获取文本在 TextView 中的位置 [英] get position of the text inside a TextView

问题描述

假设我在 TextView 中有以下文本ADD TEST"，如下所示

如您所见，TextView 中的文本与 TextView 的宽度和高度不同.

我想要的是在 TextView

中获取文本的 x,y 位置

解决方案

看看几个 Paint 方法:

suppose I have the following text 'ADD TEST' inside TextView as shown below

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

解决方案

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));
    }
}

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