一、setHomeAsUpIndicator()

getSupportActionBar().setHomeAsUpIndicator(R.drawable.btn_back);

跟踪源码(ToolbarWidgetWrapper.java)最终发现调用了这个方法

private void ensureNavButtonView() {
       if (mNavButtonView == null) {
           mNavButtonView = new ImageButton(getContext(), null,
                   R.attr.toolbarNavigationButtonStyle);
           final LayoutParams lp = generateDefaultLayoutParams();
           lp.gravity = GravityCompat.START | (mButtonGravity & Gravity.VERTICAL_GRAVITY_MASK);
           mNavButtonView.setLayoutParams(lp);
       }
   }

toolbarNavigationButtonStyle 找到样式找到

<item name="toolbarNavigationButtonStyle">@style/Widget.AppCompat.Toolbar.Button.Navigation</item>

最终样式

<style name="Base.Widget.AppCompat.Toolbar.Button.Navigation" parent="android:Widget">    <item name="android:background">?attr/controlBackground</item>    <item name="android:minWidth">56dp</item>    <item name="android:scaleType">center</item></style>

可见是因为android:minWidth 在做怪

解决：

Paste_Image.png

<item name="toolbarNavigationButtonStyle">@style/MyToolbarNavigationButtonStyle</item>
    </style>

    <style name="MyToolbarNavigationButtonStyle" parent="Widget.AppCompat.Toolbar.Button.Navigation">
        <item name="android:minWidth">0dp</item>
        <item name="android:paddingLeft">@dimen/View_margin_10</item>
    </style>

二、setlogo()

public void setLogo(Drawable drawable) {
       if (drawable != null) {
           ensureLogoView();
           if (!isChildOrHidden(mLogoView)) {
               addSystemView(mLogoView, true);
           }
       } else if (mLogoView != null && isChildOrHidden(mLogoView)) {
           removeView(mLogoView);
           mHiddenViews.remove(mLogoView);
       }
       if (mLogoView != null) {
           mLogoView.setImageDrawable(drawable);
       }
   }

   private void ensureLogoView() {
           if (mLogoView == null) {
               mLogoView = new ImageView(getContext());
           }
       }