In XML Button size changes with its Font size

问题

I know this sounds simple but I wanted to change a button's font size to fill the Button .Even though the text doesn't take all the space inside the button when I decrease text height for example the Button's height decreases as well.Is there any way I can change The text-size so it fills that space inside the Button or do I have to just use an Image Button .

Here is the case :-

        <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:background="@android:color/black"
        android:id="@+id/led"
        >


         <Button
            android:id="@+id/grow"
            android:layout_width="match_parent"
            android:layout_height="39dp"
            android:layout_marginRight="1dp"
            android:layout_weight="1"
            android:textSize="15dp"
            android:background="@color/Lightbrown"
            android:text="A▲"

            android:textAllCaps="false"
         />

        <Button
            android:layout_width="match_parent"
            android:layout_height="39dp"
            android:text="A▼"
            android:textAllCaps="false"
            android:id="@+id/shrink"
            android:background="@color/Lightbrown"
            android:layout_marginRight="1dp"
            android:layout_weight="1"
            android:padding="0dp"
            android:textSize="10dp"

            />

See I used my Linearlayout as a background for my Buttons the second button's size changes with its font size I just want its size to remain the same as the first Button but with a smaller textsize.

回答1:

Update

Your second button is not actually smaller, it is just aligned in a way you wouldn't necessarily expect.

Horizontal LinearLayouts with TextView (or subclass, which Button is) children will "baseline align" the children. That means they will make sure that the bottom edge of all the text in the row is at the same height. Since your second button uses smaller text, the text bottom would be higher up inside the button, so the LinearLayout forces the whole button down to accomodate.

Add this attribute to your LinearLayout:

android:baselineAligned="false"

Original

First, I assume you're using android:layout_height="wrap_content". If you don't want your button's height to scale with font size, you'll have to change this to some fixed value (or match_parent if you want it to be the same size as its parent).

As for why the text "doesn't take up all the space", that's because Buttons have padding built into them automatically. You can remove this padding by defining android:padding="0dp"

However, you'll soon notice that the button looks really bad if you give it no padding and too-large text. How to solve that is really up to the requirements of your design.

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="32dp"
        android:layout_gravity="center_horizontal"
        android:padding="0dp"
        android:textSize="36sp"
        android:text="Hello world"/>

</FrameLayout>

回答2:

Use a fixed size instead of wrap_content for your button.

f that doesn't work for your design, consider overlaying a TextView on top of your Button (with ConstraintLayout or FrameLayout or RelativeLayout). After that, you can set the TextView's focusable, focusableInTouchMode, and clickable properties to false so that it doesn't intercept your Button's clicks.

来源：https://stackoverflow.com/questions/45337745/in-xml-button-size-changes-with-its-font-size