uitest/canvas.go
Functions
func Clear
func (c *MockCanvas) Clear(color widget.Color) {
c.Clears = append(c.Clears, color)
}
func ClipBounds
ClipBounds returns a large default clip rectangle.
func (c *MockCanvas) ClipBounds() geometry.Rect {
return geometry.NewRect(0, 0, 10000, 10000)
}
func DrawCircle
DrawCircle records the center, radius, and color arguments.
func (c *MockCanvas) DrawCircle(center geometry.Point, radius float32, color widget.Color) {
c.Circles = append(c.Circles, DrawCircleCall{Center: center, Radius: radius, Color: color})
}
func DrawImage
DrawImage records the image and position arguments.
func (c *MockCanvas) DrawImage(img image.Image, at geometry.Point) {
c.Images = append(c.Images, DrawImageCall{Image: img, At: at})
}
func DrawLine
DrawLine records the from, to, color, and stroke width arguments.
func (c *MockCanvas) DrawLine(from, to geometry.Point, color widget.Color, strokeWidth float32) {
c.Lines = append(c.Lines, DrawLineCall{From: from, To: to, Color: color, StrokeWidth: strokeWidth})
}
func DrawRect
DrawRect records the rect and color arguments.
func (c *MockCanvas) DrawRect(r geometry.Rect, color widget.Color) {
c.Rects = append(c.Rects, DrawRectCall{Bounds: r, Color: color})
}
func DrawRoundRect
DrawRoundRect records the rect, color, and radius arguments.
func (c *MockCanvas) DrawRoundRect(r geometry.Rect, color widget.Color, radius float32) {
c.RoundRects = append(c.RoundRects, DrawRoundRectCall{Bounds: r, Color: color, Radius: radius})
}
func DrawStyledText
DrawStyledText records all styled text drawing arguments.
func (c *MockCanvas) DrawStyledText(text string, bounds geometry.Rect, style widget.TextStyle) {
c.StyledTexts = append(c.StyledTexts, DrawStyledTextCall{
Text: text, Bounds: bounds, Style: style,
})
}
func DrawText
DrawText records all text drawing arguments.
func (c *MockCanvas) DrawText(text string, bounds geometry.Rect, fontSize float32, color widget.Color, bold bool, align widget.TextAlign) {
c.Texts = append(c.Texts, DrawTextCall{
Text: text, Bounds: bounds, FontSize: fontSize, Color: color, Bold: bold, Align: align,
})
}
func FillRectDirect
FillRectDirect records as DrawRect — mock does not distinguish CPU/GPU path.
func (c *MockCanvas) FillRectDirect(r geometry.Rect, color widget.Color) {
c.Rects = append(c.Rects, DrawRectCall{Bounds: r, Color: color})
}
func MeasureStyledText
MeasureStyledText returns an approximate width for the given text.
Uses average character width (0.5 * fontSize) for test predictability.
func (c *MockCanvas) MeasureStyledText(text string, style widget.TextStyle) float32 {
return float32(len([]rune(text))) * style.FontSize * 0.5
}
func MeasureText
MeasureText returns an approximate width for the given text.
Uses average character width (0.5 * fontSize) for test predictability.
func (c *MockCanvas) MeasureText(text string, fontSize float32, _ bool) float32 {
return float32(len([]rune(text))) * fontSize * 0.5
}
func PopClip
PopClip increments the pop clip counter.
func (c *MockCanvas) PopClip() {
c.PopClipCount++
}
func PopTransform
PopTransform restores the previous transform offset.
func (c *MockCanvas) PopTransform() {
c.PopTransformCount++
if len(c.transformStack) > 0 {
lastIdx := len(c.transformStack) - 1
c.currentOffset = c.transformStack[lastIdx]
c.transformStack = c.transformStack[:lastIdx]
}
}
func PushClip
PushClip records the clip rectangle.
func (c *MockCanvas) PushClip(r geometry.Rect) {
c.Clips = append(c.Clips, r)
}
func PushClipRoundRect
PushClipRoundRect records the clip rounded rectangle and radius.
func (c *MockCanvas) PushClipRoundRect(r geometry.Rect, radius float32) {
c.ClipRoundRects = append(c.ClipRoundRects, ClipRoundRectCall{Bounds: r, Radius: radius})
}
func PushTransform
PushTransform records the translation offset and updates the cumulative offset.
func (c *MockCanvas) PushTransform(offset geometry.Point) {
c.Transforms = append(c.Transforms, offset)
c.transformStack = append(c.transformStack, c.currentOffset)
c.currentOffset = c.currentOffset.Add(offset)
}
func ReplayScene
ReplayScene is a no-op for the mock canvas.
func (c *MockCanvas) ReplayScene(_ *scene.Scene) {}
func Reset
Reset clears all recorded calls, returning the canvas to its initial state.
func (c *MockCanvas) Reset() {
c.Clears = c.Clears[:0]
c.Rects = c.Rects[:0]
c.StrokeRects = c.StrokeRects[:0]
c.RoundRects = c.RoundRects[:0]
c.StrokeRoundRects = c.StrokeRoundRects[:0]
c.Circles = c.Circles[:0]
c.StrokeCircles = c.StrokeCircles[:0]
c.StrokeArcs = c.StrokeArcs[:0]
c.StrokeArcStyleds = c.StrokeArcStyleds[:0]
c.Lines = c.Lines[:0]
c.Texts = c.Texts[:0]
c.StyledTexts = c.StyledTexts[:0]
c.Images = c.Images[:0]
c.Clips = c.Clips[:0]
c.ClipRoundRects = c.ClipRoundRects[:0]
c.Transforms = c.Transforms[:0]
c.PopClipCount = 0
c.PopTransformCount = 0
c.transformStack = c.transformStack[:0]
c.currentOffset = geometry.Point{}
}
func ScreenOriginBase
ScreenOriginBase returns the screen-space base offset (always zero for mock).
func (c *MockCanvas) ScreenOriginBase() geometry.Point { return geometry.Point{} }
func StrokeArc
StrokeArc records the center, radius, angles, color, and stroke width arguments.
func (c *MockCanvas) StrokeArc(center geometry.Point, radius float32,
startAngle, sweepAngle float64, color widget.Color, strokeWidth float32) {
c.StrokeArcs = append(c.StrokeArcs, StrokeArcCall{
Center: center, Radius: radius,
StartAngle: startAngle, SweepAngle: sweepAngle,
Color: color, StrokeWidth: strokeWidth,
})
}
func StrokeArcStyled
StrokeArcStyled records the center, radius, angles, color, stroke width, and line cap.
func (c *MockCanvas) StrokeArcStyled(center geometry.Point, radius float32,
startAngle, sweepAngle float64, color widget.Color, strokeWidth float32, lineCap widget.LineCap) {
c.StrokeArcStyleds = append(c.StrokeArcStyleds, StrokeArcStyledCall{
Center: center, Radius: radius,
StartAngle: startAngle, SweepAngle: sweepAngle,
Color: color, StrokeWidth: strokeWidth, Cap: lineCap,
})
}
func StrokeCircle
StrokeCircle records the center, radius, color, and stroke width arguments.
func (c *MockCanvas) StrokeCircle(center geometry.Point, radius float32, color widget.Color, strokeWidth float32) {
c.StrokeCircles = append(c.StrokeCircles, StrokeCircleCall{
Center: center, Radius: radius, Color: color, StrokeWidth: strokeWidth,
})
}
func StrokeRect
StrokeRect records the rect, color, and stroke width arguments.
func (c *MockCanvas) StrokeRect(r geometry.Rect, color widget.Color, strokeWidth float32) {
c.StrokeRects = append(c.StrokeRects, StrokeRectCall{Bounds: r, Color: color, StrokeWidth: strokeWidth})
}
func StrokeRoundRect
StrokeRoundRect records the rect, color, radius, and stroke width arguments.
func (c *MockCanvas) StrokeRoundRect(r geometry.Rect, color widget.Color, radius float32, strokeWidth float32) {
c.StrokeRoundRects = append(c.StrokeRoundRects, StrokeRoundRectCall{
Bounds: r, Color: color, Radius: radius, StrokeWidth: strokeWidth,
})
}
func TotalDrawCalls
TotalDrawCalls returns the total number of recorded draw operations
(excluding clip and transform operations).
func (c *MockCanvas) TotalDrawCalls() int {
return len(c.Clears) + len(c.Rects) + len(c.StrokeRects) +
len(c.RoundRects) + len(c.StrokeRoundRects) +
len(c.Circles) + len(c.StrokeCircles) + len(c.StrokeArcs) +
len(c.StrokeArcStyleds) + len(c.Lines) + len(c.Texts) + len(c.StyledTexts) + len(c.Images)
}
func TransformOffset
TransformOffset returns the current cumulative transform offset.
func (c *MockCanvas) TransformOffset() geometry.Point {
return c.currentOffset
}
Structs
type DrawRectCall struct
DrawRectCall records a single DrawRect invocation.
type DrawRectCall struct {
Bounds geometry.Rect
Color widget.Color
}
type StrokeRectCall struct
StrokeRectCall records a single StrokeRect invocation.
type StrokeRectCall struct {
Bounds geometry.Rect
Color widget.Color
StrokeWidth float32
}
type DrawRoundRectCall struct
DrawRoundRectCall records a single DrawRoundRect invocation.
type DrawRoundRectCall struct {
Bounds geometry.Rect
Color widget.Color
Radius float32
}
type StrokeRoundRectCall struct
StrokeRoundRectCall records a single StrokeRoundRect invocation.
type StrokeRoundRectCall struct {
Bounds geometry.Rect
Color widget.Color
Radius float32
StrokeWidth float32
}
type DrawCircleCall struct
DrawCircleCall records a single DrawCircle invocation.
type DrawCircleCall struct {
Center geometry.Point
Radius float32
Color widget.Color
}
type StrokeCircleCall struct
StrokeCircleCall records a single StrokeCircle invocation.
type StrokeCircleCall struct {
Center geometry.Point
Radius float32
Color widget.Color
StrokeWidth float32
}
type StrokeArcCall struct
StrokeArcCall records a single StrokeArc invocation.
type StrokeArcCall struct {
Center geometry.Point
Radius float32
StartAngle float64
SweepAngle float64
Color widget.Color
StrokeWidth float32
}
type StrokeArcStyledCall struct
StrokeArcStyledCall records a single StrokeArcStyled invocation.
type StrokeArcStyledCall struct {
Center geometry.Point
Radius float32
StartAngle float64
SweepAngle float64
Color widget.Color
StrokeWidth float32
Cap widget.LineCap
}
type DrawLineCall struct
DrawLineCall records a single DrawLine invocation.
type DrawLineCall struct {
From geometry.Point
To geometry.Point
Color widget.Color
StrokeWidth float32
}
type DrawTextCall struct
DrawTextCall records a single DrawText invocation.
type DrawTextCall struct {
Text string
Bounds geometry.Rect
FontSize float32
Color widget.Color
Bold bool
Align widget.TextAlign
}
type DrawStyledTextCall struct
DrawStyledTextCall records a single DrawStyledText invocation.
type DrawStyledTextCall struct {
Text string
Bounds geometry.Rect
Style widget.TextStyle
}
type DrawImageCall struct
DrawImageCall records a single DrawImage invocation.
type DrawImageCall struct {
Image image.Image
At geometry.Point
}
type ClipRoundRectCall struct
ClipRoundRectCall records a single PushClipRoundRect invocation.
type ClipRoundRectCall struct {
Bounds geometry.Rect
Radius float32
}
type MockCanvas struct
MockCanvas records all draw calls for verification in tests.
It implements [widget.Canvas] and stores each invocation in typed slices.
Use [MockCanvas.Reset] to clear all recorded calls between test phases.
Example:
canvas := &uitest.MockCanvas{}
myWidget.Draw(ctx, canvas)
if len(canvas.Rects) != 1 {
t.Errorf("expected 1 rect, got %d", len(canvas.Rects))
}
type MockCanvas struct {
// Clears records arguments passed to Clear.
Clears []widget.Color
// Rects records arguments passed to DrawRect.
Rects []DrawRectCall
// StrokeRects records arguments passed to StrokeRect.
StrokeRects []StrokeRectCall
// RoundRects records arguments passed to DrawRoundRect.
RoundRects []DrawRoundRectCall
// StrokeRoundRects records arguments passed to StrokeRoundRect.
StrokeRoundRects []StrokeRoundRectCall
// Circles records arguments passed to DrawCircle.
Circles []DrawCircleCall
// StrokeCircles records arguments passed to StrokeCircle.
StrokeCircles []StrokeCircleCall
// StrokeArcs records arguments passed to StrokeArc.
StrokeArcs []StrokeArcCall
// StrokeArcStyleds records arguments passed to StrokeArcStyled.
StrokeArcStyleds []StrokeArcStyledCall
// Lines records arguments passed to DrawLine.
Lines []DrawLineCall
// Texts records arguments passed to DrawText.
Texts []DrawTextCall
// StyledTexts records arguments passed to DrawStyledText.
StyledTexts []DrawStyledTextCall
// Images records arguments passed to DrawImage.
Images []DrawImageCall
// Clips records arguments passed to PushClip.
Clips []geometry.Rect
// ClipRoundRects records arguments passed to PushClipRoundRect.
ClipRoundRects []ClipRoundRectCall
// Transforms records arguments passed to PushTransform.
Transforms []geometry.Point
// PopClipCount tracks how many times PopClip was called.
PopClipCount int
// PopTransformCount tracks how many times PopTransform was called.
PopTransformCount int
// transformStack tracks cumulative offsets for TransformOffset().
transformStack []geometry.Point
// currentOffset is the current cumulative transform offset.
currentOffset geometry.Point
}
Clear records the color argument.