using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using System.Threading.Tasks;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.Storage;
using Windows.Storage.FileProperties;
using Windows.UI;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Media.Imaging;
using Windows.UI.Xaml.Navigation;
using WindowsPreview.Media.Ocr;
namespace OCRImgReadText
{
public sealed partial class MainPage : Page
{
// Bitmap holder of currently loaded image.
private WriteableBitmap bitmap;
// OCR engine instance used to extract text from images.
private OcrEngine ocrEngine;
public MainPage()
{
this.InitializeComponent();
ocrEngine = new OcrEngine(OcrLanguage.English);
TextOverlay.Children.Clear();
}
protected override async void OnNavigatedTo(NavigationEventArgs e)
{ //Get local image
var file = await Windows.ApplicationModel.Package.Current.InstalledLocation.GetFileAsync("TestImages\\SQuotes.jpg");
await LoadImage(file);
}
private async Task LoadImage(StorageFile file)
{
ImageProperties imgProp = await file.Properties.GetImagePropertiesAsync();
using (var imgStream = await file.OpenAsync(FileAccessMode.Read))
{
bitmap = new WriteableBitmap((int)imgProp.Width, (int)imgProp.Height);
bitmap.SetSource(imgStream);
PreviewImage.Source = bitmap;
}
}
private async void ExtractText_Click(object sender, RoutedEventArgs e)
{
//// Prevent another OCR request, since only image can be processed at the time at same OCR engine instance.
//ExtractTextButton.IsEnabled = false;
// Check whether is loaded image supported for processing.
// Supported image dimensions are between 40 and 2600 pixels.
if (bitmap.PixelHeight < 40 ||
bitmap.PixelHeight > 2600 ||
bitmap.PixelWidth < 40 ||
bitmap.PixelWidth > 2600)
{
ImageText.Text = "Image size is not supported." +
Environment.NewLine +
"Loaded image size is " + bitmap.PixelWidth + "x" + bitmap.PixelHeight + "." +
Environment.NewLine +
"Supported image dimensions are between 40 and 2600 pixels.";
//ImageText.Style = (Style)Application.Current.Resources["RedTextStyle"];
return;
}
// This main API call to extract text from image.
var ocrResult = await ocrEngine.RecognizeAsync((uint)bitmap.PixelHeight, (uint)bitmap.PixelWidth, bitmap.PixelBuffer.ToArray());
// OCR result does not contain any lines, no text was recognized.
if (ocrResult.Lines != null)
{
// Used for text overlay.
// Prepare scale transform for words since image is not displayed in original format.
var scaleTrasform = new ScaleTransform
{
CenterX = 0,
CenterY = 0,
ScaleX = PreviewImage.ActualWidth / bitmap.PixelWidth,
ScaleY = PreviewImage.ActualHeight / bitmap.PixelHeight,
};
if (ocrResult.TextAngle != null)
{
PreviewImage.RenderTransform = new RotateTransform
{
Angle = (double)ocrResult.TextAngle,
CenterX = PreviewImage.ActualWidth / 2,
CenterY = PreviewImage.ActualHeight / 2
};
}
string extractedText = "";
// Iterate over recognized lines of text.
foreach (var line in ocrResult.Lines)
{
// Iterate over words in line.
foreach (var word in line.Words)
{
var originalRect = new Rect(word.Left, word.Top, word.Width, word.Height);
var overlayRect = scaleTrasform.TransformBounds(originalRect);
var wordTextBlock = new TextBlock()
{
Height = overlayRect.Height,
Width = overlayRect.Width,
FontSize = overlayRect.Height * 0.8,
Text = word.Text,
};
// Define position, background, etc.
var border = new Border()
{
Margin = new Thickness(overlayRect.Left, overlayRect.Top, 0, 0),
Height = overlayRect.Height,
Width = overlayRect.Width,
Background=new SolidColorBrush(Colors.Orange),Opacity=0.5,HorizontalAlignment=HorizontalAlignment.Left,VerticalAlignment=VerticalAlignment.Top,
Child = wordTextBlock,
};
OverlayTextButton.IsEnabled = true;
// Put the filled textblock in the results grid.
TextOverlay.Children.Add(border);
extractedText += word.Text + " ";
}
extractedText += Environment.NewLine;
}
ImageText.Text = extractedText;
}
else
{
ImageText.Text = "No text.";
}
}
private void OverlayText_Click(object sender, RoutedEventArgs e)
{
if(TextOverlay.Visibility==Visibility.Visible)
{
TextOverlay.Visibility = Visibility.Collapsed;
}
else
{
TextOverlay.Visibility = Visibility.Visible;
}
}
}
}
