Theme.MaterialComponents 不会改变对话框标题的字体

Question

我正在为我们的应用程序使用材料组件主题。现在我们想要一个自定义字体，我设法在下面的主题中几乎无处不在地应用它，它使用textAppearance...由材料组件定义的各种属性。

这非常有效，并且该主题也几乎适用于所有地方的 AlertDialogs——消息文本和按钮具有自定义字体，按钮具有正确的强调色等。

无论如何，只有对话框标题保持 Roboto 字体。

<!-- externalized font name for easier change -->
<string name="font_regular" translatable="false" tools:ignore="ReferenceType">@font/atma_regular</string>

<style name="Theme.App" parent="Theme.MaterialComponents.Light.NoActionBar">
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
    <item name="android:textColorPrimary">@color/textColorPrimary</item>
    <item name="android:textColorSecondary">@color/textColorSecondary</item>

    <item name="textAppearanceHeadline1">@style/TextAppearance.App.Button</item>
    <item name="textAppearanceHeadline2">@style/TextAppearance.App.Button</item>
    <item name="textAppearanceHeadline3">@style/TextAppearance.App.Button</item>
    <item name="textAppearanceHeadline4">@style/TextAppearance.App.Button</item>
    <item name="textAppearanceHeadline5">@style/TextAppearance.App.Button</item>
    <item name="textAppearanceHeadline6">@style/TextAppearance.App.Button</item>
    <item name="textAppearanceSubtitle1">@style/TextAppearance.App.Subtitle1</item>
    <item name="textAppearanceSubtitle2">@style/TextAppearance.App.Subtitle2</item>
    <item name="textAppearanceBody1">@style/TextAppearance.App.Body1</item>
    <item name="textAppearanceBody2">@style/TextAppearance.App.Body2</item>
    <item name="textAppearanceButton">@style/TextAppearance.App.Button</item>
    <item name="android:textAppearanceLarge">@style/TextAppearance.App.Large</item>
    <item name="android:textAppearanceMedium">@style/TextAppearance.App.Medium</item>
    <item name="android:textAppearanceSmall">@style/TextAppearance.App.Small</item>
</style>

<style name="TextAppearance.App.Subtitle1" parent="TextAppearance.MaterialComponents.Subtitle1">
    <item name="fontFamily">@string/font_regular</item>
    <item name="android:fontFamily">@string/font_regular</item>
</style>
...

我试图为警报对话框定义一个额外的主题，如下所示：

<style name="Theme.App" parent="Theme.MaterialComponents.Light.NoActionBar">
    ...
    <item name="alertDialogTheme">@style/Theme.App.AlertDialog</item>
    ...
</style>

<style name="Theme.App.AlertDialog" parent="Theme.MaterialComponents.Light.Dialog.Alert">
    <item name="android:windowTitleStyle">@style/TextAppearance.App.DialogWindowTitle</item>
</style>

<style name="TextAppearance.App.DialogWindowTitle" parent="ThemeOverlay.MaterialComponents.Dialog.Alert">
    <item name="fontFamily">@string/font_regular</item>
    <item name="android:fontFamily">@string/font_regular</item>
    <item name="android:textSize">30sp</item>
</style>

但这会重置所有地方的颜色和字体。唯一应用的是 textSize。

实现这一目标真的不应该那么难，但我现在没有想法。我可以以编程方式应用字体，但这会非常难看。

Answer 1

正如您所提到的，AlertDialog创建者使用应用程序主题中的属性MaterialAlertDialogBuilder定义的样式。textAppearanceSubtitle1

否则，您可以使用以下内容更改AlertDialog使用的样式：

new MaterialAlertDialogBuilder(MainActivity.this,
    R.style.MyTitle_ThemeOverlay_MaterialComponents_MaterialAlertDialog)
    .setTitle("Title")
    .setMessage("Message......")
    .setPositiveButton("ok", null)
    .setNegativeButton("Cancel", null)
    .show();

在您的风格中，您必须自定义materialAlertDialogTitleTextStyle属性：

  <style name="MyTitle_ThemeOverlay.MaterialComponents.MaterialAlertDialog" parent="@style/ThemeOverlay.MaterialComponents.MaterialAlertDialog">
    <item name="materialAlertDialogTitleTextStyle">@style/MyTitle_MaterialAlertDialog.MaterialComponents.Title.Text</item>
  </style>
  <style name="MyTitle_MaterialAlertDialog.MaterialComponents.Title.Text" parent="@style/MaterialAlertDialog.MaterialComponents.Title.Text">
    <item name="android:textAppearance">@style/MyTitle_TextAppearance.MaterialComponents.Subtitle1</item>
  </style>
  <style name="MyTitle_TextAppearance.MaterialComponents.Subtitle1" parent="TextAppearance.MaterialComponents.Subtitle1">
    <item name="fontFamily">....</item>
    <item name="android:fontFamily">....</item>
    <item name="android:textStyle">.....</item>
  </style>