Shapedetection module: Blink side implementation

third_party/WebKit/Source/modules/shapedetection/FaceDetector.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/shapedetection/FaceDetector.h"
 
-#include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMException.h"
+#include "core/dom/DOMRect.h"
+#include "core/dom/Document.h"
+#include "core/fetch/ImageResource.h"
+#include "core/frame/LocalFrame.h"
+#include "core/html/HTMLImageElement.h"
+#include "platform/graphics/Image.h"
+#include "public/platform/InterfaceProvider.h"
+#include "third_party/skia/include/core/SkImage.h"
+#include "third_party/skia/include/core/SkImageInfo.h"
 
 namespace blink {
 
-FaceDetector* FaceDetector::create() {
-  return new FaceDetector();
+namespace {
+
+mojo::ScopedSharedBufferHandle getSharedBufferHandle(
+    const HTMLImageElement* img) {
+  ImageResource* const imageResource = img->cachedImage();
+  if (!imageResource) {
+    DLOG(ERROR) << "Failed to convert HTMLImageElement to ImageSource.";
+    return mojo::ScopedSharedBufferHandle();
+  }
+
+  Image* const blinkImage = imageResource->getImage();
+  if (!blinkImage) {
+    DLOG(ERROR) << "Failed to convert ImageSource to blink::Image.";

[mcasas, 2016/10/03 22:18:09]

nit: just for cases like this, we can also consider:

DLOG_IF(ERROR, !blinkImage) << "Failed...";
if (!blinkImage)
  return mojo::ScopedSharedBufferHandle();

which allows us to spare a line of text ! :)

[xianglu, 2016/10/04 00:58:26]

Yeah. But in that way the message will be too long to fit in the same line.

+    return mojo::ScopedSharedBufferHandle();
+  }
+
+  const sk_sp<SkImage> image = blinkImage->imageForCurrentFrame();
+  DCHECK_EQ(img->naturalWidth(), image->width());
+  DCHECK_EQ(img->naturalHeight(), image->height());
+
+  if (!image) {
+    DLOG(ERROR) << "Failed to convert blink::Image to sk_sp<SkImage>.";
+    return mojo::ScopedSharedBufferHandle();
+  }
+
+  const SkImageInfo skiaInfo =
+      SkImageInfo::MakeN32(image->width(), image->height(), image->alphaType());
+
+  const uint32_t allocationSize = skiaInfo.getSafeSize(skiaInfo.minRowBytes());
+  mojo::ScopedSharedBufferHandle sharedBufferHandle =
+      mojo::SharedBufferHandle::Create(allocationSize);
+  const mojo::ScopedSharedBufferMapping mappedBuffer =
+      sharedBufferHandle->Map(allocationSize);
+  DCHECK(mappedBuffer);
+
+  const SkPixmap pixmap(skiaInfo, mappedBuffer.get(), skiaInfo.minRowBytes());
+  if (!image->readPixels(pixmap, 0, 0)) {
+    DLOG(ERROR) << "Failed to read pixels from sk_sp<SkImage>.";
+    return mojo::ScopedSharedBufferHandle();
+  }
+
+  return sharedBufferHandle;
+}
+
+}  // anonymous namespace
+
+FaceDetector* FaceDetector::create(const Document& document) {
+  return new FaceDetector(*document.frame());
+}
+
+FaceDetector::FaceDetector(LocalFrame& frame) {
+  DCHECK(!m_service.is_bound());
+  DCHECK(frame.interfaceProvider());
+  frame.interfaceProvider()->getInterface(mojo::GetProxy(&m_service));
 }
 
 ScriptPromise FaceDetector::detect(ScriptState* scriptState,
-                                   const HTMLImageElement* image) {
+                                   const HTMLImageElement* img) {
   ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
   ScriptPromise promise = resolver->promise();
-  resolver->reject(DOMException::create(NotSupportedError, "Not implemented"));
+
+  if (!m_service) {
+    resolver->reject(DOMException::create(
+        NotFoundError, "Face detection service unavailable."));
+    return promise;
+  }
+
+  if (!img) {
+    resolver->reject(DOMException::create(
+        SyntaxError, "The provided HTMLImageElement is empty."));
+    return promise;
+  }
+
+  // TODO(xianglu): Add security check when the spec is ready. https://crbug.com/646083

[mcasas, 2016/10/03 22:18:09]

nit: reflow this comment line to 80 chars wide plz.

[xianglu, 2016/10/04 00:58:26]

Done.

+  mojo::ScopedSharedBufferHandle sharedBufferHandle =
+      getSharedBufferHandle(img);
+  if (!sharedBufferHandle->is_valid()) {
+    resolver->reject(
+        DOMException::create(SyntaxError, "Failed to get sharedBufferHandle."));
+    return promise;
+  }
+
+  m_serviceRequests.add(resolver);
+  DCHECK(m_service.is_bound());
+  m_service->DetectFace(std::move(sharedBufferHandle), img->naturalWidth(),
+                        img->naturalHeight(),
+                        convertToBaseCallback(WTF::bind(
+                            &FaceDetector::onDetectFace, wrapPersistent(this),
+                            wrapPersistent(resolver))));
+  sharedBufferHandle.reset();
   return promise;
 }
 
+void FaceDetector::onDetectFace(
+    ScriptPromiseResolver* resolver,
+    mojom::blink::FaceDetectionResultPtr faceDetectionResult) {
+  if (!m_serviceRequests.contains(resolver))
+    return;
+
+  HeapVector<Member<DOMRect>> detectedFaces;
+  for (const auto& boundingBox : faceDetectionResult->boundingBoxes) {
+    detectedFaces.append(DOMRect::create(boundingBox->x, boundingBox->y,

[mcasas, 2016/10/03 22:18:09]

nit: consider adding here a contract on the bounding box:
DCHECK_LE(boundingBox->x + boundingBox->width, 1.0);
DCHECK_LE(boundingBox->y + boundingBox->height, 1.0);

[xianglu, 2016/10/04 00:58:26]

Done.

+                                         boundingBox->width,
+                                         boundingBox->height));
+  }
+
+  resolver->resolve(detectedFaces);
+  m_serviceRequests.remove(resolver);
+}
+
+DEFINE_TRACE(FaceDetector) {
+  visitor->trace(m_serviceRequests);
+}
+
 }  // namespace blink