在 Canvas 上拖放和调整图像大小 [英] Drag, drop and resize images on Canvas
问题描述
我想在我的通用 Windows 应用程序中创建一个拖放界面.用户将能够将图像从 ListView
(或类似的)拖放到 Canvas
,在那里他们可以调整图像大小和移动图像.
I want to create a drag and drop interface in my Universal Windows App. Users will be able to drag and drop images from a ListView
(or similar) to a Canvas
where they can resize and move the images.
我已经找到了移动图像的方法,但现在我似乎无法找到接受多点触控的方法,找不到合适的图像来调整大小,并调整图像本身的大小.
I have found how to move the images, but now I can't seem to find a way to accept multitouch, find the appropriate image to resize, and resize the image itself.
有没有简单的方法可以做到这一点?
Is there a simple way to do this?
推荐答案
这就是我最终采用的方法:
This is what I eventually went with:
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
namespace KindEnGezin.Windows.Views.MenuItems
{
public sealed partial class DrawView : Page
{
public DrawView()
{
InitializeComponent();
}
private void Image_OnManipulationStarted(object sender, ManipulationStartedRoutedEventArgs e)
{
((Image)sender).Opacity = 0.4;
}
private void Image_OnManipulationDelta(object sender, ManipulationDeltaRoutedEventArgs e)
{
var image = (Image)sender;
var transform = (CompositeTransform)image.RenderTransform;
// LEFT-RIGHT bounds
if (e.Delta.Translation.X < 0) // Going left
{
if (DrawingArea.ActualWidth / 2 + (transform.TranslateX + e.Delta.Translation.X) - image.ActualWidth / 2 > 0)
{
// Staying inside, apply translation
transform.TranslateX += e.Delta.Translation.X;
}
else
{
// Trying to go outside, because scale sucks to work with, move image back inside
transform.TranslateX = image.ActualWidth / 2 - DrawingArea.ActualWidth / 2;
}
}
else // Going right
{
if (DrawingArea.ActualWidth / 2 - (transform.TranslateX + e.Delta.Translation.X) +
image.ActualWidth * (0.5 - transform.ScaleX) > 0)
{
// Staying inside, apply translation
transform.TranslateX += e.Delta.Translation.X;
}
else
{
// Trying to go outside, because scale sucks to work with, move image back inside
transform.TranslateX = image.ActualWidth * (0.5 - transform.ScaleX) + DrawingArea.ActualWidth / 2;
}
}
// UP-DOWN bounds
if (e.Delta.Translation.Y < 0) // Going up
{
if (DrawingArea.ActualHeight / 2 + (transform.TranslateY + e.Delta.Translation.Y) - image.ActualHeight / 2 > 0)
{
// Staying inside, apply translation
transform.TranslateY += e.Delta.Translation.Y;
}
else
{
// Trying to go outside, because scale sucks to work with, move image back inside
transform.TranslateY = image.ActualHeight / 2 - DrawingArea.ActualHeight / 2;
}
}
else // Going down
{
if (DrawingArea.ActualHeight / 2 - (transform.TranslateY + e.Delta.Translation.Y) +
image.ActualHeight * (0.5 - transform.ScaleY) > 0)
{
// Staying inside, apply translation
transform.TranslateY += e.Delta.Translation.Y;
}
else
{
// Trying to go outside, because scale sucks to work with, move image back inside
transform.TranslateY = image.ActualHeight * (0.5 - transform.ScaleY) + DrawingArea.ActualHeight / 2;
}
}
}
// Only allow scaling when both dimensions are smaller than the drawingarea
if (image.ActualHeight*(transform.ScaleY*e.Delta.Scale) < DrawingArea.ActualHeight &&
image.ActualWidth*(transform.ScaleX*e.Delta.Scale) < DrawingArea.ActualWidth)
{
transform.ScaleX *= e.Delta.Scale;
transform.ScaleY *= e.Delta.Scale;
}
private void Image_OnManipulationCompleted(object sender, ManipulationCompletedRoutedEventArgs e)
{
((Image)sender).Opacity = 1;
}
}
}
和 XAML:
<Grid
Name="DrawingArea">
<Image
Source="../../Assets/Images/BigLogo.png"
Width="150"
Height="150"
ManipulationMode="TranslateX , TranslateY, Scale"
ManipulationStarted="Image_OnManipulationStarted"
ManipulationDelta="Image_OnManipulationDelta"
ManipulationCompleted="Image_OnManipulationCompleted">
<Image.RenderTransform>
<CompositeTransform/>
</Image.RenderTransform>
</Image>
</Grid>
这仅使用一个静态名称,用于包含这些图像的 Grid
.这样做允许将图像动态添加到 Grid
.
This is only using one static name, for the Grid
that contains these images. Doing this allows one to add images dynamically to the Grid
.
当图像超出边界时,我一直试图阻止缩放图像,但是我在尝试实现它时遇到了很多麻烦,所以当我检测到它试图移动时,我只是将它移动到边界超出范围.
I have been messing around with trying to block scaling the image when it goes outside of the bounds, but I had a lot of trouble trying to implement it, so I just move it to the boundary when I detect it's trying to move outside of the bounds.
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