I try to display an image, stored as blob in a table.
So I need to convert a byte[] into a Vaadin Image class (I guess that's the best way to display it ?).
I try this solution (4 years old):
https://vaadin.com/forum/thread/10271496/byte-array-to-vaadin-image
it's not working :
new StreamResource.StreamSource() { -> Cannot resolve symbol 'StreamSource'
How can I do it in Vaadin 13 ?
Here is a solution:
private Image convertToImage(byte[] imageData)
{
StreamResource streamResource = new StreamResource("isr", new InputStreamFactory() {
#Override
public InputStream createInputStream() {
return new ByteArrayInputStream(imageData);
}
});
return new Image(streamResource, "photo");
}
I'm working on Xmarin Forms(PCL) project, I want to convert the StackLayout to Image / buffer and send it to printer for hard print.
Can anyone suggest how to do it in (Xamarin.Android & Xamarin.iOS).
You can't. Xamarin does not have that kind of feature. You should write a Renderer for your UIComponent.
Fortunately there is an Objective-C iOS implementation, and an Android one as well. You can inspire from them.
Taken from this link, which I have personally used, quite a while back though, the following code will take a screenshot of the entire page.
I ended up modifying the code to only take a screenshot of a specific view on the page and also changed a few other things but this example is what I based it off of, so let me know if you would rather see that code and/or if something below is not working for you.
First you create an interface in your Forms project, IScreenshotManager.cs for example:
public interface IScreenshotManager {
Task<byte[]> CaptureAsync();
}
Now we need to implement our interface in Android, ScreenshotManager.cs for example:
public class ScreenshotManager : IScreenshotManager {
public static Activity Activity { get; set; }
public async System.Threading.Tasks.Task<byte[]> CaptureAsync() {
if(Activity == null) {
throw new Exception("You have to set ScreenshotManager.Activity in your Android project");
}
var view = Activity.Window.DecorView;
view.DrawingCacheEnabled = true;
Bitmap bitmap = view.GetDrawingCache(true);
byte[] bitmapData;
using (var stream = new MemoryStream()) {
bitmap.Compress(Bitmap.CompressFormat.Png, 0, stream);
bitmapData = stream.ToArray();
}
return bitmapData;
}
}
Then set ScreenshotManager.Activity in MainActivity:
public class MainActivity : Xamarin.Forms.Platform.Android.FormsApplicationActivity {
protected override async void OnCreate(Android.OS.Bundle bundle) {
...
ScreenshotManager.Activity = this; //There are better ways to do this but this is what the example from the link suggests
...
}
}
Finally we implement this on iOS, ScreenshotManager.cs:
public class ScreenshotManager : IScreenshotManager {
public async System.Threading.Tasks.Task<byte[]> CaptureAsync() {
var view = UIApplication.SharedApplication.KeyWindow.RootViewController.View;
UIGraphics.BeginImageContext(view.Frame.Size);
view.DrawViewHierarchy(view.Frame, true);
var image = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
using(var imageData = image.AsPNG()) {
var bytes = new byte[imageData.Length];
System.Runtime.InteropServices.Marshal.Copy(imageData.Bytes, bytes, 0, Convert.ToInt32(imageData.Length));
return bytes;
}
}
}
I'm uploading an image to my site using the following code,
The Image uploading just fine but, how ever
I need to fix the following things :
-I'm getting this kind of Url
C:\Users\Me\Documents\Visual Studio 2013\Projects\Wow\WowMvc5\WowMvc5\images\gallery\Picture 022.jpg,
Instead of relevant folder Url
-I thing in order to avoid an error of 2 images this the same name it would be better to create a folder under images for each image (or any better idea )
Thank you for your time
public async Task<ActionResult> Create([Bind(Include = "TakeAwayId,TakeAwayName,description,Price,DishUrl,quantity,DishesAmount,GenreId")] TakeAway takeaway)
{
var path = Server.MapPath("~/Images/gallery/");
foreach (string item in Request.Files)
{
HttpPostedFileBase file = Request.Files[item];
if (file.ContentLength == 0)
{
continue;
}
string SavedFileName = System.IO.Path.GetFileName(file.FileName);
SavedFileName = Server.MapPath
("~" + "/images/gallery/" + SavedFileName);
file.SaveAs(SavedFileName);
takeaway.DishUrl = SavedFileName;
}
if (ModelState.IsValid)
{
db.takeaway.Add(takeaway);
await db.SaveChangesAsync();
return RedirectToAction("Index");
}
ViewBag.GenreId = new SelectList(db.genre, "GenreId", "GenreName", takeaway.GenreId);
return View(takeaway);
}
What I would do is name and save each picture using a HashCode.
By definition, It's very improbable that 2 different strings, when transformed using a hash algorithm, will have the same output. Just to be sure, add a random string to the original name of the image.
string newName = (oldName + random).GetHashCode().ToString()
filename_1.jpg
where cnt is incremental count
if(file.exists()
{
string cnt = file.split("");
String newFileName = filename+""+(cnt+1)+".jpg";
}
I am using jqgrid (standard) with EF 4 + MVC3. I'd like to implement excel export. Which method you would suggest me?
To generate excel, I'd like to use this library by Dr Stephen Walther, which has three types of output and allows to define headers too. Please tell me if you find it valid for my purpose.
I ask this question because I am still approaching to implement excel export and I found several techniques. Some suggest making a csv export, others indicate that it should return a JSON output and it is not clear to me whether this capability is present in the free version of jqgrid. In any case, I would like to pass the data to Walther's object.
About the jqgrid code, I found this interesting answer by Oleg, but I do not understand if could be applied to my needs.
Unfortunately, by now I only found parts of solutions for excel export with EF MVC, but no solution or complete examples...
About the MVC logic, I am going to implement and develop this code as kindly suggested by #Tommy.
Please sorry if the question could be silly, I am just a (enthusiast) beginner.
Thanks for your precious help!
Best Regards
As I wrote before (see here and here for example) the best way to export grid data to XML is the usage of Open XML SDK 2.0.
The post of Dr Stephen Walther shows how to create HTML file which can be read by Excel. It's not Excel file and have to be still converted to Excel format. The usage of CSV has even more problems. Depend on the content in the source table the automatic conversion to Excel data types can be absolutely wrong. In one project which I developed for a customer the grid contained information about software products: product name, version, and so on. The software version looks sometime as the date (1.3.1963 for example) and such cells will be wrong converted (in German one use '.' as the separator in the date). As the result one had really hard problems. The usage of CSV with texts having commas inside will be also frequently wrong imported. Even when one quotes the cells having commas (,) and escaped the texts having quotas the import still be wrong especially in the first column. I don't want to explain here the whole history of all attempts and errors, but after all I decide to give up with the usage of CSV and HTML and started to use Open XML SDK 2.0 which allows to create real Excel files with extension XLSX. The way seems me perfect because one don't need any Office
components installed on the server, no additional licenses.
The only restriction is that one should be able to use DocumentFormat.OpenXml.dll, so your server program should run on any Windows operation system. As it's well known, XLSX file is ZIP file which contains some XML files inside. If you still don't know that I recommend you to rename the XLSX file to ZIP file and extract it. The Open XML SDK 2.0 is the library which works with XLSX file like with XML files. So no additional Office components are required.
One can find a lot of information how to use Open XML SDK 2.0 (see here, here and here). Many helpful code examples one cam find directly on the MSDN (see here). Nevertheless the practical usage of Open XML SDK 2.0 is not so easy at least at the first time. So I created a demo from the parts of the code which I used myself.
You can download the demo project from here. The demo is an extension of the demos from the answer and this one.
To export data I use the DataForExcel helper class. It has constructor in the form
DataForExcel(string[] headers, DataType[] colunmTypes, List<string[]> data,
string sheetName)
or in a little simplified form
DataForExcel(string[] headers, List<string[]> data, string sheetName)
and the only public method
CreateXlsxAndFillData(Stream stream)
The usage of the class to create Excel file can be like the following
var excelData = new DataForExcel (
// column Header
new[]{"Col1", "Col2", "Col3"},
new[]{DataForExcel.DataType.String, DataForExcel.DataType.Integer,
DataForExcel.DataType.String},
new List<string[]> {
new[] {"a", "1", "c1"},
new[] {"a", "2", "c2"}
},
"Test Grid");
Stream stream = new FileStream ("Test.xlsx", FileMode.Create);
excelData.CreateXlsxAndFillData (stream);
stream.Close();
The usage in the demo from ASP.NET MVC is the following
static readonly string[] HeadersQuestions = {
"Id", "Votes", "Title"
};
static readonly DataForExcel.DataType[] ColunmTypesQuestions = {
DataForExcel.DataType.Integer,
DataForExcel.DataType.Integer,
DataForExcel.DataType.String
};
public ActionResult ExportAllQuestionsToExcel () {
var context = new HaackOverflowEntities ();
var questions = context.Questions;
questions.MergeOption = MergeOption.NoTracking; // we don't want to update the data
// to be able to use ToString() below which is NOT exist in the LINQ to Entity
// we should include in query only the properies which we will use below
var query = questions.ToList ();
if (query.Count == 0)
return new EmptyResult ();
var data = new List<string[]> (query.Count);
data.AddRange (query.Select (item => new[] {
item.Id.ToString(CultureInfo.InvariantCulture),
item.Votes.ToString(CultureInfo.InvariantCulture),
item.Title
}));
return new ExcelResult (HeadersQuestions, ColunmTypesQuestions, data,
"Questions.xlsx", "Questions");
}
where ExcelResult are defined as
public class ExcelResult : ActionResult {
private readonly DataForExcel _data;
private readonly string _fileName;
public ExcelResult (string[] headers, List<string[]> data, string fileName, string sheetName) {
_data = new DataForExcel (headers, data, sheetName);
_fileName = fileName;
}
public ExcelResult (string[] headers, DataForExcel.DataType[] colunmTypes, List<string[]> data, string fileName, string sheetName) {
_data = new DataForExcel (headers, colunmTypes, data, sheetName);
_fileName = fileName;
}
public override void ExecuteResult (ControllerContext context) {
var response = context.HttpContext.Response;
response.ClearContent();
response.ClearHeaders();
response.Cache.SetMaxAge (new TimeSpan (0));
using (var stream = new MemoryStream()) {
_data.CreateXlsxAndFillData (stream);
//Return it to the client - strFile has been updated, so return it.
response.AddHeader ("content-disposition", "attachment; filename=" + _fileName);
// see http://filext.com/faq/office_mime_types.php
response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
response.ContentEncoding = Encoding.UTF8;
stream.WriteTo (response.OutputStream);
}
response.Flush();
response.Close();
}
}
To make the code full I have to include the code of the class DataForExcel:
public class DataForExcel {
public enum DataType {
String,
Integer
}
private readonly string[] _headers;
private readonly DataType[] _colunmTypes;
private readonly List<string[]> _data;
private readonly string _sheetName = "Grid1";
private readonly SortedSet<string> _os = new SortedSet<string> ();
private string[] _sharedStrings;
private static string ConvertIntToColumnHeader(int index) {
var sb = new StringBuilder ();
while (index > 0) {
if (index <= 'Z' - 'A') // index=0 -> 'A', 25 -> 'Z'
break;
sb.Append (ConvertIntToColumnHeader (index / ('Z' - 'A' + 1) - 1));
index = index % ('Z' - 'A' + 1);
}
sb.Append ((char)('A' + index));
return sb.ToString ();
}
private static Row CreateRow(UInt32 index, IList<string> data) {
var r = new Row { RowIndex = index };
for (var i = 0; i < data.Count; i++)
r.Append (new OpenXmlElement[] { CreateTextCell (ConvertIntToColumnHeader (i), index, data[i]) });
return r;
}
private Row CreateRowWithSharedStrings(UInt32 index, IList<string> data) {
var r = new Row { RowIndex = index };
for (var i = 0; i < data.Count; i++)
r.Append (new OpenXmlElement[] { CreateSharedTextCell (ConvertIntToColumnHeader (i), index, data[i]) });
return r;
}
private Row CreateRowWithSharedStrings(UInt32 index, IList<string> data, IList<DataType> colunmTypes) {
var r = new Row { RowIndex = index };
for (var i = 0; i < data.Count; i++)
if (colunmTypes != null && i < colunmTypes.Count && colunmTypes[i] == DataType.Integer)
r.Append (new OpenXmlElement[] { CreateNumberCell (ConvertIntToColumnHeader (i), index, data[i]) });
else
r.Append (new OpenXmlElement[] { CreateSharedTextCell (ConvertIntToColumnHeader (i), index, data[i]) });
return r;
}
private static Cell CreateTextCell(string header, UInt32 index, string text) {
// create Cell with InlineString as a child, which has Text as a child
return new Cell (new InlineString (new Text { Text = text })) {
// Cell properties
DataType = CellValues.InlineString,
CellReference = header + index
};
}
private Cell CreateSharedTextCell(string header, UInt32 index, string text) {
for (var i=0; i<_sharedStrings.Length; i++) {
if (String.Compare (_sharedStrings[i], text, StringComparison.Ordinal) == 0) {
return new Cell (new CellValue { Text = i.ToString (CultureInfo.InvariantCulture) }) {
// Cell properties
DataType = CellValues.SharedString,
CellReference = header + index
};
}
}
// create Cell with InlineString as a child, which has Text as a child
throw new InstanceNotFoundException();
}
private static Cell CreateNumberCell(string header, UInt32 index, string numberAsString) {
// create Cell with CellValue as a child, which has Text as a child
return new Cell (new CellValue { Text = numberAsString }) {
// Cell properties
CellReference = header + index
};
}
private void FillSharedStringTable(IEnumerable<string> data) {
foreach (var item in data)
_os.Add (item);
}
private void FillSharedStringTable(IList<string> data, IList<DataType> colunmTypes) {
for (var i = 0; i < data.Count; i++)
if (colunmTypes == null || i >= colunmTypes.Count || colunmTypes[i] == DataType.String)
_os.Add (data[i]);
}
public DataForExcel(string[] headers, List<string[]> data, string sheetName) {
_headers = headers;
_data = data;
_sheetName = sheetName;
}
public DataForExcel(string[] headers, DataType[] colunmTypes, List<string[]> data, string sheetName) {
_headers = headers;
_colunmTypes = colunmTypes;
_data = data;
_sheetName = sheetName;
}
private void FillSpreadsheetDocument(SpreadsheetDocument spreadsheetDocument) {
// create and fill SheetData
var sheetData = new SheetData ();
// first row is the header
sheetData.AppendChild (CreateRow (1, _headers));
//const UInt32 iAutoFilter = 2;
// skip next row (number 2) for the AutoFilter
//var i = iAutoFilter + 1;
UInt32 i = 2;
// first of all collect all different strings in OrderedSet<string> _os
foreach (var dataRow in _data)
if (_colunmTypes != null)
FillSharedStringTable (dataRow, _colunmTypes);
else
FillSharedStringTable (dataRow);
_sharedStrings = _os.ToArray ();
foreach (var dataRow in _data)
sheetData.AppendChild (_colunmTypes != null
? CreateRowWithSharedStrings (i++, dataRow, _colunmTypes)
: CreateRowWithSharedStrings (i++, dataRow));
var sst = new SharedStringTable ();
foreach (var text in _os)
sst.AppendChild (new SharedStringItem (new Text (text)));
// add empty workbook and worksheet to the SpreadsheetDocument
var workbookPart = spreadsheetDocument.AddWorkbookPart ();
var worksheetPart = workbookPart.AddNewPart<WorksheetPart> ();
var shareStringPart = workbookPart.AddNewPart<SharedStringTablePart> ();
shareStringPart.SharedStringTable = sst;
shareStringPart.SharedStringTable.Save ();
// add sheet data to Worksheet
worksheetPart.Worksheet = new Worksheet (sheetData);
worksheetPart.Worksheet.Save ();
// fill workbook with the Worksheet
spreadsheetDocument.WorkbookPart.Workbook = new Workbook (
new FileVersion { ApplicationName = "Microsoft Office Excel" },
new Sheets (
new Sheet {
Name = _sheetName,
SheetId = (UInt32Value)1U,
// generate the id for sheet
Id = workbookPart.GetIdOfPart (worksheetPart)
}
)
);
spreadsheetDocument.WorkbookPart.Workbook.Save ();
spreadsheetDocument.Close ();
}
public void CreateXlsxAndFillData(Stream stream) {
// Create workbook document
using (var spreadsheetDocument = SpreadsheetDocument.Create (stream, SpreadsheetDocumentType.Workbook)) {
FillSpreadsheetDocument (spreadsheetDocument);
}
}
}
The above code create new XLSX file directly. You can extend the code to support more data types as String and Integer which I used in the code.
In more professional version of your application you can create some XLSX templates for exporting different tables. In the code you can place the data in the cells instead, so modify the spreadsheet instead of creating. In the way you can create perfect formatted XLSX files. The examples from the MSDN (see here) will help you to implement the way when it will be required.
UPDATED: The answer contains updated code which allows generate Excel documented with more cell formatting.
I looked at Stephen's post and it's old as hell, which btw doesn't make it wrong.
If you don't need custom formatting, headers and styles, then I think use CSV as it's very simple.
More importantly, don't think that excel export from MVC site that internally uses EF for data access is harder than, say, Ruby on Rails site that uses ActiveRecord. For me it's independent concerns, export shouldn't new anything about underlying technologies (at least not directly), just the structure of your data, that's all.
Search for codeplex libraries that allows to do Excel reading/writing and export, there are plenty of them these days, many really good solutions that's regularly maintained and tested by thousand of developers all over the globe. If I were you I won't use Stephen solution because it looks like he occasionally typed it in a notepad and then pasted to the post - no unit tests, no extensibility points + it's in VB so it even harder to understand, but may be that's just me.
Hope this help and good luck
I have a MVC application, which creates a Chart in the business logic like this:
StatisticsModel.Chart.Width = 150
StatisticsModel.Chart.Height = 300
StatisticsModel.Chart.Attributes.Add("align", "left")
StatisticsModel.Chart.Titles.Add("Statistics for: " + StatisticsModel.ProductNumbers)
StatisticsModel.Chart.ChartAreas.Add(New ChartArea)
StatisticsModel.Chart.Series.Add(New Series)
StatisticsModel.Chart.Series(0).ChartType = SeriesChartType.Column
StatisticsModel.Chart.Series(0).Points.DataBindXY(StatisticsModel.FailedTPDescriptionList, "key", StatisticsModel.FailedTPDescriptionList, "value")
Now, I am trying to implement it in the View, but I have read many articles, and they suggest me to put the chart in a different controller. But that would mean I have to send the Chart object there, as I have many functions, that require a chart, and I thought the easiest way is to implement it in the Model, and then rendering it from there.
I tried using: http://code-inside.de/blog-in/2008/11/27/howto-use-the-new-aspnet-chart-controls-with-aspnet-mvc/
But the:
#Code
Dim writer As New HtmlTextWriter(Page.Response.Output)
End Code
Didn't work for me. I am using VB.NET
Can anyone help me? Suggestions are very welcome.
There are many, many ways of creating and showing charts in MVC, and the link you referred to is pretty good IMHO. I'm using c#, but the way I'm doing it is to use an img-tag in the view and point the src-attribute to a Controller action:
<img id="diagram" src="<%=Url.Action("DrawChartImage", "Home") %>" alt="Chart Diagram" />
The controller action returns a FileContentResult:
public ActionResult DrawChartImage()
{
using (var chartHelper = new ChartHelper())
{
//get data
var data = GetSomeDataForTheChart();
//draw chart
chartHelper.Draw(data);
//return chart as png image
return File(chartHelper.Image, "image/png");
}
}
The ChartHelper class implements IDisposable and has a helper property (Image) which returns the chart as a file, NOTE this is just sample/snippet code to show what I mean:
public class ChartHelper : IDisposable
{
private readonly Chart _chart;
public Chart Chart
{
get
{
return _chart;
}
}
public byte[] Image
{
get
{
using (var ms = new MemoryStream())
{
_chart.SaveImage(ms);
return ms.GetBuffer();
}
}
}
public ChartHelper()
{
_chart = new Chart();
_chart.Height = 300;
_chart.Width = 800;
_chart.ImageType = ChartImageType.Png;
_chart.Titles.Add("some title");
_chart.Legends.Add("some legend");
_chart.ChartAreas.Add("some chart area");
}
public void Draw(List<Data> data)
{
var dataArrays = GetDataArrays(data); //another helper method...
var series = new Series(tag);
series.Name = tag;
series.Legend = "tags";
series.ChartType = SeriesChartType.Spline;
series.BorderWidth = 4;
//sample way to add data below...
series.Points.DataBindXY(dataArrays.Item1, dataArrays.Item2);
_chart.Series.Add(series);
}
public void Dispose()
{
_chart.Dispose();
}
}
Works pretty well for me, hope it helps even if it's in C#.
EDIT If you want to create the image/chart in business logic called from your "main" Controller action, maybe you can do something like this where you generate the image/chart and then save it to disk, cache or database and pick it up from the image rendering controller action:
public ActionResult Index()
{
//this is call to your business logic or similar which generates the chart
byte[] image = GenerateImage();
//save image to cache, disk or from database
HttpContext.Cache["image"] = image;
return View();
}
public ActionResult Image()
{
//get image from cache, disk or from database
var image = HttpContext.Cache["image"] as byte[];
return File(image, "image/png");
}
//some sample/dummy code to generate image from a template
private byte[] GenerateImage()
{
using (var ms = new MemoryStream())
{
using (var image = System.Drawing.Image.FromFile(#"c:/temp/template.png"))
using (var brush = new SolidBrush(System.Drawing.Color.Black))
using (var bmp = new System.Drawing.Bitmap(image, image.Width, image.Height))
using (var g = System.Drawing.Graphics.FromImage(bmp))
{
g.DrawString(DateTime.Now.ToLongTimeString(), new Font("Consolas", 10), brush, 10, 10);
bmp.Save(ms, ImageFormat.Png);
}
return ms.ToArray();
}
}
And the view would be:
<img src="#Url.Action("Image")"/>