[英]How to capture screen programatically in windows phone 8.1 SDK?
任何想法如何從代碼中捕獲SDK 8.1 windows手機中的屏幕? 對於Windows Phone 7.5我已經看過代碼並試圖使用,但它失敗了。 :(
您可以使用RenderTargetBitmap
並將其傳遞給表示頁面的FrameworkElement,然后從中呈現位圖。
private async Task<RenderTargetBitmap> CreateBitmapFromElement(FrameworkElement uielement)
{
try
{
var renderTargetBitmap = new RenderTargetBitmap();
await renderTargetBitmap.RenderAsync(uielement);
return renderTargetBitmap;
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine(ex);
}
return null;
}
嘗試類似的東西:
private async void ButtonBase_OnClick(object sender, RoutedEventArgs e)
{
this.imagePreview.Source = await CreateBitmapFromElement(this);
}
頁面上的XAML是:
<Grid x:Name="controlsGrid">
<Button Click="ButtonBase_OnClick">take screenshot</Button>
<Image x:Name="imagePreview"
Height="200" VerticalAlignment="Bottom"
Stretch="UniformToFill" />
</Grid>
要將渲染圖像保存為圖像文件,我們必須將其發送到流,將其編碼為我們想要的文件類型。
這是我們可以使用的方法(它包含一個UI元素,一個流和一個Guid):
//Creates RenderTargetBitmap from UI Element
async Task<RenderTargetBitmap> CaptureToStreamAsync(FrameworkElement uielement, IRandomAccessStream stream, Guid encoderId)
{
try
{
var renderTargetBitmap = new RenderTargetBitmap();
await renderTargetBitmap.RenderAsync(uielement);
var pixels = await renderTargetBitmap.GetPixelsAsync();
var logicalDpi = DisplayInformation.GetForCurrentView().LogicalDpi;
var encoder = await BitmapEncoder.CreateAsync(encoderId, stream);
encoder.SetPixelData(
BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Ignore,
(uint)renderTargetBitmap.PixelWidth,
(uint)renderTargetBitmap.PixelHeight,
logicalDpi,
logicalDpi,
pixels.ToArray());
await encoder.FlushAsync();
return renderTargetBitmap;
}
然后,我們可以使用Windows Phone 8.1上的FileSavePicker類來確定文件類型,名稱和保存位置。
void CreateFileSavePicker()
{
//Create the picker object
FileSavePicker savePicker = new FileSavePicker();
// Dropdown of file types the user can save the file as
savePicker.FileTypeChoices.Add
(
"Image", new List<string>() { ".jpg" });
// Default file name if the user does not type one in or select // a file to replace
savePicker.SuggestedFileName = "Screenshot";
savePicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
//// Open the picker for the user to pick a file
savePicker.ContinuationData["Operation"] = "SomeDataOrOther";
savePicker.PickSaveFileAndContinue();
}
當用戶選擇文件位置時,它將返回到ContinueFileSavePicker。
public async void ContinueFileSavePicker(Windows.ApplicationModel.Activation.FileSavePickerContinu ationEventArgs args)
{
StorageFile file = args.File;
if (file != null)
{
// Prevent updates to the remote version of the file until we finish making changes and call CompleteUpdatesAsync.
CachedFileManager.DeferUpdates(file);
Guid encoderId = BitmapEncoder.JpegEncoderId;
try
{
using (var stream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
await CaptureToStreamAsync(LayoutRoot, stream, encoderId);
}
}
catch (Exception ex)
{
DisplayMessage(ex.Message);
}
}
}
更多細節在這里 。
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