1 files changed, 87 insertions, 0 deletions
diff --git a/core/java/android/util/RotationUtils.java b/core/java/android/util/RotationUtils.java
index a44ed59c14d4..0ac2c9c25ad1 100644
--- a/core/java/android/util/RotationUtils.java
+++ b/core/java/android/util/RotationUtils.java
@@ -21,7 +21,10 @@ import static android.view.Surface.ROTATION_180;
 import static android.view.Surface.ROTATION_270;
 import static android.view.Surface.ROTATION_90;
 
+import android.annotation.Dimension;
 import android.graphics.Insets;
+import android.graphics.Matrix;
+import android.graphics.Rect;
 import android.view.Surface.Rotation;
 
 /**
@@ -69,4 +72,88 @@ public class RotationUtils {
         }
         return rotated;
     }
+
+    /**
+     * Rotates bounds as if parentBounds and bounds are a group. The group is rotated from
+     * oldRotation to newRotation. This assumes that parentBounds is at 0,0 and remains at 0,0 after
+     * rotation. The bounds will be at the same physical position in parentBounds.
+     *
+     * Only 'inOutBounds' is mutated.
+     */
+    public static void rotateBounds(Rect inOutBounds, Rect parentBounds, @Rotation int oldRotation,
+            @Rotation int newRotation) {
+        rotateBounds(inOutBounds, parentBounds, deltaRotation(oldRotation, newRotation));
+    }
+
+    /**
+     * Rotates bounds as if parentBounds and bounds are a group. The group is rotated by `delta`
+     * 90-degree counter-clockwise increments. This assumes that parentBounds is at 0,0 and
+     * remains at 0,0 after rotation. The bounds will be at the same physical position in
+     * parentBounds.
+     *
+     * Only 'inOutBounds' is mutated.
+     */
+    public static void rotateBounds(Rect inOutBounds, Rect parentBounds, @Rotation int rotation) {
+        final int origLeft = inOutBounds.left;
+        final int origTop = inOutBounds.top;
+        switch (rotation) {
+            case ROTATION_0:
+                return;
+            case ROTATION_90:
+                inOutBounds.left = inOutBounds.top;
+                inOutBounds.top = parentBounds.right - inOutBounds.right;
+                inOutBounds.right = inOutBounds.bottom;
+                inOutBounds.bottom = parentBounds.right - origLeft;
+                return;
+            case ROTATION_180:
+                inOutBounds.left = parentBounds.right - inOutBounds.right;
+                inOutBounds.right = parentBounds.right - origLeft;
+                inOutBounds.top = parentBounds.bottom - inOutBounds.bottom;
+                inOutBounds.bottom = parentBounds.bottom - origTop;
+                return;
+            case ROTATION_270:
+                inOutBounds.left = parentBounds.bottom - inOutBounds.bottom;
+                inOutBounds.bottom = inOutBounds.right;
+                inOutBounds.right = parentBounds.bottom - inOutBounds.top;
+                inOutBounds.top = origLeft;
+        }
+    }
+
+    /** @return the rotation needed to rotate from oldRotation to newRotation. */
+    @Rotation
+    public static int deltaRotation(int oldRotation, int newRotation) {
+        int delta = newRotation - oldRotation;
+        if (delta < 0) delta += 4;
+        return delta;
+    }
+
+    /**
+     * Sets a matrix such that given a rotation, it transforms physical display
+     * coordinates to that rotation's logical coordinates.
+     *
+     * @param rotation the rotation to which the matrix should transform
+     * @param out the matrix to be set
+     */
+    public static void transformPhysicalToLogicalCoordinates(@Rotation int rotation,
+            @Dimension int physicalWidth, @Dimension int physicalHeight, Matrix out) {
+        switch (rotation) {
+            case ROTATION_0:
+                out.reset();
+                break;
+            case ROTATION_90:
+                out.setRotate(270);
+                out.postTranslate(0, physicalWidth);
+                break;
+            case ROTATION_180:
+                out.setRotate(180);
+                out.postTranslate(physicalWidth, physicalHeight);
+                break;
+            case ROTATION_270:
+                out.setRotate(90);
+                out.postTranslate(physicalHeight, 0);
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown rotation: " + rotation);
+        }
+    }
 }