问题
How to get the position of text on the screen in an image using Mobile Vision API, and how to draw a rectangle around them?
Example:
回答1:
How to do it
Put an ImageView in the layout
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ImageView
android:layout_width="match_parent"
android:layout_height="250.0dp"
android:minWidth="25px"
android:minHeight="25px"
android:id="@+id/imageView1" />
</LinearLayout>
Instantiate ImageView in onCreate Method
ImageView imgView;
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.activity_main);
imgView = FindViewById<ImageView>(Resource.Id.imageView1);
OCR();
}
THIS IS IMPORTANT CODE FOR GETTING TEXT AND DRAWING RECTANGLE ON IT
Please read Comments on top of code
public void OCR()
{
//Convert The Image To Bitmap
Bitmap bitmap = BitmapFactory.DecodeResource(ApplicationContext.Resources, Resource.Mipmap.lineindent);
TextRecognizer textRecognizer = new TextRecognizer.Builder(ApplicationContext).Build();
if (!textRecognizer.IsOperational)
{
Log.Error("Main Activity", "Dependencies not available");
// Check android for low storage so dependencies can be loaded, DEPRICATED CHANGE LATER
IntentFilter intentLowStorage = new IntentFilter(Intent.ActionDeviceStorageLow);
bool hasLowStorage = RegisterReceiver(null, intentLowStorage) != null;
if (hasLowStorage)
{
Toast.MakeText(this, "Low Memory On Disk", ToastLength.Long);
Log.Error("Main Activity", "Low Memory On Disk");
}
}
else
{
Frame frame = new Frame.Builder().SetBitmap(bitmap).Build();
SparseArray items = textRecognizer.Detect(frame);
List<TextBlock> blocks = new List<TextBlock>();
TextBlock myItem = null;
for (int i = 0; i < items.Size(); ++i)
{
myItem = (TextBlock)items.ValueAt(i);
//Add All TextBlocks to the `blocks` List
blocks.Add(myItem);
}
//END OF DETECTING TEXT
//The Color of the Rectangle to Draw on top of Text
Paint rectPaint = new Paint();
rectPaint.Color = Color.White;
rectPaint.SetStyle(Paint.Style.Stroke);
rectPaint.StrokeWidth = (4.0f);
//Create the Canvas object,
//Which ever way you do image that is ScreenShot for example, you
//need the views Height and Width to draw recatngles
//because the API detects the position of Text on the View
//So Dimesnions are important for Draw method to draw at that Text
//Location
Bitmap tempBitmap = Bitmap.CreateBitmap(bitmap.Width, bitmap.Height, Bitmap.Config.Rgb565);
Canvas canvas = new Canvas(tempBitmap);
canvas.DrawBitmap(bitmap, 0, 0, null);
//Loop through each `Block`
foreach (TextBlock textBlock in blocks)
{
IList<IText> textLines = textBlock.Components;
//loop Through each `Line`
foreach (IText currentLine in textLines)
{
IList<IText> words = currentLine.Components;
//Loop through each `Word`
foreach (IText currentword in words)
{
//Get the Rectangle/boundingBox of the word
RectF rect = new RectF(currentword.BoundingBox);
rectPaint.Color = Color.Black;
//Finally Draw Rectangle/boundingBox around word
canvas.DrawRect(rect, rectPaint);
//Set image to the `View`
imgView.SetImageDrawable(new BitmapDrawable(Resources, tempBitmap));
}
}
}
}
}
RESULT
If you want the Rectangle on Lines then remove the code from words loops and put it in the Lines loop, same goes to the blocks
来源：https://stackoverflow.com/questions/53141349/how-to-get-position-of-text-in-an-image-using-mobile-vision-api