Android TabLayout 自定义指示器宽度

Question

我想减小指示器的宽度 - 例如，使其宽度不是整个标签宽度，而是标签宽度的 1/2。
这就是我需要做的所有事情，所以我不想下载一些自定义库并搜索可以执行此操作的位置。

有没有办法做到这一点，还是我应该自己写这样的视图？

Answer 1

试试这个。

public void setIndicator (TabLayout tabs,int leftDip,int rightDip){  
   Class<?> tabLayout = tabs.getClass();  
   Field tabStrip = null;  
   try {  
       tabStrip = tabLayout.getDeclaredField("mTabStrip");  
   } catch (NoSuchFieldException e) {  
       e.printStackTrace();  
   }  

   tabStrip.setAccessible(true);  
   LinearLayout llTab = null;  
   try {  
       llTab = (LinearLayout) tabStrip.get(tabs);  
   } catch (IllegalAccessException e) {  
       e.printStackTrace();  
   }  

   int left = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, leftDip, Resources.getSystem().getDisplayMetrics());  
   int right = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, rightDip, Resources.getSystem().getDisplayMetrics());  

   for (int i = 0; i < llTab.getChildCount(); i++) {  
       View child = llTab.getChildAt(i);  
       child.setPadding(0, 0, 0, 0);  
       LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(0, LinearLayout.LayoutParams.MATCH_PARENT, 1);  
       params.leftMargin = left;  
       params.rightMargin = right;  
       child.setLayoutParams(params);  
       child.invalidate();  
   }  
}

然后

tab.post(new Runnable() {  
       @Override  
       public void run() {  
           setIndicator(tab,60,60);  
       }  
});

我的修改w/o反射（要设置自定义视图！）。

for (int i = 0; i < tabs.getTabCount(); i++) {
    TabLayout.Tab tab = tabs.getTabAt(i);
    if (tab != null) {
        View customView = tab.getCustomView();
        if (customView != null) {
            View targetViewToApplyMargin = (View) customView.getParent();
            ViewGroup.MarginLayoutParams layoutParams = (ViewGroup.MarginLayoutParams) targetViewToApplyMargin.getLayoutParams();

            layoutParams.rightMargin = totalTabMargin;
                    targetViewToApplyMargin.setLayoutParams(layoutParams);
        }
    }
}

Answer 2

可以复制TabLayout，修改Indicator计算宽度的逻辑。请参阅 updateIndicatorPosition() 和 animateIndicatorToPosition()。一个简单的演示 https://github.com/xybean/CustomTabLayout

Answer 3

对于最终解决此问题的任何人，我找到了一个简单的解决方案，其中包含约 90% 的制表符宽度指示器的矢量绘图：

ic_tab_indicator_24dp:

<vector
android:height="24dp"
android:width="24dp"
android:viewportHeight="24.0"
android:viewportWidth="24.0"
xmlns:android="http://schemas.android.com/apk/res/android">
<path
    android:strokeWidth="4"
    android:fillColor="@android:color/white"
    android:pathData="M2,0 L22,0 L22,24 L2,24 z"/>

然后在布局中设置tabIndicator：

app:tabIndicator="@drawable/ic_tab_indicator_24dp"

或在styles.xml:

<item name="tabIndicator">@drawable/ic_tab_indicator_24dp</item>

编辑： 由于我的解决方案越来越受到关注，我想补充一点，您只需修改 pathData ("M2,0 L22,0 L22,24 L2,24 z") 更改 2 和 22 就可以玩宽度值。添加到 2 的量应该从 22 中减去。即："M4,0 L20,0 L20,24 L4,24 z" 或 "M6,0 L18,0 L18,24 L6,24 z"...

Answer 4

尝试了所有这些解决方案，但都不满意，最后我自己找到了解决方案，我们只需要修改 SlidingTabIndicator 的 indicatorLeft 和 indicatorRight 字段，扩展 tablayout 并在需要时调用 setIndicaotrWidth() ，例如：

setIndicatorWidth(70);

全部代码：

import android.content.Context;
import android.content.res.Resources;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewTreeObserver;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.google.android.material.tabs.TabLayout;

import java.lang.reflect.Field;

import androidx.annotation.NonNull;

public class TabLayoutEx extends TabLayout {

    public TabLayoutEx(Context context) {
        this(context, null);
    }

    public TabLayoutEx(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public TabLayoutEx(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(attrs);
    }

    private void init(AttributeSet attrs) {
        setTabIndicatorFullWidth(false);
        setIndicatorWidth(70);
    }



    private class DefPreDrawListener implements ViewTreeObserver.OnPreDrawListener {

        private LinearLayout tabStrip = null;
        private int tabWidth;
        private Field fieldLeft;
        private Field fieldRight;

        public void setTabStrip(LinearLayout tabStrip, int width) {
            try {
                this.tabStrip = tabStrip;
                this.tabWidth = width;
                Class cls = tabStrip.getClass();
                fieldLeft = cls.getDeclaredField("indicatorLeft");
                fieldLeft.setAccessible(true);
                fieldRight = cls.getDeclaredField("indicatorRight");
                fieldRight.setAccessible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        @Override
        public boolean onPreDraw() {
            try {
                if (tabWidth > 0) {
                    int left = fieldLeft.getInt(this.tabStrip);
                    int right = fieldRight.getInt(this.tabStrip);
                    //根据目标宽度及现在的宽度调整为合适的left和right
                    int diff = right - left - tabWidth;
                    left = left + diff / 2;
                    right = right - diff / 2;
                    fieldLeft.setInt(this.tabStrip, left);
                    fieldRight.setInt(this.tabStrip, right);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return true;
        }
    }

    private DefPreDrawListener defPreDrawListener = new DefPreDrawListener();

    public void setIndicatorWidth(int widthDp) {
        Class<?> tabLayout = TabLayout.class;
        Field tabStrip = null;
        try {
            tabStrip = tabLayout.getDeclaredField("slidingTabIndicator");
            tabStrip.setAccessible(true);
            LinearLayout tabIndicator = (LinearLayout) tabStrip.get(this);
            int width = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, widthDp, Resources.getSystem().getDisplayMetrics());
            //avoid add preDrawListener multi times
            tabIndicator.getViewTreeObserver().removeOnPreDrawListener(defPreDrawListener);
            tabIndicator.getViewTreeObserver().addOnPreDrawListener(defPreDrawListener);
            defPreDrawListener.setTabStrip(tabIndicator, width);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

Answer 5

如果您想要一个固定大小的标签指示器，您可以通过 drawable 创建一个固定大小的指示器形状来实现：

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:gravity="center">
        <shape android:shape="rectangle">
            <solid android:color="@color/colorAccent" />
            <corners
                android:topLeftRadius="2dp"
                android:topRightRadius="2dp" />
            <size
                android:width="16dp"
                android:height="2dp" />
        </shape>
    </item>
</layer-list>

然后在 TabLayout 上，您可以将标签指示器设置为可绘制。同时，您还必须设置 tabIndicatorColor

 app:tabIndicatorColor="@color/tabIndicatorColor"
 app:tabIndicator="@drawable/tab_indicator"

因为可绘制对象本身将形状置于其边界内的中心，指示器将具有固定大小。

如果想让指示器匹配标签的宽度，可以去掉tabIndicatorandroid:gravity。

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape android:shape="rectangle">
            <solid android:color="@color/colorAccent" />
            <corners
                radius="2dp" />
            <size
                android:width="16dp"
                android:height="2dp" />
        </shape>
    </item>
</layer-list>

Android TabLayout 自定义指示器宽度

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android-tablayout