Android在TextView中剪辑/剪切字符

Question

I've got a textview as a single line in a GridLayout. It should fill out the whole screen in width.

So when I click a button I append a new character to the textview with term.append(String.valueOf(value)); Where term is the textview.

But there is no clipping, means I can fill the textview with a lot of characters over the actual size of the TexView. I want to stop adding characters after the textview is full. Alternatively I could horizontal scrolling, but that doesn't work neither.

I tried the following code:

Paint p = new Paint();
if (term.getMaxWidth() > p.measureText(term.getText().toString()))
                term.append(String.valueOf(value));

but it the value for term.getMaxWidth() (same for LayoutParams().width) is way too high.

This is my style xml:

<GridLayout
    android:layout_width="368dp"
    android:layout_height="495dp"
    android:layout_marginTop="8dp"
    android:columnCount="4"
    android:alignmentMode="alignMargins"
    app:layout_constraintTop_toTopOf="parent"
    android:layout_marginLeft="16dp"
    app:layout_constraintLeft_toLeftOf="parent"
    android:layout_marginRight="16dp"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintBottom_toBottomOf="parent"
    android:layout_marginBottom="8dp"
    android:foregroundGravity="center"
    app:layout_constraintHorizontal_bias="0.0"
    app:layout_constraintVertical_bias="0.0">


    <TextView
        android:id="@+id/textView3"
        android:layout_width="355dp"
        android:maxWidth="355dp"
        android:layout_height="62dp"
        android:layout_columnSpan="4"
        android:text="@string/calc_term"
        android:textSize="30sp"
        android:maxLines="1"
        android:scrollHorizontally="false"
        android:isScrollContainer="false"
        android:ellipsize="start" />

Thank you

Answer 1

Try like this:

android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:minWidth="300dp"

Answer 2

Ok I got a solution by myself: The Paint object doesn't know about the scaling of the text. Therefore I need to use the TextViews own Paint object.

TextPaint paint = term.getPaint();
            if (term.getWidth() > paint.measureText(term.getText().toString())
                                        + paint.measureText(String.valueOf(value)))
                term.append(String.valueOf(value));

does the trick. Where value is the new character.