Add camera focus distances API.

Applications can use this API to estimate the distance
between the subject and the camera.

bug:1955650
Change-Id: Ie6c8ea4971759cab6c9bcdda2c5ceb5925791c27

api/current.xml

@@ -75570,6 +75570,19 @@
  visibility="public"
 >
 </method>
+<method name="getFocusDistances"
+ return="void"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="output" type="float[]">
+</parameter>
+</method>
 <method name="getFocusMode"
  return="java.lang.String"
  abstract="false"
@@ -76492,6 +76505,39 @@
  visibility="public"
 >
 </field>
+<field name="FOCUS_DISTANCE_FAR_INDEX"
+ type="int"
+ transient="false"
+ volatile="false"
+ value="2"
+ static="true"
+ final="true"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</field>
+<field name="FOCUS_DISTANCE_NEAR_INDEX"
+ type="int"
+ transient="false"
+ volatile="false"
+ value="0"
+ static="true"
+ final="true"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</field>
+<field name="FOCUS_DISTANCE_OPTIMAL_INDEX"
+ type="int"
+ transient="false"
+ volatile="false"
+ value="1"
+ static="true"
+ final="true"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</field>
 <field name="FOCUS_MODE_AUTO"
  type="java.lang.String"
  transient="false"

core/java/android/hardware/Camera.java

@@ -762,6 +762,8 @@ public class Camera {
         private static final String KEY_ZOOM_RATIOS = "zoom-ratios";
         private static final String KEY_ZOOM_SUPPORTED = "zoom-supported";
         private static final String KEY_SMOOTH_ZOOM_SUPPORTED = "smooth-zoom-supported";
+        private static final String KEY_FOCUS_DISTANCES = "focus-distances";
+
         // Parameter key suffix for supported values.
         private static final String SUPPORTED_VALUES_SUFFIX = "-values";
 
@@ -874,10 +876,30 @@ public class Camera {
          */
         public static final String FOCUS_MODE_EDOF = "edof";
 
+        // Indices for focus distance array.
+        /**
+         * The array index of near focus distance for use with
+         * {@link #getFocusDistances(float[])}.
+         */
+        public static final int FOCUS_DISTANCE_NEAR_INDEX = 0;
+
+        /**
+         * The array index of optimal focus distance for use with
+         * {@link #getFocusDistances(float[])}.
+         */
+        public static final int FOCUS_DISTANCE_OPTIMAL_INDEX = 1;
+
+        /**
+         * The array index of far focus distance for use with
+         * {@link #getFocusDistances(float[])}.
+         */
+        public static final int FOCUS_DISTANCE_FAR_INDEX = 2;
+
         /**
          * Continuous focus mode. The camera continuously tries to focus. This
          * is ideal for shooting video or shooting photo of moving object.
          * Continuous focus starts when {@link #autoFocus(AutoFocusCallback)} is
+         * called. Continuous focus stops when {@link #cancelAutoFocus()} is
          * called. AutoFocusCallback will be only called once as soon as the
          * picture is in focus.
          */
@@ -1814,6 +1836,42 @@ public class Camera {
             return TRUE.equals(str);
         }
 
+        /**
+         * Gets the distances from the camera to where an object appears to be
+         * in focus. The object is sharpest at the optimal focus distance. The
+         * depth of field is the far focus distance minus near focus distance.
+         *
+         * Focus distances may change after calling {@link
+         * #autoFocus(AutoFocusCallback)}, {@link #cancelAutoFocus}, or {@link
+         * #startPreview()}. Applications can call {@link #getParameters()}
+         * and this method anytime to get the latest focus distances. If the
+         * focus mode is FOCUS_MODE_EDOF, the values may be all 0, which means
+         * focus distance is not applicable. If the focus mode is
+         * FOCUS_MODE_CONTINUOUS and autofocus has started, focus distances may
+         * change from time to time.
+         *
+         * Far focus distance > optimal focus distance > near focus distance. If
+         * the far focus distance is infinity, the value will be
+         * Float.POSITIVE_INFINITY.
+         *
+         * @param output focus distances in meters. output must be a float
+         *        array with three elements. Near focus distance, optimal focus
+         *        distance, and far focus distance will be filled in the array.
+         * @see #NEAR_FOCUS_DISTANCE_INDEX
+         * @see #OPTIMAL_FOCUS_DISTANCE_INDEX
+         * @see #FAR_FOCUS_DISTANCE_INDEX
+         */
+        public void getFocusDistances(float[] output) {
+            if (output == null || output.length != 3) {
+                throw new IllegalArgumentException(
+                        "output must be an float array with three elements.");
+            }
+            List<Float> distances = splitFloat(get(KEY_FOCUS_DISTANCES));
+            output[0] = distances.get(0);
+            output[1] = distances.get(1);
+            output[2] = distances.get(2);
+        }
+
         // Splits a comma delimited string to an ArrayList of String.
         // Return null if the passing string is null or the size is 0.
         private ArrayList<String> split(String str) {
@@ -1843,6 +1901,21 @@ public class Camera {
             return substrings;
         }
 
+        // Splits a comma delimited string to an ArrayList of Float.
+        // Return null if the passing string is null or the size is 0.
+        private ArrayList<Float> splitFloat(String str) {
+            if (str == null) return null;
+
+            StringTokenizer tokenizer = new StringTokenizer(str, ",");
+            ArrayList<Float> substrings = new ArrayList<Float>();
+            while (tokenizer.hasMoreElements()) {
+                String token = tokenizer.nextToken();
+                substrings.add(Float.parseFloat(token));
+            }
+            if (substrings.size() == 0) return null;
+            return substrings;
+        }
+
         // Returns the value of a float parameter.
         private float getFloat(String key, float defaultValue) {
             try {

include/camera/CameraParameters.h

@@ -221,9 +221,30 @@ public:
     // Example value: "true". Read only.
     static const char KEY_SMOOTH_ZOOM_SUPPORTED[];
 
+    // The distances (in meters) from the camera to where an object appears to
+    // be in focus. The object is sharpest at the optimal focus distance. The
+    // depth of field is the far focus distance minus near focus distance.
+    //
+    // Applications can read this parameter anytime to get the latest focus
+    // distances. If the focus mode is FOCUS_MODE_EDOF, the values may be all
+    // 0, which means focus distance is not applicable. If the focus mode is
+    // FOCUS_MODE_CONTINUOUS and autofocus has started, focus distances may
+    // change from time to time.
+    //
+    // Far focus distance > optimal focus distance > near focus distance. If
+    // the far focus distance is infinity, the value should be "Infinity" (case
+    // sensitive). The format is three float values separated by commas. The
+    // first is near focus distance. The second is optimal focus distance. The
+    // third is far focus distance.
+    // Example value: "0.95,1.9,Infinity" or "0.049,0.05,0.051". Read only.
+    static const char KEY_FOCUS_DISTANCES[];
+
     // Value for KEY_ZOOM_SUPPORTED or KEY_SMOOTH_ZOOM_SUPPORTED.
     static const char TRUE[];
 
+    // Value for KEY_FOCUS_DISTANCES.
+    static const char INFINITY[];
+
     // Values for white balance settings.
     static const char WHITE_BALANCE_AUTO[];
     static const char WHITE_BALANCE_INCANDESCENT[];

libs/camera/CameraParameters.cpp

@@ -69,8 +69,10 @@ const char CameraParameters::KEY_MAX_ZOOM[] = "max-zoom";
 const char CameraParameters::KEY_ZOOM_RATIOS[] = "zoom-ratios";
 const char CameraParameters::KEY_ZOOM_SUPPORTED[] = "zoom-supported";
 const char CameraParameters::KEY_SMOOTH_ZOOM_SUPPORTED[] = "smooth-zoom-supported";
+const char CameraParameters::KEY_FOCUS_DISTANCES[] = "focus-distances";
 
 const char CameraParameters::TRUE[] = "true";
+const char CameraParameters::INFINITY[] = "Infinity";
 
 // Values for white balance settings.
 const char CameraParameters::WHITE_BALANCE_AUTO[] = "auto";