使用Xamarin Forms显示图像 [英] Displaying an image with Xamarin Forms

问题描述

已解决: 答案是更新所有nuget程序包，并以较新版本的Android为目标.现在，图像将按预期加载.我对此不满意，因为我完全使用了Xamarin提供的代码，并且以较新版本为目标已经弃用了代码所依赖的某些项目.最初的版本是Xamarin.Forms v23，我更新到了V25

我有一个全新的Xamarin表单项目，具有一个简单的视图，试图在其中显示图像.我尝试了几种方法来显示图像，但我一点也没有运气.

I have a brand new Xamarin forms project with a simple view in which I'm trying to display an image. I've tried several ways of getting an image to display and I am not having any luck at all.

我正在使用<image>，我也尝试过FFImageLoader控件.

I'm using <image> and I have also tried FFImageLoader control as well.

<StackLayout Orientation="Vertical">

        <ff:CachedImage Source="https://static.pexels.com/photos/104827/cat-pet-animal-domestic-104827.jpeg" WidthRequest="100" HeightRequest="100" />

        <Button x:Name="btn" Text="Image" Clicked="Button_Clicked" />

        <Frame OutlineColor="Red">
            <Image x:Name="StupidImage" Source="{Binding Thumbnail}"  Aspect="Fill" HeightRequest="100" WidthRequest="100"   />
        </Frame>

        </StackLayout>

这是当前视图.我还直接将Source设置为没有结果的值.

This is the current view. I've also set the Source directly to a value with no result.

我能够获得图像的流.我能够从流中读取所有字节.我构建了一个调试可视化器，以将字节显示为图像.从来源获取图像不是问题.获取图像控件以显示图像是一个问题.

I'm able to get a stream for the image. I'm able to read all of the bytes from the stream. I built a debug visualizer to display the bytes as an image. Getting the image from a source is not a problem. Getting the image control(s) to display the image is a problem.

我尝试与视图模型绑定.当失败时，我尝试直接设置来源

I tried binding with a view model. When that failed, I tried that directly setting the source

StupidImage.Source = ImageSource.FromStream(() => result.Stream);

我还制作了字节的副本并尝试了

I also made a copy of the bytes and tried

StupidImage.Source = ImageSource.FromStream(() => new MemoryStream(imageBytes));

我尝试了ImageSource.FromFile()和.FromUri.我尝试将图像作为资源添加到项目中.每次尝试都相同，读取了资源并且字节可用，但是图像控件只是不显示它.

I've tried ImageSource.FromFile() and .FromUri. I tried adding an image to the project as a resource. Each try was the same, the resource was read and the bytes were available, but the image control just doesn't display it.

我认为这可能是大小问题，因此我设置了控件的大小.没有.我以为这可能是分辨率问题，所以我使用了较小的图像.我尝试了几种不同质量的图像.

I thought maybe it was a size problem, so I set the size of the control. Nothing. I thought maybe it was a resolution problem, so I used a smaller image. I tried several different images of varying quality.

然后我放弃了图像控件，得到了FFImageLoading nuget包，并给了它直接指向图像的URL.与FFImageLoading示例使用的示例相同.仍然没有图像.

Then I gave up on the image control and I got the FFImageLoading nuget package and gave it a direct url to an image. Same example that FFImageLoading examples used. Still no image.

我尝试了模拟器，并尝试了2种不同的物理设备.结果相同.

I tried the emulator and I tried 2 different physical devices. Same result.

我还尝试使用btn.Image = "whatever.jpg"在按钮上设置图像，结果相同.

I also tried setting an image on a button using btn.Image = "whatever.jpg" with the same result.

这是每次的结果.我迷路了.如何显示图像?

This is the result every time. I'm lost. How do I get images to display?

我确实做到了这一点，但仅限于模拟器

I did get this to work, but only on the emulator

<Image x:Name="StupidImage" Source="https://static.pexels.com/photos/104827/cat-pet-animal-domestic-104827.jpeg" />

和

StupidImage.Source = ImageSource.FromUri(new Uri("https://static.pexels.com/photos/104827/cat-pet-animal-domestic-104827.jpeg"));

编辑2-澄清

我的目标是允许用户从设备中选择照片，然后显示其预览.

My goal is to allow the user to select a photo from the device and then display a preview of it.

推荐答案

如果您想在应用中使用图片，则可以将其加载到共享项目中，例如

If you want to use images in you app you can load them into your Shared Project, like

请确保将构建操作更改为嵌入式资源

然后在您的代码中

image.Source = ImageSource.FromResource("App5.Images.useravatar.png");

记下资源名称.

和XAML

<ContentPage.Content>
    <StackLayout>
        <Image x:Name="image" WidthRequest="50"/>
    </StackLayout>
</ContentPage.Content>

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