1 files changed, 43 insertions, 0 deletions
diff --git a/core/jni/android_hardware_Camera.cpp b/core/jni/android_hardware_Camera.cpp
index 4cf317e..3bb6af3 100644
--- a/core/jni/android_hardware_Camera.cpp
+++ b/core/jni/android_hardware_Camera.cpp
@@ -79,6 +79,8 @@ struct fields_t {
 static fields_t fields;
 static Mutex sLock;
 
+int bwDataSize = 0;
+
 // provides persistent context for calls from native code to Java
 class JNICameraContext: public CameraListener
 {
@@ -933,6 +935,44 @@ static jstring android_hardware_Camera_getParameters(JNIEnv *env, jobject thiz)
     return env->NewStringUTF(params8.string());
 }
 
+static void android_hardware_Camera_rgbToBw(JNIEnv *env, jobject thiz, jbyteArray pixelBuffer, jint bufWidth, jint bufHeight)
+{
+    int width = bufWidth;
+    int height = bufHeight;
+    int size = width * height;
+
+    static jbyte* pixeldata;
+    static jbyte* luminances;
+
+    if(bwDataSize != size) {
+        pixeldata = (jbyte *)malloc(size*2);
+        luminances = (jbyte *)malloc(size);
+        bwDataSize = size;
+        ALOGV("Allocated buffer of size %d", size);
+    }
+
+    env->GetByteArrayRegion(pixelBuffer, 0, size*2, pixeldata);
+
+    // Convert the entire image to grayscale
+    for (int y = 0; y < height; y++) {
+        int offset = y * width *2;
+        for (int x = 0; x < width *2; x+=2) {
+            jbyte pixel = pixeldata[offset +x];
+            jbyte pixel2 = pixeldata[offset +x + 1];
+            // little endian
+            // GGGBBBBB | RRRRRGGG
+            jbyte b = (jbyte)(pixel & 0x1f); // 5 bits
+            jbyte g = (jbyte)(((pixel >> 5) & 0x07)  | ((pixel2 & 0x07) << 3)); // 6 bits
+            jbyte r = (jbyte)((pixel2 >> 3) & 0x1f); // 5 bits
+
+            // Calculate luminance cheaply, favoring green.
+            luminances[(offset + x)/2] = (jbyte)((r + g + b) << 1);
+        }
+    }
+
+    env->SetByteArrayRegion(pixelBuffer, 0, size, luminances);
+}
+
 static void android_hardware_Camera_reconnect(JNIEnv *env, jobject thiz)
 {
     ALOGV("reconnect");
@@ -1146,6 +1186,9 @@ static JNINativeMethod camMethods[] = {
   { "native_getParameters",
     "()Ljava/lang/String;",
     (void *)android_hardware_Camera_getParameters },
+  { "native_rgbToBw",
+    "([BII)V",
+    (void *)android_hardware_Camera_rgbToBw },
   { "reconnect",
     "()V",
     (void*)android_hardware_Camera_reconnect },