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Commit 3748600b authored by Martijn Coenen's avatar Martijn Coenen
Browse files

NFC: Allow apps to specify they're done with tag. 

When an application is no longer interested in
communicating with a tag, but the tag is kept in
range of the device for a long amount of time, we
will burn a lot of power keeping the connection
to it alive.

Instead, allow the app to signal it's "done" with
the tag, which allows us to put the controller
in a low-power mode. This will save power in scenarios
such as an NFC tag embedded in a car dock or
wireless charging dock.

Bug: 26426491
Change-Id: I7a0149ede46e0c7610b06ed1776344b772677350
parent 8414c671

api/current.txt

+1 −0
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@@ -24246,6 +24246,7 @@ package android.nfc { 














  public final class Tag implements android.os.Parcelable {















    method public int describeContents();













    method public boolean done(int);















    method public byte[] getId();















    method public java.lang.String[] getTechList();















    method public void writeToParcel(android.os.Parcel, int);

























api/system-current.txt



+1
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@@ -26246,6 +26246,7 @@ package android.nfc {



























  public final class Tag implements android.os.Parcelable {















    method public int describeContents();













    method public boolean done(int);















    method public byte[] getId();















    method public java.lang.String[] getTechList();















    method public void writeToParcel(android.os.Parcel, int);

























api/test-current.txt



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@@ -24254,6 +24254,7 @@ package android.nfc {



























  public final class Tag implements android.os.Parcelable {















    method public int describeContents();













    method public boolean done(int);















    method public byte[] getId();















    method public java.lang.String[] getTechList();















    method public void writeToParcel(android.os.Parcel, int);

























core/java/android/nfc/INfcTag.aidl



+1
−1




























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@@ -25,13 +25,13 @@ import android.nfc.TransceiveResult;













 */















interface INfcTag















{













    int close(int nativeHandle);















    int connect(int nativeHandle, int technology);















    int reconnect(int nativeHandle);















    int[] getTechList(int nativeHandle);















    boolean isNdef(int nativeHandle);















    boolean isPresent(int nativeHandle);















    TransceiveResult transceive(int nativeHandle, in byte[] data, boolean raw);













    boolean done(int nativeHandle, int debounceMs);































    NdefMessage ndefRead(int nativeHandle);















    int ndefWrite(int nativeHandle, in NdefMessage msg);

































core/java/android/nfc/Tag.java



+36
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@@ -214,6 +214,42 @@ public final class Tag implements Parcelable {













        return techIntList;















    }





























    /**













     * Signals that you are no longer interested in communicating with this tag













     * for as long as it remains in range.













     *













     * All future attempted communication to this tag will fail with {@link IOException}.













     * The NFC controller will be put in a low-power polling mode, allowing the device













     * to save power in cases where it's "attached" to a tag all the time (eg a tag in













     * car dock).













     *













     * Additionally the debounceMs parameter allows you to specify for how long the tag needs













     * to have gone out of range, before it will be dispatched again.













     *













     * Note: the NFC controller typically polls at a pretty slow interval (100 - 500 ms).













     * This means that if the tag repeatedly goes in and out of range (for example, in













     * case of a flaky connection), and the controller happens to poll every time the













     * tag is out of range, it *will* re-dispatch the tag after debounceMs, despite the tag













     * having been "in range" during the interval.













     *













     * Note 2: if a tag with another UID is detected after this API is called, its effect













     * will be cancelled; if this tag shows up before the amount of time specified in













     * debounceMs, it will be dispatched again.













     *













     * Note 3: some tags have a random UID, in which case this API won't work.













     *













     * @param debounceMs minimum amount of time the tag needs to be out of range before being













     *                   dispatched again.













     * @return false if the Tag couldn't be found (or has gone out of range), true otherwise













     */













    public boolean done(int debounceMs) {













        try {













            return mTagService.done(getServiceHandle(), debounceMs);













        } catch (RemoteException e) {













            return false;













        }













    }





























    private static HashMap<String, Integer> getTechStringToCodeMap() {















        HashMap<String, Integer> techStringToCodeMap = new HashMap<String, Integer>();