FloatingActionButton with text instead of image

问题:

I'm trying to figure out how can be modified FloatingActionButton from android support library. Can it be used with the text instead of image?

Something like this one:

I see it extends ImageButton so I think not. Am I right?

Is this correct in terms of Material Design in general?

回答1:

Thanks to all.

Here is easy workaround which I found for this question. Works correctly for Android 4+, for Android 5+ is added specific parameter android:elevation to draw TextView over FloatingActionButton.

<FrameLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|right">

    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@android:color/transparent" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="@android:string/ok"
        android:elevation="16dp"
        android:textColor="@android:color/white"
        android:textAppearance="?android:attr/textAppearanceMedium" />
</FrameLayout>

回答2:

convert a text into bitmap and use it. its super easy.

fab.setImageBitmap(textAsBitmap("OK", 40, Color.WHITE));

//method to convert your text to image
public static Bitmap textAsBitmap(String text, float textSize, int textColor) {
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setTextSize(textSize);
    paint.setColor(textColor);
    paint.setTextAlign(Paint.Align.LEFT);
    float baseline = -paint.ascent(); // ascent() is negative
    int width = (int) (paint.measureText(text) + 0.0f); // round
    int height = (int) (baseline + paint.descent() + 0.0f);
    Bitmap image = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);

    Canvas canvas = new Canvas(image);
    canvas.drawText(text, 0, baseline, paint);
    return image;
}

回答3:

FABs are usually used in CoordinatorLayouts. You can use this:

<android.support.design.widget.CoordinatorLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto">

    <android.support.design.widget.FloatingActionButton
            android:id="@+id/fab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom|end"
            android:layout_margin="@dimen/fab_margin"               
            app:backgroundTint="@color/colorPrimary" />

      <TextView android:layout_height="wrap_content"
              android:layout_width="wrap_content"
              android:text="OK"
              android:elevation="6dp"
              android:textSize="18dp"
              android:textColor="#fff"
              app:layout_anchor="@id/fab"
              app:layout_anchorGravity="center"/>

</android.support.design.widget.CoordinatorLayout>

This is what does the work

app:layout_anchor="@id/fab"
app:layout_anchorGravity="center"

Result:

If you're using some layout_behavior for your FAB, you'll have to make a similar layout_behavior for the TextView

回答4:

You can't set text for FloatingActionButton from the support library, but what you can do, is create a text image directly from android studio : File -> New -> Image Asset, and then use it for your button.

In the terms of Material Design; they didn't mention using text with FloatingActionButton, and I don't see any reason for doing that since you don't really have much space for a text.

回答5:

I was needing text in a FAB but instead I just went with a TextView with a circular drawable background:

  <TextView
        android:layout_margin="10dp"
        android:layout_gravity="right"
        android:gravity="center"
        android:background="@drawable/circle_background"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#FFF"
        android:textStyle="bold"
        android:fontFamily="sans-serif"
        android:text="AuthId"
        android:textSize="15dp"
        android:elevation="10dp"/>

Here is the drawable(circle_backgroung.xml):

<?xml version="1.0" encoding="utf-8"?>
<shape
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">

<solid
    android:color="#666666"/>

<size
    android:width="60dp"
    android:height="60dp"/>
</shape>

回答6:

Answer of @NandanKumarSingh https://stackoverflow.com/a/39965170/5279156 works but i have made some changes with fab in code (not xml because they will be overwritten in class methods)

fab.setTextBitmap("ANDROID", 100f, Color.WHITE)
fab.scaleType = ImageView.ScaleType.CENTER
fab.adjustViewBounds = false

Where setTextBitmap is an extension for ImageView class with similar functionality but it supports multilne text

fun ImageView.setTextBitmap(text: String, textSize: Float, textColor: Int) {
    val paint = Paint(Paint.ANTI_ALIAS_FLAG)
    paint.textSize = textSize
    paint.color = textColor
    paint.textAlign = Paint.Align.LEFT
    val lines = text.split(newLine())
    var maxWidth = 0
    for (line in lines) {
        val width = paint.measureText(line).toInt()
        if (width > maxWidth) {
            maxWidth = width
        }
    }
    val height = paint.descent() - paint.ascent()
    val bitmap = Bitmap.createBitmap(maxWidth, height.toInt() * lines.size, Bitmap.Config.ARGB_8888)
    val canvas = Canvas(bitmap)
    var y = - paint.ascent()
    for (line in lines) {
        canvas.drawText(line, 0f, y, paint)
        y += height
    }
    setImageBitmap(bitmap)
}