diff --git a/libs/gui/GLConsumerUtils.cpp b/libs/gui/GLConsumerUtils.cpp
new file mode 100644
index 0000000..7a06c3d
--- /dev/null
+++ b/libs/gui/GLConsumerUtils.cpp
@@ -0,0 +1,125 @@
+/*
+ * Copyright (C) 2010 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.
+ */
+
+#define LOG_TAG "GLConsumerUtils"
+//#define LOG_NDEBUG 0
+
+#include <gui/GLConsumer.h>
+#include <math/mat4.h>
+#include <system/window.h>
+#include <utils/Log.h>
+
+namespace android {
+
+void GLConsumer::computeTransformMatrix(float outTransform[16],
+        const sp<GraphicBuffer>& buf, const Rect& cropRect, uint32_t transform,
+        bool filtering) {
+    // Transform matrices
+    static const mat4 mtxFlipH(
+        -1, 0, 0, 0,
+        0, 1, 0, 0,
+        0, 0, 1, 0,
+        1, 0, 0, 1
+    );
+    static const mat4 mtxFlipV(
+        1, 0, 0, 0,
+        0, -1, 0, 0,
+        0, 0, 1, 0,
+        0, 1, 0, 1
+    );
+    static const mat4 mtxRot90(
+        0, 1, 0, 0,
+        -1, 0, 0, 0,
+        0, 0, 1, 0,
+        1, 0, 0, 1
+    );
+
+    mat4 xform;
+    if (transform & NATIVE_WINDOW_TRANSFORM_FLIP_H) {
+        xform *= mtxFlipH;
+    }
+    if (transform & NATIVE_WINDOW_TRANSFORM_FLIP_V) {
+        xform *= mtxFlipV;
+    }
+    if (transform & NATIVE_WINDOW_TRANSFORM_ROT_90) {
+        xform *= mtxRot90;
+    }
+
+    if (!cropRect.isEmpty()) {
+        float tx = 0.0f, ty = 0.0f, sx = 1.0f, sy = 1.0f;
+        float bufferWidth = buf->getWidth();
+        float bufferHeight = buf->getHeight();
+        float shrinkAmount = 0.0f;
+        if (filtering) {
+            // In order to prevent bilinear sampling beyond the edge of the
+            // crop rectangle we may need to shrink it by 2 texels in each
+            // dimension.  Normally this would just need to take 1/2 a texel
+            // off each end, but because the chroma channels of YUV420 images
+            // are subsampled we may need to shrink the crop region by a whole
+            // texel on each side.
+            switch (buf->getPixelFormat()) {
+                case PIXEL_FORMAT_RGBA_8888:
+                case PIXEL_FORMAT_RGBX_8888:
+                case PIXEL_FORMAT_RGBA_FP16:
+                case PIXEL_FORMAT_RGBA_1010102:
+                case PIXEL_FORMAT_RGB_888:
+                case PIXEL_FORMAT_RGB_565:
+                case PIXEL_FORMAT_BGRA_8888:
+                    // We know there's no subsampling of any channels, so we
+                    // only need to shrink by a half a pixel.
+                    shrinkAmount = 0.5;
+                    break;
+
+                default:
+                    // If we don't recognize the format, we must assume the
+                    // worst case (that we care about), which is YUV420.
+                    shrinkAmount = 1.0;
+                    break;
+            }
+        }
+
+        // Only shrink the dimensions that are not the size of the buffer.
+        if (cropRect.width() < bufferWidth) {
+            tx = (float(cropRect.left) + shrinkAmount) / bufferWidth;
+            sx = (float(cropRect.width()) - (2.0f * shrinkAmount)) /
+                    bufferWidth;
+        }
+        if (cropRect.height() < bufferHeight) {
+            ty = (float(bufferHeight - cropRect.bottom) + shrinkAmount) /
+                    bufferHeight;
+            sy = (float(cropRect.height()) - (2.0f * shrinkAmount)) /
+                    bufferHeight;
+        }
+
+        mat4 crop(
+            sx, 0, 0, 0,
+            0, sy, 0, 0,
+            0, 0, 1, 0,
+            tx, ty, 0, 1
+        );
+        xform = crop * xform;
+    }
+
+    // GLConsumer uses the GL convention where (0, 0) is the bottom-left
+    // corner and (1, 1) is the top-right corner.  Add an additional vertical
+    // flip after all other transforms to map from GL convention to buffer
+    // queue memory layout, where (0, 0) is the top-left corner.
+    xform = mtxFlipV * xform;
+
+    memcpy(outTransform, xform.asArray(), sizeof(xform));
+}
+
+}; // namespace android