Question

我一直在使用Windows 8.1 RT应用，用户使用 Stretch = Uniform 加载图片。图像可以尽可能小并且尽可能大。剪切发生在我的用户控件中，当我点击/按住屏幕/图像时出现我的用户控件。当我点击并按住并将手指/鼠标移动到背景中的图像时，会发生剪切。

我面临的问题是

每当应用程序首次在模拟器上加载时，并且在第一次执行点击/单击并按住时，用户控件将显示在屏幕的左上角，然后它会显示在屏幕上方我的点击/保持区域。我需要的是它应该总是出现在我点击并按住的任何地方，每当我点击并按住时。释放手指/鼠标时，它应该会崩溃。
我正在使用中心转换。我希望我的鼠标当前所在的区域（像素）正好在用户控件的中心中显示，如果我正在加载480 * 800甚至更小的小分辨率图像，我的老鼠没有进入中心。为了更清楚，想象一下，我正在点击并按住人眼的 CORNEA 。角膜应显示在用户控制的中心，上方和下方的区域应覆盖部分的其余部分
1. 我不希望我的控件超出我的图像边界，如果我的鼠标位于图像的最后一个像素，则应显示图像的某些部分和背景的某些部分。
我需要旋转控件，如 video 所示找到下面的完整代码。

MainPage.xaml中

<Page
    x:Class="App78.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:App78"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid
        x:Name="LayoutGrid"
        Margin="0,0"
        Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
        Holding="LayoutGrid_Holding"
        PointerMoved="LayoutGrid_OnPointerMoved"
        PointerWheelChanged="LayoutGrid_OnPointerWheelChanged"
        PointerPressed="LayoutGrid_OnPointerPressed"
        PointerReleased="LayoutGrid_OnPointerReleased">
        <Image
            x:Name="BigImage"
            HorizontalAlignment="Center"
            VerticalAlignment="Center"
            Stretch="Uniform"
            Source="http://blog.al.com/space-news/2009/04/iss015e22574.jpg" />

        <local:Magnifier VerticalAlignment="Top" HorizontalAlignment="Left" x:Name="MagnifierTip" Visibility="Collapsed" />
    </Grid>
</Page>

MainPage.xaml.cs中

using System;
using System.Diagnostics;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Media.Imaging;

namespace App78
{
    public sealed partial class MainPage : Page
    {
        private double zoomScale = 2;
        private double pointerX = 0;
        private double pointerY = 0;
        private const double MinZoomScale = .25;
        private const double MaxZoomScale = 32;


        public MainPage()
        {
            this.InitializeComponent();

            var bi = (BitmapImage)BigImage.Source;
            bi.ImageOpened += bi_ImageOpened;
            this.SizeChanged += MainPage_SizeChanged;
        }

        void MainPage_SizeChanged(object sender, Windows.UI.Xaml.SizeChangedEventArgs e)
        {
            this.UpdateImageLayout();
        }

        void bi_ImageOpened(object sender, Windows.UI.Xaml.RoutedEventArgs e)
        {
            this.UpdateImageLayout();
        }

        private void UpdateImageLayout()
        {
            var bi = (BitmapImage)BigImage.Source;
            if (bi.PixelWidth < this.LayoutGrid.ActualWidth &&
                bi.PixelHeight < this.LayoutGrid.ActualHeight)
            {
                this.BigImage.Stretch = Stretch.None;
            }
            else
            {
                this.BigImage.Stretch = Stretch.Uniform;
            }

            this.UpdateMagnifier();
        }

        private void LayoutGrid_OnPointerMoved(object sender, PointerRoutedEventArgs e)
        {
            //DV: If pointer is not in contact we can ignore it
            if (!e.Pointer.IsInContact) { return; }

            var point = e.GetCurrentPoint(this.LayoutGrid);
            this.pointerX = point.Position.X;
            this.pointerY = point.Position.Y;
            this.UpdateMagnifier();
        }

        private void UpdateMagnifier()
        {
            var bi = (BitmapImage)BigImage.Source;

            double offsetX = 0;
            double offsetY = 0;
            double imageScale = 1;

            var imageRatio = (double)bi.PixelWidth / bi.PixelHeight;
            var gridRatio = this.LayoutGrid.ActualWidth / this.LayoutGrid.ActualHeight;

            if (bi.PixelWidth < this.LayoutGrid.ActualWidth &&
                bi.PixelHeight < this.LayoutGrid.ActualHeight)
            {
                offsetX = 0.5 * (this.LayoutGrid.ActualWidth - bi.PixelWidth);
                offsetY = 0.5 * (this.LayoutGrid.ActualHeight - bi.PixelHeight);
                //imageScale = 1; - remains
            }
            else if (imageRatio < gridRatio)
            {
                offsetX = 0.5 * (this.LayoutGrid.ActualWidth - imageRatio * this.LayoutGrid.ActualHeight);
                offsetY = 0;
                imageScale = BigImage.ActualHeight / bi.PixelHeight;
            }
            else
            {
                offsetX = 0;
                offsetY = 0.5 * (this.LayoutGrid.ActualHeight - this.LayoutGrid.ActualWidth / imageRatio);
                imageScale = BigImage.ActualWidth / bi.PixelWidth;
            }

            //DV: This is probably not need anymore
           //MagnifierTip.MagnifierTransform.X = this.pointerX;
           //MagnifierTip.MagnifierTransform.Y = this.pointerY;
            MagnifierTip.PositionTransform.X = (-this.pointerX + offsetX) / imageScale;
            MagnifierTip.PositionTransform.Y = (-this.pointerY + offsetY) / imageScale;

            //DV: I haven't tested the Scaling/Zoom
            MagnifierTip.ZoomTransform.ScaleX = imageScale * zoomScale;
            MagnifierTip.ZoomTransform.ScaleY = imageScale * zoomScale;

            MagnifierTip.CenterTransform.X = MagnifierTip.MagnifierEllipse.ActualWidth / 2 - MagnifierTip.MagnifierEllipse.StrokeThickness / 2;
            MagnifierTip.CenterTransform.Y = MagnifierTip.MagnifierEllipse.ActualHeight / 2 - MagnifierTip.MagnifierEllipse.StrokeThickness / 2;

            //DV: I added a GlobalGrid Transform which translates every children
            MagnifierTip.MagnifierTransformGrid.X = this.pointerX - (MagnifierTip.ActualWidth / 2);
            MagnifierTip.MagnifierTransformGrid.Y = this.pointerY - (MagnifierTip.ActualHeight); ;

        }

        private void LayoutGrid_OnPointerWheelChanged(object sender, PointerRoutedEventArgs e)
        {
            if (e.GetCurrentPoint(this.LayoutGrid).Properties.MouseWheelDelta > 0)
            {
                zoomScale = Math.Max(MinZoomScale, Math.Min(MaxZoomScale, zoomScale * 1.2));
            }
            else
            {
                zoomScale = Math.Max(MinZoomScale, Math.Min(MaxZoomScale, zoomScale / 1.2));
            }

            this.UpdateMagnifier();
        }


        //DV: Holding usually only works with touch https://msdn.microsoft.com/en-us/library/windows/apps/windows.ui.xaml.uielement.holding.aspx?f=255&MSPPError=-2147217396
        private void LayoutGrid_Holding(object sender, HoldingRoutedEventArgs e)
        {
            //
        }

        //DV: pointer pressed supports both mouse and touch but fires immeadiatley. You'll have to figure out a delay strategy or using holding for touch and right click for mouse
        private void LayoutGrid_OnPointerPressed(object sender, PointerRoutedEventArgs e)
        {
            MagnifierTip.Visibility = Windows.UI.Xaml.Visibility.Visible;
        }

        //DV: pointer released supports both mouse and touch.
        private void LayoutGrid_OnPointerReleased(object sender, PointerRoutedEventArgs e)
        {
            MagnifierTip.Visibility = Windows.UI.Xaml.Visibility.Collapsed;
        }
    }
}

Magnifier.XAML

<UserControl
    x:Class="App78.Magnifier"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:App78"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Height="230"
    Width="170">


    <Grid Height="230" Width="170">

        <!-- DV: This is the global transform I added -->
        <Grid.RenderTransform>
            <TransformGroup>
                <TranslateTransform x:Name="MagnifierTransformGrid" x:FieldModifier="public"/>
            </TransformGroup>
        </Grid.RenderTransform>
        <Ellipse Opacity="1" Visibility="Visible" Fill="{ThemeResource ApplicationPageBackgroundThemeBrush}"  HorizontalAlignment="Center" VerticalAlignment="Top" IsHitTestVisible="False" Width="135" Height="128"  StrokeThickness="3" Margin="0,17,0,0" />
        <Ellipse x:Name="MagnifierEllipse" x:FieldModifier="public" Opacity="1" Visibility="Visible" HorizontalAlignment="Left" VerticalAlignment="Top" IsHitTestVisible="False" Width="150" Height="150" Stroke="White" StrokeThickness="3" Margin="11,8,0,0" >
            <Ellipse.Fill>
                <ImageBrush
                    ImageSource="http://blog.al.com/space-news/2009/04/iss015e22574.jpg"
                    Stretch="None"
                    AlignmentX="Left"
                    AlignmentY="Top">
                    <ImageBrush.Transform>
                        <TransformGroup>
                            <TranslateTransform x:FieldModifier="public"
                                x:Name="CenterTransform"/>
                            <TranslateTransform x:FieldModifier="public"
                                x:Name="PositionTransform"/>
                            <ScaleTransform x:FieldModifier="public"
                                x:Name="ZoomTransform"/>
                        </TransformGroup>
                    </ImageBrush.Transform>
                </ImageBrush>
            </Ellipse.Fill>
        </Ellipse>
        <Path Data="M25.533,0C15.457,0,7.262,8.199,7.262,18.271c0,9.461,13.676,19.698,17.63,32.338 c0.085,0.273,0.34,0.459,0.626,0.457c0.287-0.004,0.538-0.192,0.619-0.467c3.836-12.951,17.666-22.856,17.667-32.33 C43.803,8.199,35.607,0,25.533,0z M25.533,32.131c-7.9,0-14.328-6.429-14.328-14.328c0-7.9,6.428-14.328,14.328-14.328 c7.898,0,14.327,6.428,14.327,14.328C39.86,25.702,33.431,32.131,25.533,32.131z"
              Fill="#FFF4F4F5"
              Stretch="Fill"
              Stroke="Black"
              UseLayoutRounding="False"
              Height="227"
              Width="171" ></Path>
    </Grid>
</UserControl>

为方便起见，可以从here下载项目。为了更好地理解，我希望您看到video。这正是我需要实现的目标。

Answer 1

我使用了一些更改和三角函数here。

<强> MainPage.xaml中

<Page
    x:Class="MagnifierApp.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:MagnifierApp"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid
        x:Name="LayoutGrid"
        Margin="0,0"
        Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
        PointerMoved="LayoutGrid_OnPointerMoved"
        PointerWheelChanged="LayoutGrid_OnPointerWheelChanged"
        PointerPressed="LayoutGrid_OnPointerPressed"
        PointerReleased="LayoutGrid_OnPointerReleased">
        <Image
            x:Name="BigImage"
            HorizontalAlignment="Center"
            VerticalAlignment="Center"
            Stretch="Uniform"
            Source="http://blog.al.com/space-news/2009/04/iss015e22574.jpg" />
        <local:Magnifier
            x:Name="MagnifierTip"
            VerticalAlignment="Top"
            HorizontalAlignment="Left"
            Visibility="Collapsed" />
    </Grid>
</Page>

<强> MainPage.xaml.cs中

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

namespace MagnifierApp
{
    public sealed partial class MainPage : Page
    {
        private double zoomScale = 2;
        private double pointerX = 0;
        private double pointerY = 0;
        private const double MinZoomScale = .25;
        private const double MaxZoomScale = 32;
        private bool isFirst = true;

        public MainPage()
        {
            this.InitializeComponent();

            var bi = (BitmapImage)BigImage.Source;
            bi.ImageOpened += bi_ImageOpened;
            this.SizeChanged += MainPage_SizeChanged;
        }

        void MainPage_SizeChanged(object sender, Windows.UI.Xaml.SizeChangedEventArgs e)
        {
            this.UpdateImageLayout();
        }

        void bi_ImageOpened(object sender, Windows.UI.Xaml.RoutedEventArgs e)
        {
            this.UpdateImageLayout();
        }

        private void UpdateImageLayout()
        {
            var bi = (BitmapImage)BigImage.Source;

            if (bi.PixelWidth < this.LayoutGrid.ActualWidth &&
                bi.PixelHeight < this.LayoutGrid.ActualHeight)
            {
                this.BigImage.Stretch = Stretch.None;
            }
            else
            {
                this.BigImage.Stretch = Stretch.Uniform;
            }

            this.UpdateMagnifier();
        }

        private void LayoutGrid_OnPointerMoved(object sender, PointerRoutedEventArgs e)
        {
            if (!e.Pointer.IsInContact)
            {
                return;
            }

            var point = e.GetCurrentPoint(this.LayoutGrid);
            this.pointerX = point.Position.X;
            this.pointerY = point.Position.Y;
            this.UpdateMagnifier();
        }

        private void LayoutGrid_OnPointerWheelChanged(object sender, PointerRoutedEventArgs e)
        {
            if (e.GetCurrentPoint(this.LayoutGrid).Properties.MouseWheelDelta > 0)
            {
                zoomScale = Math.Max(MinZoomScale, Math.Min(MaxZoomScale, zoomScale * 1.2));
            }
            else
            {
                zoomScale = Math.Max(MinZoomScale, Math.Min(MaxZoomScale, zoomScale / 1.2));
            }

            this.UpdateMagnifier();
        }

        private void LayoutGrid_OnPointerPressed(object sender, PointerRoutedEventArgs e)
        {
            if (!e.Pointer.IsInContact) { return; }

            var point = e.GetCurrentPoint(this.LayoutGrid);

            this.pointerX = point.Position.X;
            this.pointerY = point.Position.Y;
            this.UpdateMagnifier();
            MagnifierTip.Visibility = Windows.UI.Xaml.Visibility.Visible;
        }

        private void LayoutGrid_OnPointerReleased(object sender, PointerRoutedEventArgs e)
        {
            MagnifierTip.Visibility = Windows.UI.Xaml.Visibility.Collapsed;
        }

        private void UpdateMagnifier()
        {
            var bi = (BitmapImage)BigImage.Source;

            double offsetX;
            double offsetY;
            double imageScale;
            CalculateImageScaleAndOffsets(bi, out offsetX, out offsetY, out imageScale);

            MagnifierTip.PositionTransform.X = (-this.pointerX + offsetX) / imageScale;
            MagnifierTip.PositionTransform.Y = (-this.pointerY + offsetY) / imageScale;
            MagnifierTip.ZoomTransform.ScaleX = imageScale * zoomScale;
            MagnifierTip.ZoomTransform.ScaleY = imageScale * zoomScale;

            MagnifierTip.CenterTransform.X = MagnifierTip.MagnifierEllipse.ActualWidth / 2 - MagnifierTip.MagnifierEllipse.StrokeThickness / 2;
            MagnifierTip.CenterTransform.Y = MagnifierTip.MagnifierEllipse.ActualHeight / 2 - MagnifierTip.MagnifierEllipse.StrokeThickness / 2;

            MagnifierTip.MagnifierTranslateTransform.X = this.pointerX - (MagnifierTip.ActualWidth / 2);
            MagnifierTip.MagnifierTranslateTransform.Y = this.pointerY - (MagnifierTip.ActualHeight);

            bool tooHigh = MagnifierTip.MagnifierTranslateTransform.Y < 0;
            bool tooLeft = MagnifierTip.MagnifierTranslateTransform.X < 0;
            bool tooRight = MagnifierTip.MagnifierTranslateTransform.X + MagnifierTip.ActualWidth > this.LayoutGrid.ActualWidth;

            if (tooHigh || tooLeft || tooRight)
            {
                double angle = 0.0;

                if (tooLeft && !tooHigh)
                {
                    var dx = -MagnifierTip.MagnifierTranslateTransform.X;
                    var r = MagnifierTip.ActualHeight - MagnifierTip.ActualWidth / 2;
                    var arad = Math.Asin(dx / r);
                    angle = arad * 180 / Math.PI;
                }
                else if (tooLeft && tooHigh)
                {
                    var dx = -MagnifierTip.MagnifierTranslateTransform.X;
                    var dy = -MagnifierTip.MagnifierTranslateTransform.Y;
                    var r = MagnifierTip.ActualHeight - MagnifierTip.ActualWidth / 2;
                    var arad1 = Math.Asin(dx / r);
                    var arad2 = Math.Acos((r - dy) / r);
                    var arad = Math.Max(arad1, arad2);
                    angle = arad * 180 / Math.PI;
                }
                else if (tooHigh && !tooRight)
                {
                    var dy = -MagnifierTip.MagnifierTranslateTransform.Y;
                    var r = MagnifierTip.ActualHeight - MagnifierTip.ActualWidth / 2;
                    var arad = Math.Acos((r - dy) / r);

                    if (MagnifierTip.MagnifierTranslateTransform.X + Math.Sin(arad) * r + MagnifierTip.ActualWidth > this.LayoutGrid.ActualWidth)
                    {
                        arad = -arad;
                    }

                    angle = arad * 180 / Math.PI;
                }
                else if (tooHigh)
                {
                    var dy = -MagnifierTip.MagnifierTranslateTransform.Y;
                    var dx = MagnifierTip.MagnifierTranslateTransform.X + MagnifierTip.ActualWidth - this.LayoutGrid.ActualWidth;
                    var r = MagnifierTip.ActualHeight - MagnifierTip.ActualWidth / 2;
                    var arad1 = -Math.Acos((r - dy) / r);
                    var arad2 = -Math.Asin(dx / r);
                    var arad = Math.Min(arad1, arad2);
                    angle = arad * 180 / Math.PI;
                }
                else //if (tooRight)
                {
                    var dx = MagnifierTip.MagnifierTranslateTransform.X + MagnifierTip.ActualWidth - this.LayoutGrid.ActualWidth;
                    var r = MagnifierTip.ActualHeight - MagnifierTip.ActualWidth / 2;
                    var arad = -Math.Asin(dx / r);
                    angle = arad * 180 / Math.PI;
                }

                MagnifierTip.RotateTransform.Angle = angle;
                MagnifierTip.LensRotateTransform.Angle = -angle;
            }
            else
            {
                MagnifierTip.RotateTransform.Angle = 0;
                MagnifierTip.LensRotateTransform.Angle = 0;
            }
        }

        private void CalculateImageScaleAndOffsets(BitmapImage bi, out double offsetX, out double offsetY, out double imageScale)
        {
            var imageRatio = (double)bi.PixelWidth / bi.PixelHeight;
            var gridRatio = this.LayoutGrid.ActualWidth / this.LayoutGrid.ActualHeight;

            if (bi.PixelWidth < this.LayoutGrid.ActualWidth &&
                bi.PixelHeight < this.LayoutGrid.ActualHeight)
            {
                offsetX = 0.5 * (this.LayoutGrid.ActualWidth - bi.PixelWidth);
                offsetY = 0.5 * (this.LayoutGrid.ActualHeight - bi.PixelHeight);
                imageScale = 1;
            }
            else if (imageRatio < gridRatio)
            {
                offsetX = 0.5 * (this.LayoutGrid.ActualWidth - imageRatio * this.LayoutGrid.ActualHeight);
                offsetY = 0;
                imageScale = BigImage.ActualHeight / bi.PixelHeight;
            }
            else
            {
                offsetX = 0;
                offsetY = 0.5 * (this.LayoutGrid.ActualHeight - this.LayoutGrid.ActualWidth / imageRatio);
                imageScale = BigImage.ActualWidth / bi.PixelWidth;
            }
        }
    }
}

<强> Magnifier.xaml

<UserControl
    x:Class="MagnifierApp.Magnifier"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:MagnifierApp"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Height="227"
    Width="170">
    <Grid
        Height="227"
        Width="170"
        RenderTransformOrigin="0.5,1">
        <Grid.RenderTransform>
            <TransformGroup>
                <RotateTransform
                    x:FieldModifier="public"
                    x:Name="RotateTransform"
                    Angle="0" />
                <TranslateTransform
                    x:Name="MagnifierTranslateTransform"
                    x:FieldModifier="public" />
            </TransformGroup>
        </Grid.RenderTransform>
        <Ellipse
            HorizontalAlignment="Left"
            VerticalAlignment="Top"
            IsHitTestVisible="False"
            Width="152"
            Height="152"
            Fill="{ThemeResource ApplicationPageBackgroundThemeBrush}"
            Margin="9,10,0,0"
            RenderTransformOrigin="0.5,0.5"
            StrokeThickness="0">
        </Ellipse>
        <Ellipse
            x:Name="MagnifierEllipse"
            x:FieldModifier="public"
            HorizontalAlignment="Left"
            VerticalAlignment="Top"
            IsHitTestVisible="False"
            Width="152"
            Height="152"
            Stroke="White"
            Margin="9,10,0,0"
            RenderTransformOrigin="0.5,0.5"
            StrokeThickness="0">
            <Ellipse.RenderTransform>
                <RotateTransform
                    x:FieldModifier="public"
                    x:Name="LensRotateTransform"
                    Angle="0" />
            </Ellipse.RenderTransform>
            <Ellipse.Fill>
                <ImageBrush
                    ImageSource="http://blog.al.com/space-news/2009/04/iss015e22574.jpg"
                    Stretch="None"
                    AlignmentX="Left"
                    AlignmentY="Top">
                    <ImageBrush.Transform>
                        <TransformGroup>
                            <TranslateTransform
                                x:FieldModifier="public"
                                x:Name="PositionTransform" />
                            <ScaleTransform
                                x:FieldModifier="public"
                                x:Name="ZoomTransform" />
                            <TranslateTransform
                                x:FieldModifier="public"
                                x:Name="CenterTransform" />
                        </TransformGroup>
                    </ImageBrush.Transform>
                </ImageBrush>
            </Ellipse.Fill>
        </Ellipse>
        <Path
            Data="M85,11 C43.8548,11 10.5,44.3548 10.5,85.5 C10.5,126.645 43.8548,160 85,160 C126.145,160 159.5,126.645 159.5,85.5 C159.5,44.3548 126.145,11 85,11 z M85,0.5 C131.668,0.5 169.5,38.3319 169.5,85 C169.5,103.959 163.256,121.459 152.713,135.558 L151.895,136.625 L152,136.625 L84.2999,226 L18,136.625 L18.1054,136.625 L17.2872,135.558 C6.74375,121.459 0.5,103.959 0.5,85 C0.5,38.3319 38.3319,0.5 85,0.5 z"
            Margin="0,0.5,0,0"
            Stretch="Fill"
            Stroke="Black"
            UseLayoutRounding="False"
            StrokeThickness="0"
            Fill="White" />
    </Grid>
</UserControl>

Answer 2

此处的修复1是即使在

内也更新放大镜

Bool

因此更新的方法看起来像

LayoutGrid_OnPointerPressed

这为您提供了所期望的行为。

解决边界问题

相对于BitImage而不是LayoutGrid计算上面的指针值。

if（this.pointerX＆lt; 0.0 || this.pointerY＆lt; 0.0）返回; if（this.pointerX＆gt; BigImage.ActualWidth || this.pointerY＆gt; BigImage.ActualHeight）返回; var bi =（BitmapImage）BigImage.Source;

到达边缘时的旋转就是在到达边缘时仔细计算旋转角度并应用旋转变换。

 private void LayoutGrid_OnPointerPressed(object sender, PointerRoutedEventArgs e)
        {
            MagnifierTip.Visibility = Windows.UI.Xaml.Visibility.Visible;

            var point = e.GetCurrentPoint(this.LayoutGrid);
            this.pointerX = point.Position.X;
            this.pointerY = point.Position.Y;
            this.UpdateMagnifier();
        }

希望这会有所帮助。

使用“变换”剪切低分辨率图像并将其指定给我的用户控件

2 个答案: