Canvas
Table of contents
Drawing interface of CanvasView
Interface description
ClearRect(x, y, width, height float64)
Erases the pixels in a rectangular area by setting them to transparent black
ClipPath(path Path)
Turns the path into the current clipping region. It replaces any previous clipping region
ClipRect(x, y, width, height float64)
Turns the rectangle into the current clipping region. It replaces any previous clipping region
DrawImage(x, y float64, image Image)
Draws the image at the (x, y) position
DrawImageFragment(srcX, srcY, srcWidth, srcHeight, dstX, dstY, dstWidth, dstHeight float64, image Image)
Draws the fragment (described by srcX, srcY, srcWidth, srcHeight) of image in the rectangle (dstX, dstY, dstWidth, dstHeight), scaling in height and width if necessary
DrawImageInRect(x, y, width, height float64, image Image)
Draws the image in the rectangle (x, y, width, height), scaling in height and width if necessary
DrawLine(x0, y0, x1, y1 float64)
Draws a line according to the current strokeStyle and other context settings
FillAndStrokeEllipse(x, y, radiusX, radiusY, rotation float64)
Draws a ellipse that is filled according to the current FillStyle and is stroked (outlined) according to the current strokeStyle and other context settings
FillAndStrokePath(path Path)
Draws a path that is filled according to the current FillStyle and is stroked (outlined) according to the current strokeStyle and other context settings
FillAndStrokeRect(x, y, width, height float64)
Draws a rectangle that is filled according to the current FillStyle and is stroked (outlined) according to the current strokeStyle and other context settings
FillAndStrokeRoundedRect(x, y, width, height, r float64)
Draws a rounded rectangle that is filled according to the current FillStyle and is stroked (outlined) according to the current strokeStyle and other context settings
FillEllipse(x, y, radiusX, radiusY, rotation float64)
Draws a ellipse that is filled according to the current FillStyle. x, y - coordinates of the ellipse's center; radiusX - the ellipse's major-axis radius. Must be non-negative; radiusY - the ellipse's minor-axis radius. Must be non-negative; rotation - the rotation of the ellipse, expressed in radians.
FillPath(path Path)
Draws a path that is filled according to the current FillStyle.
FillRect(x, y, width, height float64)
Draws a rectangle that is filled according to the current FillStyle.
FillRoundedRect(x, y, width, height, r float64)
Draws a rounded rectangle that is filled according to the current FillStyle.
FillText(x, y float64, text string)
Draws a text string at the specified coordinates, filling the string's characters with the current FillStyle
Height() float64
Returns the height in pixels of the canvas area
NewPath() Path
Creates a new Path object
NewPathFromSvg(data string) Path
Creates a new Path and initialize it by a string consisting of SVG path data
ResetShadow()
Sets shadow parameters to default values (invisible shadow)
ResetTransformation()
Resets the current transform to the identity matrix
Restore()
Restores the most recently saved canvas state by popping the top entry in the drawing state stack. If there is no saved state, this method does nothing
Save()
Saves the entire state of the canvas by pushing the current state onto a stack
SetFont(name string, size SizeUnit)
Sets the current text style to use when drawing text
SetFontWithParams(name string, size SizeUnit, params FontParams)
Sets the current text style to use when drawing text
SetImageFillStyle(image Image, repeat int)
Set the image as the filling pattern. repeat - indicating how to repeat the pattern's image. Possible values are: NoRepeat (0) - neither direction, RepeatXY (1) - both directions, RepeatX (2) - horizontal only, RepeatY (3) - vertical only
SetLineCap(cap int)
Sets the shape used to draw the end points of lines. Possible values are: ButtCap (0), RoundCap (1), SquareCap (2). All other values are ignored
SetLineDash(dash []float64, offset float64)
Sets the line dash pattern used when stroking lines. dash - an array of values that specify alternating lengths of lines and gaps which describe the pattern. offset - the line dash offset
SetLineJoin(join int)
Sets the shape used to join two line segments where they meet. Possible values are: MiterJoin (0), RoundJoin (1), BevelJoin (2). All other values are ignored
SetLineWidth(width float64)
Sets the line width, in coordinate space units. Zero, negative, Infinity, and NaN values are ignored.
SetLinearGradientFillStyle(x0, y0 float64, color0 Color, x1, y1 float64, color1 Color, stopPoints []GradientPoint)
Sets a gradient along the line connecting two given coordinates to use inside shapes x0, y0 - coordinates of the start point; x1, y1 - coordinates of the end point; startColor, endColor - the start and end color stopPoints - the array of stop points
SetLinearGradientStrokeStyle(x0, y0 float64, color0 Color, x1, y1 float64, color1 Color, stopPoints []GradientPoint)
Sets a gradient along the line connecting two given coordinates to use for the strokes (outlines) around shapes x0, y0 - coordinates of the start point; x1, y1 - coordinates of the end point; color0, color1 - the start and end color stopPoints - the array of stop points
SetRadialGradientFillStyle(x0, y0, r0 float64, color0 Color, x1, y1, r1 float64, color1 Color, stopPoints []GradientPoint)
Sets a radial gradient using the size and coordinates of two circles to use inside shapes x0, y0 - coordinates of the center of the start circle; r0 - the radius of the start circle; x1, y1 - coordinates the center of the end circle; r1 - the radius of the end circle; color0, color1 - the start and end color stopPoints - the array of stop points
SetRadialGradientStrokeStyle(x0, y0, r0 float64, color0 Color, x1, y1, r1 float64, color1 Color, stopPoints []GradientPoint)
Sets a radial gradient using the size and coordinates of two circles to use for the strokes (outlines) around shapes x0, y0 - coordinates of the center of the start circle; r0 - the radius of the start circle; x1, y1 - coordinates the center of the end circle; r1 - the radius of the end circle; color0, color1 - the start and end color stopPoints - the array of stop points
SetRotation(angle float64)
Adds a rotation to the transformation matrix. angle - the rotation angle, clockwise in radians
SetScale(x, y float64)
Adds a scaling transformation to the canvas units horizontally and/or vertically. x - scaling factor in the horizontal direction. A negative value flips pixels across the vertical axis. A value of 1 results in no horizontal scaling; y - scaling factor in the vertical direction. A negative value flips pixels across the horizontal axis. A value of 1 results in no vertical scaling
SetShadow(offsetX, offsetY, blur float64, color Color)
Sets shadow parameters: offsetX, offsetY - the distance that shadows will be offset horizontally and vertically; blur - the amount of blur applied to shadows. Must be non-negative; color - the color of shadows
SetSolidColorFillStyle(color Color)
Sets the color to use inside shapes
SetSolidColorStrokeStyle(color Color)
Sets color to use for the strokes (outlines) around shapes
SetTextAlign(align int)
Sets the current text alignment used when drawing text. Possible values are: LeftAlign (0), RightAlign (1), CenterAlign (2), StartAlign (3) and EndAlign (4). All other values are ignored
SetTextBaseline(baseline int)
Sets the current text baseline used when drawing text. Possible values are: AlphabeticBaseline (0), TopBaseline (1), MiddleBaseline (2), BottomBaseline (3), HangingBaseline (4) and IdeographicBaseline (5). All other values are ignored
SetTransformation(xScale, yScale, xSkew, ySkew, dx, dy float64)
Multiplies the current transformation with the matrix described by the arguments of this method. This allow to scale, rotate, translate (move), and skew the context. The transformation matrix is described by: ⎡ xScale xSkew dx ⎤ ⎢ ySkew yScale dy ⎥ ⎣ 0 0 1 ⎦ xScale, yScale - horizontal and vertical scaling. A value of 1 results in no scaling; xSkew, ySkew - horizontal and vertical skewing; dx, dy - horizontal and vertical translation (moving)
SetTranslation(x, y float64)
Adds a translation transformation to the current matrix. x - distance to move in the horizontal direction. Positive values are to the right, and negative to the left; y - distance to move in the vertical direction. Positive values are down, and negative are up.
StrokeEllipse(x, y, radiusX, radiusY, rotation float64)
Draws a ellipse that is stroked (outlined) according to the current strokeStyle and other context settings
StrokePath(path Path)
Draws a path that is stroked (outlined) according to the current strokeStyle and other context settings
StrokeRect(x, y, width, height float64)
Draws a rectangle that is stroked (outlined) according to the current strokeStyle and other context settings
StrokeRoundedRect(x, y, width, height, r float64)
Draws a rounded rectangle that is stroked (outlined) according to the current strokeStyle and other context settings
StrokeText(x, y float64, text string)
Draws the outlines of the characters of a string at the specified coordinates
TextMetrics(text string, fontName string, fontSize SizeUnit, fontParams FontParams) TextMetrics
Calculates metrics of the text drawn by a given font
View() CanvasView
Return the view for the drawing
Width() float64
Returns the width in pixels of the canvas area