如何将Android.Graphics.Bitmap转换为System.Drawing.Bitmap并返回

Question

我在Xamarin应用程序(API 28(中得到了这段代码：

我试图找到一种将位图转换为图形对象的方法(https://learn.microsoft.com/en-us/dotnet/api/system.drawing.graphics?view=dotnet-plat-ext-3.1(，目标是使用插值模式并应用过滤器，然后恢复更改，但我没有找到一个关于如何做到这一点的例子。

我发现：将图形对象转换为位图对象但这不是我想要的，因为，我得到了这个代码：

private Android.Graphics.Bitmap GetBitmap(Drawable d, System.Drawing.Size? bounds)
{
...some code regarding width and height, and then
var bd = d as BitmapDrawable;
if (bd != null)
{
Android.Graphics.Bitmap src = bd.Bitmap;
if (width == src.Width && height == src.Height)
{
return src;
}
else
{
Graphics myGraphics = Graphics.FromImage(src);  // here is the problem
// USE G TO SET InterpolationMode 
// convert resulting G somehow back to Android.Graphics.Bitmap, and return it insted of the bottom line
return Android.Graphics.Bitmap.CreateScaledBitmap(src, width, height, true);
}
}
}

错误代码：

Cannot convert from Android.Graphics.Bitmap to System.Drawing.Bitmap

我需要一些关于如何解决这个问题的建议，任何帮助都将不胜感激。

谢谢你抽出时间。

Answer 1

您需要首先将src转换为Steram。检查以下代码

public static Stream RaiseImage(Android.Graphics.Bitmap bitmap)
{

MemoryStream ms = new MemoryStream();
bitmap.Compress(Android.Graphics.Bitmap.CompressFormat.Png, 100, ms);
return ms;
}
private Android.Graphics.Bitmap GetBitmap(Drawable d, System.Drawing.Size? bounds)
{
// ...some code regarding width and height, and then
var bd = d as BitmapDrawable;
Android.Graphics.Bitmap bitmap = bd.Bitmap;
Stream src=  RaiseImage(bitmap);
Image image = System.Drawing.Image.FromStream(src);
Graphics myGraphics = Graphics.FromImage(image);  // here is the problem
// USE G TO SET InterpolationMode 
// convert resulting G somehow back to Android.Graphics.Bitmap, and return it insted of the bottom line
return Android.Graphics.Bitmap.CreateScaledBitmap(src, width, height, true);


}