BitmapCanvas class

A painting canvas that includes standard Canvas vector operations, as well as bitmap operations.

Clients must adhere to the lifecycle contract of this object.

Start a new image: To begin painting a new image, call startRecording(), which prepares a new image for painting.

Paint desired content: Vector commands run on the GPU. Pixel painting commands run on the CPU. As a result, these commands must be issued in phases.

When you want to start painting pixels, call startBitmapTransaction.

When you want to shift from pixel painting to vector commands, call endBitmapTransaction.

Produce the final image: To produce an image that you can access, call finishRecording(). The resulting image is available in publishedImage.

You can display the publishedImage in a widget, save it to a file, or send it over the network.

Implemented types

Constructors

BitmapCanvas.new({required Size size})

Properties

canvas → Canvas
Collects traditional Flutter vector operations, which are painted by Flutter's rendering system.
no setter
hashCode → int
The hash code for this object.
no setterinherited
isDrawing → bool
Whether this canvas is in the process of painting a frame.
no setter
pixels → ByteData?
Pixel buffer that holds all pixel values during a bitmap transaction.
no setter
publishedImage → Image?
The latest image to be produced by this BitmapPaintingContext.
no setter
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
size → Size
The size of the painting region.
final

Methods

clipPath(Path path, {bool doAntiAlias = true}) → void
Reduces the clip region to the intersection of the current clip and the given Path.
override
clipRect(Rect rect, {ClipOp clipOp = ClipOp.intersect, bool doAntiAlias = true}) → void
Reduces the clip region to the intersection of the current clip and the given rectangle.
override
clipRRect(RRect rrect, {bool doAntiAlias = true}) → void
Reduces the clip region to the intersection of the current clip and the given rounded rectangle.
override
clipRSuperellipse(RSuperellipse rsuperellipse, {bool doAntiAlias = true}) → void
Reduces the clip region to the intersection of the current clip and the given rounded superellipse.
inherited
drawArc(Rect rect, double startAngle, double sweepAngle, bool useCenter, Paint paint) → void
Draw an arc scaled to fit inside the given rectangle.
override
drawAtlas(Image atlas, List<RSTransform> transforms, List<Rect> rects, List<Color>? colors, BlendMode? blendMode, Rect? cullRect, Paint paint) → void
Draws many parts of an image - the atlas - onto the canvas.
override
drawCircle(Offset center, double radius, Paint paint) → void
Draws a circle centered at the point given by the first argument and that has the radius given by the second argument, with the Paint given in the third argument. Whether the circle is filled or stroked (or both) is controlled by Paint.style.
override
drawColor(Color color, BlendMode blendMode) → void
Paints the given Color onto the canvas, applying the given BlendMode, with the given color being the source and the background being the destination.
override
drawDRRect(RRect outer, RRect inner, Paint paint) → void
Draws a shape consisting of the difference between two rounded rectangles with the given Paint. Whether this shape is filled or stroked (or both) is controlled by Paint.style.
override
drawImage(Image image, Offset offset, Paint paint) → void
Draws the given Image into the canvas with its top-left corner at the given Offset. The image is composited into the canvas using the given Paint.
override
drawImageNine(Image image, Rect center, Rect dst, Paint paint) → void
Draws the given Image into the canvas using the given Paint.
override
drawImageRect(Image image, Rect src, Rect dst, Paint paint) → void
Draws the subset of the given image described by the src argument into the canvas in the axis-aligned rectangle given by the dst argument.
override
drawLine(Offset p1, Offset p2, Paint paint) → void
Draws a line between the given points using the given paint. The line is stroked, the value of the Paint.style is ignored for this call.
override
drawOval(Rect rect, Paint paint) → void
Draws an axis-aligned oval that fills the given axis-aligned rectangle with the given Paint. Whether the oval is filled or stroked (or both) is controlled by Paint.style.
override
drawPaint(Paint paint) → void
Fills the canvas with the given Paint.
override
drawParagraph(Paragraph paragraph, Offset offset) → void
Draws the text in the given Paragraph into this canvas at the given Offset.
override
drawPath(Path path, Paint paint) → void
Draws the given Path with the given Paint.
override
drawPicture(Picture picture) → void
Draw the given picture onto the canvas. To create a picture, see PictureRecorder.
override
drawPoints(PointMode pointMode, List<Offset> points, Paint paint) → void
Draws a sequence of points according to the given PointMode.
override
drawRawAtlas(Image atlas, Float32List rstTransforms, Float32List rects, Int32List? colors, BlendMode? blendMode, Rect? cullRect, Paint paint) → void
Draws many parts of an image - the atlas - onto the canvas.
override
drawRawPoints(PointMode pointMode, Float32List points, Paint paint) → void
Draws a sequence of points according to the given PointMode.
override
drawRect(Rect rect, Paint paint) → void
Draws a rectangle with the given Paint. Whether the rectangle is filled or stroked (or both) is controlled by Paint.style.
override
drawRRect(RRect rrect, Paint paint) → void
Draws a rounded rectangle with the given Paint. Whether the rectangle is filled or stroked (or both) is controlled by Paint.style.
override
drawRSuperellipse(RSuperellipse rsuperellipse, Paint paint) → void
Draws a rounded superellipse with the given Paint. The shape is filled, and the value of the Paint.style is ignored for this call.
inherited
drawShadow(Path path, Color color, double elevation, bool transparentOccluder) → void
Draws a shadow for a Path representing the given material elevation.
override
drawVertices(Vertices vertices, BlendMode blendMode, Paint paint) → void
Draws a set of Vertices onto the canvas as one or more triangles.
override
endBitmapTransaction() → Future<void>
Paints the latest pixels onto the canvas.
finishRecording() → Future<void>
Produces a new publishedImage based on all the commands that were run since startRecording.
get(int x, int y) → Future<Color>
Returns the color of the pixel at the given (x,y).
getDestinationClipBounds() → Rect
Returns the conservative bounds of the combined result of all clip methods executed within the current save stack of this Canvas object, as measured in the destination coordinate space in which the Picture will be rendered.
inherited
getLocalClipBounds() → Rect
Returns the conservative bounds of the combined result of all clip methods executed within the current save stack of this Canvas object, as measured in the local coordinate space under which rendering operations are currently performed.
inherited
getRegion({required int x, required int y, required int width, required int height}) → Future<Image>
Returns the colors of all pixels in the given region, represented as an Image.
getSaveCount() → int
Returns the number of items on the save stack, including the initial state. This means it returns 1 for a clean canvas, and that each call to save and saveLayer increments it, and that each matching call to restore decrements it.
override
getTransform() → Float64List
Returns the current transform including the combined result of all transform methods executed since the creation of this Canvas object, and respecting the save/restore history.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
restore() → void
Pops the current save stack, if there is anything to pop. Otherwise, does nothing.
override
restoreToCount(int count) → void
Restores the save stack to a previous level as might be obtained from getSaveCount. If count is less than 1, the stack is restored to its initial state. If count is greater than the current getSaveCount then nothing happens.
inherited
rotate(double radians) → void
Add a rotation to the current transform. The argument is in radians clockwise.
override
save() → void
Saves a copy of the current transform and clip on the save stack.
override
saveLayer(Rect? bounds, Paint paint) → void
Saves a copy of the current transform and clip on the save stack, and then creates a new group which subsequent calls will become a part of. When the save stack is later popped, the group will be flattened into a layer and have the given paint's Paint.colorFilter and Paint.blendMode applied.
override
scale(double sx, [double? sy]) → void
Add an axis-aligned scale to the current transform, scaling by the first argument in the horizontal direction and the second in the vertical direction.
override
set({required int x, required int y, required Color color}) → void
Sets the pixel at the given (x,y) to the given color.
setRegion({required Image image, int x = 0, int y = 0}) → Future<void>
Sets all pixels in the given region to the colors specified by the given image.
skew(double sx, double sy) → void
Add an axis-aligned skew to the current transform, with the first argument being the horizontal skew in rise over run units clockwise around the origin, and the second argument being the vertical skew in rise over run units clockwise around the origin.
override
startBitmapTransaction() → Future<void>
Prepares the BitmapCanvas to execute a series of bitmap manipulations.
startRecording() → void
Starts a new image.
toString() → String
A string representation of this object.
inherited
transform(Float64List matrix4) → void
Multiply the current transform by the specified 4⨉4 transformation matrix specified as a list of values in column-major order.
override
translate(double dx, double dy) → void
Add a translation to the current transform, shifting the coordinate space horizontally by the first argument and vertically by the second argument.
override

Operators

operator ==(Object other) → bool
The equality operator.
inherited