Xamarin表格-调整相机图片大小 [英] Xamarin Forms - Resize Camera Picture
问题描述
有人帮助我获得了使用Xamarin Forms Labs相机拍照的代码:
Someone helped me get this code for taking a picture using xamarin forms labs camera:
picker = DependencyService.Get<IMediaPicker> ();
task = picker.TakePhotoAsync (new CameraMediaStorageOptions {
DefaultCamera = CameraDevice.Rear,
MaxPixelDimension = 800,
});
img.BackgroundColor = Color.Gray;
Device.StartTimer (TimeSpan.FromMilliseconds (250), () => {
if (task != null) {
if (task.Status == TaskStatus.RanToCompletion) {
Device.BeginInvokeOnMainThread (async () => {
//img.Source = ImageSource.FromStream (() => task.Result.Source);
var fileAccess = Resolver.Resolve<IFileAccess> ();
string imageName = "img_user_" + User.CurrentUser().id + "_" + DateTime.Now.ToString ("yy_MM_dd_HH_mm_ss") + ".jpg";
fileName = imageName;
fileAccess.WriteStream (imageName, task.Result.Source);
fileLocation = fileAccess.FullPath(imageName);
FileStream fileStream = new FileStream(fileAccess.FullPath(imageName), FileMode.Open, System.IO.FileAccess.Read);
imageUrl = (string)test[0]["url"];
img.Source = imageUrl;
});
}
return task.Status != TaskStatus.Canceled
&& task.Status != TaskStatus.Faulted
&& task.Status != TaskStatus.RanToCompletion;
}
return true;
});
它可以保存图像，但是所拍摄的手机照片的实际尺寸很大，有没有办法调整其尺寸.
It saves the image, but the actual size of the phone picture taken is huge, is there a way to resize it.
推荐答案
更新:原始答案没有用，请参见下面的更新答案.问题是PCL库非常慢，并且消耗了太多内存.
UPDATE: The original answer is not useful, see below for updated answer. The issue was the PCL library was very slow and consumed too much memory.
原始答案(请勿使用):
ORIGINAL ANSWER (do not use):
我找到了一个图像I/O库ImageTools-PCL，我将它在github上分叉了，并减少了不能在Xamarin中进行编译，将修改降至最低，结果似乎行得通.
I found an image I/O library, ImageTools-PCL, which I forked on github and trimmed down what wouldn't compile in Xamarin, keeping the modifications to minimum and the result seems to work.
要使用它下载链接的存储库，请使用Xamarin进行编译，然后将Build文件夹中的DLL添加到您的Forms项目中.
To use it download the linked repository, compile it with Xamarin and add the DLLs from Build folder to your Forms project.
要调整图像大小，您可以执行此操作(应适合您问题的内容)
To resize an image you can do this (should fit the context of your question)
var decoder = new ImageTools.IO.Jpeg.JpegDecoder ();
ImageTools.ExtendedImage inImage = new ImageTools.ExtendedImage ();
decoder.Decode (inImage, task.Result.Source);
var outImage = ImageTools.ExtendedImage.Resize (inImage, 1024, new ImageTools.Filtering.BilinearResizer ());
var encoder = new ImageTools.IO.Jpeg.JpegEncoder ();
encoder.Encode (outImage, fileAccess.CreateStream (imageName));
ImageSource imgSource = ImageSource.FromFile (fileAccess.FullPath (imageName));
更新后的答案:
UPDATED ANSWER:
从nuget获取Xamarin.XLabs，了解有关使用解析器的信息，并使用以下方法创建IImageService接口Resize方法.
Get Xamarin.XLabs from nuget, learn about using Resolver, create an IImageService interface with Resize method.
iOS的实现
public class ImageServiceIOS: IImageService{
public void ResizeImage(string sourceFile, string targetFile, float maxWidth, float maxHeight)
{
if (File.Exists(sourceFile) && !File.Exists(targetFile))
{
using (UIImage sourceImage = UIImage.FromFile(sourceFile))
{
var sourceSize = sourceImage.Size;
var maxResizeFactor = Math.Min(maxWidth / sourceSize.Width, maxHeight / sourceSize.Height);
if (!Directory.Exists(Path.GetDirectoryName(targetFile)))
Directory.CreateDirectory(Path.GetDirectoryName(targetFile));
if (maxResizeFactor > 0.9)
{
File.Copy(sourceFile, targetFile);
}
else
{
var width = maxResizeFactor * sourceSize.Width;
var height = maxResizeFactor * sourceSize.Height;
UIGraphics.BeginImageContextWithOptions(new CGSize((float)width, (float)height), true, 1.0f);
// UIGraphics.GetCurrentContext().RotateCTM(90 / Math.PI);
sourceImage.Draw(new CGRect(0, 0, (float)width, (float)height));
var resultImage = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
if (targetFile.ToLower().EndsWith("png"))
resultImage.AsPNG().Save(targetFile, true);
else
resultImage.AsJPEG().Save(targetFile, true);
}
}
}
}
}
Android服务的实现:
Implementation of the service for Android:
public class ImageServiceDroid: IImageService{
public void ResizeImage(string sourceFile, string targetFile, float maxWidth, float maxHeight)
{
if (!File.Exists(targetFile) && File.Exists(sourceFile))
{
// First decode with inJustDecodeBounds=true to check dimensions
var options = new BitmapFactory.Options()
{
InJustDecodeBounds = false,
InPurgeable = true,
};
using (var image = BitmapFactory.DecodeFile(sourceFile, options))
{
if (image != null)
{
var sourceSize = new Size((int)image.GetBitmapInfo().Height, (int)image.GetBitmapInfo().Width);
var maxResizeFactor = Math.Min(maxWidth / sourceSize.Width, maxHeight / sourceSize.Height);
string targetDir = System.IO.Path.GetDirectoryName(targetFile);
if (!Directory.Exists(targetDir))
Directory.CreateDirectory(targetDir);
if (maxResizeFactor > 0.9)
{
File.Copy(sourceFile, targetFile);
}
else
{
var width = (int)(maxResizeFactor * sourceSize.Width);
var height = (int)(maxResizeFactor * sourceSize.Height);
using (var bitmapScaled = Bitmap.CreateScaledBitmap(image, height, width, true))
{
using (Stream outStream = File.Create(targetFile))
{
if (targetFile.ToLower().EndsWith("png"))
bitmapScaled.Compress(Bitmap.CompressFormat.Png, 100, outStream);
else
bitmapScaled.Compress(Bitmap.CompressFormat.Jpeg, 95, outStream);
}
bitmapScaled.Recycle();
}
}
image.Recycle();
}
else
Log.E("Image scaling failed: " + sourceFile);
}
}
}
}
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