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scroller.go
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scroller.go
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package widget
import (
"image/color"
"fyne.io/fyne"
"fyne.io/fyne/canvas"
"fyne.io/fyne/driver/desktop"
"fyne.io/fyne/internal/widget"
"fyne.io/fyne/theme"
)
// ScrollDirection represents the directions in which a ScrollContainer can scroll its child content.
//
// Deprecated: use container.ScrollDirection instead.
type ScrollDirection int
// Constants for valid values of ScrollDirection.
const (
// Deprecated: use container.ScrollBoth instead
ScrollBoth ScrollDirection = iota
// Deprecated: use container.ScrollHorizontalOnly instead
ScrollHorizontalOnly
// Deprecated: use container.ScrollVerticalOnly instead
ScrollVerticalOnly
)
type scrollBarOrientation int
// We default to vertical as 0 due to that being the original orientation offered
const (
scrollBarOrientationVertical scrollBarOrientation = 0
scrollBarOrientationHorizontal scrollBarOrientation = 1
scrollContainerMinSize = 32 // TODO consider the smallest useful scroll view?
)
type scrollBarRenderer struct {
widget.BaseRenderer
scrollBar *scrollBar
minSize fyne.Size
}
func (r *scrollBarRenderer) BackgroundColor() color.Color {
return theme.ScrollBarColor()
}
func (r *scrollBarRenderer) Layout(_ fyne.Size) {
}
func (r *scrollBarRenderer) MinSize() fyne.Size {
return r.minSize
}
func (r *scrollBarRenderer) Refresh() {
}
var _ desktop.Hoverable = (*scrollBar)(nil)
var _ fyne.Draggable = (*scrollBar)(nil)
type scrollBar struct {
BaseWidget
area *scrollBarArea
draggedDistance int
dragStart int
isDragged bool
orientation scrollBarOrientation
}
func (b *scrollBar) CreateRenderer() fyne.WidgetRenderer {
return &scrollBarRenderer{scrollBar: b}
}
func (b *scrollBar) Cursor() desktop.Cursor {
return desktop.DefaultCursor
}
func (b *scrollBar) DragEnd() {
b.isDragged = false
}
func (b *scrollBar) Dragged(e *fyne.DragEvent) {
if !b.isDragged {
b.isDragged = true
switch b.orientation {
case scrollBarOrientationHorizontal:
b.dragStart = b.Position().X
case scrollBarOrientationVertical:
b.dragStart = b.Position().Y
}
b.draggedDistance = 0
}
switch b.orientation {
case scrollBarOrientationHorizontal:
b.draggedDistance += e.DraggedX
case scrollBarOrientationVertical:
b.draggedDistance += e.DraggedY
}
b.area.moveBar(b.draggedDistance+b.dragStart, b.Size())
}
func (b *scrollBar) MouseIn(e *desktop.MouseEvent) {
b.area.MouseIn(e)
}
func (b *scrollBar) MouseMoved(*desktop.MouseEvent) {
}
func (b *scrollBar) MouseOut() {
b.area.MouseOut()
}
func newScrollBar(area *scrollBarArea) *scrollBar {
b := &scrollBar{area: area, orientation: area.orientation}
b.ExtendBaseWidget(b)
return b
}
type scrollBarAreaRenderer struct {
widget.BaseRenderer
area *scrollBarArea
bar *scrollBar
}
func (r *scrollBarAreaRenderer) BackgroundColor() color.Color {
return color.Transparent
}
func (r *scrollBarAreaRenderer) Layout(_ fyne.Size) {
var barHeight, barWidth, barX, barY int
switch r.area.orientation {
case scrollBarOrientationHorizontal:
barWidth, barHeight, barX, barY = r.barSizeAndOffset(r.area.scroll.Offset.X, r.area.scroll.Content.Size().Width, r.area.scroll.Size().Width)
default:
barHeight, barWidth, barY, barX = r.barSizeAndOffset(r.area.scroll.Offset.Y, r.area.scroll.Content.Size().Height, r.area.scroll.Size().Height)
}
r.bar.Move(fyne.NewPos(barX, barY))
r.bar.Resize(fyne.NewSize(barWidth, barHeight))
}
func (r *scrollBarAreaRenderer) MinSize() fyne.Size {
var min int
min = theme.ScrollBarSize()
if !r.area.isLarge {
min = theme.ScrollBarSmallSize() * 2
}
switch r.area.orientation {
case scrollBarOrientationHorizontal:
return fyne.NewSize(theme.ScrollBarSize(), min)
default:
return fyne.NewSize(min, theme.ScrollBarSize())
}
}
func (r *scrollBarAreaRenderer) Refresh() {
r.Layout(r.area.Size())
canvas.Refresh(r.bar)
}
func (r *scrollBarAreaRenderer) barSizeAndOffset(contentOffset, contentLength, scrollLength int) (length, width, lengthOffset, widthOffset int) {
if scrollLength < contentLength {
portion := float64(scrollLength) / float64(contentLength)
length = int(float64(scrollLength) * portion)
if length < theme.ScrollBarSize() {
length = theme.ScrollBarSize()
}
} else {
length = scrollLength
}
if contentOffset != 0 {
lengthOffset = int(float64(scrollLength-length) * (float64(contentOffset) / float64(contentLength-scrollLength)))
}
if r.area.isLarge {
width = theme.ScrollBarSize()
} else {
widthOffset = theme.ScrollBarSmallSize()
width = theme.ScrollBarSmallSize()
}
return
}
var _ desktop.Hoverable = (*scrollBarArea)(nil)
type scrollBarArea struct {
BaseWidget
isLarge bool
scroll *ScrollContainer
orientation scrollBarOrientation
}
func (a *scrollBarArea) CreateRenderer() fyne.WidgetRenderer {
bar := newScrollBar(a)
return &scrollBarAreaRenderer{BaseRenderer: widget.NewBaseRenderer([]fyne.CanvasObject{bar}), area: a, bar: bar}
}
func (a *scrollBarArea) MouseIn(*desktop.MouseEvent) {
a.isLarge = true
a.scroll.Refresh()
}
func (a *scrollBarArea) MouseMoved(*desktop.MouseEvent) {
}
func (a *scrollBarArea) MouseOut() {
a.isLarge = false
a.scroll.Refresh()
}
func (a *scrollBarArea) moveBar(offset int, barSize fyne.Size) {
switch a.orientation {
case scrollBarOrientationHorizontal:
a.scroll.Offset.X = a.computeScrollOffset(barSize.Width, offset, a.scroll.Size().Width, a.scroll.Content.Size().Width)
default:
a.scroll.Offset.Y = a.computeScrollOffset(barSize.Height, offset, a.scroll.Size().Height, a.scroll.Content.Size().Height)
}
if f := a.scroll.onOffsetChanged; f != nil {
f()
}
a.scroll.refreshWithoutOffsetUpdate()
}
func (a *scrollBarArea) computeScrollOffset(length, offset, scrollLength, contentLength int) int {
maxOffset := scrollLength - length
if offset < 0 {
offset = 0
} else if offset > maxOffset {
offset = maxOffset
}
ratio := float32(offset) / float32(maxOffset)
scrollOffset := int(ratio * float32(contentLength-scrollLength))
return scrollOffset
}
func newScrollBarArea(scroll *ScrollContainer, orientation scrollBarOrientation) *scrollBarArea {
a := &scrollBarArea{scroll: scroll, orientation: orientation}
a.ExtendBaseWidget(a)
return a
}
type scrollContainerRenderer struct {
widget.BaseRenderer
scroll *ScrollContainer
vertArea *scrollBarArea
horizArea *scrollBarArea
leftShadow, rightShadow *widget.Shadow
topShadow, bottomShadow *widget.Shadow
oldMinSize fyne.Size
}
func (r *scrollContainerRenderer) layoutBars(size fyne.Size) {
if r.scroll.Direction != ScrollHorizontalOnly {
r.vertArea.Resize(fyne.NewSize(r.vertArea.MinSize().Width, size.Height))
r.vertArea.Move(fyne.NewPos(r.scroll.Size().Width-r.vertArea.Size().Width, 0))
r.topShadow.Resize(fyne.NewSize(size.Width, 0))
r.bottomShadow.Resize(fyne.NewSize(size.Width, 0))
r.bottomShadow.Move(fyne.NewPos(0, r.scroll.size.Height))
}
if r.scroll.Direction != ScrollVerticalOnly {
r.horizArea.Resize(fyne.NewSize(size.Width, r.horizArea.MinSize().Height))
r.horizArea.Move(fyne.NewPos(0, r.scroll.Size().Height-r.horizArea.Size().Height))
r.leftShadow.Resize(fyne.NewSize(0, size.Height))
r.rightShadow.Resize(fyne.NewSize(0, size.Height))
r.rightShadow.Move(fyne.NewPos(r.scroll.size.Width, 0))
}
r.updatePosition()
}
func (r *scrollContainerRenderer) Layout(size fyne.Size) {
c := r.scroll.Content
c.Resize(c.MinSize().Max(size))
r.layoutBars(size)
}
func (r *scrollContainerRenderer) MinSize() fyne.Size {
return r.scroll.MinSize()
}
func (r *scrollContainerRenderer) Refresh() {
if len(r.BaseRenderer.Objects()) == 0 || r.BaseRenderer.Objects()[0] != r.scroll.Content {
// push updated content object to baseRenderer
r.BaseRenderer.SetObjects([]fyne.CanvasObject{r.scroll.Content})
}
if r.oldMinSize == r.scroll.Content.MinSize() && r.oldMinSize == r.scroll.Content.Size() &&
(r.scroll.Size().Width <= r.oldMinSize.Width && r.scroll.Size().Height <= r.oldMinSize.Height) {
r.layoutBars(r.scroll.Size())
return
}
r.oldMinSize = r.scroll.Content.MinSize()
r.Layout(r.scroll.Size())
}
func (r *scrollContainerRenderer) handleAreaVisibility(contentSize int, scrollSize int, area *scrollBarArea) {
if contentSize <= scrollSize {
area.Hide()
} else if r.scroll.Visible() {
area.Show()
}
}
func (r *scrollContainerRenderer) handleShadowVisibility(offset int, contentSize int, scrollSize int, shadowStart fyne.CanvasObject, shadowEnd fyne.CanvasObject) {
if !r.scroll.Visible() {
return
}
if offset > 0 {
shadowStart.Show()
} else {
shadowStart.Hide()
}
if offset < contentSize-scrollSize {
shadowEnd.Show()
} else {
shadowEnd.Hide()
}
}
func (r *scrollContainerRenderer) updatePosition() {
scrollSize := r.scroll.Size()
contentSize := r.scroll.Content.Size()
r.scroll.Content.Move(fyne.NewPos(-r.scroll.Offset.X, -r.scroll.Offset.Y))
if r.scroll.Direction != ScrollHorizontalOnly {
r.handleAreaVisibility(contentSize.Height, scrollSize.Height, r.vertArea)
r.handleShadowVisibility(r.scroll.Offset.Y, contentSize.Height, scrollSize.Height, r.topShadow, r.bottomShadow)
Renderer(r.vertArea).Layout(r.scroll.size)
}
if r.scroll.Direction != ScrollVerticalOnly {
r.handleAreaVisibility(contentSize.Width, scrollSize.Width, r.horizArea)
r.handleShadowVisibility(r.scroll.Offset.X, contentSize.Width, scrollSize.Width, r.leftShadow, r.rightShadow)
Renderer(r.horizArea).Layout(r.scroll.size)
}
if r.scroll.Direction != ScrollHorizontalOnly {
canvas.Refresh(r.vertArea) // this is required to force the canvas to update, we have no "Redraw()"
} else {
canvas.Refresh(r.horizArea) // this is required like above but if we are horizontal
}
}
// ScrollContainer defines a container that is smaller than the Content.
// The Offset is used to determine the position of the child widgets within the container.
//
// Deprecated: use container.Scroll instead.
type ScrollContainer struct {
BaseWidget
minSize fyne.Size
Direction ScrollDirection
Content fyne.CanvasObject
Offset fyne.Position
onOffsetChanged func()
}
// CreateRenderer is a private method to Fyne which links this widget to its renderer
func (s *ScrollContainer) CreateRenderer() fyne.WidgetRenderer {
s.ExtendBaseWidget(s)
scr := &scrollContainerRenderer{
BaseRenderer: widget.NewBaseRenderer([]fyne.CanvasObject{s.Content}),
scroll: s,
}
if s.Direction != ScrollHorizontalOnly {
scr.vertArea = newScrollBarArea(s, scrollBarOrientationVertical)
scr.topShadow = widget.NewShadow(widget.ShadowBottom, widget.SubmergedContentLevel)
scr.bottomShadow = widget.NewShadow(widget.ShadowTop, widget.SubmergedContentLevel)
scr.SetObjects(append(scr.Objects(), scr.vertArea, scr.topShadow, scr.bottomShadow))
}
if s.Direction != ScrollVerticalOnly {
scr.horizArea = newScrollBarArea(s, scrollBarOrientationHorizontal)
scr.leftShadow = widget.NewShadow(widget.ShadowRight, widget.SubmergedContentLevel)
scr.rightShadow = widget.NewShadow(widget.ShadowLeft, widget.SubmergedContentLevel)
scr.SetObjects(append(scr.Objects(), scr.horizArea, scr.leftShadow, scr.rightShadow))
}
return scr
}
//ScrollToBottom will scroll content to container bottom - to show latest info which end user just added
func (s *ScrollContainer) ScrollToBottom() {
s.Offset.Y = s.Content.Size().Height - s.Size().Height
s.Refresh()
}
//ScrollToTop will scroll content to container top
func (s *ScrollContainer) ScrollToTop() {
s.Offset.Y = 0
s.Refresh()
}
// DragEnd will stop scrolling on mobile has stopped
func (s *ScrollContainer) DragEnd() {
}
// Dragged will scroll on any drag - bar or otherwise - for mobile
func (s *ScrollContainer) Dragged(e *fyne.DragEvent) {
if !fyne.CurrentDevice().IsMobile() {
return
}
if s.updateOffset(e.DraggedX, e.DraggedY) {
s.refreshWithoutOffsetUpdate()
}
}
// MinSize returns the smallest size this widget can shrink to
func (s *ScrollContainer) MinSize() fyne.Size {
min := fyne.NewSize(scrollContainerMinSize, scrollContainerMinSize).Max(s.minSize)
switch s.Direction {
case ScrollHorizontalOnly:
min.Height = fyne.Max(min.Height, s.Content.MinSize().Height)
case ScrollVerticalOnly:
min.Width = fyne.Max(min.Width, s.Content.MinSize().Width)
}
return min
}
// SetMinSize specifies a minimum size for this scroll container.
// If the specified size is larger than the content size then scrolling will not be enabled
// This can be helpful to appear larger than default if the layout is collapsing this widget.
func (s *ScrollContainer) SetMinSize(size fyne.Size) {
s.minSize = size
}
// Refresh causes this widget to be redrawn in it's current state
func (s *ScrollContainer) Refresh() {
s.updateOffset(0, 0)
s.refreshWithoutOffsetUpdate()
}
func (s *ScrollContainer) refreshWithoutOffsetUpdate() {
s.BaseWidget.Refresh()
}
// Resize sets a new size for the scroll container.
func (s *ScrollContainer) Resize(size fyne.Size) {
if size != s.size {
s.size = size
s.Refresh()
}
}
// Scrolled is called when an input device triggers a scroll event
func (s *ScrollContainer) Scrolled(ev *fyne.ScrollEvent) {
dx, dy := ev.DeltaX, ev.DeltaY
if s.Size().Width < s.Content.MinSize().Width && s.Size().Height >= s.Content.MinSize().Height && dx == 0 {
dx, dy = dy, dx
}
if s.updateOffset(dx, dy) {
s.refreshWithoutOffsetUpdate()
}
}
func (s *ScrollContainer) updateOffset(deltaX, deltaY int) bool {
if s.Content.Size().Width <= s.Size().Width && s.Content.Size().Height <= s.Size().Height {
if s.Offset.X != 0 || s.Offset.Y != 0 {
s.Offset.X = 0
s.Offset.Y = 0
return true
}
return false
}
s.Offset.X = computeOffset(s.Offset.X, -deltaX, s.Size().Width, s.Content.MinSize().Width)
s.Offset.Y = computeOffset(s.Offset.Y, -deltaY, s.Size().Height, s.Content.MinSize().Height)
if f := s.onOffsetChanged; f != nil {
f()
}
return true
}
func computeOffset(start, delta, outerWidth, innerWidth int) int {
offset := start + delta
if offset+outerWidth >= innerWidth {
offset = innerWidth - outerWidth
}
if offset < 0 {
offset = 0
}
return offset
}
// NewScrollContainer creates a scrollable parent wrapping the specified content.
// Note that this may cause the MinSize to be smaller than that of the passed object.
//
// Deprecated: use container.NewScroll instead.
func NewScrollContainer(content fyne.CanvasObject) *ScrollContainer {
return newScrollContainerWithDirection(ScrollBoth, content)
}
// NewHScrollContainer create a scrollable parent wrapping the specified content.
// Note that this may cause the MinSize.Width to be smaller than that of the passed object.
//
// Deprecated: use container.NewHScroll instead.
func NewHScrollContainer(content fyne.CanvasObject) *ScrollContainer {
return newScrollContainerWithDirection(ScrollHorizontalOnly, content)
}
// NewVScrollContainer create a scrollable parent wrapping the specified content.
// Note that this may cause the MinSize.Height to be smaller than that of the passed object.
//
// Deprecated: use container.NewVScroll instead.
func NewVScrollContainer(content fyne.CanvasObject) *ScrollContainer {
return newScrollContainerWithDirection(ScrollVerticalOnly, content)
}
func newScrollContainerWithDirection(direction ScrollDirection, content fyne.CanvasObject) *ScrollContainer {
s := &ScrollContainer{
Direction: direction,
Content: content,
}
s.ExtendBaseWidget(s)
return s
}