如何在WPF VB中裁剪图像 [英] HOW to crop image in WPF VB

问题描述

我不能在图像控制上裁剪图像请帮忙。



当我将画布x，y，裁剪高度和宽度转移到裁剪功能时它给出错误的小作物图片





提前致谢。



什么我试过了：

 Public Function Crop（ByVal srcBitmap As Bitmap，_ 
 ByVal cropX As Integer，ByVal cropY As Integer，ByVal cropWidth As Integer，ByVal cropHeight As Integer）As Bitmap 
 
'创建新的位图和关联的图形对象
 Dim bmp As New Bitmap（srcBitmap，cropHeight，cropWidth）
 
 Dim g As Graphics = Graphics.FromImage（bmp）
 
 Dim rect As Rectangle = New Rectangle（cropX，cropY，cropWidth，cropHeight）
'绘制指定的源位图的一部分到新的
 g.DrawImage（srcBitmap，New Rectangle（0,0，cropHeight，cropWidth），rect，GraphicsUnit.Pixel）
'清理
 srcBitmap.Dispose（）
返回bmp 
 
 
 
结束函数

解决方案

Microsoft WPF文档为您提供了一个很好的示例：如何：裁剪图像| Microsoft Docs [ ^ ]

好的，您似乎有计算错误 - 其中一个值可能是 double.NAN [ ^ ]。



此代码具有相同的问题，并且没有被响应的人接收： c＃ - 使用Canvas矩形裁剪图像 - Stack Overflow [ ^ ]



问题在于这些计算：

 rcFrom.X =（ int ） （（rect1.X）*（image1.Source.Width）/（image1.Width））; 
 rcFrom.Y =（ int ）（（rect1.Y）*（image1.Source.Height）/（image1.Height））; 
 rcFrom.Width =（ int ）（（rect1.Width）*（image1.Source.Width）/（image1.Width））; 
 rcFrom.Height =（ int ）（（rect1.Height）*（image1.Source.Height）/(image1.Height));

测试&调试显示 image1.Height 和 image1.Width 正在返回 double.NAN 属性。他们应该使用的是 image1.ActualHeight 和 Actualimage1.Width 属性。



这是代码的更正工作版本（此解决方案中的上述链接）使用图像大小3840 x 2160 jpeg图像：



XAML MainWindow：

 <   Window   
   
           x：Class   =  WpfCropImage.MainWindow  
   
           xmlns   =  http： //schemas.microsoft.com/winfx/2006/xaml/presentation\" 
   
           xmlns：x   =  http://schemas.microsoft.com/winfx/2006/xaml  
   
   
   
           mc：可忽略  =  d  
   
           xmlns：d   =  http：// schemas。 microsoft.com/expression/blend/2008\" 
   
           xmlns：mc   =  http ：//schemas.openxmlformats.org/markup-compatibility/2006  
   
   
   
          < span class =code-attribute>标题  =  CodeProject Answer  -  WPF Scale&裁剪图像  
   
          < span class =code-attribute>高度  =  600   宽度  =  1200    WindowStartupLocation   =  CenterScreen >  
 
 <  网格 >  
 <   Grid.ColumnDefinitions  >  
 <   ColumnDefinition     /  >  
 <   ColumnDefinition    宽度  = 自动  /  >  
 <   ColumnDefinition     /  >  
 <   / Grid.ColumnDefinitions  >  
 
 <  网格    x：姓名  =  Gridimage1 >  
 <  图像   名称  =  image1 < span class =code-attribute>  拉伸  =  Uniform  
   
                      < span class =code-attribute>                  来源  =  http://eskipaper.com/images/cool-morning-fog-wallpaper-1.jpg  /  >  
 <  画布      x：名称  =  BackPanel    
   
                                            高度  =  {Binding ElementName = image1，Path = ActualHeight}  
   
                                            宽度  =  {Binding ElementName = image1，Path = ActualWidth} >  
 <  矩形    x ：名称  =  selectionRectangle    
   
                                                        描边  =  LightBlue   填充  = ＃220000FF    可见性  = < span class =code-keyword> Collapsed    /  >  
 <  < span class =code-leadattribute> / Canvas  >  
 <   / Grid  >  
 <  按钮   内容  = >>    Grid.Column   =  1   名称  = 去    
   
                                  点击  =  Go_Click    FontWeight   = 粗体    
   
                                   VerticalAlignment   = 中心   保证金  =  10  /  >  
 
 <  图片    Grid.Column   =  2   名称  =  image2   拉伸  = 统一    /   >  
 
 <   / Grid  >  
 <   / Window  >  

和MainWindow代码隐藏：

更新8月16日，2017年：新的样本图像显示缩放计算不正确。下面的代码有更正。

 使用系统; 
 使用 System.Windows; 
 使用 System.Windows.Controls; 
 使用 System.Windows.Input; 
 使用 System.Windows.Media.Imaging; 
 
 命名空间 WpfCropImage 
 {
  public   partial   class  MainWindow：Window 
 {
  private   bool  isDragging; 
  private  Point anchorPoint =  new  Point（）; 
 
  public  MainWindow（）
 {
 InitializeComponent（）; 
 
 Gridimage1.MouseLeftButtonDown + =  new  MouseButtonEventHandler（image1_MouseLeftButtonDown）; 
 Gridimage1.MouseMove + =  new  MouseEventHandler（image1_MouseMove）; 
 Gridimage1.MouseLeftButtonUp + =  new  MouseButtonEventHandler（image1_MouseLeftButtonUp）; 
 
 Go.IsEnabled =  false ; 
 image2.Source =  null ; 
} 
 
  private   void  Go_Click（ object  sender，RoutedEventArgs e）
 {
  if （image1.Source！=  null ）
 {
  var  rect1 =  new  Rect（）
 {
 X = Canvas.GetLeft（selectionRectangle），
 Y = Canvas.GetTop（selectionRectangle），
 Width = selectionRectangle.Width，
高度= selectionRectangle.Height 
}; 
 
  //   PIXEls中CroppedBitmap的计算比例...  
  var  img = image1.Source  as  BitmapSource; 
  var  scaleWidth =（img.PixelWidth）/（image1.ActualWidth）; 
  var  scaleHeight =（img.PixelHeight）/（image1.ActualHeight）; 
 
  var  rcFrom =  new  Int32Rect（）
 {
 X =（ int ）（rect1.X * scaleWidth），
 Y =（ int ）（rect1.Y * scaleHeight），
 Width =（ int ）（rect1.Width * scaleWidth），
 Height =（ int ）（rect1.Height * scaleHeight）
}; 
 
 image2.Source =  new  CroppedBitmap（inputImage，rcFrom）; 
} 
} 
   #region鼠标事件
  
  private   void  image1_MouseLeftButtonDown（ object  sender，MouseButtonEventArgs e）
 {
  if （！isDragging）
 {
 anchorPoint.X = e.GetPosition（BackPanel）.X; 
 anchorPoint.Y = e.GetPosition（BackPanel）.Y; 
 isDragging =  true ; 
} 
 
} 
 
  private   void  image1_MouseMove（ object  sender，MouseEventArgs e）
 {
  if （isDragging ）
 {
  double  x = e.GetPosition（BackPanel）.X; 
  double  y = e.GetPosition（BackPanel）.Y; 
 selectionRectangle.SetValue（Canvas.LeftProperty，Math.Min（x，anchorPoint.X））; 
 selectionRectangle.SetValue（Canvas.TopProperty，Math.Min（y，anchorPoint.Y））; 
 selectionRectangle.Width = Math.Abs​​（x  -  anchorPoint.X）; 
 selectionRectangle.Height = Math.Abs​​（y  -  anchorPoint.Y）; 
 
  if （selectionRectangle.Visibility！= Visibility.Visible）
 selectionRectangle.Visibility = Visibility.Visible; 
} 
} 
 
  private   void  image1_MouseLeftButtonUp（  object  sender，MouseButtonEventArgs e）
 {
  if （isDragging）
 {
 isDragging =  false ; 
  if （selectionRectangle.Width >   0 ）
 {
 Go.Visibility = Visibility.Visible; 
 Go.IsEnabled =  true ; 
} 
  if （selectionRectangle.Visibility！= Visibility.Visible）
 selectionRectangle.Visibility = Visibility.Visible; 
} 
} 
 
  private   void  RestRect（ ）
 {
 selectionRectangle.Visibility = Visibility.Collapsed; 
 isDragging =  false ; 
} 
 
   #endregion 
 } 
} 

i cant crop image on image control please help.

when i am transfer the canvas x,y,crop height and width to crop function it gives wrong small crop image


Thanks in advance.

What I have tried:

    Public Function Crop(ByVal srcBitmap As Bitmap, _
ByVal cropX As Integer, ByVal cropY As Integer, ByVal cropWidth As Integer, ByVal cropHeight As Integer) As Bitmap

        ' Create the new bitmap and associated graphics object
        Dim bmp As New Bitmap(srcBitmap, cropHeight, cropWidth)

        Dim g As Graphics = Graphics.FromImage(bmp)

        Dim rect As Rectangle = New Rectangle(cropX, cropY, cropWidth, cropHeight)
        ' Draw the specified section of the source bitmap to the new one
        g.DrawImage(srcBitmap, New Rectangle(0, 0, cropHeight, cropWidth), rect, GraphicsUnit.Pixel)
        ' Clean up
        srcBitmap.Dispose()
        Return bmp



    End Function

解决方案

Microsoft WPF documents has a great example for you: How to: Crop an Image | Microsoft Docs[^]

Okay, it appears that you have a calculation error - one of the values may be double.NAN[^].

This code has the same problem and was not picked up by those that responded: c# - Crop Image using Canvas Rectangle - Stack Overflow[^]

The problem is with these calculations:

rcFrom.X = (int)((rect1.X) * (image1.Source.Width) /(image1.Width));
rcFrom.Y = (int)((rect1.Y) *(image1.Source.Height) / (image1.Height));
rcFrom.Width = (int)((rect1.Width) * (image1.Source.Width) /(image1.Width));
rcFrom.Height = (int)((rect1.Height) * (image1.Source.Height) /(image1.Height));

Testing & debugging has shown that image1.Height and image1.Width are returning double.NAN properties. What they should be using is image1.ActualHeight and Actualimage1.Width properties.

Here is a corrected working version of the code (above link in this solution) working with an image size of 3840 x 2160 jpeg image:

XAML MainWindow:

<Window

    x:Class="WpfCropImage.MainWindow"

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"



    mc:Ignorable="d"

    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"



    Title="CodeProject Answer - WPF Scale & Crop Images"

    Height="600" Width="1200" WindowStartupLocation="CenterScreen">

    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition Width="Auto"/>
            <ColumnDefinition />
        </Grid.ColumnDefinitions>

        <Grid x:Name="Gridimage1">
            <Image Name="image1" Stretch="Uniform"

                   Source="http://eskipaper.com/images/cool-morning-fog-wallpaper-1.jpg"/>
            <Canvas  x:Name="BackPanel" 

                     Height="{Binding ElementName=image1, Path=ActualHeight}"

                     Width="{Binding ElementName=image1, Path=ActualWidth}">
                <Rectangle x:Name="selectionRectangle" 

                           Stroke="LightBlue" Fill="#220000FF" Visibility="Collapsed" />
            </Canvas>
        </Grid>
        <Button Content=">>" Grid.Column="1" Name="Go" 

                Click="Go_Click" FontWeight="Bold" 

                VerticalAlignment="Center" Margin="10"/>

        <Image Grid.Column="2" Name="image2" Stretch="Uniform" />

    </Grid>
</Window>

And the MainWindow code-behind:
UPDATE Aug 16, 2017: The new sample image showed that the scaling calculation was incorrect. Below code has the correction.

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media.Imaging;

namespace WpfCropImage
{
    public partial class MainWindow : Window
    {
        private bool isDragging;
        private Point anchorPoint = new Point();

        public MainWindow()
        {
            InitializeComponent();

            Gridimage1.MouseLeftButtonDown += new MouseButtonEventHandler(image1_MouseLeftButtonDown);
            Gridimage1.MouseMove += new MouseEventHandler(image1_MouseMove);
            Gridimage1.MouseLeftButtonUp += new MouseButtonEventHandler(image1_MouseLeftButtonUp);

            Go.IsEnabled = false;
            image2.Source = null;
        }

        private void Go_Click(object sender, RoutedEventArgs e)
        {
            if (image1.Source != null)
            {
                var rect1 = new Rect()
                {
                    X = Canvas.GetLeft(selectionRectangle),
                    Y = Canvas.GetTop(selectionRectangle),
                    Width = selectionRectangle.Width,
                    Height = selectionRectangle.Height
                };

                // calc scale in PIXEls for CroppedBitmap...
                var img = image1.Source as BitmapSource;
                var scaleWidth = (img.PixelWidth) / (image1.ActualWidth);
                var scaleHeight = (img.PixelHeight) / (image1.ActualHeight);

                var rcFrom = new Int32Rect()
                {
                    X = (int)(rect1.X * scaleWidth),
                    Y = (int)(rect1.Y * scaleHeight),
                    Width = (int)(rect1.Width * scaleWidth),
                    Height = (int)(rect1.Height * scaleHeight)
                };

                image2.Source = new CroppedBitmap(inputImage, rcFrom);
            }
        }
        #region "Mouse events"

        private void image1_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            if (!isDragging)
            {
                anchorPoint.X = e.GetPosition(BackPanel).X;
                anchorPoint.Y = e.GetPosition(BackPanel).Y;
                isDragging = true;
            }

        }

        private void image1_MouseMove(object sender, MouseEventArgs e)
        {
            if (isDragging)
            {
                double x = e.GetPosition(BackPanel).X;
                double y = e.GetPosition(BackPanel).Y;
                selectionRectangle.SetValue(Canvas.LeftProperty, Math.Min(x, anchorPoint.X));
                selectionRectangle.SetValue(Canvas.TopProperty, Math.Min(y, anchorPoint.Y));
                selectionRectangle.Width = Math.Abs(x - anchorPoint.X);
                selectionRectangle.Height = Math.Abs(y - anchorPoint.Y);

                if (selectionRectangle.Visibility != Visibility.Visible)
                    selectionRectangle.Visibility = Visibility.Visible;
            }
        }

        private void image1_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            if (isDragging)
            {
                isDragging = false;
                if (selectionRectangle.Width > 0)
                {
                    Go.Visibility = Visibility.Visible;
                    Go.IsEnabled = true;
                }
                if (selectionRectangle.Visibility != Visibility.Visible)
                    selectionRectangle.Visibility = Visibility.Visible;
            }
        }

        private void RestRect()
        {
            selectionRectangle.Visibility = Visibility.Collapsed;
            isDragging = false;
        }

        #endregion
    }
}

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