[英]Operation is not valid due to the current state of the object
我開始開發winphone和諾基亞成像sdk。 我有兩個功能。
首先,我調用下面的函數將圖像更改為灰色
private async void PickImageCallback(object sender, PhotoResult e)
{
if (e.TaskResult != TaskResult.OK || e.ChosenPhoto == null)
{
return;
}
using (var source = new StreamImageSource(e.ChosenPhoto))
{
using (var filters = new FilterEffect(source))
{
var sampleFilter = new GrayscaleFilter();
filters.Filters = new IFilter[] { sampleFilter };
var target = new WriteableBitmap((int)CartoonImage.ActualWidth, (int)CartoonImage.ActualHeight);
var renderer = new WriteableBitmapRenderer(filters, target);
{
await renderer.RenderAsync();
_thumbnailImageBitmap = target;
CartoonImage.Source = target;
}
}
}
SaveButton.IsEnabled = true;
}
然后我調用函數將圖像更改為二進制顏色
private async void Binary(WriteableBitmap bm_image)
{
var target = new WriteableBitmap((int)CartoonImage.ActualWidth, (int)CartoonImage.ActualHeight);
MemoryStream stream= new MemoryStream();
bm_image.SaveJpeg(stream, bm_image.PixelWidth, bm_image.PixelHeight, 0, 100);
using (var source = new StreamImageSource(stream))
{
using (var filters = new FilterEffect(source))
{
var sampleFilter = new StampFilter(5, 0.7);
filters.Filters = new IFilter[] { sampleFilter };
var renderer1 =new WriteableBitmapRenderer(filters, target);
{
await renderer1.RenderAsync();
CartoonImage.Source = target;
}
}
}
}
但當它運行“await renderer1.RenderAsync();” 在第二個函數中,它不起作用。 我該如何解決呢。 您可以向我解釋“等待”和“異步”的工作原理嗎?
非常感謝你!
我大部分都在猜測,因為我不知道你得到了什么錯誤,但我很確定你的問題在於設置源代碼。 在創建StreamImageSource之前,您是否確定將內存流位置設置為開頭(0)?
嘗試添加:
stream.Position = 0;
在創建StreamImageSource之前。
而不是嘗試從可寫位圖創建內存流,我建議:
using Nokia.InteropServices.WindowsRuntime;
...
using (var source = new BitmapImageSource(bm_image.AsBitmap())
{
...
}
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