AutoTranslate: Pad view text for compatibility reasons.

Some apps operate on the view text based on layout calculations made on
the transformed text. This can cause issues (even crashes) if the
transformed text is longer than the original, as is often the case with
Translate. A previous temporary fix,
I685ae4a9752c817db81f0d736f1d746b2e4a9839, ellipsized the translated
text. This change fixes it properly by instead padding the original
text.

A followup change will make this controllable by API instead of padding
every TextView.

The en space character, U+2002, is used for the padding here. It seems
to work well in practice for multiple languages. We don't make this
configurable through API as it could make debugging harder (issues
triggered by server-side changes).

Bug: 179693024
Test: atest CtsTranslationTestCases
Test: manual - toggling between original and translated, scrolling, new
 views appearing, multiple apps
Change-Id: I9d7db5d2bc200e4042baf3267796f00cfc298f19

1 files changed, 10 insertions, 0 deletions

diff --git a/core/java/android/widget/TextView.java b/core/java/android/widget/TextView.java
index 40c79cf086fc..1953a7687cb9 100644
--- a/core/java/android/widget/TextView.java
+++ b/core/java/android/widget/TextView.java
@@ -770,6 +770,8 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
     private final boolean mUseInternationalizedInput;
     // True if fallback fonts that end up getting used should be allowed to affect line spacing.
     /* package */ boolean mUseFallbackLineSpacing;
+    // True if the view text can be padded for compat reasons, when the view is translated.
+    private final boolean mUseTextPaddingForUiTranslation;
 
     @ViewDebug.ExportedProperty(category = "text")
     @UnsupportedAppUsage
@@ -1480,6 +1482,8 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
         final int targetSdkVersion = context.getApplicationInfo().targetSdkVersion;
         mUseInternationalizedInput = targetSdkVersion >= VERSION_CODES.O;
         mUseFallbackLineSpacing = targetSdkVersion >= VERSION_CODES.P;
+        // TODO(b/179693024): Use a ChangeId instead.
+        mUseTextPaddingForUiTranslation = targetSdkVersion <= Build.VERSION_CODES.R;
 
         if (inputMethod != null) {
             Class<?> c;
@@ -2372,6 +2376,12 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
     @ViewDebug.CapturedViewProperty
     @InspectableProperty
     public CharSequence getText() {
+        if (mUseTextPaddingForUiTranslation
+                && mDefaultTranslationCallback != null
+                && mDefaultTranslationCallback.isTextPaddingEnabled()
+                && mDefaultTranslationCallback.isShowingTranslation()) {
+            return mDefaultTranslationCallback.getPaddedText(mText, mTransformed);
+        }
         return mText;
     }