Xamarin Forms - 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;
});
保存了图片，但是手机拍出来的照片实际尺寸很大，有什么办法可以调整大小.
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
UPDATE:原始答案没有用，请参阅下面的更新答案.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，我将它分叉到 github 并删减了哪些不会'不在 Xamarin 中编译，将修改保持在最低限度，结果似乎有效.
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，使用 Xamarin 编译它并将 Build 文件夹中的 DLL 添加到您的表单项目.
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，您可以这样做(应该适合您问题的上下文)
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));
<小时>
更新答案:
UPDATED ANSWER:
从 nuget 获取 Xamarin.XLabs，了解使用 Resolver，创建一个 IImageService 接口调整大小方法.
Get Xamarin.XLabs from nuget, learn about using Resolver, create an IImageService interface with Resize method.
iOS 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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