diff --git a/services/surfaceflinger/Transform.cpp b/services/surfaceflinger/Transform.cpp
index 5e27cc9..f128429 100644
--- a/services/surfaceflinger/Transform.cpp
+++ b/services/surfaceflinger/Transform.cpp
@@ -159,56 +159,32 @@
         return BAD_VALUE;
     }
 
-    mType = flags << 8;
-    float sx = (flags & FLIP_H) ? -1 : 1;
-    float sy = (flags & FLIP_V) ? -1 : 1;
-    float a=0, b=0, c=0, d=0, x=0, y=0;
-    int xmask = 0;
-
-    // computation of x,y
-    // x y
-    // 0 0  0
-    // w 0  ROT90
-    // w h  FLIPH|FLIPV
-    // 0 h  FLIPH|FLIPV|ROT90
-
-    if (flags & ROT_90) {
-        mType |= ROTATE;
-        b = -sy;
-        c = sx;
-        xmask = 1;
-    } else {
-        a = sx;
-        d = sy;
-    }
-
+    Transform H, V, R;
     if (flags & FLIP_H) {
-        mType ^= SCALE;
-        xmask ^= 1;
+        H.mType = (FLIP_H << 8) | SCALE;
+        H.mType |= isZero(w) ? IDENTITY : TRANSLATE;
+        mat33& M(H.mMatrix);
+        M[0][0] = -1;
+        M[2][0] = w;
     }
 
     if (flags & FLIP_V) {
-        mType ^= SCALE;
-        y = h;
+        V.mType = (FLIP_V << 8) | SCALE;
+        V.mType |= isZero(h) ? IDENTITY : TRANSLATE;
+        mat33& M(V.mMatrix);
+        M[1][1] = -1;
+        M[2][1] = h;
     }
 
-    if ((flags & ROT_180) == ROT_180) {
-        mType |= ROTATE;
+    if (flags & ROT_90) {
+        R.mType = (ROT_90 << 8) | ROTATE;
+        R.mType |= isZero(w) ? IDENTITY : TRANSLATE;
+        mat33& M(R.mMatrix);
+        M[0][0] = 0;    M[1][0] =-1;    M[2][0] = w;
+        M[0][1] = 1;    M[1][1] = 0;
     }
 
-    if (xmask) {
-        x = w;
-    }
-
-    if (!isZero(x) || !isZero(y)) {
-        mType |= TRANSLATE;
-    }
-
-    mat33& M(mMatrix);
-    M[0][0] = a;    M[1][0] = b;    M[2][0] = x;
-    M[0][1] = c;    M[1][1] = d;    M[2][1] = y;
-    M[0][2] = 0;    M[1][2] = 0;    M[2][2] = 1;
-
+    *this = ((H*V)*R);
     return NO_ERROR;
 }
 
diff --git a/services/surfaceflinger/Transform.h b/services/surfaceflinger/Transform.h
index 20fa11a..8fa5b86 100644
--- a/services/surfaceflinger/Transform.h
+++ b/services/surfaceflinger/Transform.h
@@ -23,6 +23,8 @@
 #include <ui/Point.h>
 #include <ui/Rect.h>
 
+#include <hardware/hardware.h>
+
 namespace android {
 
 class Region;
@@ -37,12 +39,11 @@
            explicit Transform(uint32_t orientation);
                     ~Transform();
 
-            // FIXME: must match OVERLAY_TRANSFORM_*, pull from hardware.h
             enum orientation_flags {
                 ROT_0   = 0x00000000,
-                FLIP_H  = 0x00000001,
-                FLIP_V  = 0x00000002,
-                ROT_90  = 0x00000004,
+                FLIP_H  = HAL_TRANSFORM_FLIP_H,
+                FLIP_V  = HAL_TRANSFORM_FLIP_V,
+                ROT_90  = HAL_TRANSFORM_ROT_90,
                 ROT_180 = FLIP_H|FLIP_V,
                 ROT_270 = ROT_180|ROT_90,
                 ROT_INVALID = 0x80
diff --git a/services/surfaceflinger/tests/transform/Android.mk b/services/surfaceflinger/tests/transform/Android.mk
new file mode 100644
index 0000000..6219dae
--- /dev/null
+++ b/services/surfaceflinger/tests/transform/Android.mk
@@ -0,0 +1,19 @@
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES:= \
+	TransformTest.cpp \
+	../../Transform.cpp
+
+LOCAL_SHARED_LIBRARIES := \
+	libcutils \
+	libutils \
+	libui \
+
+LOCAL_MODULE:= test-transform
+
+LOCAL_MODULE_TAGS := tests
+
+LOCAL_C_INCLUDES += ../..
+
+include $(BUILD_EXECUTABLE)
diff --git a/services/surfaceflinger/tests/transform/TransformTest.cpp b/services/surfaceflinger/tests/transform/TransformTest.cpp
new file mode 100644
index 0000000..e112c4e
--- /dev/null
+++ b/services/surfaceflinger/tests/transform/TransformTest.cpp
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2007 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <utils/Errors.h>
+#include "../../Transform.h"
+
+using namespace android;
+
+int main(int argc, char **argv)
+{
+    Transform tr90(Transform::ROT_90);
+    Transform trFH(Transform::FLIP_H);
+    Transform trFV(Transform::FLIP_V);
+
+    Transform tr90FH(Transform::ROT_90 | Transform::FLIP_H);
+    Transform tr90FV(Transform::ROT_90 | Transform::FLIP_V);
+
+    tr90.dump("tr90");
+    trFH.dump("trFH");
+    trFV.dump("trFV");
+
+    tr90FH.dump("tr90FH");
+    tr90FV.dump("tr90FV");
+
+    (trFH*tr90).dump("trFH*tr90");
+    (trFV*tr90).dump("trFV*tr90");
+
+    (tr90*trFH).dump("tr90*trFH");
+    (tr90*trFV).dump("tr90*trFV");
+
+    return 0;
+}