如何调整在C＃的WinRT图像/ winmd？ [英] How to resize Image in C# WinRT/winmd?

问题描述

我有很简单的问题，但到目前为止，我发现没有答案：如何调整JPEG图像在C＃的WinRT / WinMD项目并将其保存为新的JPEG

I've got simple question, but so far I've found no answer: how to resize jpeg image in C# WinRT/WinMD project and save it as new jpeg?

我在开发Windows 8 Metro应用下载日常的图像格式的某些网站和一​​个Live平铺显示它。问题是图像必须小于1024x1024的小，比小200kB的，否则它不会显示在瓷砖：
<一href=\"http://msdn.microsoft.com/en-us/library/windows/apps/hh465403.aspx\">http://msdn.microsoft.com/en-us/library/windows/apps/hh465403.aspx

I'm developing Windows 8 Metro application for downloading daily image form certain site and displaying it on a Live Tile. The problem is the image must be smaller than 1024x1024 and smaller than 200kB, otherwise it won't show on the tile: http://msdn.microsoft.com/en-us/library/windows/apps/hh465403.aspx

如果我得到了较大的图像，如何调整它的大小为动态磁贴是贴合？我想只是简单的调整大小一样宽/ 2和高度/ 2保持纵横比。

If I got larger image, how to resize it to be fit for the Live Tile? I'm thinking just about simple resize like width/2 and height/2 with keeping the aspect ration.

下面的具体要求是：code必须为Windows运行时组件运行，因此WriteableBitmapEx库将不会在这里工作 - 它仅适用于常规WinRT的项目。甚至有一个作为winmd项目WriteableBitmapEx分支，但它准备远远

The specific requirement here is that the code must run as Windows Runtime Component, so WriteableBitmapEx library won't work here - it's only available for regular WinRT projects. There is even a branch for WriteableBitmapEx as winmd project, but it's far from ready.

推荐答案

如何扩展和作物例如，从<一个取href=\"http://social.msdn.microsoft.com/Forums/en-US/winappswithcsharp/thread/490b9c01-db4b-434f-8aff-d5c495e67e55\">here:

Example of how to scale and crop taken from here:

async private void BitmapTransformTest()
{
    // hard coded image location
    string filePath = "C:\\Users\\Public\\Pictures\\Sample Pictures\\fantasy-dragons-wallpaper.jpg";

    StorageFile file = await StorageFile.GetFileFromPathAsync(filePath);
    if (file == null)
        return;

    // create a stream from the file and decode the image
    var fileStream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read);
    BitmapDecoder decoder = await BitmapDecoder.CreateAsync(fileStream);


    // create a new stream and encoder for the new image
    InMemoryRandomAccessStream ras = new InMemoryRandomAccessStream();
    BitmapEncoder enc = await BitmapEncoder.CreateForTranscodingAsync(ras, decoder);

    // convert the entire bitmap to a 100px by 100px bitmap
    enc.BitmapTransform.ScaledHeight = 100;
    enc.BitmapTransform.ScaledWidth = 100;


    BitmapBounds bounds = new BitmapBounds();
    bounds.Height = 50;
    bounds.Width = 50;
    bounds.X = 50;
    bounds.Y = 50;
    enc.BitmapTransform.Bounds = bounds;

    // write out to the stream
    try
    {
        await enc.FlushAsync();
    }
    catch (Exception ex)
    {
        string s = ex.ToString();
    }

    // render the stream to the screen
    BitmapImage bImg = new BitmapImage();
    bImg.SetSource(ras);
    img.Source = bImg; // image element in xaml

}

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