Camera2/3: For still captures, use widest FPS range available.

Instead of using the application-selected preview FPS range for still
captures, select the widest FPS range advertised by the device and use
it for still captures instead, to give the HAL the widest range of exposure
values to choose from possible.

Bug: 10842868
Change-Id: I0e24f5eb713a4f8df116cd5979a84390cc0974d7

3 files changed, 43 insertions, 2 deletions

diff --git a/services/camera/libcameraservice/api1/Camera2Client.cpp b/services/camera/libcameraservice/api1/Camera2Client.cpp
index e7f6c53..fb81468 100644
--- a/services/camera/libcameraservice/api1/Camera2Client.cpp
+++ b/services/camera/libcameraservice/api1/Camera2Client.cpp
@@ -326,6 +326,10 @@ status_t Camera2Client::dump(int fd, const Vector<String16>& args) {
     result.appendFormat("    Video stabilization is %s\n",
             p.videoStabilization ? "enabled" : "disabled");
 
+    result.appendFormat("    Selected still capture FPS range: %d - %d\n",
+            p.fastInfo.bestStillCaptureFpsRange[0],
+            p.fastInfo.bestStillCaptureFpsRange[1]);
+
     result.append("  Current streams:\n");
     result.appendFormat("    Preview stream ID: %d\n",
             getPreviewStreamId());
diff --git a/services/camera/libcameraservice/api1/client2/Parameters.cpp b/services/camera/libcameraservice/api1/client2/Parameters.cpp
index ad55feb..0705791 100644
--- a/services/camera/libcameraservice/api1/client2/Parameters.cpp
+++ b/services/camera/libcameraservice/api1/client2/Parameters.cpp
@@ -852,6 +852,33 @@ status_t Parameters::buildFastInfo() {
         arrayHeight = activeArraySize.data.i32[3];
     } else return NO_INIT;
 
+    // We'll set the target FPS range for still captures to be as wide
+    // as possible to give the HAL maximum latitude for exposure selection
+    camera_metadata_ro_entry_t availableFpsRanges =
+        staticInfo(ANDROID_CONTROL_AE_AVAILABLE_TARGET_FPS_RANGES, 2);
+    if (availableFpsRanges.count < 2 || availableFpsRanges.count % 2 != 0) {
+        return NO_INIT;
+    }
+
+    int32_t bestStillCaptureFpsRange[2] = {
+        availableFpsRanges.data.i32[0], availableFpsRanges.data.i32[1]
+    };
+    int32_t curRange =
+            bestStillCaptureFpsRange[1] - bestStillCaptureFpsRange[0];
+    for (size_t i = 2; i < availableFpsRanges.count; i += 2) {
+        int32_t nextRange =
+                availableFpsRanges.data.i32[i + 1] -
+                availableFpsRanges.data.i32[i];
+        if ( (nextRange > curRange) ||       // Maximize size of FPS range first
+                (nextRange == curRange &&    // Then minimize low-end FPS
+                 bestStillCaptureFpsRange[0] > availableFpsRanges.data.i32[i])) {
+
+            bestStillCaptureFpsRange[0] = availableFpsRanges.data.i32[i];
+            bestStillCaptureFpsRange[1] = availableFpsRanges.data.i32[i + 1];
+            curRange = nextRange;
+        }
+    }
+
     camera_metadata_ro_entry_t availableFaceDetectModes =
         staticInfo(ANDROID_STATISTICS_INFO_AVAILABLE_FACE_DETECT_MODES, 0, 0,
                 false);
@@ -971,6 +998,8 @@ status_t Parameters::buildFastInfo() {
 
     fastInfo.arrayWidth = arrayWidth;
     fastInfo.arrayHeight = arrayHeight;
+    fastInfo.bestStillCaptureFpsRange[0] = bestStillCaptureFpsRange[0];
+    fastInfo.bestStillCaptureFpsRange[1] = bestStillCaptureFpsRange[1];
     fastInfo.bestFaceDetectMode = bestFaceDetectMode;
     fastInfo.maxFaces = maxFaces;
 
@@ -1709,8 +1738,15 @@ status_t Parameters::updateRequest(CameraMetadata *request) const {
             &metadataMode, 1);
     if (res != OK) return res;
 
-    res = request->update(ANDROID_CONTROL_AE_TARGET_FPS_RANGE,
-            previewFpsRange, 2);
+    camera_metadata_entry_t intent =
+            request->find(ANDROID_CONTROL_CAPTURE_INTENT);
+    if (intent.data.u8[0] == ANDROID_CONTROL_CAPTURE_INTENT_STILL_CAPTURE) {
+        res = request->update(ANDROID_CONTROL_AE_TARGET_FPS_RANGE,
+                fastInfo.bestStillCaptureFpsRange, 2);
+    } else {
+        res = request->update(ANDROID_CONTROL_AE_TARGET_FPS_RANGE,
+                previewFpsRange, 2);
+    }
     if (res != OK) return res;
 
     uint8_t reqWbLock = autoWhiteBalanceLock ?
diff --git a/services/camera/libcameraservice/api1/client2/Parameters.h b/services/camera/libcameraservice/api1/client2/Parameters.h
index a7111a3..b9ca7bf 100644
--- a/services/camera/libcameraservice/api1/client2/Parameters.h
+++ b/services/camera/libcameraservice/api1/client2/Parameters.h
@@ -179,6 +179,7 @@ struct Parameters {
     struct DeviceInfo {
         int32_t arrayWidth;
         int32_t arrayHeight;
+        int32_t bestStillCaptureFpsRange[2];
         uint8_t bestFaceDetectMode;
         int32_t maxFaces;
         struct OverrideModes {