Creates an image descriptor for encoded or decoded image data, describing the width, height, and bytes per pixel for that image. This class will hold a reference on the underlying image data, and in the case of compressed data, an ImageGenerator for the data. The Codec initialization actually happens in initEncoded, making initstantiateCodec a lightweight operation. More...

#include <image_descriptor.h>

Inheritance diagram for flutter::ImageDescriptor:

Public Types
enum	PixelFormat { kRGBA8888 , kBGRA8888 , kRGBAFloat32 }

Public Types inherited from tonic::DartWrappable
enum	DartNativeFields { kPeerIndex , kNumberOfNativeFields }

Public Member Functions
	~ImageDescriptor () override=default

void	instantiateCodec (Dart_Handle codec, int target_width, int target_height)
	Associates a flutter::Codec object with the dart.ui Codec handle.

int	width () const
	The width of this image, EXIF oriented if applicable.

int	height () const
	The height of this image. EXIF oriented if applicable.

int	bytesPerPixel () const
	The bytes per pixel of the image.

int	row_bytes () const
	The byte length of the first row of the image. Defaults to width() * 4.

bool	should_resize (int target_width, int target_height) const
	Whether the given `target_width` or `target_height` differ from `width()` and `height()` respectively.

sk_sp< SkData >	data () const
	The underlying buffer for this image.

sk_sp< SkImage >	image () const

bool	is_compressed () const
	Whether this descriptor represents compressed (encoded) data or not.

const SkImageInfo &	image_info () const
	The orientation corrected image info for this image.

SkISize	get_scaled_dimensions (float scale)
	Gets the scaled dimensions of this image, if backed by an `ImageGenerator` that can perform efficient subpixel scaling.

bool	get_pixels (const SkPixmap &pixmap) const
	Gets pixels for this image transformed based on the EXIF orientation tag, if applicable.

void	dispose ()

Public Member Functions inherited from flutter::RefCountedDartWrappable< ImageDescriptor >
virtual void	RetainDartWrappableReference () const override

virtual void	ReleaseDartWrappableReference () const override

Public Member Functions inherited from fml::RefCountedThreadSafe< T >
void	Release () const

Public Member Functions inherited from fml::internal::RefCountedThreadSafeBase
void	AddRef () const

bool	HasOneRef () const

void	AssertHasOneRef () const

Public Member Functions inherited from tonic::DartWrappable
	DartWrappable ()

virtual const DartWrapperInfo &	GetDartWrapperInfo () const =0

Dart_Handle	CreateDartWrapper (DartState *dart_state)

void	AssociateWithDartWrapper (Dart_Handle wrappable)

void	ClearDartWrapper ()

Dart_WeakPersistentHandle	dart_wrapper () const

Static Public Member Functions
static Dart_Handle	initEncoded (Dart_Handle descriptor_handle, ImmutableBuffer *immutable_buffer, Dart_Handle callback_handle)
	Asynchronously initializes an ImageDescriptor for an encoded image, as long as the format is recognized by an encoder installed in the `ImageGeneratorRegistry`. Calling this method will create an `ImageGenerator` and read EXIF corrected dimensions from the image data.

static void	initRaw (Dart_Handle descriptor_handle, const fml::RefPtr< ImmutableBuffer > &data, int width, int height, int row_bytes, PixelFormat pixel_format)
	Synchronously initializes an `ImageDescriptor` for decompressed image data as specified by the `PixelFormat`.

Friends
class	ImageDecoderFixtureTest

Additional Inherited Members
Protected Member Functions inherited from fml::RefCountedThreadSafe< T >
	RefCountedThreadSafe ()

	~RefCountedThreadSafe ()

Protected Member Functions inherited from fml::internal::RefCountedThreadSafeBase
	RefCountedThreadSafeBase ()

	~RefCountedThreadSafeBase ()

bool	Release () const

void	Adopt ()

Protected Member Functions inherited from tonic::DartWrappable
virtual	~DartWrappable ()

Static Protected Member Functions inherited from tonic::DartWrappable
static Dart_PersistentHandle	GetTypeForWrapper (tonic::DartState *dart_state, const tonic::DartWrapperInfo &wrapper_info)

Detailed Description

Creates an image descriptor for encoded or decoded image data, describing the width, height, and bytes per pixel for that image. This class will hold a reference on the underlying image data, and in the case of compressed data, an ImageGenerator for the data. The Codec initialization actually happens in initEncoded, making initstantiateCodec a lightweight operation.

See also: ImageGenerator

Definition at line 32 of file image_descriptor.h.

Member Enumeration Documentation

◆ PixelFormat

enum flutter::ImageDescriptor::PixelFormat

Enumerator
kRGBA8888
kBGRA8888
kRGBAFloat32

Definition at line 37 of file image_descriptor.h.

                   {
    kRGBA8888,
    kBGRA8888,
    kRGBAFloat32,
  };

Constructor & Destructor Documentation

◆ ~ImageDescriptor()

flutter::ImageDescriptor::~ImageDescriptor ( )

overridedefault

Member Function Documentation

◆ bytesPerPixel()

int flutter::ImageDescriptor::bytesPerPixel ( ) const

inline

The bytes per pixel of the image.

Definition at line 72 of file image_descriptor.h.

72{ return image_info_.bytesPerPixel(); }

◆ data()

sk_sp< SkData > flutter::ImageDescriptor::data ( ) const

inline

The underlying buffer for this image.

Definition at line 88 of file image_descriptor.h.

88{ return buffer_; }

Referenced by flutter::ImageDecoderImpeller::DecompressTexture(), and flutter::ImageFromDecompressedData().

◆ dispose()

void flutter::ImageDescriptor::dispose ( )

inline

Definition at line 113 of file image_descriptor.h.

                 {
    buffer_.reset();
    generator_.reset();
    ClearDartWrapper();
  }

References tonic::DartWrappable::ClearDartWrapper().

◆ get_pixels()

bool flutter::ImageDescriptor::get_pixels ( const SkPixmap & pixmap ) const

Gets pixels for this image transformed based on the EXIF orientation tag, if applicable.

Definition at line 128 of file image_descriptor.cc.

                                                             {
  FML_DCHECK(generator_);
  return generator_->GetPixels(pixmap.info(), pixmap.writable_addr(),
                               pixmap.rowBytes());
}

References FML_DCHECK.

Referenced by flutter::ImageDecoderImpeller::DecompressTexture(), and flutter::ImageDecoderSkia::ImageFromCompressedData().

◆ get_scaled_dimensions()

SkISize flutter::ImageDescriptor::get_scaled_dimensions ( float scale )

inline

Gets the scaled dimensions of this image, if backed by an ImageGenerator that can perform efficient subpixel scaling.

See also: ImageGenerator::GetScaledDimensions

Definition at line 102 of file image_descriptor.h.

                                             {
    if (generator_) {
      return generator_->GetScaledDimensions(scale);
    }
    return image_info_.dimensions();
  }

Referenced by flutter::ImageDecoderImpeller::DecompressTexture(), and flutter::ImageDecoderSkia::ImageFromCompressedData().

◆ height()

int flutter::ImageDescriptor::height ( ) const

inline

The height of this image. EXIF oriented if applicable.

Definition at line 69 of file image_descriptor.h.

69{ return image_info_.height(); }

Referenced by should_resize().

◆ image()

sk_sp< SkImage > flutter::ImageDescriptor::image ( ) const

Definition at line 124 of file image_descriptor.cc.

                                            {
  return generator_->GetImage();
}

Referenced by flutter::ImageDecoderSkia::ImageFromCompressedData().

◆ image_info()

const SkImageInfo & flutter::ImageDescriptor::image_info ( ) const

inline

The orientation corrected image info for this image.

Definition at line 97 of file image_descriptor.h.

97{ return image_info_; }

Referenced by flutter::ImageDecoderImpeller::DecompressTexture(), flutter::ImageDecoderSkia::ImageFromCompressedData(), and flutter::ImageFromDecompressedData().

◆ initEncoded()

Dart_Handle flutter::ImageDescriptor::initEncoded	(	Dart_Handle	descriptor_handle,
		ImmutableBuffer *	immutable_buffer,
		Dart_Handle	callback_handle
	)

static

Asynchronously initializes an ImageDescriptor for an encoded image, as long as the format is recognized by an encoder installed in the ImageGeneratorRegistry. Calling this method will create an ImageGenerator and read EXIF corrected dimensions from the image data.

See also: ImageGeneratorRegistry

Definition at line 40 of file image_descriptor.cc.

                                                                      {
  if (!Dart_IsClosure(callback_handle)) {
    return tonic::ToDart("Callback must be a function");
  }
 
  if (!immutable_buffer) {
    return tonic::ToDart("Buffer parameter must not be null");
  }
 
  // This has to be valid because this method is called from Dart.
  auto dart_state = UIDartState::Current();
  auto registry = dart_state->GetImageGeneratorRegistry();
 
  if (!registry) {
    return tonic::ToDart(
        "Failed to access the internal image decoder "
        "registry on this isolate. Please file a bug on "
        "https://github.com/flutter/flutter/issues.");
  }
 
  auto generator =
      registry->CreateCompatibleGenerator(immutable_buffer->data());
 
  if (!generator) {
    // No compatible image decoder was found.
    return tonic::ToDart("Invalid image data");
  }
 
  auto descriptor = fml::MakeRefCounted<ImageDescriptor>(
      immutable_buffer->data(), std::move(generator));
 
  FML_DCHECK(descriptor);
 
  descriptor->AssociateWithDartWrapper(descriptor_handle);
  tonic::DartInvoke(callback_handle, {Dart_TypeVoid()});
 
  return Dart_Null();
}

References tonic::DartInvoke(), flutter::ImmutableBuffer::data(), FML_DCHECK, and tonic::ToDart().

◆ initRaw()

void flutter::ImageDescriptor::initRaw	(	Dart_Handle	descriptor_handle,
		const fml::RefPtr< ImmutableBuffer > &	data,
		int	width,
		int	height,
		int	row_bytes,
		PixelFormat	pixel_format
	)

static

Synchronously initializes an ImageDescriptor for decompressed image data as specified by the PixelFormat.

Definition at line 81 of file image_descriptor.cc.

                                                        {
  SkColorType color_type = kUnknown_SkColorType;
  SkAlphaType alpha_type = kPremul_SkAlphaType;
  switch (pixel_format) {
    case PixelFormat::kRGBA8888:
      color_type = kRGBA_8888_SkColorType;
      break;
    case PixelFormat::kBGRA8888:
      color_type = kBGRA_8888_SkColorType;
      break;
    case PixelFormat::kRGBAFloat32:
      // `PixelFormat.rgbaFloat32` is documented to not use premultiplied alpha.
      color_type = kRGBA_F32_SkColorType;
      alpha_type = kUnpremul_SkAlphaType;
      break;
  }
  FML_DCHECK(color_type != kUnknown_SkColorType);
  auto image_info = SkImageInfo::Make(width, height, color_type, alpha_type);
  auto descriptor = fml::MakeRefCounted<ImageDescriptor>(
      data->data(), std::move(image_info),
      row_bytes == -1 ? std::nullopt : std::optional<size_t>(row_bytes));
  descriptor->AssociateWithDartWrapper(descriptor_handle);
}

References alpha_type, color_type, data, FML_DCHECK, height, and width.

◆ instantiateCodec()

void flutter::ImageDescriptor::instantiateCodec	(	Dart_Handle	codec,
		int	target_width,
		int	target_height
	)

Associates a flutter::Codec object with the dart.ui Codec handle.

Definition at line 110 of file image_descriptor.cc.

                                                          {
  fml::RefPtr<Codec> ui_codec;
  if (!generator_ || generator_->GetFrameCount() == 1) {
    ui_codec = fml::MakeRefCounted<SingleFrameCodec>(
        static_cast<fml::RefPtr<ImageDescriptor>>(this), target_width,
        target_height);
  } else {
    ui_codec = fml::MakeRefCounted<MultiFrameCodec>(generator_);
  }
  ui_codec->AssociateWithDartWrapper(codec_handle);
}

◆ is_compressed()

bool flutter::ImageDescriptor::is_compressed ( ) const

inline

Whether this descriptor represents compressed (encoded) data or not.

Definition at line 94 of file image_descriptor.h.

94{ return !!generator_; }

Referenced by flutter::ImageDecoderImpeller::DecompressTexture().

◆ row_bytes()

int flutter::ImageDescriptor::row_bytes ( ) const

inline

The byte length of the first row of the image. Defaults to width() * 4.

Definition at line 76 of file image_descriptor.h.

                        {
    return row_bytes_.value_or(
        static_cast<size_t>(image_info_.width() * image_info_.bytesPerPixel()));
  }

Referenced by flutter::ImageDecoderImpeller::DecompressTexture(), and flutter::ImageFromDecompressedData().

◆ should_resize()

bool flutter::ImageDescriptor::should_resize	(	int	target_width,
		int	target_height
	)		const

inline

Whether the given target_width or target_height differ from width() and height() respectively.

Definition at line 83 of file image_descriptor.h.

                                                                {
    return target_width != width() || target_height != height();
  }

References height(), and width().

Referenced by flutter::ImageDecoderSkia::ImageFromCompressedData().

◆ width()

int flutter::ImageDescriptor::width ( ) const

inline

The width of this image, EXIF oriented if applicable.

Definition at line 66 of file image_descriptor.h.

66{ return image_info_.width(); }

Referenced by should_resize().

Friends And Related Symbol Documentation

◆ ImageDecoderFixtureTest

friend class ImageDecoderFixtureTest

friend

Definition at line 137 of file image_descriptor.h.

The documentation for this class was generated from the following files:

lib/ui/painting/image_descriptor.h
lib/ui/painting/image_descriptor.cc

Public Types

Public Member Functions

Static Public Member Functions

Friends

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ PixelFormat

Constructor & Destructor Documentation

◆ ~ImageDescriptor()

Member Function Documentation

◆ bytesPerPixel()

◆ data()

◆ dispose()

◆ get_pixels()

◆ get_scaled_dimensions()

◆ height()

◆ image()

◆ image_info()

◆ initEncoded()

◆ initRaw()

◆ instantiateCodec()

◆ is_compressed()

◆ row_bytes()

◆ should_resize()

◆ width()

Friends And Related Symbol Documentation

◆ ImageDecoderFixtureTest