After reading an image with the ImageDescriptor API and resizing it by instantiating a codec I am trying to write the resized version in the application directory.
I saw that the when converting the frame into byte data I have a format which is rawUnmodified which I assumed would write the resized image in the same format as the original image. But when I tried to load the resized image I get an image format exception.
Example code:
//read the original image and obtain the image descriptor
var imageData = await file.readAsBytes();
final ImmutableBuffer buffer = await ImmutableBuffer.fromUint8List(imageData);
final imDescr = await ImageDescriptor.encoded(buffer);
//resize the image, get the first frame and convert it to bytes
Codec codec = await imDescr.instantiateCodec(targetWidth: 100, targetHeight: 100);
FrameInfo frameInfo = await codec.getNextFrame();
var bytes = await frameInfo.image.toByteData(
format: ImageByteFormat.rawUnmodified,
//note when using the png format it works, but I would like to have it in the original image format(in this case its jpg)
);
//write the resized image
Directory appDir = await getApplicationDocumentsDirectory();
var path = appDir.path;
var file = File('$path/test1.jpg');
await file.writeAsBytes(bytes.buffer.asUint8List(bytes.offsetInBytes, bytes.lengthInBytes));
In the ImageByteFormat api it says: rawUnmodified -> Unencoded bytes, in the image's existing format. For example, a grayscale image may use a single 8-bit channel for each pixel.
But when I try to show this image the format is wrong. Anybody have an idea how to fix this?
Why use image ImageDescriptor, You can do it easily by image package
File resizeImage(File imageFile, String imageFormat, int targetWidth, int targetHeight) {
im.Image tempImage = im.decodeImage(imageFile.readAsBytesSync());
tempImage = im.bakeOrientation(tempImage);
tempImage = im.copyResize(tempImage, width: targetWidth, height: targetHeight);
File newImage;
if (imageFormat == 'jpg') {
newImage = File('newpath/test.jpg');
newImage.writeAsBytesSync(im.encodeJpg(tempImage));
return newImage;
} else if (imageFormat == 'png') {
newImage = File('newpath/test.png');
newImage.writeAsBytesSync(im.encodePng(tempImage));
return newImage;
} else {
throw ('Unknown Image Format');
}
}
Related
I am using the following sample to resize the uploaded images with Blazor WebAssembly
https://www.prowaretech.com/Computer/Blazor/Examples/WebApi/UploadImages .
Still I need the original file too to be converted to base64 too and I don't know how can I access it...
I tried to find the file's original width and height to pass its to RequestImageFileAsync function but no success...
I need to store both files : the original one and the resized one.
Can you help me, please ?
Thank You Very Much !
The InputFile control emits an IBrowserFile type. RequestImageFileAsync is a convenience method on IBrowserFile to resize the image and convert the type. The result is still an IBrowserFile.
One way to do what you are asking is with SixLabors.ImageSharp. Based on the ProWareTech example, something like this...
async Task OnChange(InputFileChangeEventArgs e)
{
var files = e.GetMultipleFiles(); // get the files selected by the users
foreach(var file in files)
{
//Original-sized file
var buf1 = new byte[file.Size];
using (var stream = file.OpenReadStream())
{
await stream.ReadAsync(buf1); // copy the stream to the buffer
}
origFilesBase64.Add(new ImageFile { base64data = Convert.ToBase64String(buf1), contentType = file.ContentType, fileName = file.Name }); // convert to a base64 string!!
//Resized File
var resizedFile = await file.RequestImageFileAsync(file.ContentType, 640, 480); // resize the image file
var buf = new byte[resizedFile.Size]; // allocate a buffer to fill with the file's data
using (var stream = resizedFile.OpenReadStream())
{
await stream.ReadAsync(buf); // copy the stream to the buffer
}
filesBase64.Add(new ImageFile { base64data = Convert.ToBase64String(buf), contentType = file.ContentType, fileName = file.Name }); // convert to a base64 string!!
}
//To get the image Sizes for first image
ImageSharp.Image origImage = Image.Load<*imagetype*>(origFilesBase64[0])
int origImgHeight = origImage.Height;
int origImgWidth = origImage.Width;
ImageSharp.Image resizedImage = Image.Load<*imagetype*>(filesBase64[0])
int resizedImgHeight = resizedImage.Height;
int resizedImgWidth = resizedImage.Width;
}
Good day ,I am generating certificates and for this I have a template where I must write user data, for the moment I am creating the certificates in pdf format, but the ideal would be to use images or convert those pdf to image since it is easier for the user to handle images, I have not found any library capable of writing in images that works correctly.
At the moment I am trying to use Image. https://pub.dev/packages/image.
I have the following code, but it fails to add a text fragment in the image.
imagecert = await ManagerDB().getcertificate(certificatetemplate); //imagecert is uint8list
if (imagecert != null) {
mg.Image ima = mg.Image.fromBytes(300, 200, List.from(imagecert)); Image works with list<int>
mg.Image imag = mg.drawString(ima, mg.arial_14, 0, 0, 'Hello World'); //here the code does not work
List<int> data = mg.encodePng(imag);
Uint8List bytes = Uint8List.fromList(data);
setState(() {});
return bytes;
} else {
print("Enlace no encontrado");
}
I don't know if there is a simpler solution to write text in an image. It is required to store those images.
Thank you
you can put image inside widget and add to that widget text
and converted to image using globalKey (don't forget to pass globalKey to key of that sepecific widget )
Future<Uint8List> _convertWidgetToImage(GlobalKey globalKey) async {
RenderRepaintBoundary boundary =
globalKey.currentContext!.findRenderObject() as RenderRepaintBoundary;
ui.Image image = await boundary.toImage();
ByteData byteData =
(await (image.toByteData(format: ui.ImageByteFormat.png)))!;
Uint8List pngBytes = byteData.buffer.asUint8List();
return pngBytes;
}
I'm trying to change image size from uint8list data.
There are lots of Image classes in Flutter as you know,
and The final type of image I want to get is ui.Image.
I get Uint8List Image(.jpg) data from socket communication.
Now, I want to set the size of the image and get the Image of ui.Image at the end.
I tried to do that through (dart:ui : ui, package:image/image.dart : IMG)
IMG.Image img = IMG.decodeImage(data);
IMG.Image resized = IMG.copyResize(img, width: 400, height: 200);
ui.Codec codec = await ui.instantiateImageCodec(IMG.encodeJpg(resized));
ui.Image image = (await codec.getNextFrame()).image;
,but It freezes the app.
How can I do that? Is there any way? Thank you.
Additionally,
In "flutter/lib/src/widgets/image.dart",
Image.memory(Uint8List, width, height) can make it be easy to set image size.
Is there any way to get Uint8List from that Image widget?
I resized the image data in Uint8List like below.
import package:image/image.dart as IMG
Uint8List resizeImage(Uint8List data) {
Uint8List resizedData = data;
IMG.Image img = IMG.decodeImage(data);
IMG.Image resized = IMG.copyResize(img, width: img.width*2, height: img.height*2);
resizedData = IMG.encodeJpg(resized);
return resizedData;
}
IMG : flutter image package
Have you tried using ui.decodeImageFromList instead of ui.instantiateImageCodec and getNextFrame() ?
import 'dart:ui' as ui;
ui.decodeImageFromList(IMG.encodeJpg(resized), (ui.Image img) {
// returned ui.Image
});
In my Xamarin Forms app, I have an image under androidProject/Resources/drawable/myImage.png. To load these from Xamarin, you can simply do
Image myImage = new Image() { Source = ImageSource.FromFile("myImage.png") };
However, there is no way to draw an Image using NGraphics. Instead, NGraphics DrawImage(IImage) requires an IImage. As far as I can tell, there's no way to turn a Xamarin.Forms.Image into an NGraphics.IImage. In fact, the only way I could find to load IImage is
IImage myImage = Platform.LoadImage("myImage.png");
However, this doesn't work because under the hood this uses BitmapFactory.decodeFile(), which requires the absolute file path. And I couldn't find any way to get the absolute file path of a resource (if it even exists?)
So, how do I actually load and display an image using NGraphics?
NGraphics does not provide any helpers to load images from your Platforms Resource files.
You could do something as follows. However, it will add some overhead converting back and forth between bitmap -> stream -> bitmap.
Android:
Stream GetDrawableStream(Context context, int resourceId)
{
var drawable = ResourcesCompat.GetDrawable(context.Resources, resourceId, context.Theme);
if (drawable is BitmapDrawable bitmapDrawable)
{
var stream = new MemoryStream();
var bitmap = bitmapDrawable.Bitmap;
bitmap.Compress(Bitmap.CompressFormat.Png, 80, stream);
bitmap.Recycle();
return stream;
}
return null;
}
iOS:
Stream GetImageStream(string fileName)
{
using (var image = UIImage.FromFile(fileName))
using (var imageData = image.AsPNG())
{
var byteArray = new byte[imageData.Length];
System.Runtime.InteropServices.Marshal.Copy(imageData.Bytes, byteArray, 0, Convert.ToInt32(imageData.Length));
var stream = new MemoryStream(byteArray);
return stream;
}
return null;
}
However, you could go directly from Bitmap to BitmapImage on Android instead like:
BitmapImage GetBitmapFromDrawable(Context context, int resourceId)
{
var drawable = ResourcesCompat.GetDrawable(context.Resources, resourceId, context.Theme);
if (drawable is BitmapDrawable bitmapDrawable)
{
var bitmap = bitmapDrawable.Bitmap;
return new BitmapImage(bitmap);
}
return null;
}
And on iOS:
CGImageImage GetImageStream(string fileName)
{
var iOSimage = UIImage.FromFile(fileName);
var cgImage = new CGImageImage(iOSImage.CGImage, iOSImage.Scale);
return cgImage;
}
BitmapImage and CGImageImage implement IImage in NGraphics.
I'm trying to implement an UI where the user can edit and apply effects to an uploaded image, and want to save the BlendMode merged to the image. It's possible to save the result of the blended image or apply it using the Canvas?
There are some packages that apply some specific filters, but I want something more customizable for the end user.
I already saw some examples of how to implement Canvas to draw images, but can't figure it out how to use to load an image an apply the blend related in the docs. Anyone could give an example?
UPDATED:
For who has the same question, bellow follows the code with how to save a image from canvas to a file with blendMode applied.
But I still haven't the result expected. The quality of the image generated isn't the same as the original image, neither the blend seems to be the blend that i've applied. And i can't save as jpg, just as png file.
So, how can i load an image, apply a blend with canvas and save as a jpg file, without losing quality?
CODE:
const kCanvasSize = 200.0;
class CanvasImageToFile {
CanvasImageToFile._();
static final instance = CanvasImageToFile._();
ByteData _readFromFile(File file) {
// File file = getSomeCorrectFile();
Uint8List bytes = file.readAsBytesSync();
return ByteData.view(bytes.buffer);
}
Future<File> _writeToFile(ByteData data) async {
String dir = (await getTemporaryDirectory()).path;
String filePath = '$dir/tempImage.jpg';
final buffer = data.buffer;
return new File(filePath).writeAsBytes(
buffer.asUint8List(data.offsetInBytes, data.lengthInBytes));
}
Future<ui.Image> _loadImageSource(File imageSource) async {
// ByteData data = await rootBundle.load(asset);
ByteData data = _readFromFile(imageSource);
ui.Codec codec = await ui.instantiateImageCodec(data.buffer.asUint8List());
ui.FrameInfo fi = await codec.getNextFrame();
return fi.image;
}
Future<File> generateImage(File imageSource) async {
File imageResult;
ui.Image image;
await _loadImageSource(imageSource).then((value) {
image = value;
});
if (image != null) {
final recorder = ui.PictureRecorder();
var rect =
Rect.fromPoints(Offset(0.0, 0.0), Offset(kCanvasSize, kCanvasSize));
final canvas = Canvas(recorder, rect);
Size outputSize = rect.size;
Paint paint = new Paint();
//OVERLAY - BlendMode uses the previously drawn content as a mask
paint.blendMode = BlendMode.colorBurn;
paint.color = Colors.red;
// paint.colorFilter = ColorFilter.mode(Colors.blue, BlendMode.colorDodge);
// paint = Paint()..color = Colors.red;
// paint = Paint()..blendMode = BlendMode.multiply;
//Image
Size inputSize = Size(image.width.toDouble(), image.height.toDouble());
final FittedSizes fittedSizes =
applyBoxFit(BoxFit.cover, inputSize, outputSize);
final Size sourceSize = fittedSizes.source;
final Rect sourceRect =
Alignment.center.inscribe(sourceSize, Offset.zero & inputSize);
canvas.saveLayer(rect, paint);
canvas.drawImageRect(
image, sourceRect, rect, paint);
canvas.restore();
final picture = recorder.endRecording();
final img = await picture.toImage(200, 200);
final byteData = await img.toByteData(format: ImageByteFormat.png);
await _writeToFile(byteData).then((value) {
imageResult = value;
});
return imageResult;
}
After some research e some adjust at decoding image from png to rawUnmodified in my previous code using (Bitmap package), i could save the image with the original format (jpg) and achieved what i wanted. If there's anyone who have the same question, bellow follows the code to load an image with canvas, apply a blend and write to a file with the same quality:
Future<File> generateImage(
File imageSource, Color color, BlendMode blendMode) async {
File imageResult;
ui.Image image;
await _loadImageSource(imageSource).then((value) {
image = value;
});
if (image != null) {
final recorder = ui.PictureRecorder();
var rect = Rect.fromPoints(Offset(0.0, 0.0),
Offset(image.width.toDouble(), image.height.toDouble()));
final canvas = Canvas(recorder, rect);
Size outputSize = rect.size;
Paint paint = new Paint();
//OVERLAY - BlendMode uses the previously drawn content as a mask
// paint.blendMode = blendMode;
// paint.color = color;
paint.colorFilter = ColorFilter.mode(color, blendMode);
//Image
Size inputSize = Size(image.width.toDouble(), image.height.toDouble());
final FittedSizes fittedSizes =
applyBoxFit(BoxFit.contain, inputSize, outputSize);
final Size sourceSize = fittedSizes.source;
final Rect sourceRect =
Alignment.center.inscribe(sourceSize, Offset.zero & inputSize);
canvas.drawImageRect(image, sourceRect, rect, paint);
final picture = recorder.endRecording();
final img = await picture.toImage(image.width, image.height);
ByteData byteData =
await img.toByteData(format: ui.ImageByteFormat.rawUnmodified);
Bitmap bitmap = Bitmap.fromHeadless(
image.width, image.height, byteData.buffer.asUint8List());
Uint8List headedIntList = bitmap.buildHeaded();
await _writeToFile(headedIntList.buffer.asByteData()).then((value) {
imageResult = value;
});
return imageResult;
}
}