Abstract 2D rendering surface. More...

#include </d/a/AeonGUI/AeonGUI/include/aeongui/Canvas.hpp>

Inheritance diagram for AeonGUI::Canvas:

Collaboration diagram for AeonGUI::Canvas:

Classes
struct	PickBounds
	Device-space bounding box for a pick-tracked element. More...

Public Member Functions
virtual void	ResizeViewport (uint32_t aWidth, uint32_t aHeight)=0
	Resize the rendering viewport.
virtual const uint8_t *	GetPixels () const =0
	Get a pointer to the raw pixel data.
virtual size_t	GetWidth () const =0
	Get the width of the canvas in pixels.
virtual size_t	GetHeight () const =0
	Get the height of the canvas in pixels.
virtual size_t	GetStride () const =0
	Get the stride (bytes per row) of the pixel buffer.
virtual void	Clear ()=0
	Clear the canvas to transparent.
virtual void	SetFillColor (const ColorAttr &aColor)=0
	Set the fill color.
virtual const ColorAttr &	GetFillColor () const =0
	Get the current fill color.
virtual void	SetStrokeColor (const ColorAttr &aColor)=0
	Set the stroke color.
virtual const ColorAttr &	GetStrokeColor () const =0
	Get the current stroke color.
virtual void	SetStrokeWidth (double aWidth)=0
	Set the stroke width.
virtual double	GetStrokeWidth () const =0
	Get the current stroke width.
virtual void	SetStrokeOpacity (double aWidth)=0
	Set the stroke opacity.
virtual double	GetStrokeOpacity () const =0
	Get the current stroke opacity.
virtual void	SetFillOpacity (double aWidth)=0
	Set the fill opacity.
virtual double	GetFillOpacity () const =0
	Get the current fill opacity.
virtual void	SetOpacity (double aWidth)=0
	Set the global opacity.
virtual double	GetOpacity () const =0
	Get the current global opacity.
virtual void	Draw (const Path &aPath)=0
	Draw a path using the current fill and stroke settings.
virtual void	DrawImage (const uint8_t *aPixels, size_t aImageWidth, size_t aImageHeight, size_t aImageStride, double aX, double aY, double aWidth, double aHeight, double aOpacity)=0
	Draw a raster image.
virtual void	DrawText (const std::string &aText, double aX, double aY, const std::string &aFontFamily, double aFontSize, int aFontWeight, int aFontStyle)=0
virtual double	MeasureText (const std::string &aText, const std::string &aFontFamily, double aFontSize, int aFontWeight, int aFontStyle) const =0
virtual void	DrawTextOnPath (const std::string &aText, const Path &aPath, double aStartOffset, const std::string &aFontFamily, double aFontSize, int aFontWeight, int aFontStyle, bool aReverse=false, bool aClosed=false)=0
virtual void	SetViewBox (const ViewBox &aViewBox, const PreserveAspectRatio &aPreserveAspectRatio)=0
	Set the SVG viewBox and preserveAspectRatio.
virtual void	SetTransform (const Matrix2x3 &aMatrix)=0
	Replace the current transformation matrix.
virtual void	Transform (const Matrix2x3 &aMatrix)=0
	Pre-multiply the current transformation matrix.
virtual void	Save ()=0
	Save the current graphics state (transform, clipping, etc.).
virtual void	Restore ()=0
	Restore the previously saved graphics state.
virtual void *	GetNativeSurface () const =0
	Get the native rendering surface handle.
virtual void	PushGroup ()=0
	Begin an offscreen group for filter/compositing.
virtual void	PopGroup ()=0
	End an offscreen group and composite back.
virtual void	ApplyDropShadow (double aDx, double aDy, double aStdDeviationX, double aStdDeviationY, const Color &aFloodColor, double aFloodOpacity)=0
	Apply a drop-shadow filter to the current group content.
void	SetHitTesting (bool aHitTesting)
	Enable or disable hit-testing mode.
bool	IsHitTesting () const
	Query whether the canvas is in hit-testing mode.
void	SetPickId (uint8_t aPickId)
	Set the current pick ID for subsequent Draw calls.
virtual uint8_t	PickAtPoint (double aX, double aY) const =0
	Read the pick ID at the given viewport coordinates.
virtual void	ResetPick ()=0
	Clear the pick buffer and reset for a new frame.
virtual void	SetClipRect (double aX, double aY, double aWidth, double aHeight)=0
	Set a device-space clip rectangle on both render and pick surfaces.
virtual std::unique_ptr< Path >	CreatePath () const =0
	Create a new Path object suitable for this canvas backend.
virtual	~Canvas ()=0
	Virtual destructor.
const PickBounds &	GetPickBounds (uint8_t aId) const
	Get the cached device-space bounds for a pick ID.

Protected Attributes
bool	mHitTesting {false}
	True when in hit-testing mode.
uint8_t	mPickId {0}
	Current pick ID for Draw calls.
std::array< PickBounds, 256 >	mPickBounds {}
	Cached device-space bounds per pick ID.

Detailed Description

Abstract 2D rendering surface.

Provides a pure virtual interface for drawing paths, images, and text onto a pixel buffer. Concrete implementations (e.g. CairoCanvas) supply the actual rendering back-end.

Member Function Documentation

◆ ApplyDropShadow()

virtual void AeonGUI::Canvas::ApplyDropShadow	(	double	aDx,
		double	aDy,
		double	aStdDeviationX,
		double	aStdDeviationY,
		const Color &	aFloodColor,
		double	aFloodOpacity )

pure virtual

Apply a drop-shadow filter to the current group content.

Must be called between PushGroup() and PopGroup(). The implementation captures the group, creates a blurred shadow, offsets it, and composites it under the original content.

Parameters

aDx	Horizontal offset of the shadow.
aDy	Vertical offset of the shadow.
aStdDeviationX	Horizontal Gaussian blur standard deviation.
aStdDeviationY	Vertical Gaussian blur standard deviation.
aFloodColor	Shadow color.
aFloodOpacity	Shadow opacity [0.0, 1.0].

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ Clear()

virtual void AeonGUI::Canvas::Clear ( )

pure virtual

Clear the canvas to transparent.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ CreatePath()

virtual std::unique_ptr< Path > AeonGUI::Canvas::CreatePath ( ) const

pure virtual

Create a new Path object suitable for this canvas backend.

Returns: A new empty Path instance.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ Draw()

virtual void AeonGUI::Canvas::Draw ( const Path & aPath )

pure virtual

Draw a path using the current fill and stroke settings.

Parameters

aPath The path to draw.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ DrawImage()

virtual void AeonGUI::Canvas::DrawImage	(	const uint8_t *	aPixels,
		size_t	aImageWidth,
		size_t	aImageHeight,
		size_t	aImageStride,
		double	aX,
		double	aY,
		double	aWidth,
		double	aHeight,
		double	aOpacity )

pure virtual

Draw a raster image.

Parameters

aPixels	Pointer to source BGRA pixel data.
aImageWidth	Width of the source image in pixels.
aImageHeight	Height of the source image in pixels.
aImageStride	Stride of the source image in bytes.
aX	Destination X coordinate.
aY	Destination Y coordinate.
aWidth	Destination width in user units.
aHeight	Destination height in user units.
aOpacity	Opacity for the image [0.0, 1.0].

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ DrawText()

virtual void AeonGUI::Canvas::DrawText	(	const std::string &	aText,
		double	aX,
		double	aY,
		const std::string &	aFontFamily,
		double	aFontSize,
		int	aFontWeight,
		int	aFontStyle )

pure virtual

Draw text at the given position using the specified font description and size.

Parameters

aText	The UTF-8 text string to render.
aX	The x coordinate for the text start position.
aY	The y coordinate for the text baseline.
aFontFamily	Font family name (e.g. "sans-serif").
aFontSize	Font size in CSS pixels.
aFontWeight	CSS font weight (400 = normal, 700 = bold).
aFontStyle	0 = normal, 1 = italic, 2 = oblique.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ DrawTextOnPath()

virtual void AeonGUI::Canvas::DrawTextOnPath	(	const std::string &	aText,
		const Path &	aPath,
		double	aStartOffset,
		const std::string &	aFontFamily,
		double	aFontSize,
		int	aFontWeight,
		int	aFontStyle,
		bool	aReverse = false,
		bool	aClosed = false )

pure virtual

Draw text along a path. Each glyph is positioned and rotated to follow the path.

Parameters

aText	The UTF-8 text string to render.
aPath	The path to follow.
aStartOffset	Starting distance along the path in user units.
aFontFamily	Font family name.
aFontSize	Font size in CSS pixels.
aFontWeight	CSS font weight (400 = normal, 700 = bold).
aFontStyle	0 = normal, 1 = italic, 2 = oblique.
aReverse	If true, render glyph order against the path direction.
aClosed	If true, treat the path as closed for offset wrapping.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ GetFillColor()

virtual const ColorAttr & AeonGUI::Canvas::GetFillColor ( ) const

pure virtual

Get the current fill color.

Returns: Reference to the current fill color.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ GetFillOpacity()

virtual double AeonGUI::Canvas::GetFillOpacity ( ) const

pure virtual

Get the current fill opacity.

Returns: Opacity in [0.0, 1.0].

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ GetHeight()

virtual size_t AeonGUI::Canvas::GetHeight ( ) const

pure virtual

Get the height of the canvas in pixels.

Returns: Height in pixels.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ GetNativeSurface()

virtual void * AeonGUI::Canvas::GetNativeSurface ( ) const

pure virtual

Get the native rendering surface handle.

Returns: Pointer to the underlying surface (e.g. cairo_surface_t).

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ GetOpacity()

virtual double AeonGUI::Canvas::GetOpacity ( ) const

pure virtual

Get the current global opacity.

Returns: Opacity in [0.0, 1.0].

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ GetPickBounds()

const PickBounds & AeonGUI::Canvas::GetPickBounds ( uint8_t aId ) const

inline

Get the cached device-space bounds for a pick ID.

Parameters

aId	Pick ID (1-255).

Returns: Reference to the cached bounds.

◆ GetPixels()

virtual const uint8_t * AeonGUI::Canvas::GetPixels ( ) const

pure virtual

Get a pointer to the raw pixel data.

Returns: Pointer to BGRA pixel data, or nullptr if empty.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ GetStride()

virtual size_t AeonGUI::Canvas::GetStride ( ) const

pure virtual

Get the stride (bytes per row) of the pixel buffer.

Returns: Stride in bytes.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ GetStrokeColor()

virtual const ColorAttr & AeonGUI::Canvas::GetStrokeColor ( ) const

pure virtual

Get the current stroke color.

Returns: Reference to the current stroke color.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ GetStrokeOpacity()

virtual double AeonGUI::Canvas::GetStrokeOpacity ( ) const

pure virtual

Get the current stroke opacity.

Returns: Opacity in [0.0, 1.0].

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ GetStrokeWidth()

virtual double AeonGUI::Canvas::GetStrokeWidth ( ) const

pure virtual

Get the current stroke width.

Returns: Stroke width in user units.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ GetWidth()

virtual size_t AeonGUI::Canvas::GetWidth ( ) const

pure virtual

Get the width of the canvas in pixels.

Returns: Width in pixels.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ IsHitTesting()

bool AeonGUI::Canvas::IsHitTesting ( ) const

inline

Query whether the canvas is in hit-testing mode.

Returns: True if hit-testing is active.

◆ MeasureText()

virtual double AeonGUI::Canvas::MeasureText	(	const std::string &	aText,
		const std::string &	aFontFamily,
		double	aFontSize,
		int	aFontWeight,
		int	aFontStyle ) const

pure virtual

Measure the width of text with the given font parameters.

Parameters

aText	The UTF-8 text string to measure.
aFontFamily	Font family name.
aFontSize	Font size in CSS pixels.
aFontWeight	CSS font weight.
aFontStyle	Font style (0=normal, 1=italic, 2=oblique).

Returns: The logical width in CSS pixels.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ PickAtPoint()

virtual uint8_t AeonGUI::Canvas::PickAtPoint	(	double	aX,
		double	aY ) const

pure virtual

Read the pick ID at the given viewport coordinates.

Parameters

aX	X coordinate in viewport pixels.
aY	Y coordinate in viewport pixels.

Returns: Pick ID at that pixel, or 0 if empty / out of bounds.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ PopGroup()

virtual void AeonGUI::Canvas::PopGroup ( )

pure virtual

End an offscreen group and composite back.

Pops the group pushed by PushGroup() and paints it back to the underlying surface.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ PushGroup()

virtual void AeonGUI::Canvas::PushGroup ( )

pure virtual

Begin an offscreen group for filter/compositing.

All subsequent drawing is redirected to a temporary surface. Call PopGroup() to retrieve and composite the result.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ ResetPick()

virtual void AeonGUI::Canvas::ResetPick ( )

pure virtual

Clear the pick buffer and reset for a new frame.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ ResizeViewport()

virtual void AeonGUI::Canvas::ResizeViewport	(	uint32_t	aWidth,
		uint32_t	aHeight )

pure virtual

Resize the rendering viewport.

Parameters

aWidth	New width in pixels.
aHeight	New height in pixels.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ Restore()

virtual void AeonGUI::Canvas::Restore ( )

pure virtual

Restore the previously saved graphics state.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ Save()

virtual void AeonGUI::Canvas::Save ( )

pure virtual

Save the current graphics state (transform, clipping, etc.).

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ SetClipRect()

virtual void AeonGUI::Canvas::SetClipRect	(	double	aX,
		double	aY,
		double	aWidth,
		double	aHeight )

pure virtual

Set a device-space clip rectangle on both render and pick surfaces.

Must be called between Save() and Restore().

Parameters

aX	X of clip rect (device pixels).
aY	Y of clip rect (device pixels).
aWidth	Width (device pixels).
aHeight	Height (device pixels).

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ SetFillColor()

virtual void AeonGUI::Canvas::SetFillColor ( const ColorAttr & aColor )

pure virtual

Set the fill color.

Parameters

aColor The fill color to set.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ SetFillOpacity()

virtual void AeonGUI::Canvas::SetFillOpacity ( double aWidth )

pure virtual

Set the fill opacity.

Parameters

aWidth Opacity value in the range [0.0, 1.0].

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ SetHitTesting()

void AeonGUI::Canvas::SetHitTesting ( bool aHitTesting )

inline

Enable or disable hit-testing mode.

When true, filter effects (PushGroup/PopGroup/ApplyDropShadow) are skipped to avoid expensive pixel processing during elementFromPoint traversals.

Parameters

aHitTesting True to enable hit-testing mode, false to disable.

◆ SetOpacity()

virtual void AeonGUI::Canvas::SetOpacity ( double aWidth )

pure virtual

Set the global opacity.

Parameters

aWidth Opacity value in the range [0.0, 1.0].

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ SetPickId()

void AeonGUI::Canvas::SetPickId ( uint8_t aPickId )

inline

Set the current pick ID for subsequent Draw calls.

When non-zero, Draw(path) also fills the path on the internal pick buffer using this value. Set to 0 to disable pick rendering for non-geometry nodes.

Parameters

aPickId The pick ID to assign (0 disables pick rendering).

◆ SetStrokeColor()

virtual void AeonGUI::Canvas::SetStrokeColor ( const ColorAttr & aColor )

pure virtual

Set the stroke color.

Parameters

aColor The stroke color to set.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ SetStrokeOpacity()

virtual void AeonGUI::Canvas::SetStrokeOpacity ( double aWidth )

pure virtual

Set the stroke opacity.

Parameters

aWidth Opacity value in the range [0.0, 1.0].

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ SetStrokeWidth()

virtual void AeonGUI::Canvas::SetStrokeWidth ( double aWidth )

pure virtual

Set the stroke width.

Parameters

aWidth The stroke width in user units.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ SetTransform()

virtual void AeonGUI::Canvas::SetTransform ( const Matrix2x3 & aMatrix )

pure virtual

Replace the current transformation matrix.

Parameters

aMatrix The new 2x3 transformation matrix.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ SetViewBox()

virtual void AeonGUI::Canvas::SetViewBox	(	const ViewBox &	aViewBox,
		const PreserveAspectRatio &	aPreserveAspectRatio )

pure virtual

Set the SVG viewBox and preserveAspectRatio.

Parameters

aViewBox	The viewBox rectangle.
aPreserveAspectRatio	How to align and scale.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

◆ Transform()

virtual void AeonGUI::Canvas::Transform ( const Matrix2x3 & aMatrix )

pure virtual

Pre-multiply the current transformation matrix.

Parameters

aMatrix The matrix to concatenate.

Implemented in AeonGUI::CairoCanvas, and AeonGUI::SkiaCanvas.

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

/d/a/AeonGUI/AeonGUI/include/aeongui/Canvas.hpp
/d/a/AeonGUI/AeonGUI/core/Canvas.cpp

Classes

Public Member Functions

Protected Attributes

Detailed Description

Member Function Documentation

◆ ApplyDropShadow()

◆ Clear()

◆ CreatePath()

◆ Draw()

◆ DrawImage()

◆ DrawText()

◆ DrawTextOnPath()

◆ GetFillColor()

◆ GetFillOpacity()

◆ GetHeight()

◆ GetNativeSurface()

◆ GetOpacity()

◆ GetPickBounds()

◆ GetPixels()

◆ GetStride()

◆ GetStrokeColor()

◆ GetStrokeOpacity()

◆ GetStrokeWidth()

◆ GetWidth()

◆ IsHitTesting()

◆ MeasureText()

◆ PickAtPoint()

◆ PopGroup()

◆ PushGroup()

◆ ResetPick()

◆ ResizeViewport()

◆ Restore()

◆ Save()

◆ SetClipRect()

◆ SetFillColor()

◆ SetFillOpacity()

◆ SetHitTesting()

◆ SetOpacity()

◆ SetPickId()

◆ SetStrokeColor()

◆ SetStrokeOpacity()

◆ SetStrokeWidth()

◆ SetTransform()

◆ SetViewBox()

◆ Transform()