ROI.Height = System.Math.Abs((int)(bottomrigthY - topLeftY)); 
    Canvas.SetLeft(ROI, topLeftX); 
    Canvas.SetTop(ROI, topLeftY); 
    setRect = false; 
    commandReturnTB.Text = topLeftX + "," + topLeftY + "--" + bottomRightX + "," + bottomrigthY; 
}