[英]Cannot convert bitmap to byte[]
所以我正在制作一个 Xamarin.Forms 应用程序。 我有一个 StackLayout,我正在拍摄其中的快照(仅元素,而不是整个屏幕。)
这是界面:
public interface IViewSnapShot
{
Task<byte[]> CaptureAsync(Xamarin.Forms.View view);
}
这是事件:
private async Task SavePic_ClickedAsync(object sender, EventArgs e)
{
var imageByte = await DependencyService.Get<IViewSnapShot>().CaptureAsync(BlueprintSnapshot);
}
这是特定于 Android 平台的:
public class MakeViewSnapshot : IViewSnapShot
{
Task<byte[]> IViewSnapShot.CaptureAsync(Xamarin.Forms.View view)
{
var nativeView = view.GetRenderer().View;
var wasDrawingCacheEnabled = nativeView.DrawingCacheEnabled;
nativeView.DrawingCacheEnabled = true;
nativeView.BuildDrawingCache(false);
Bitmap bitmap = nativeView.GetDrawingCache(false);
// TODO: Save bitmap and return filepath
nativeView.DrawingCacheEnabled = wasDrawingCacheEnabled;
byte[] bitmapData;
using (var stream = new MemoryStream())
{
bitmap.Compress(Bitmap.CompressFormat.Png, 0, stream);
bitmapData = stream.ToArray();
}
return bitmapData;
}
}
问题是bitmapData
给出错误
无法将类型“byte[]”隐式转换为“System.Threading.Tasks.Task”
我有搜索互联网,每篇文章都说这是将位图转换为字节 [] 数组的方法。 知道如何解决这个错误吗?
稍后我想将 byte[] 数组上传到 web api。
您可以使用Task.FromResult()将结果包装到Task
,而不是返回byte[]
:
return Task.FromResult(bitmapData);
您的代码可能如下所示:
public class MakeViewSnapshot : IViewSnapShot
{
Task<byte[]> IViewSnapShot.CaptureAsync(Xamarin.Forms.View view)
{
var nativeView = view.GetRenderer().View;
var wasDrawingCacheEnabled = nativeView.DrawingCacheEnabled;
nativeView.DrawingCacheEnabled = true;
nativeView.BuildDrawingCache(false);
Bitmap bitmap = nativeView.GetDrawingCache(false);
// TODO: Save bitmap and return filepath
nativeView.DrawingCacheEnabled = wasDrawingCacheEnabled;
byte[] bitmapData;
using (var stream = new MemoryStream())
{
bitmap.Compress(Bitmap.CompressFormat.Png, 0, stream);
bitmapData = stream.ToArray();
}
return Task.FromResult(bitmapData);
}
}
然后稍后当您想要获取CaptureAsync()
返回的byte[]
,您只需要调用:
byte[] result = CaptureAsync(<Your_parameters>).Result;
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