Reland CursorAnchorInfo#createForAdditionalParentMatrix()

This logically relands the CL [1], which added an @hide method
CursorAnchorInfo#createForAdditionalParentMatrix().
The corresponding change was once removed in [2].
This is a preparation to reland a change that supports
InputMethodManager#reportActivityView() again.

[1] Ic7f9057623ffc61ec7a6121735dc39adecf4649d
[2] I0a05453eeed863db5bfe4b965ab4bcbad67f2783

Bug: 224424149
Test: CursorAnchorInfoTest
Change-Id: I0a411453c7c26795d28e913a96be8eb8fa3684d7

core/java/android/view/inputmethod/CursorAnchorInfo.java

@@ -415,7 +415,7 @@ public final class CursorAnchorInfo implements Parcelable {
                             "required when positional parameters are specified.");
                 }
             }
-            return new CursorAnchorInfo(this);
+            return CursorAnchorInfo.create(this);
         }
 
         /**
@@ -440,31 +440,93 @@ public final class CursorAnchorInfo implements Parcelable {
         }
     }
 
-    private CursorAnchorInfo(final Builder builder) {
-        mSelectionStart = builder.mSelectionStart;
-        mSelectionEnd = builder.mSelectionEnd;
-        mComposingTextStart = builder.mComposingTextStart;
-        mComposingText = builder.mComposingText;
-        mInsertionMarkerFlags = builder.mInsertionMarkerFlags;
-        mInsertionMarkerHorizontal = builder.mInsertionMarkerHorizontal;
-        mInsertionMarkerTop = builder.mInsertionMarkerTop;
-        mInsertionMarkerBaseline = builder.mInsertionMarkerBaseline;
-        mInsertionMarkerBottom = builder.mInsertionMarkerBottom;
-        mCharacterBoundsArray = builder.mCharacterBoundsArrayBuilder != null
-                ? builder.mCharacterBoundsArrayBuilder.build() : null;
-        mEditorBoundsInfo = builder.mEditorBoundsInfo;
-        mMatrixValues = new float[9];
+    private static CursorAnchorInfo create(Builder builder) {
+        final SparseRectFArray characterBoundsArray =
+                builder.mCharacterBoundsArrayBuilder != null
+                        ? builder.mCharacterBoundsArrayBuilder.build()
+                        : null;
+        final float[] matrixValues = new float[9];
         if (builder.mMatrixInitialized) {
-            System.arraycopy(builder.mMatrixValues, 0, mMatrixValues, 0, 9);
+            System.arraycopy(builder.mMatrixValues, 0, matrixValues, 0, 9);
         } else {
-            Matrix.IDENTITY_MATRIX.getValues(mMatrixValues);
+            Matrix.IDENTITY_MATRIX.getValues(matrixValues);
         }
 
+        return new CursorAnchorInfo(builder.mSelectionStart, builder.mSelectionEnd,
+                builder.mComposingTextStart, builder.mComposingText, builder.mInsertionMarkerFlags,
+                builder.mInsertionMarkerHorizontal, builder.mInsertionMarkerTop,
+                builder.mInsertionMarkerBaseline, builder.mInsertionMarkerBottom,
+                characterBoundsArray, builder.mEditorBoundsInfo, matrixValues);
+    }
+
+    private CursorAnchorInfo(int selectionStart, int selectionEnd, int composingTextStart,
+            @Nullable CharSequence composingText, int insertionMarkerFlags,
+            float insertionMarkerHorizontal, float insertionMarkerTop,
+            float insertionMarkerBaseline, float insertionMarkerBottom,
+            @Nullable SparseRectFArray characterBoundsArray,
+            @Nullable EditorBoundsInfo editorBoundsInfo,
+            @NonNull float[] matrixValues) {
+        mSelectionStart = selectionStart;
+        mSelectionEnd = selectionEnd;
+        mComposingTextStart = composingTextStart;
+        mComposingText = composingText;
+        mInsertionMarkerFlags = insertionMarkerFlags;
+        mInsertionMarkerHorizontal = insertionMarkerHorizontal;
+        mInsertionMarkerTop = insertionMarkerTop;
+        mInsertionMarkerBaseline = insertionMarkerBaseline;
+        mInsertionMarkerBottom = insertionMarkerBottom;
+        mCharacterBoundsArray = characterBoundsArray;
+        mEditorBoundsInfo = editorBoundsInfo;
+        mMatrixValues = matrixValues;
+
         // To keep hash function simple, we only use some complex objects for hash.
-        int hash = Objects.hashCode(mComposingText);
-        hash *= 31;
-        hash += Arrays.hashCode(mMatrixValues);
-        mHashCode = hash;
+        int hashCode = Objects.hashCode(mComposingText);
+        hashCode *= 31;
+        hashCode += Arrays.hashCode(mMatrixValues);
+        mHashCode = hashCode;
+    }
+
+    /**
+     * Creates a new instance of {@link CursorAnchorInfo} by applying {@code parentMatrix} to
+     * the coordinate transformation matrix.
+     *
+     * @param original     {@link CursorAnchorInfo} to be cloned from.
+     * @param parentMatrix {@link Matrix} to be applied to {@code original.getMatrix()}
+     * @return A new instance of {@link CursorAnchorInfo} whose {@link CursorAnchorInfo#getMatrix()}
+     *         returns {@code parentMatrix * original.getMatrix()}.
+     * @hide
+     */
+    public static CursorAnchorInfo createForAdditionalParentMatrix(CursorAnchorInfo original,
+            @NonNull Matrix parentMatrix) {
+        return new CursorAnchorInfo(original.mSelectionStart, original.mSelectionEnd,
+                original.mComposingTextStart, original.mComposingText,
+                original.mInsertionMarkerFlags, original.mInsertionMarkerHorizontal,
+                original.mInsertionMarkerTop, original.mInsertionMarkerBaseline,
+                original.mInsertionMarkerBottom, original.mCharacterBoundsArray,
+                original.mEditorBoundsInfo, computeMatrixValues(parentMatrix, original));
+    }
+
+    /**
+     * Returns a float array that represents {@link Matrix} elements for
+     * {@code parentMatrix * info.getMatrix()}.
+     *
+     * @param parentMatrix {@link Matrix} to be multiplied.
+     * @param info         {@link CursorAnchorInfo} to provide {@link Matrix} to be multiplied.
+     * @return {@code parentMatrix * info.getMatrix()}.
+     */
+    private static float[] computeMatrixValues(@NonNull Matrix parentMatrix,
+            @NonNull CursorAnchorInfo info) {
+        if (parentMatrix.isIdentity()) {
+            return info.mMatrixValues;
+        }
+
+        final Matrix newMatrix = new Matrix();
+        newMatrix.setValues(info.mMatrixValues);
+        newMatrix.postConcat(parentMatrix);
+
+        final float[] matrixValues = new float[9];
+        newMatrix.getValues(matrixValues);
+        return matrixValues;
     }
 
     /**

core/tests/coretests/src/android/view/inputmethod/CursorAnchorInfoTest.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.view.inputmethod;
+
+import static org.junit.Assert.assertEquals;
+
+import android.graphics.Matrix;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@SmallTest
+@RunWith(AndroidJUnit4.class)
+public class CursorAnchorInfoTest {
+    @Test
+    public void testCreateForAdditionalParentMatrix() {
+        final Matrix originalMatrix = new Matrix();
+        originalMatrix.setTranslate(10.0f, 20.0f);
+        final CursorAnchorInfo.Builder builder = new CursorAnchorInfo.Builder();
+        builder.setMatrix(originalMatrix);
+
+        final CursorAnchorInfo originalInstance = builder.build();
+
+        assertEquals(originalMatrix, originalInstance.getMatrix());
+
+        final Matrix additionalParentMatrix = new Matrix();
+        additionalParentMatrix.setTranslate(1.0f, 2.0f);
+
+        final Matrix newMatrix = new Matrix(originalMatrix);
+        newMatrix.postConcat(additionalParentMatrix);
+
+        builder.reset();
+        builder.setMatrix(newMatrix);
+        // An instance created by the standard Builder class.
+        final CursorAnchorInfo newInstanceByBuilder = builder.build();
+
+        // An instance created by an @hide method.
+        final CursorAnchorInfo newInstanceByMethod =
+                CursorAnchorInfo.createForAdditionalParentMatrix(
+                        originalInstance, additionalParentMatrix);
+
+        assertEquals(newMatrix, newInstanceByBuilder.getMatrix());
+        assertEquals(newMatrix, newInstanceByMethod.getMatrix());
+        assertEquals(newInstanceByBuilder.hashCode(), newInstanceByMethod.hashCode());
+    }
+}