Android MaterialButton的一些问题

MaterialButton和MaterialCardView的都新增了边框属性，我们没必要为了一个边框写那么多shape，一旦多了谁着得住。

1、在使用MaterialButton注意一点是它必须设置android:textAppearance属性，不然会崩溃

This component requires that you specify a valid TextAppearance attribute. Update your app theme to inherit from Theme.MaterialComponents (or a descendant)

 public MaterialButton(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);TypedArray attributes = ThemeEnforcement.obtainStyledAttributes(context, attrs, styleable.MaterialButton, defStyleAttr, style.Widget_MaterialComponents_Button, new int[0]);this.iconPadding = attributes.getDimensionPixelSize(styleable.MaterialButton_iconPadding, 0);this.iconTintMode = ViewUtils.parseTintMode(attributes.getInt(styleable.MaterialButton_iconTintMode, -1), Mode.SRC_IN);this.iconTint = MaterialResources.getColorStateList(this.getContext(), attributes, styleable.MaterialButton_iconTint);this.icon = MaterialResources.getDrawable(this.getContext(), attributes, styleable.MaterialButton_icon);this.iconGravity = attributes.getInteger(styleable.MaterialButton_iconGravity, 1);this.iconSize = attributes.getDimensionPixelSize(styleable.MaterialButton_iconSize, 0);this.materialButtonHelper = new MaterialButtonHelper(this);this.materialButtonHelper.loadFromAttributes(attributes);attributes.recycle();this.setCompoundDrawablePadding(this.iconPadding);this.updateIcon();}

private static void checkTextAppearance(Context context, AttributeSet set, @StyleableRes int[] attrs, @AttrRes int defStyleAttr, @StyleRes int defStyleRes, @StyleableRes int... textAppearanceResIndices) {TypedArray themeEnforcementAttrs = context.obtainStyledAttributes(set, styleable.ThemeEnforcement, defStyleAttr, defStyleRes);boolean enforceTextAppearance = themeEnforcementAttrs.getBoolean(styleable.ThemeEnforcement_enforceTextAppearance, false);if (!enforceTextAppearance) {themeEnforcementAttrs.recycle();} else {boolean validTextAppearance;if (textAppearanceResIndices != null && textAppearanceResIndices.length != 0) {validTextAppearance = isCustomTextAppearanceValid(context, set, attrs, defStyleAttr, defStyleRes, textAppearanceResIndices);} else {validTextAppearance = themeEnforcementAttrs.getResourceId(styleable.ThemeEnforcement_android_textAppearance, -1) != -1;}themeEnforcementAttrs.recycle();if (!validTextAppearance) {throw new IllegalArgumentException("This component requires that you specify a valid TextAppearance attribute. Update your app theme to inherit from Theme.MaterialComponents (or a descendant).");}}}

它会检查textApearance属性，解决方式有两种如下

1、添加它就好

android:textAppearance="?android:attr/textAppearanceButton"

2、application或activity或控件的theme继承自Theme.MaterialComponents.xxxx,使type能够找到这个属性，如

 <com.google.android.material.button.MaterialButtonandroid:id="@+id/btn_ok"android:layout_width="0dp"android:layout_height="wrap_content"android:layout_marginTop="18dp"android:gravity="center"android:text="确认办理"android:textColor="#ffffffff"android:textSize="24sp"android:visibility="visible"app:backgroundTint="#FFA54C"android:theme="@style/Theme.MaterialComponents.Light.DarkActionBar"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent" />

其实想了想，也许以后MaterialComponents的text相关组件都会进行这种操作吧。

2、在使用MaterialButton时候可能遇到背景颜色不能充满控件的问题。

如果按照以前默认的方式添加背景颜色，我们发现背景颜色不能充满上下编剧，我们对比使用appcompatButton

<androidx.appcompat.widget.AppCompatButtonandroid:id="@+id/btn_cancel"android:layout_width="0dp"android:layout_height="wrap_content"android:layout_marginTop="18dp"android:gravity="center"android:text="确认办理"android:textColor="#ffffffff"android:textSize="24sp"android:theme="@style/Theme.MaterialComponents.Light"android:visibility="visible"android:background="#FFA54C"app:layout_constraintBottom_toTopOf="@id/btn_ok"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent" /><com.google.android.material.button.MaterialButtonandroid:id="@+id/btn_ok"android:layout_width="0dp"android:layout_height="wrap_content"android:layout_marginTop="18dp"android:gravity="center"android:text="确认办理"android:textColor="#ffffffff"android:textSize="24sp"android:theme="@style/Theme.MaterialComponents.Light"android:visibility="visible"android:background="#FFA54C"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent" />

1、从上面的图片可以看出它们的背景颜色不一样。MaterialButton是不受android:background控制的，官方建议我们设置app:backgroundHint来进行背景的更改。

2、AppCompatButton如果设置了android:background会覆盖上下左右的间距，MaterialButton则不会

3、MaterialButton设置了app:backgroundHint左右是没有间距的，而上下有。AppCompatButton设置了app:backgroundHint是上下左右都有间距

找到原因https://github.com/material-components/material-components-android/blob/master/docs/components/MaterialButton.md#attributes

Note: MaterialButton is visually different from Button and AppCompatButton. One of the main differences is that AppCompatButton has a 4dp inset on the left and right sides, whereas MaterialButton does not. To add an inset to match AppCompatButton, set android:insetLeft and android:insetRight on the button to 4dp, or change the spacing on the button's parent layout.

反正AppCompatButton左右留了4个dp的占位，而MaterialButton没有。

试验

<com.google.android.material.button.MaterialButtonandroid:id="@+id/btn_ok"android:layout_width="0dp"android:layout_height="wrap_content"android:layout_marginTop="18dp"android:gravity="center"android:padding="5dp"app:cornerRadius="0dp"android:insetLeft="50dp"android:insetTop="0dp"android:insetBottom="0dp"android:insetRight="50dp"android:textAppearance="@style/Widget.MaterialComponents.Button"android:text="确认办理"android:textColor="#ffffffff"android:textSize="24sp"android:visibility="visible"app:backgroundTint="#FFA54C"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"/>

通过设置上下左右inset控制button绘制的范围，背景颜色也能控制。那么我们就解决了这个问题了

方案：

设置insetTop和insetBottom为0dp