Bug 1965114 part 2: Add a new imgIContainer.intrinsicSize attr as a shorthand for getting width & height. r=tnikkel

This is mostly just a convenience shorthand to avoid running the same
boilerplate/error-checking code in the implementation of the 'width' and
'height' attributes, for the benefit of callers that need both sizes.  But,
beyond that convenience: this also lets us elegantly express the case where an
image simply lacks an intrinsic width and/or height (not due to any error, but
simply because it's e.g. an SVG that has no preferred size in either or both of
its axes).  This is a state we'll need to be able to detect and give special
treatment to in a forthcoming patch for bug 1935269.

Differential Revision: https://phabricator.services.mozilla.com/D248526

image/ClippedImage.cpp

@@ -195,6 +195,17 @@ ClippedImage::GetHeight(int32_t* aHeight) {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+ClippedImage::GetIntrinsicSize(ImageIntrinsicSize* aIntrinsicSize) {
+  if (!ShouldClip()) {
+    return InnerImage()->GetIntrinsicSize(aIntrinsicSize);
+  }
+
+  aIntrinsicSize->mWidth = Some(mClip.Width());
+  aIntrinsicSize->mHeight = Some(mClip.Height());
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 ClippedImage::GetIntrinsicSizeInAppUnits(nsSize* aSize) {
   if (!ShouldClip()) {

image/ClippedImage.h

@@ -35,6 +35,7 @@ class ClippedImage : public ImageWrapper {
 
   NS_IMETHOD GetWidth(int32_t* aWidth) override;
   NS_IMETHOD GetHeight(int32_t* aHeight) override;
+  NS_IMETHOD GetIntrinsicSize(ImageIntrinsicSize* aIntrinsicSize) override;
   NS_IMETHOD GetIntrinsicSizeInAppUnits(nsSize* aSize) override;
   AspectRatio GetIntrinsicRatio() override;
   NS_IMETHOD_(already_AddRefed<SourceSurface>)

image/DynamicImage.cpp

@@ -97,6 +97,15 @@ nsresult DynamicImage::GetNativeSizes(nsTArray<IntSize>&) {
 
 size_t DynamicImage::GetNativeSizesLength() { return 0; }
 
+NS_IMETHODIMP
+DynamicImage::GetIntrinsicSize(ImageIntrinsicSize* aIntrinsicSize) {
+  IntSize intSize(mDrawable->Size());
+  aIntrinsicSize->mWidth = Some(intSize.width);
+  aIntrinsicSize->mHeight = Some(intSize.height);
+
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 DynamicImage::GetIntrinsicSizeInAppUnits(nsSize* aSize) {
   // XXXdholbert This probably needs to be scaled; see bug 1965106.

image/ImageWrapper.cpp

@@ -114,6 +114,11 @@ size_t ImageWrapper::GetNativeSizesLength() {
   return mInnerImage->GetNativeSizesLength();
 }
 
+NS_IMETHODIMP
+ImageWrapper::GetIntrinsicSize(ImageIntrinsicSize* aIntrinsicSize) {
+  return mInnerImage->GetIntrinsicSize(aIntrinsicSize);
+}
+
 NS_IMETHODIMP
 ImageWrapper::GetIntrinsicSizeInAppUnits(nsSize* aSize) {
   return mInnerImage->GetIntrinsicSizeInAppUnits(aSize);

image/RasterImage.cpp

@@ -207,6 +207,20 @@ RasterImage::GetHeight(int32_t* aHeight) {
   return NS_OK;
 }
 
+//******************************************************************************
+NS_IMETHODIMP
+RasterImage::GetIntrinsicSize(ImageIntrinsicSize* aIntrinsicSize) {
+  NS_ENSURE_ARG_POINTER(aIntrinsicSize);
+
+  if (mError) {
+    return NS_ERROR_FAILURE;
+  }
+
+  aIntrinsicSize->mWidth = Some(mSize.width);
+  aIntrinsicSize->mHeight = Some(mSize.height);
+  return NS_OK;
+}
+
 //******************************************************************************
 void RasterImage::MediaFeatureValuesChangedAllDocuments(
     const mozilla::MediaFeatureChange& aChange) {}

image/VectorImage.cpp

@@ -447,6 +447,7 @@ static Maybe<int32_t> ClampedPxLengthOrNothing(
 // imgIContainer methods
 
 //******************************************************************************
+
 NS_IMETHODIMP
 VectorImage::GetWidth(int32_t* aWidth) {
   if (mError || !mIsFullyLoaded) {
@@ -507,6 +508,25 @@ VectorImage::GetHeight(int32_t* aHeight) {
   return NS_OK;
 }
 
+//******************************************************************************
+NS_IMETHODIMP
+VectorImage::GetIntrinsicSize(ImageIntrinsicSize* aIntrinsicSize) {
+  if (mError || !mIsFullyLoaded) {
+    return NS_ERROR_FAILURE;
+  }
+  SVGSVGElement* rootElem = mSVGDocumentWrapper->GetRootSVGElem();
+  if (MOZ_UNLIKELY(!rootElem)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  aIntrinsicSize->mWidth =
+      ClampedPxLengthOrNothing(rootElem->GetIntrinsicWidth());
+  aIntrinsicSize->mHeight =
+      ClampedPxLengthOrNothing(rootElem->GetIntrinsicHeight());
+
+  return NS_OK;
+}
+
 //******************************************************************************
 NS_IMETHODIMP
 VectorImage::GetIntrinsicSizeInAppUnits(nsSize* aSize) {

image/imgIContainer.idl

@@ -43,12 +43,34 @@ class ImageIntRegion;
 class WebRenderImageProvider;
 struct Orientation;
 struct Resolution;
+
+/**
+ * This represents an image's intrinsic size, in units of pixels (the same
+ * units as our 'width' and 'height' attributes).  Both components are
+ * optional, because an image (particularly a vector image) may lack an
+ * intrinsic width and/or height.
+ *
+ * We use signed types for the components, but the values are expected to be
+ * nonnegative; any negative values should be considered an error. (Zero is
+ * valid, though.)
+ *
+ * Note that this is similar to a gfx::IntSize, except for the use of Maybe<>
+ * to reflect that the components are optional.  This is also similar to
+ * nsIFrame.h's mozilla::IntrinsicSize class, with the difference being pixel
+ * units here vs. nscoord units there.
+ */
+struct ImageIntrinsicSize {
+  Maybe<int32_t> mWidth;
+  Maybe<int32_t> mHeight;
+};
+
 }
 }
 
 %}
 
 native AspectRatio(mozilla::AspectRatio);
+native ImageIntrinsicSize(mozilla::image::ImageIntrinsicSize);
 native ImgDrawResult(mozilla::image::ImgDrawResult);
 [ptr] native gfxContext(gfxContext);
 [ref] native gfxMatrix(gfxMatrix);
@@ -98,6 +120,20 @@ interface imgIContainer : nsISupports
    */
   readonly attribute int32_t height;
 
+  /**
+   * The intrinsic size of this image in pixels.  The values and units here are
+   * the same as those that the 'width' and 'height' attributes (declared
+   * above) would return.
+   *
+   * If an image lacks an intrinsic width and/or height, then that component
+   * will be Nothing() in the returned value. (This is different from the
+   * 'width' and 'height' attributes; they treat this case as an error, for
+   * historical reasons, but we can handle it more elegantly here.)
+   *
+   * In case of any error, an exception will be thrown.
+   */
+  [noscript] readonly attribute ImageIntrinsicSize intrinsicSize;
+
   /**
    * The intrinsic size of this image in appunits. If the image has no intrinsic
    * size in a dimension, -1 will be returned for that dimension. In the case of