如何使用 Mobile Vision API 获取图像中文本的位置? [英] How to get position of text in an image using Mobile Vision API?

问题描述

如何使用 Mobile Vision API 获取图像中文本在屏幕上的位置，以及如何在它们周围绘制一个矩形?

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?

示例:

推荐答案

怎么做

在布局中放置一个ImageView

<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>

在onCreate方法中实例化ImageView

ImageView imgView;
    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        SetContentView(Resource.Layout.activity_main);

        imgView = FindViewById<ImageView>(Resource.Id.imageView1);
        OCR();
    }

这是获取文本和在其上绘制矩形的重要代码

请阅读代码顶部的评论

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));


                    }

                }
            }

        }
    }

结果

如果您想要 Lines 上的矩形，则从 words 循环中删除代码并将其放入 Lines 循环中，同样适用于块

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

这篇关于如何使用 Mobile Vision API 获取图像中文本的位置?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！