Get //flutter/flow building on Fuchsia (#2899)

BUILD.gn

@@ -2,11 +2,11 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-# This target will be built if no target is specified when invoking ninja.
 group("flutter") {
   testonly = true
 
   deps = [
+    "//flutter/flow",
     "//flutter/glue",
   ]
 

flow/BUILD.gn

@@ -47,9 +47,17 @@ source_set("flow") {
 
   deps = [
     "//flutter/glue",
+    "//flutter/skia",
     "//lib/ftl",
     "//mojo/services/gfx/composition/interfaces",
-    "//mojo/skia",
-    "//flutter/skia",
   ]
+
+  if (is_fuchsia) {
+    # TODO(abarth): In principle, we should add "//mojo/public/c/gpu" as a
+    # dependency, but that doesn't work currently because GPU support on Fuchsia
+    # is still a work in progress.
+    include_dirs = [
+      "//mojo/public/c/gpu",
+    ]
+  }
 }

flow/layers/child_scene_layer.cc

@@ -4,13 +4,37 @@
 
 #include "flutter/flow/layers/child_scene_layer.h"
 
-#include "mojo/skia/type_converters.h"
-
 namespace flow {
+namespace {
+
+mojo::TransformPtr GetTransformFromSkMatrix(const SkMatrix& input) {
+  // Expand 3x3 to 4x4.
+  auto output = mojo::Transform::New();
+  output->matrix.resize(16u);
+  output->matrix[0] = input[0];
+  output->matrix[1] = input[1];
+  output->matrix[2] = 0.f;
+  output->matrix[3] = input[2];
+  output->matrix[4] = input[3];
+  output->matrix[5] = input[4];
+  output->matrix[6] = 0.f;
+  output->matrix[7] = input[5];
+  output->matrix[8] = 0.f;
+  output->matrix[9] = 0.f;
+  output->matrix[10] = 1.f;
+  output->matrix[11] = 0.f;
+  output->matrix[12] = input[6];
+  output->matrix[13] = input[7];
+  output->matrix[14] = 0.f;
+  output->matrix[15] = input[8];
+  return output.Pass();
+}
 
 // TODO(abarth): We need to figure out how to allocate these ids sensibly.
 static uint32_t next_id = 10;
 
+}  // namespace
+
 ChildSceneLayer::ChildSceneLayer() : device_pixel_ratio_(1.0f) {}
 
 ChildSceneLayer::~ChildSceneLayer() {}
@@ -42,7 +66,7 @@ void ChildSceneLayer::UpdateScene(mojo::gfx::composition::SceneUpdate* update,
   child_node->content_clip = mojo::RectF::New();
   child_node->content_clip->width = physical_size_.width();
   child_node->content_clip->height = physical_size_.height();
-  child_node->content_transform = mojo::Transform::From(transform_);
+  child_node->content_transform = GetTransformFromSkMatrix(transform_);
   update->nodes.insert(id, child_node.Pass());
   container->child_node_ids.push_back(id);
 }

flow/open_gl.h

@@ -7,19 +7,19 @@
 
 #include "lib/ftl/build_config.h"
 
-#if OS_IOS
+#if defined(OS_IOS)
 
 #include <OpenGLES/ES2/gl.h>
 
-#elif OS_MACOSX
+#elif defined(OS_MACOSX)
 
 #include <OpenGL/gl.h>
 
-#elif OS_ANDROID
+#elif defined(OS_ANDROID) || defined(OS_FUCHSIA)
 
 #include <GLES2/gl2.h>
 
-#elif OS_LINUX
+#elif defined(OS_LINUX)
 
 #include <GL/gl.h>
 

skia/BUILD.gn

@@ -2,6 +2,16 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+if (is_fuchsia) {
+
+group("skia") {
+  # TODO(abarth): Switch the non-Fuchsia build over to using Skia's BUILD.gn
+  # files as well.
+  public_deps = [ "//third_party/skia" ]
+}
+
+} else {
+
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
@@ -553,3 +563,5 @@ source_set("skia_opts") {
 
   visibility = [ ":skia" ]
 }
+
+}  # if (is_fuchsia)