Camera: API1: Improve ZSL mode activation heuristics

- Don't engage ZSL if picture size is too small
- Don't engage ZSL if picture size matches preview size
- Include ZSL choice in dumpsys

Bug: 29620318
Change-Id: Ie8e0c5a9e1ed9f177d701f22996c4c1f4b81a71e
diff --git a/services/camera/libcameraservice/api1/Camera2Client.cpp b/services/camera/libcameraservice/api1/Camera2Client.cpp
index c8e64fe..005dd69 100644
--- a/services/camera/libcameraservice/api1/Camera2Client.cpp
+++ b/services/camera/libcameraservice/api1/Camera2Client.cpp
@@ -322,6 +322,9 @@
             p.fastInfo.bestStillCaptureFpsRange[0],
             p.fastInfo.bestStillCaptureFpsRange[1]);
 
+    result.appendFormat("    Use zero shutter lag: %s\n",
+            p.useZeroShutterLag() ? "yes" : "no");
+
     result.append("  Current streams:\n");
     result.appendFormat("    Preview stream ID: %d\n",
             getPreviewStreamId());
@@ -813,7 +816,7 @@
         }
     }
 
-    if (params.zslMode && !params.recordingHint &&
+    if (params.useZeroShutterLag() &&
             getRecordingStreamId() == NO_STREAM) {
         res = updateProcessorStream(mZslProcessor, params);
         if (res != OK) {
@@ -1362,7 +1365,7 @@
 
             return OK;
         }
-        if (l.mParameters.zslMode) {
+        if (l.mParameters.allowZslMode) {
             mZslProcessor->clearZslQueue();
         }
     }
@@ -1460,7 +1463,7 @@
 
         // Clear ZSL buffer queue when Jpeg size is changed.
         bool jpegStreamChanged = mJpegProcessor->getStreamId() != lastJpegStreamId;
-        if (l.mParameters.zslMode && jpegStreamChanged) {
+        if (l.mParameters.allowZslMode && jpegStreamChanged) {
             ALOGV("%s: Camera %d: Clear ZSL buffer queue when Jpeg size is changed",
                     __FUNCTION__, mCameraId);
             mZslProcessor->clearZslQueue();
@@ -1495,7 +1498,7 @@
     if (res != OK) return res;
     Parameters::focusMode_t focusModeAfter = l.mParameters.focusMode;
 
-    if (l.mParameters.zslMode && focusModeAfter != focusModeBefore) {
+    if (l.mParameters.allowZslMode && focusModeAfter != focusModeBefore) {
         mZslProcessor->clearZslQueue();
     }
 
diff --git a/services/camera/libcameraservice/api1/client2/CaptureSequencer.cpp b/services/camera/libcameraservice/api1/client2/CaptureSequencer.cpp
index e3d6906..05adb29 100644
--- a/services/camera/libcameraservice/api1/client2/CaptureSequencer.cpp
+++ b/services/camera/libcameraservice/api1/client2/CaptureSequencer.cpp
@@ -338,7 +338,7 @@
         return DONE;
     }
 
-    else if (l.mParameters.zslMode &&
+    else if (l.mParameters.useZeroShutterLag() &&
             l.mParameters.state == Parameters::STILL_CAPTURE &&
             l.mParameters.flashMode != Parameters::FLASH_MODE_ON) {
         nextState = ZSL_START;
diff --git a/services/camera/libcameraservice/api1/client2/Parameters.cpp b/services/camera/libcameraservice/api1/client2/Parameters.cpp
index 5779176..9d5f33c 100644
--- a/services/camera/libcameraservice/api1/client2/Parameters.cpp
+++ b/services/camera/libcameraservice/api1/client2/Parameters.cpp
@@ -908,12 +908,12 @@
     property_get("camera.disable_zsl_mode", value, "0");
     if (!strcmp(value,"1") || slowJpegMode) {
         ALOGI("Camera %d: Disabling ZSL mode", cameraId);
-        zslMode = false;
+        allowZslMode = false;
     } else {
-        zslMode = true;
+        allowZslMode = true;
     }
 
-    ALOGI("%s: zslMode: %d slowJpegMode %d", __FUNCTION__, zslMode, slowJpegMode);
+    ALOGI("%s: allowZslMode: %d slowJpegMode %d", __FUNCTION__, allowZslMode, slowJpegMode);
 
     state = STOPPED;
 
@@ -1127,6 +1127,8 @@
     ALOGV("Camera %d: Flexible YUV %s supported",
             cameraId, fastInfo.useFlexibleYuv ? "is" : "is not");
 
+    fastInfo.maxJpegSize = getMaxSize(getAvailableJpegSizes());
+
     return OK;
 }
 
@@ -2231,6 +2233,25 @@
     return pictureSizeOverriden;
 }
 
+bool Parameters::useZeroShutterLag() const {
+    // If ZSL mode is disabled, don't use it
+    if (!allowZslMode) return false;
+    // If recording hint is enabled, don't do ZSL
+    if (recordingHint) return false;
+    // If still capture size is no bigger than preview or video size,
+    // don't do ZSL
+    if (pictureWidth <= previewWidth || pictureHeight <= previewHeight ||
+            pictureWidth <= videoWidth || pictureHeight <= videoHeight) {
+        return false;
+    }
+    // If still capture size is less than quarter of max, don't do ZSL
+    if ((pictureWidth * pictureHeight) <
+            (fastInfo.maxJpegSize.width * fastInfo.maxJpegSize.height / 4) ) {
+        return false;
+    }
+    return true;
+}
+
 const char* Parameters::getStateName(State state) {
 #define CASE_ENUM_TO_CHAR(x) case x: return(#x); break;
     switch(state) {
diff --git a/services/camera/libcameraservice/api1/client2/Parameters.h b/services/camera/libcameraservice/api1/client2/Parameters.h
index c437722..f4bb34c 100644
--- a/services/camera/libcameraservice/api1/client2/Parameters.h
+++ b/services/camera/libcameraservice/api1/client2/Parameters.h
@@ -161,9 +161,9 @@
     bool previewCallbackOneShot;
     bool previewCallbackSurface;
 
-    bool zslMode;
+    bool allowZslMode;
     // Whether the jpeg stream is slower than 30FPS and can slow down preview.
-    // When slowJpegMode is true, zslMode must be false to avoid slowing down preview.
+    // When slowJpegMode is true, allowZslMode must be false to avoid slowing down preview.
     bool slowJpegMode;
 
     // Overall camera state
@@ -219,6 +219,7 @@
         DefaultKeyedVector<uint8_t, OverrideModes> sceneModeOverrides;
         float minFocalLength;
         bool useFlexibleYuv;
+        Size maxJpegSize;
     } fastInfo;
 
     // Quirks information; these are short-lived flags to enable workarounds for
@@ -271,6 +272,8 @@
     status_t recoverOverriddenJpegSize();
     // if video snapshot size is currently overridden
     bool isJpegSizeOverridden();
+    // whether zero shutter lag should be used for non-recording operation
+    bool useZeroShutterLag() const;
 
     // Calculate the crop region rectangle, either tightly about the preview
     // resolution, or a region just based on the active array; both take
diff --git a/services/camera/libcameraservice/api1/client2/StreamingProcessor.cpp b/services/camera/libcameraservice/api1/client2/StreamingProcessor.cpp
index a2c9712..de42fb2 100644
--- a/services/camera/libcameraservice/api1/client2/StreamingProcessor.cpp
+++ b/services/camera/libcameraservice/api1/client2/StreamingProcessor.cpp
@@ -115,7 +115,7 @@
 
         // Use CAMERA3_TEMPLATE_ZERO_SHUTTER_LAG for ZSL streaming case.
         if (client->getCameraDeviceVersion() >= CAMERA_DEVICE_API_VERSION_3_0) {
-            if (params.zslMode && !params.recordingHint) {
+            if (params.useZeroShutterLag() && !params.recordingHint) {
                 res = device->createDefaultRequest(CAMERA3_TEMPLATE_ZERO_SHUTTER_LAG,
                         &mPreviewRequest);
             } else {