我正在开发一个通用应用程序,在我的共享代码中,我尝试从网络下载图像并将图像保存到 LocalFolder。
我正在使用 HttpClient 从用户给定的 url 下载图像并读取客户端响应以保存图像。我正在使用下面的代码进行保存,但无法找到 Writeable SaveJpeg 方法。
HttpResponseMessage response = await httpClient.GetAsync(imageUri);
await Task.Run(async () =>
{
if (response.IsSuccessStatusCode)
{
// save image locally
StorageFolder folder = await ApplicationData.Current.LocalFolder.CreateFolderAsync("Images", CreationCollisionOption.OpenIfExists);
BitmapImage bmp = new BitmapImage();
var buffer = await response.Content.ReadAsBufferAsync();
InMemoryRandomAccessStream ras = new InMemoryRandomAccessStream();
DataWriter writer = new DataWriter(ras.GetOutputStreamAt(0));
writer.WriteBuffer(buffer);
bmp.SetSource(ras);
}
});
将图像响应保存到具有图像质量%的本地文件夹的最佳方法是什么(适用于 WP 和 Windows)。
您应该直接保存流而不是保存BitmapImage
.
像这样的东西。
var ras = new InMemoryRandomAccessStream();
var writer = new DataWriter(ras);
writer.WriteBuffer(buffer);
await writer.StoreAsync();
var inputStream = ras.GetInputStreamAt(0);
// you can still use this to display it on the UI though
//bmp.SetSource(ras);
// write the picture into this folder
var storageFile = await folder.CreateFileAsync("image1.jpg", CreationCollisionOption.GenerateUniqueName);
using (var storageStream = await storageFile.OpenAsync(FileAccessMode.ReadWrite))
{
await RandomAccessStream.CopyAndCloseAsync(inputStream, storageStream.GetOutputStreamAt(0));
}
Update
您可以使用BitmapEncoder
当传入属性 dpi 值时SetPixelData
.
using (var storageStream = await storageFile.OpenAsync(FileAccessMode.ReadWrite))
{
var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, storageStream);
var pixelStream = yourWriteableBitmap.PixelBuffer.AsStream();
var pixels = new byte[pixelStream.Length];
await pixelStream.ReadAsync(pixels, 0, pixels.Length);
encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore, (uint)yourWriteableBitmap.PixelWidth, (uint)yourWriteableBitmap.PixelHeight, 48, 48, pixels);
await encoder.FlushAsync();
}
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