Add setFontVariationOverride instead of changing setFontVariationSettings behavior

Bug: 361260253
Test: CtsWidgetTestCases
Test: CtsTextTestCases
Test: CtsGraphicsTestCases
Test: minikin_tests
Flag: com.android.text.flags.typeface_redesign_readonly
Change-Id: I6a45314f28fea4237ec2d10bc24b5814325fd5b4

1 files changed, 71 insertions, 0 deletions

diff --git a/graphics/java/android/graphics/Paint.java b/graphics/java/android/graphics/Paint.java
index 3378cc11d565..b332cf0d751f 100644
--- a/graphics/java/android/graphics/Paint.java
+++ b/graphics/java/android/graphics/Paint.java
@@ -19,6 +19,7 @@ package android.graphics;
 import static com.android.text.flags.Flags.FLAG_DEPRECATE_ELEGANT_TEXT_HEIGHT_API;
 import static com.android.text.flags.Flags.FLAG_FIX_LINE_HEIGHT_FOR_LOCALE;
 import static com.android.text.flags.Flags.FLAG_LETTER_SPACING_JUSTIFICATION;
+import static com.android.text.flags.Flags.FLAG_TYPEFACE_REDESIGN_READONLY;
 import static com.android.text.flags.Flags.FLAG_VERTICAL_TEXT_LAYOUT;
 
 import android.annotation.ColorInt;
@@ -57,6 +58,7 @@ import java.lang.annotation.RetentionPolicy;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
 
@@ -96,6 +98,7 @@ public class Paint {
     private LocaleList      mLocales;
     private String          mFontFeatureSettings;
     private String          mFontVariationSettings;
+    private String          mFontVariationOverride;
 
     private float           mShadowLayerRadius;
     private float           mShadowLayerDx;
@@ -2140,6 +2143,12 @@ public class Paint {
      * @see #getFontVariationSettings()
      * @see FontVariationAxis
      */
+    // Add following API description once the setFontVariationOverride becomes public.
+    // This method generates new variation instance of the {@link Typeface} instance and set it to
+    // this object. Therefore, subsequent {@link #setTypeface(Typeface)} call will clear the font
+    // variation settings. Also, creating variation instance of the Typeface requires non trivial
+    // amount of time and memories, therefore consider using
+    // {@link #setFontVariationOverride(String, int)} for better performance.
     public boolean setFontVariationSettings(String fontVariationSettings) {
         final String settings = TextUtils.nullIfEmpty(fontVariationSettings);
         if (settings == mFontVariationSettings
@@ -2174,6 +2183,68 @@ public class Paint {
     }
 
     /**
+     * Sets TrueType or OpenType font variation settings for overriding.
+     *
+     * The settings string is constructed from multiple pairs of axis tag and style values. The axis
+     * tag must contain four ASCII characters and must be wrapped with single quotes (U+0027) or
+     * double quotes (U+0022). Axis strings that are longer or shorter than four characters, or
+     * contain characters outside of U+0020..U+007E are invalid.
+     *
+     * If invalid font variation settings is provided, this method does nothing and returning false
+     * with printing error message to the logcat.
+     *
+     * Different from {@link #setFontVariationSettings(String)}, this overrides the font variation
+     * settings which is already assigned to the font instance. For example, if the underlying font
+     * is configured as {@code 'wght' 500, 'ital' 1}, and if the override is specified as
+     * {@code 'wght' 700, `wdth` 150}, then the effective font variation setting is
+     * {@code `wght' 700, 'ital' 1, 'wdth' 150}. The `wght` value is updated by override, 'ital'
+     * value is preserved because no overrides, and `wdth` value is added by override.
+     *
+     * @param fontVariationOverride font variation settings. You can pass null or empty string as
+     *                              no variation settings.
+     *
+     * @return true if the provided font variation settings is valid. Otherwise returns false.
+     *
+     * @see #getFontVariationSettings()
+     * @see #setFontVariationSettings(String)
+     * @see #getFontVariationOverride()
+     * @see FontVariationAxis
+     */
+    @FlaggedApi(FLAG_TYPEFACE_REDESIGN_READONLY)
+    public boolean setFontVariationOverride(@Nullable String fontVariationOverride) {
+        if (Objects.equals(fontVariationOverride, mFontVariationOverride)) {
+            return true;
+        }
+
+        List<FontVariationAxis> axes;
+        try {
+            axes = FontVariationAxis.fromFontVariationSettingsForList(fontVariationOverride);
+        } catch (IllegalArgumentException e) {
+            Log.i(TAG, "failed to parse font variation settings.", e);
+            return false;
+        }
+        long builderPtr = nCreateFontVariationBuilder(axes.size());
+        for (int i = 0; i < axes.size(); ++i) {
+            FontVariationAxis axis = axes.get(i);
+            nAddFontVariationToBuilder(
+                    builderPtr, axis.getOpenTypeTagValue(), axis.getStyleValue());
+        }
+        nSetFontVariationOverride(mNativePaint, builderPtr);
+        mFontVariationOverride = fontVariationOverride;
+        return true;
+    }
+
+    /**
+     * Gets the current font variation override value.
+     *
+     * @return a current font variation override value.
+     */
+    @FlaggedApi(FLAG_TYPEFACE_REDESIGN_READONLY)
+    public @Nullable String getFontVariationOverride() {
+        return mFontVariationOverride;
+    }
+
+    /**
      * Get the current value of start hyphen edit.
      *
      * The default value is 0 which is equivalent to {@link #START_HYPHEN_EDIT_NO_EDIT}.