diff --git a/gl_compositor.cpp b/gl_compositor.cpp
new file mode 100644
index 0000000..c7aeff4
--- /dev/null
+++ b/gl_compositor.cpp
@@ -0,0 +1,1013 @@
+/*
+ * Copyright (C) 2015 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 "GLCompositor"
+
+#include <sstream>
+#include <string>
+#include <vector>
+
+#include <cutils/log.h>
+
+#define EGL_EGLEXT_PROTOTYPES
+#define GL_GLEXT_PROTOTYPES
+
+#include <EGL/egl.h>
+#include <EGL/eglext.h>
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+
+#include <hardware/hardware.h>
+#include <hardware/hwcomposer.h>
+
+#include <ui/GraphicBuffer.h>
+#include <ui/PixelFormat.h>
+
+#include <cutils/properties.h>
+#include <sync/sync.h>
+#include <sw_sync.h>
+
+#include "drm_hwcomposer.h"
+
+#include "gl_compositor.h"
+#include "seperate_rects.h"
+
+// TODO(zachr): use hwc_drm_bo to turn buffer handles into textures
+#ifndef EGL_NATIVE_HANDLE_ANDROID_NVX
+#define EGL_NATIVE_HANDLE_ANDROID_NVX 0x322A
+#endif
+
+#define MAX_OVERLAPPING_LAYERS 64
+
+namespace android {
+
+struct GLCompositor::texture_from_handle {
+  EGLImageKHR image;
+  GLuint texture;
+};
+
+static const char *get_gl_error(void);
+static const char *get_egl_error(void);
+static bool has_extension(const char *extension, const char *extensions);
+
+template <typename T>
+int AllocResource(std::vector<T> &array) {
+  for (typename std::vector<T>::iterator it = array.begin(); it != array.end();
+       ++it) {
+    if (!it->is_some()) {
+      return std::distance(array.begin(), it);
+    }
+  }
+
+  array.push_back(T());
+  return array.size() - 1;
+}
+
+template <typename T>
+void FreeResource(std::vector<T> &array, int index) {
+  if (index == (int)array.size() - 1) {
+    array.pop_back();
+  } else if (index >= 0 && (unsigned)index < array.size()) {
+    array[index].Reset();
+  }
+}
+
+struct GLTarget {
+  sp<GraphicBuffer> fb;
+  EGLImageKHR egl_fb_image;
+  GLuint gl_fb;
+  GLuint gl_fb_tex;
+  bool forgotten;
+  unsigned composition_count;
+
+  GLTarget()
+      : egl_fb_image(EGL_NO_IMAGE_KHR),
+        gl_fb(0),
+        gl_fb_tex(0),
+        forgotten(true),
+        composition_count(0) {
+  }
+
+  void Reset() {
+    fb.clear();
+    egl_fb_image = EGL_NO_IMAGE_KHR;
+    gl_fb = 0;
+    gl_fb_tex = 0;
+    forgotten = true;
+    composition_count = 0;
+  }
+
+  bool is_some() const {
+    return egl_fb_image != EGL_NO_IMAGE_KHR;
+  }
+};
+
+struct GLCompositor::priv_data {
+  EGLDisplay egl_display;
+  EGLContext egl_ctx;
+
+  EGLDisplay saved_egl_display;
+  EGLContext saved_egl_ctx;
+  EGLSurface saved_egl_read;
+  EGLSurface saved_egl_draw;
+
+  int current_target;
+  std::vector<GLTarget> targets;
+  std::vector<GLComposition *> compositions;
+
+  std::vector<GLint> blend_programs;
+  GLuint vertex_buffer;
+
+  priv_data()
+      : egl_display(EGL_NO_DISPLAY),
+        egl_ctx(EGL_NO_CONTEXT),
+        saved_egl_display(EGL_NO_DISPLAY),
+        saved_egl_ctx(EGL_NO_CONTEXT),
+        saved_egl_read(EGL_NO_SURFACE),
+        saved_egl_draw(EGL_NO_SURFACE),
+        current_target(-1) {
+  }
+};
+
+class GLComposition : public Composition {
+ public:
+  struct LayerData {
+    hwc_layer_1 layer;
+    hwc_drm_bo bo;
+  };
+
+  GLComposition(GLCompositor *owner) : compositor(owner), target_handle(-1) {
+  }
+
+  virtual ~GLComposition() {
+    if (compositor == NULL) {
+      return;
+    }
+
+    // Removes this composition from the owning compositor automatically.
+    std::vector<GLComposition *> &compositions =
+        compositor->priv_->compositions;
+    std::vector<GLComposition *>::iterator it =
+        std::find(compositions.begin(), compositions.end(), this);
+    if (it != compositions.end()) {
+      compositions.erase(it);
+    }
+
+    GLTarget *target = &compositor->priv_->targets[target_handle];
+    target->composition_count--;
+    compositor->CheckAndDestroyTarget(target_handle);
+  }
+
+  virtual int AddLayer(int display, hwc_layer_1 *layer, hwc_drm_bo *bo) {
+    (void)display;
+    if (layer->compositionType != HWC_OVERLAY) {
+      ALOGE("Must add layers with compositionType == HWC_OVERLAY");
+      return 1;
+    }
+
+    if (layer->handle == 0) {
+      ALOGE("Must add layers with valid buffer handle");
+      return 1;
+    }
+
+    layer_data.push_back(LayerData());
+    LayerData &layer_datum = layer_data.back();
+    layer_datum.layer = *layer;
+    layer_datum.bo = *bo;
+
+    return 0;
+  }
+
+  virtual unsigned GetRemainingLayers(int display, unsigned num_needed) const {
+    (void)display;
+    return num_needed;
+  }
+
+  GLCompositor *compositor;
+  int target_handle;
+  std::vector<LayerData> layer_data;
+};
+
+struct RenderingCommand {
+  struct TextureSource {
+    unsigned texture_index;
+    float crop_bounds[4];
+    float alpha;
+  };
+
+  float bounds[4];
+  unsigned texture_count;
+  TextureSource textures[MAX_OVERLAPPING_LAYERS];
+
+  RenderingCommand() : texture_count(0) {
+  }
+};
+
+static void ConstructCommands(const GLComposition &composition,
+                              std::vector<RenderingCommand> *commands) {
+  std::vector<seperate_rects::Rect<float> > in_rects;
+  std::vector<seperate_rects::RectSet<uint64_t, float> > out_rects;
+  int i;
+
+  for (unsigned rect_index = 0; rect_index < composition.layer_data.size();
+       rect_index++) {
+    const struct hwc_layer_1 &layer = composition.layer_data[rect_index].layer;
+    seperate_rects::Rect<float> rect;
+    in_rects.push_back(seperate_rects::Rect<float>(
+        layer.displayFrame.left, layer.displayFrame.top,
+        layer.displayFrame.right, layer.displayFrame.bottom));
+  }
+
+  seperate_frects_64(in_rects, &out_rects);
+
+  for (unsigned rect_index = 0; rect_index < out_rects.size(); rect_index++) {
+    const seperate_rects::RectSet<uint64_t, float> &out_rect =
+        out_rects[rect_index];
+    commands->push_back(RenderingCommand());
+    RenderingCommand &cmd = commands->back();
+
+    memcpy(cmd.bounds, out_rect.rect.bounds, sizeof(cmd.bounds));
+
+    uint64_t tex_set = out_rect.id_set.getBits();
+    for (unsigned i = composition.layer_data.size() - 1; tex_set != 0x0; i--) {
+      if (tex_set & (0x1 << i)) {
+        tex_set &= ~(0x1 << i);
+
+        const struct hwc_layer_1 &layer = composition.layer_data[i].layer;
+
+        seperate_rects::Rect<float> display_rect(
+            layer.displayFrame.left, layer.displayFrame.top,
+            layer.displayFrame.right, layer.displayFrame.bottom);
+        float display_size[2] = {
+            display_rect.bounds[2] - display_rect.bounds[0],
+            display_rect.bounds[3] - display_rect.bounds[1]};
+
+        seperate_rects::Rect<float> crop_rect(
+            layer.sourceCropf.left, layer.sourceCropf.top,
+            layer.sourceCropf.right, layer.sourceCropf.bottom);
+        float crop_size[2] = {crop_rect.bounds[2] - crop_rect.bounds[0],
+                              crop_rect.bounds[3] - crop_rect.bounds[1]};
+
+        RenderingCommand::TextureSource &src = cmd.textures[cmd.texture_count];
+        cmd.texture_count++;
+        src.texture_index = i;
+
+        for (int b = 0; b < 4; b++) {
+          float bound_percent = (cmd.bounds[b] - display_rect.bounds[b % 2]) /
+                                display_size[b % 2];
+          src.crop_bounds[b] =
+              crop_rect.bounds[b % 2] + bound_percent * crop_size[b % 2];
+        }
+
+        if (layer.blending == HWC_BLENDING_NONE) {
+          src.alpha = 1.0f;
+          // This layer is opaque. There is no point in using layers below this
+          // one.
+          break;
+        }
+
+        src.alpha = layer.planeAlpha / 255.0f;
+      }
+    }
+  }
+}
+
+GLCompositor::GLCompositor() {
+  priv_ = new priv_data;
+}
+
+GLCompositor::~GLCompositor() {
+  if (BeginContext()) {
+    goto destroy_ctx;
+  }
+
+  glBindFramebuffer(GL_FRAMEBUFFER, 0);
+  glBindTexture(GL_TEXTURE_2D, 0);
+
+  for (std::vector<GLTarget>::iterator it = priv_->targets.end();
+       it != priv_->targets.begin(); it = priv_->targets.end()) {
+    --it;
+    glDeleteFramebuffers(1, &it->gl_fb);
+    glDeleteTextures(1, &it->gl_fb_tex);
+    eglDestroyImageKHR(priv_->egl_display, it->egl_fb_image);
+    priv_->targets.erase(it);
+  }
+
+  for (std::vector<GLComposition *>::iterator it = priv_->compositions.end();
+       it != priv_->compositions.begin(); it = priv_->compositions.end()) {
+    --it;
+
+    // Prevents compositor from trying to erase itself
+    (*it)->compositor = NULL;
+    delete *it;
+    priv_->compositions.erase(it);
+  }
+
+destroy_ctx:
+  eglMakeCurrent(priv_->egl_display,
+                 EGL_NO_SURFACE /* No default draw surface */,
+                 EGL_NO_SURFACE /* No default draw read */, EGL_NO_CONTEXT);
+  eglDestroyContext(priv_->egl_display, priv_->egl_ctx);
+
+  EndContext();
+  delete priv_;
+}
+
+int GLCompositor::Init() {
+  int ret = 0;
+  const char *egl_extensions;
+  const char *gl_extensions;
+  EGLint num_configs;
+  EGLint attribs[] = {EGL_WIDTH, 1, EGL_HEIGHT, 1, EGL_NONE, EGL_NONE};
+  EGLConfig egl_config;
+
+  // clang-format off
+  const GLfloat verts[] = {
+    0.0f,  0.0f,    0.0f, 0.0f,
+    0.0f,  1.0f,    0.0f, 1.0f,
+    1.0f,  0.0f,    1.0f, 0.0f,
+    1.0f,  1.0f,    1.0f, 1.0f
+  };
+  // clang-format on
+
+  const EGLint config_attribs[] = {EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
+                                   EGL_RED_SIZE, 8, EGL_GREEN_SIZE, 8,
+                                   EGL_BLUE_SIZE, 8, EGL_NONE};
+
+  const EGLint context_attribs[] = {EGL_CONTEXT_CLIENT_VERSION, 3, EGL_NONE};
+
+  priv_->egl_display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
+  if (priv_->egl_display == EGL_NO_DISPLAY) {
+    ALOGE("Failed to get egl display");
+    ret = 1;
+    goto out;
+  }
+
+  if (!eglInitialize(priv_->egl_display, NULL, NULL)) {
+    ALOGE("Failed to initialize egl: %s", get_egl_error());
+    ret = 1;
+    goto out;
+  }
+
+  egl_extensions = eglQueryString(priv_->egl_display, EGL_EXTENSIONS);
+
+  // These extensions are all technically required but not always reported due
+  // to meta EGL filtering them out.
+  if (!has_extension("EGL_KHR_image_base", egl_extensions))
+    ALOGW("EGL_KHR_image_base extension not supported");
+
+  if (!has_extension("EGL_ANDROID_image_native_buffer", egl_extensions))
+    ALOGW("EGL_ANDROID_image_native_buffer extension not supported");
+
+  if (!has_extension("EGL_ANDROID_native_fence_sync", egl_extensions))
+    ALOGW("EGL_ANDROID_native_fence_sync extension not supported");
+
+  if (!eglChooseConfig(priv_->egl_display, config_attribs, &egl_config, 1,
+                       &num_configs)) {
+    ALOGE("eglChooseConfig() failed with error: %s", get_egl_error());
+    goto out;
+  }
+
+  priv_->egl_ctx =
+      eglCreateContext(priv_->egl_display, egl_config,
+                       EGL_NO_CONTEXT /* No shared context */, context_attribs);
+
+  if (priv_->egl_ctx == EGL_NO_CONTEXT) {
+    ALOGE("Failed to create OpenGL ES Context: %s", get_egl_error());
+    ret = 1;
+    goto out;
+  }
+
+  ret = BeginContext();
+  if (ret)
+    goto out;
+
+  gl_extensions = (const char *)glGetString(GL_EXTENSIONS);
+
+  if (!has_extension("GL_OES_EGL_image", gl_extensions))
+    ALOGW("GL_OES_EGL_image extension not supported");
+
+  glGenBuffers(1, &priv_->vertex_buffer);
+  glBindBuffer(GL_ARRAY_BUFFER, priv_->vertex_buffer);
+  glBufferData(GL_ARRAY_BUFFER, sizeof(verts), verts, GL_STATIC_DRAW);
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+
+  if (GenerateShaders()) {
+    ret = 1;
+    goto end_ctx;
+  }
+
+end_ctx:
+  EndContext();
+
+out:
+  return ret;
+}
+
+Targeting *GLCompositor::targeting() {
+  return (Targeting *)this;
+}
+
+int GLCompositor::CreateTarget(sp<GraphicBuffer> &buffer) {
+  int ret;
+
+  ret = BeginContext();
+  if (ret)
+    return -1;
+
+  int target_handle = AllocResource(priv_->targets);
+  GLTarget *target = &priv_->targets[target_handle];
+
+  target->fb = buffer;
+
+  target->egl_fb_image = eglCreateImageKHR(
+      priv_->egl_display, EGL_NO_CONTEXT, EGL_NATIVE_BUFFER_ANDROID,
+      (EGLClientBuffer)target->fb->getNativeBuffer(), NULL /* no attribs */);
+
+  if (target->egl_fb_image == EGL_NO_IMAGE_KHR) {
+    ALOGE("Failed to make image from target buffer: %s", get_egl_error());
+    ret = -1;
+    goto fail_create_image;
+  }
+
+  glGenTextures(1, &target->gl_fb_tex);
+  glBindTexture(GL_TEXTURE_2D, target->gl_fb_tex);
+  glEGLImageTargetTexture2DOES(GL_TEXTURE_2D,
+                               (GLeglImageOES)target->egl_fb_image);
+  glBindTexture(GL_TEXTURE_2D, 0);
+
+  glGenFramebuffers(1, &target->gl_fb);
+  glBindFramebuffer(GL_FRAMEBUFFER, target->gl_fb);
+  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
+                         target->gl_fb_tex, 0);
+
+  if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
+    ALOGE("Failed framebuffer check for created target buffer");
+    ret = 1;
+    goto fail_framebuffer_status;
+  }
+
+  target->forgotten = false;
+
+  ret = target_handle;
+  goto out;
+
+fail_framebuffer_status:
+  glBindFramebuffer(GL_FRAMEBUFFER, 0);
+  glDeleteFramebuffers(1, &target->gl_fb);
+  glDeleteTextures(1, &target->gl_fb_tex);
+  eglDestroyImageKHR(priv_->egl_display, target->egl_fb_image);
+  target->gl_fb = 0;
+  target->gl_fb_tex = 0;
+  target->egl_fb_image = EGL_NO_IMAGE_KHR;
+
+fail_create_image:
+  target->fb.clear();
+  FreeResource(priv_->targets, target_handle);
+
+out:
+  EndContext();
+  return ret;
+}
+
+void GLCompositor::SetTarget(int target_handle) {
+  if (target_handle >= 0 && (unsigned)target_handle < priv_->targets.size()) {
+    GLTarget *target = &priv_->targets[target_handle];
+    if (target->is_some()) {
+      priv_->current_target = target_handle;
+      return;
+    }
+  }
+
+  priv_->current_target = -1;
+}
+
+void GLCompositor::ForgetTarget(int target_handle) {
+  if (target_handle >= 0 && (unsigned)target_handle < priv_->targets.size()) {
+    if (target_handle == priv_->current_target) {
+      priv_->current_target = -1;
+    }
+
+    GLTarget *target = &priv_->targets[target_handle];
+    if (target->is_some()) {
+      target->forgotten = true;
+      CheckAndDestroyTarget(target_handle);
+      return;
+    }
+  }
+
+  ALOGE("Failed to forget target because of invalid handle");
+}
+
+void GLCompositor::CheckAndDestroyTarget(int target_handle) {
+  GLTarget *target = &priv_->targets[target_handle];
+  if (target->composition_count == 0 && target->forgotten) {
+    if (BeginContext() == 0) {
+      glDeleteFramebuffers(1, &target->gl_fb);
+      glDeleteTextures(1, &target->gl_fb_tex);
+      eglDestroyImageKHR(priv_->egl_display, target->egl_fb_image);
+      EndContext();
+    }
+
+    FreeResource(priv_->targets, target_handle);
+  }
+}
+
+Composition *GLCompositor::CreateComposition() {
+  if (priv_->current_target >= 0 &&
+      (unsigned)priv_->current_target < priv_->targets.size()) {
+    GLTarget *target = &priv_->targets[priv_->current_target];
+    if (target->is_some()) {
+      GLComposition *composition = new GLComposition(this);
+      composition->target_handle = priv_->current_target;
+      target->composition_count++;
+      priv_->compositions.push_back(composition);
+      return composition;
+    }
+  }
+
+  ALOGE("Failed to create composition because of invalid target handle %d",
+        priv_->current_target);
+
+  return NULL;
+}
+
+int GLCompositor::QueueComposition(Composition *composition) {
+  if (composition) {
+    int ret = DoComposition(*(GLComposition *)composition);
+    delete composition;
+    return ret;
+  }
+
+  ALOGE("Failed to queue composition because of invalid composition handle");
+
+  return -EINVAL;
+}
+
+int GLCompositor::Composite() {
+  return 0;
+}
+
+int GLCompositor::BeginContext() {
+  priv_->saved_egl_display = eglGetCurrentDisplay();
+  priv_->saved_egl_ctx = eglGetCurrentContext();
+
+  if (priv_->saved_egl_display != priv_->egl_display ||
+      priv_->saved_egl_ctx != priv_->egl_ctx) {
+    priv_->saved_egl_read = eglGetCurrentSurface(EGL_READ);
+    priv_->saved_egl_draw = eglGetCurrentSurface(EGL_DRAW);
+  } else {
+    return 0;
+  }
+
+  if (!eglMakeCurrent(priv_->egl_display, EGL_NO_SURFACE, EGL_NO_SURFACE,
+                      priv_->egl_ctx)) {
+    ALOGE("Failed to make the OpenGL ES Context current: %s", get_egl_error());
+    return 1;
+  }
+  return 0;
+}
+
+int GLCompositor::EndContext() {
+  if (priv_->saved_egl_display != eglGetCurrentDisplay() ||
+      priv_->saved_egl_ctx != eglGetCurrentContext()) {
+    if (!eglMakeCurrent(priv_->saved_egl_display, priv_->saved_egl_read,
+                        priv_->saved_egl_draw, priv_->saved_egl_ctx)) {
+      ALOGE("Failed to make the OpenGL ES Context current: %s",
+            get_egl_error());
+      return 1;
+    }
+  }
+
+  return 0;
+}
+
+GLint CompileAndCheckShader(GLenum type, unsigned source_count,
+                            const GLchar **sources, std::string *shader_log) {
+  GLint status;
+  GLint shader = glCreateShader(type);
+  if (!shader) {
+    *shader_log = "glCreateShader failed";
+    return 0;
+  }
+  glShaderSource(shader, source_count, sources, NULL);
+  glCompileShader(shader);
+  glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
+  if (!status) {
+    if (shader_log) {
+      GLint log_length;
+      glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &log_length);
+      shader_log->resize(log_length);
+      glGetShaderInfoLog(shader, log_length, NULL, &(*shader_log)[0]);
+    }
+    glDeleteShader(shader);
+    return 0;
+  }
+
+  return shader;
+}
+
+int GLCompositor::GenerateShaders() {
+  // Limits: GL_MAX_VARYING_COMPONENTS, GL_MAX_TEXTURE_IMAGE_UNITS,
+  // GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS
+  // clang-format off
+  const GLchar *shader_preamble = "#version 300 es\n#define LAYER_COUNT ";
+
+  const GLchar *vertex_shader_source =
+"\n"
+"precision mediump int;                                                     \n"
+"uniform vec4 uViewport;                                                    \n"
+"uniform sampler2D uLayerTextures[LAYER_COUNT];                             \n"
+"uniform vec4 uLayerCrop[LAYER_COUNT];                                      \n"
+"in vec2 vPosition;                                                         \n"
+"in vec2 vTexCoords;                                                        \n"
+"out vec2 fTexCoords[LAYER_COUNT];                                          \n"
+"void main() {                                                              \n"
+"  for (int i = 0; i < LAYER_COUNT; i++) {                                  \n"
+"    fTexCoords[i] = (uLayerCrop[i].xy + vTexCoords * uLayerCrop[i].zw) /   \n"
+"                     vec2(textureSize(uLayerTextures[i], 0));              \n"
+"  }                                                                        \n"
+"  vec2 scaledPosition = uViewport.xy + vPosition * uViewport.zw;           \n"
+"  gl_Position = vec4(scaledPosition * vec2(2.0) - vec2(1.0), 0.0, 1.0);    \n"
+"}                                                                          \n";
+
+  const GLchar *fragment_shader_source =
+"\n"
+"precision mediump float;                                                   \n"
+"uniform sampler2D uLayerTextures[LAYER_COUNT];                             \n"
+"uniform float uLayerAlpha[LAYER_COUNT];                                    \n"
+"in vec2 fTexCoords[LAYER_COUNT];                                           \n"
+"out vec4 oFragColor;                                                       \n"
+"void main() {                                                              \n"
+"  vec3 color = vec3(0.0, 0.0, 0.0);                                        \n"
+"  float alphaCover = 1.0;                                                  \n"
+"  for (int i = 0; i < LAYER_COUNT; i++) {                                  \n"
+"    vec4 texSample = texture(uLayerTextures[i], fTexCoords[i]);            \n"
+"    float a = texSample.a * uLayerAlpha[i];                                \n"
+"    color += a * alphaCover * texSample.rgb;                               \n"
+"    alphaCover *= 1.0 - a;                                                 \n"
+"    if (alphaCover <= 0.5/255.0)                                           \n"
+"      break;                                                               \n"
+"  }                                                                        \n"
+"  oFragColor = vec4(color, 1.0);                                           \n"
+"}                                                                          \n";
+  // clang-format on
+
+  int i, ret = 1;
+  GLint max_texture_images, vertex_shader, fragment_shader, program, status;
+  std::string shader_log;
+
+  glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS, &max_texture_images);
+
+  for (i = 1; i <= max_texture_images; i++) {
+    std::ostringstream layer_count_formatter;
+    layer_count_formatter << i;
+    std::string layer_count(layer_count_formatter.str());
+    const GLchar *shader_sources[3] = {shader_preamble, layer_count.c_str(),
+                                       NULL};
+
+    shader_sources[2] = vertex_shader_source;
+    vertex_shader = CompileAndCheckShader(GL_VERTEX_SHADER, 3, shader_sources,
+                                          ret ? &shader_log : NULL);
+    if (!vertex_shader) {
+      if (ret) {
+        ALOGE("Failed to make vertex shader:\n%s", shader_log.c_str());
+      }
+      break;
+    }
+
+    shader_sources[2] = fragment_shader_source;
+    fragment_shader = CompileAndCheckShader(
+        GL_FRAGMENT_SHADER, 3, shader_sources, ret ? &shader_log : NULL);
+    if (!fragment_shader) {
+      if (ret) {
+        ALOGE("Failed to make fragment shader:\n%s", shader_log.c_str());
+      }
+      goto delete_vs;
+    }
+
+    program = glCreateProgram();
+    if (!program) {
+      if (ret)
+        ALOGE("Failed to create program %s", get_gl_error());
+      goto delete_fs;
+    }
+
+    glAttachShader(program, vertex_shader);
+    glAttachShader(program, fragment_shader);
+    glBindAttribLocation(program, 0, "vPosition");
+    glBindAttribLocation(program, 1, "vTexCoords");
+    glLinkProgram(program);
+    glDetachShader(program, vertex_shader);
+    glDeleteShader(vertex_shader);
+    glDetachShader(program, fragment_shader);
+    glDeleteShader(fragment_shader);
+
+    glGetProgramiv(program, GL_LINK_STATUS, &status);
+    if (!status) {
+      if (ret) {
+        GLint log_length;
+        glGetProgramiv(program, GL_INFO_LOG_LENGTH, &log_length);
+        std::string program_log(log_length, ' ');
+        glGetProgramInfoLog(program, log_length, NULL, &program_log[0]);
+        ALOGE("Failed to link program: \n%s", program_log.c_str());
+      }
+      glDeleteProgram(program);
+      break;
+    }
+
+    ret = 0;
+    priv_->blend_programs.push_back(program);
+
+    continue;
+
+  delete_fs:
+    glDeleteShader(fragment_shader);
+
+  delete_vs:
+    glDeleteShader(vertex_shader);
+
+    if (ret)
+      break;
+  }
+
+  return ret;
+}
+
+int GLCompositor::DoComposition(const GLComposition &composition) {
+  int ret = 0;
+  size_t i;
+  std::vector<struct texture_from_handle> layer_textures;
+  std::vector<RenderingCommand> commands;
+
+  if (composition.layer_data.size() == 0) {
+    return -EALREADY;
+  }
+
+  if (BeginContext()) {
+    return -EINVAL;
+  }
+
+  GLTarget *target = &priv_->targets[composition.target_handle];
+  GLint frame_width = target->fb->getWidth();
+  GLint frame_height = target->fb->getHeight();
+  EGLSyncKHR finished_sync;
+
+  for (i = 0; i < composition.layer_data.size(); i++) {
+    const struct hwc_layer_1 *layer = &composition.layer_data[i].layer;
+
+    if (ret) {
+      if (layer->acquireFenceFd >= 0)
+        close(layer->acquireFenceFd);
+      continue;
+    }
+
+    layer_textures.push_back(texture_from_handle());
+    ret = CreateTextureFromHandle(layer->handle, &layer_textures.back());
+    if (!ret) {
+      ret = DoFenceWait(layer->acquireFenceFd);
+    }
+    if (ret) {
+      layer_textures.pop_back();
+      ret = -EINVAL;
+    }
+  }
+
+  if (ret) {
+    goto destroy_textures;
+  }
+
+  ConstructCommands(composition, &commands);
+
+  glBindFramebuffer(GL_FRAMEBUFFER, target->gl_fb);
+
+  glViewport(0, 0, frame_width, frame_height);
+
+  glClearColor(1.0f, 1.0f, 0.0f, 1.0f);
+  glClear(GL_COLOR_BUFFER_BIT);
+
+  glBindBuffer(GL_ARRAY_BUFFER, priv_->vertex_buffer);
+  glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 4, NULL);
+  glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 4,
+                        (void *)(sizeof(float) * 2));
+  glEnableVertexAttribArray(0);
+  glEnableVertexAttribArray(1);
+
+  for (std::vector<RenderingCommand>::iterator it = commands.begin();
+       it != commands.end(); ++it) {
+    const RenderingCommand &cmd = *it;
+
+    if (cmd.texture_count <= 0) {
+      continue;
+    }
+
+    // TODO(zachr): handle the case of too many overlapping textures for one
+    // area by falling back to rendering as many layers as possible using
+    // multiple blending passes.
+    if (cmd.texture_count > priv_->blend_programs.size()) {
+      ALOGE("Too many layers to render in one area");
+      continue;
+    }
+
+    GLint program = priv_->blend_programs[cmd.texture_count - 1];
+    glUseProgram(program);
+    GLint gl_viewport_loc = glGetUniformLocation(program, "uViewport");
+    GLint gl_tex_loc = glGetUniformLocation(program, "uLayerTextures");
+    GLint gl_crop_loc = glGetUniformLocation(program, "uLayerCrop");
+    GLint gl_alpha_loc = glGetUniformLocation(program, "uLayerAlpha");
+    glUniform4f(gl_viewport_loc, cmd.bounds[0] / (float)frame_width,
+                cmd.bounds[1] / (float)frame_height,
+                (cmd.bounds[2] - cmd.bounds[0]) / (float)frame_width,
+                (cmd.bounds[3] - cmd.bounds[1]) / (float)frame_height);
+
+    for (unsigned src_index = 0; src_index < cmd.texture_count; src_index++) {
+      const RenderingCommand::TextureSource &src = cmd.textures[src_index];
+      glUniform1f(gl_alpha_loc + src_index, src.alpha);
+      glUniform4f(gl_crop_loc + src_index, src.crop_bounds[0],
+                  src.crop_bounds[1], src.crop_bounds[2] - src.crop_bounds[0],
+                  src.crop_bounds[3] - src.crop_bounds[1]);
+
+      glUniform1i(gl_tex_loc + src_index, src_index);
+      glActiveTexture(GL_TEXTURE0 + src_index);
+      glBindTexture(GL_TEXTURE_2D, layer_textures[src.texture_index].texture);
+    }
+
+    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+
+    for (unsigned src_index = 0; src_index < cmd.texture_count; src_index++) {
+      glActiveTexture(GL_TEXTURE0 + src_index);
+      glBindTexture(GL_TEXTURE_2D, 0);
+    }
+  }
+
+  glActiveTexture(GL_TEXTURE0);
+  glDisableVertexAttribArray(0);
+  glDisableVertexAttribArray(1);
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+  glUseProgram(0);
+
+  glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+  finished_sync =
+      eglCreateSyncKHR(priv_->egl_display, EGL_SYNC_NATIVE_FENCE_ANDROID, NULL);
+  if (finished_sync != EGL_NO_SYNC_KHR) {
+    glFlush();  // Creates the syncpoint
+    ret = eglDupNativeFenceFDANDROID(priv_->egl_display, finished_sync);
+    eglDestroySyncKHR(priv_->egl_display, finished_sync);
+    if (ret != EGL_NO_NATIVE_FENCE_FD_ANDROID) {
+      goto destroy_textures;
+    }
+  }
+
+  // Used as a fallback if the native sync fence fails.
+  ret = -EALREADY;
+  glFinish();
+
+destroy_textures:
+  for (i = 0; i < layer_textures.size(); i++)
+    DestroyTextureFromHandle(layer_textures[i]);
+
+  EndContext();
+
+  return ret;
+}
+
+int GLCompositor::DoFenceWait(int acquireFenceFd) {
+  int ret = 0;
+
+  EGLint attribs[] = {EGL_SYNC_NATIVE_FENCE_FD_ANDROID, acquireFenceFd,
+                      EGL_NONE};
+  EGLSyncKHR egl_sync = eglCreateSyncKHR(
+      priv_->egl_display, EGL_SYNC_NATIVE_FENCE_ANDROID, attribs);
+  if (egl_sync == EGL_NO_SYNC_KHR) {
+    ALOGE("Failed to make EGLSyncKHR from acquireFenceFd: %s", get_egl_error());
+    close(acquireFenceFd);
+    return 1;
+  }
+
+  EGLint success = eglWaitSyncKHR(priv_->egl_display, egl_sync, 0);
+  if (success == EGL_FALSE) {
+    ALOGE("Failed to wait for acquire: %s", get_egl_error());
+    ret = 1;
+  }
+  eglDestroySyncKHR(priv_->egl_display, egl_sync);
+
+  return ret;
+}
+
+int GLCompositor::CreateTextureFromHandle(buffer_handle_t handle,
+                                          struct texture_from_handle *tex) {
+  EGLImageKHR image = eglCreateImageKHR(
+      priv_->egl_display, EGL_NO_CONTEXT, EGL_NATIVE_HANDLE_ANDROID_NVX,
+      (EGLClientBuffer)handle, NULL /* no attribs */);
+
+  if (image == EGL_NO_IMAGE_KHR) {
+    ALOGE("Failed to make image %s %p", get_egl_error(), handle);
+    return 1;
+  }
+
+  glGenTextures(1, &tex->texture);
+  glBindTexture(GL_TEXTURE_2D, tex->texture);
+  glEGLImageTargetTexture2DOES(GL_TEXTURE_2D, (GLeglImageOES)image);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+
+  tex->image = image;
+
+  return 0;
+}
+
+void GLCompositor::DestroyTextureFromHandle(
+    const struct texture_from_handle &tex) {
+  glDeleteTextures(1, &tex.texture);
+  eglDestroyImageKHR(priv_->egl_display, tex.image);
+}
+
+static const char *get_gl_error(void) {
+  switch (glGetError()) {
+    case GL_NO_ERROR:
+      return "GL_NO_ERROR";
+    case GL_INVALID_ENUM:
+      return "GL_INVALID_ENUM";
+    case GL_INVALID_VALUE:
+      return "GL_INVALID_VALUE";
+    case GL_INVALID_OPERATION:
+      return "GL_INVALID_OPERATION";
+    case GL_INVALID_FRAMEBUFFER_OPERATION:
+      return "GL_INVALID_FRAMEBUFFER_OPERATION";
+    case GL_OUT_OF_MEMORY:
+      return "GL_OUT_OF_MEMORY";
+    default:
+      return "Unknown error";
+  }
+}
+
+static const char *get_egl_error(void) {
+  switch (eglGetError()) {
+    case EGL_SUCCESS:
+      return "EGL_SUCCESS";
+    case EGL_NOT_INITIALIZED:
+      return "EGL_NOT_INITIALIZED";
+    case EGL_BAD_ACCESS:
+      return "EGL_BAD_ACCESS";
+    case EGL_BAD_ALLOC:
+      return "EGL_BAD_ALLOC";
+    case EGL_BAD_ATTRIBUTE:
+      return "EGL_BAD_ATTRIBUTE";
+    case EGL_BAD_CONTEXT:
+      return "EGL_BAD_CONTEXT";
+    case EGL_BAD_CONFIG:
+      return "EGL_BAD_CONFIG";
+    case EGL_BAD_CURRENT_SURFACE:
+      return "EGL_BAD_CURRENT_SURFACE";
+    case EGL_BAD_DISPLAY:
+      return "EGL_BAD_DISPLAY";
+    case EGL_BAD_SURFACE:
+      return "EGL_BAD_SURFACE";
+    case EGL_BAD_MATCH:
+      return "EGL_BAD_MATCH";
+    case EGL_BAD_PARAMETER:
+      return "EGL_BAD_PARAMETER";
+    case EGL_BAD_NATIVE_PIXMAP:
+      return "EGL_BAD_NATIVE_PIXMAP";
+    case EGL_BAD_NATIVE_WINDOW:
+      return "EGL_BAD_NATIVE_WINDOW";
+    case EGL_CONTEXT_LOST:
+      return "EGL_CONTEXT_LOST";
+    default:
+      return "Unknown error";
+  }
+}
+
+static bool has_extension(const char *extension, const char *extensions) {
+  const char *start, *where, *terminator;
+  start = extensions;
+  for (;;) {
+    where = (char *)strstr((const char *)start, extension);
+    if (!where)
+      break;
+    terminator = where + strlen(extension);
+    if (where == start || *(where - 1) == ' ')
+      if (*terminator == ' ' || *terminator == '\0')
+        return true;
+    start = terminator;
+  }
+  return false;
+}
+
+}  // namespace android