Sunday, September 30, 2018

get position of the text inside a TextView

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suppose i have the following text 'ADD TEST' inside TextView as shown below enter image description here

as you can see the text inside the textView does not have the same width and height as textView .

what i want is to get the x,y position of text inside the textView

2 Answers

Answers 1

Y value

You can use textView.getTextSize() or textView.getPaint().getTextSize() to get the actual used text size in pixels (as Float).

Next, we need the total height of the text view, which we can find as follows:

textView.measure(0, 0); // We must call this to let it calculate the heights int height = textView.getMeasuredHeight(); 

However, the final size that we need can also have decimals. So lets make it a float for more precision:

float totalHeight = (float) height; 

Now that we know the values, we can calculate the y value of the text inside the view:

// The spacing between the views is `totalHeight - textSize` // We have a spacing at the top and the bottom, so we divide it by 2 float yValue = (totalHeight - textSize) / 2 

X value

Furthermore, the xValue is just the x value of the text view itself when using android:includeFontPadding="false".

Answers 2

Take a look at a couple of Paint methods: getTextBounds() and measureText. We can use these to determine the offset of the text within the TextView. Once the offset within the TextView is determined, we can add that to the location of the TextView itself to determine the screen coordinates of the text if that is desired.

I have also found the article "Android 101: Typography" to be useful in understanding some of the complexities of typography.

The following example finds the bounds of the text within three TextViews and draws a rectangle around the text. The rectangle contains the (x, y) coordinates of the text within the TextView.

activity_main.xml
A simple layout for demonstration.

<android.support.constraint.ConstraintLayout     android:id="@+id/layout"     android:layout_width="match_parent"     android:layout_height="match_parent"     tools:context=".MainActivity">      <TextView         android:id="@+id/textView1"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginTop="24dp"         android:background="@android:color/holo_blue_light"         android:padding="24dp"         android:text="Hello World"         android:textColor="@android:color/black"         android:textSize="50sp"         app:layout_constraintLeft_toLeftOf="parent"         app:layout_constraintRight_toRightOf="parent"         app:layout_constraintTop_toTopOf="parent" />      <TextView         android:id="@+id/textView2"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginTop="24dp"         android:background="@android:color/holo_blue_light"         android:padding="24dp"         android:text="Hello Worldly"         android:textColor="@android:color/black"         android:textSize="50sp"         app:layout_constraintLeft_toLeftOf="parent"         app:layout_constraintRight_toRightOf="parent"         app:layout_constraintTop_toBottomOf="@id/textView1" />      <TextView         android:id="@+id/textView3"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginTop="24dp"         android:background="@android:color/holo_blue_light"         android:padding="24dp"         android:text="aaaaaaaaaa"         android:textColor="@android:color/black"         android:textSize="50sp"         app:layout_constraintLeft_toLeftOf="parent"         app:layout_constraintRight_toRightOf="parent"         app:layout_constraintTop_toBottomOf="@id/textView2" />  </android.support.constraint.ConstraintLayout> 

MainActivity.java

public class MainActivity extends AppCompatActivity {      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          drawTextBounds((TextView) findViewById(R.id.textView1));         drawTextBounds((TextView) findViewById(R.id.textView2));         drawTextBounds((TextView) findViewById(R.id.textView3));     }      private void drawTextBounds(TextView textView) {         // Force measure of text pre-layout.         textView.measure(0, 0);         String s = (String) textView.getText();          // bounds will store the rectangle that will circumscribe the text.         Rect bounds = new Rect();         Paint textPaint = textView.getPaint();          // Get the bounds for the text. Top and bottom are measured from the baseline. Left         // and right are measured from 0.         textPaint.getTextBounds(s, 0, s.length(), bounds);         int baseline = textView.getBaseline();         bounds.top = baseline + bounds.top;         bounds.bottom = baseline + bounds.bottom;         int startPadding = textView.getPaddingStart();         bounds.left += startPadding;          // textPaint.getTextBounds() has already computed a value for the width of the text,          // however, Paint#measureText() gives a more accurate value.         bounds.right = (int) textPaint.measureText(s, 0, s.length()) + startPadding;          // At this point, (x, y) of the text within the TextView is (bounds.left, bounds.top)         // Draw the bounding rectangle.         Bitmap bitmap = Bitmap.createBitmap(textView.getMeasuredWidth(),                                             textView.getMeasuredHeight(),                                             Bitmap.Config.ARGB_8888);         Canvas canvas = new Canvas(bitmap);         Paint rectPaint = new Paint();         rectPaint.setColor(Color.RED);         rectPaint.setStyle(Paint.Style.STROKE);         rectPaint.setStrokeWidth(1);         canvas.drawRect(bounds, rectPaint);         textView.setForeground(new BitmapDrawable(getResources(), bitmap));     } } 

enter image description here

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