private async Task <List <ReferenceRatio> > ocrImage(byte[] bytes)
{
// Analyze image to recognize text
VisionServiceClient client = new VisionServiceClient(VISION_API_KEY, VISION_API_ENDPOINT);
OcrResults results = null;
try
{
results = await client.RecognizeTextAsync(new MemoryStream(bytes), LANGUAGE, false /* detectRotation */);
}
catch (Exception ex)
{
Debug.WriteLine($"Error analyzing image: {ex.Message}");
return(null); // Abort
}
// Print recognized text to the console
Debug.WriteLine($"Got {results.Regions?.Count()} results");
List <ReferenceRatio> references = new List <ReferenceRatio>();
foreach (var region in results.Regions)
{
// Flatten lines of words into a list of words
List <Word> words = region.Lines.ToList().SelectMany(line => line.Words).ToList();
Debug.WriteLine($"Words: {words.Select(word => word.Text).Aggregate((word1, word2) => word1 + " " + word2)}");
// Look for latitude or longitude reference text
for (int i = 0; i < words.Count; ++i)
{
if (words[i].Text.ToLower() == "latitude" || words[i].Text.ToLower() == "longitude")
{
// Parse axis
PolarAxis axis = words[i].Text.ToLower() == "latitude" ? PolarAxis.Latitude : PolarAxis.Longitude;
// Parse pixel value
int pixel;
try
{
pixel = int.Parse(words[i + 1].Text);
}
catch
{
Debug.WriteLine($"Failed to parse pixel value: {words[i + 1].Text}");
continue;
}
// Parse polar value
float polar;
try
{
polar = float.Parse(words[i + 2].Text);
}
catch
{
Debug.WriteLine($"Failed to parse polar value: {words[i + 2].Text}");
continue;
}
// Create reference ratio from detected values
var reference = new ReferenceRatio(pixel, polar, axis);
Debug.WriteLine($"Created reference: {reference}");
references.Add(reference);
}
}
}
return(references);
}
// Draw a reference line on the canvas for debugging purposes
private static void drawReferenceLine(SKCanvas canvas, Point origin, Size size, ReferenceRatio reference, SKPaint paint)
{
switch (reference.Axis)
{
case ReferenceRatio.PolarAxis.Latitude: // Draw horizontal latitude line
float y = (float)(origin.Y + reference.Pixel);
canvas.DrawLine((float)origin.X, y, (float)(origin.X + size.Width), y, paint);
canvas.DrawText(reference.Polar.ToString(), (float)((size.Width / 2.0f) + origin.X), y, paint);
break;
case ReferenceRatio.PolarAxis.Longitude: // Draw vertical longitude line
float x = (float)(origin.X + reference.Pixel);
canvas.DrawLine(x, (float)origin.Y, x, (float)(origin.Y + size.Height), paint);
canvas.DrawText(reference.Polar.ToString(), x, (float)((size.Height / 2.0f) + origin.Y), paint);
break;
default: throw new ArgumentException($"Unknown polar axis: {reference.Axis}. When did that get invented?!");
}
}
