使用mvvm从Image Control获取加载的Image [英] Get the loaded Image from Image Control using mvvm

问题描述

我在检索WPF图像控件中显示的图像时出现问题

I have a problem with retrieving the image shown in my WPF Image Control

<Image x:Name="img" RenderTransformOrigin="0.5, 0.5" Source="{Binding ImageSource, Source={x:Static vm:ItemProvider.instance}, UpdateSourceTrigger=PropertyChanged}" >
                                            <Image.RenderTransform>
                                                <RotateTransform CenterX="0" CenterY="0" Angle="{Binding ElementName=ScrollBar, Path=Value}" />
                                            </Image.RenderTransform>

                                        </Image>

我使用滚动条旋转图像

我想检索它，如控件所示

And i want to retrieve it as shown in the control

这是我如何将图像加载到图像控件

this is how i load image to the Image Control

        private byte[] _ImageSource;
        public byte[] ImageSource
        {
            get { return _ImageSource; }
            set
            {
                _ImageSource = value;
                RaisePropertyChanged("ImageSource");
            }
        }

我正在尝试检索图片中显示的图片获取 ImageSource 进行控制，但它们不一样。我将图像旋转90度。但是当我加载它时，返回的图像是相同的。

I am trying to retrieve the image shown in the Image Control by getting the ImageSource but they are not the same. I rotate the Image 90 degrees. But the return Image is the same when i load it.

但是使用后面的代码我可以像这样访问图像

but using code behind i can access the image like this

img.Source 然后我将源转换为字节数组

img.Source then i convert the source into byte array

推荐答案

旋转Image元素不会在其Source属性中旋转ImageSource。

Rotating the Image element does in no way rotate the ImageSource in its Source property.

要创建旋转的ImageSource，请使用 TransformedBitmap ：

To create a rotated ImageSource, use a TransformedBitmap:

var sourceBitmap = new BitmapImage();

using (var stream = new MemoryStream(ImageSource))
{
    sourceBitmap.BeginInit();
    sourceBitmap.CacheOption = BitmapCacheOption.OnLoad;
    sourceBitmap.StreamSource = stream;
    sourceBitmap.EndInit();
}

// This should be another view model property that the Slider is bound to.
// Only multiples of 90 degrees are valid values.
var rotationAngle = 90d;

var rotation = new RotateTransform(rotationAngle);

var rotatedBitmap = new TransformedBitmap(sourceBitmap, rotation);

---

为避免您必须创建新来源每次转换的位图，您应该将ImageSource属性的类型从 byte [] 更改为 ImageSource 。

为了将其写回另一个 byte [] ，请使用 BitmapEncoder之一类，例如 PngBitapEncoder 。

In order to write this back into another byte[], use one of the BitmapEncoder classes, e.g. PngBitapEncoder.

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