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// Copyright 2019-2022 Graham Clark. All rights reserved. Use of this source
// code is governed by the MIT license that can be found in the LICENSE
// file.
// Package shadow adds a drop shadow effect to a widget.
package shadow
import (
"fmt"
"github.com/gcla/gowid"
tcell "github.com/gdamore/tcell/v2"
)
//======================================================================
type IOffset interface {
Offset() int
}
type IWidget interface {
gowid.ICompositeWidget
IOffset
}
// Widget will render a drop shadow underneath and to the right of the inner widget,
// providing a simple 3D effect.
//
// Offset is the number of lines to extend the drop shadow down - it is
// extended right by 2*Offset because terminal cells aren't square.
//
type Widget struct {
gowid.IWidget
offset int // Means y offset, x is 2*y because cells are not squares -
// we just guess at a reasonable look for a reasonable
// aspect ratio
*gowid.Callbacks
gowid.SubWidgetCallbacks
}
func New(inner gowid.IWidget, offset int) *Widget {
res := &Widget{
IWidget: inner,
offset: offset,
}
res.SubWidgetCallbacks = gowid.SubWidgetCallbacks{CB: &res.Callbacks}
var _ gowid.ICompositeWidget = res
var _ IWidget = res
return res
}
func (w *Widget) String() string {
return fmt.Sprintf("shadow[%v]", w.SubWidget())
}
func (w *Widget) SubWidget() gowid.IWidget {
return w.IWidget
}
func (w *Widget) SetSubWidget(wi gowid.IWidget, app gowid.IApp) {
w.IWidget = wi
gowid.RunWidgetCallbacks(w, gowid.SubWidgetCB{}, app, w)
}
func (w *Widget) Offset() int {
return w.offset
}
func (w *Widget) SetOffset(x int, app gowid.IApp) {
w.offset = x
}
func (w *Widget) UserInput(ev interface{}, size gowid.IRenderSize, focus gowid.Selector, app gowid.IApp) bool {
return UserInput(w, ev, size, focus, app)
}
func (w *Widget) Render(size gowid.IRenderSize, focus gowid.Selector, app gowid.IApp) gowid.ICanvas {
return Render(w, size, focus, app)
}
func (w *Widget) SubWidgetSize(size gowid.IRenderSize, focus gowid.Selector, app gowid.IApp) gowid.IRenderSize {
return SubWidgetSize(w, size, focus, app)
}
func (w *Widget) RenderSize(size gowid.IRenderSize, focus gowid.Selector, app gowid.IApp) gowid.IRenderBox {
return RenderSize(w, size, focus, app)
}
//''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
func UserInput(w gowid.ICompositeWidget, ev interface{}, size gowid.IRenderSize, focus gowid.Selector, app gowid.IApp) bool {
subSize := w.SubWidgetSize(size, focus, app)
if evm, ok := ev.(*tcell.EventMouse); ok {
ss := w.SubWidget().RenderSize(subSize, focus, app)
mx, my := evm.Position()
if my < ss.BoxRows() && my >= 0 && mx < ss.BoxColumns() && mx >= 0 {
return gowid.UserInputIfSelectable(w.SubWidget(), ev, subSize, focus, app)
}
} else {
return gowid.UserInputIfSelectable(w.SubWidget(), ev, subSize, focus, app)
}
return false
}
func Render(w IWidget, size gowid.IRenderSize, focus gowid.Selector, app gowid.IApp) gowid.ICanvas {
newSize := w.SubWidgetSize(size, focus, app)
innerCanvas := w.SubWidget().Render(newSize, focus, app)
shadowCanvas := gowid.NewCanvasOfSizeExt(innerCanvas.BoxColumns(), innerCanvas.BoxRows(),
gowid.MakeCell(' ', gowid.MakeTCellColorExt(tcell.ColorDefault), gowid.MakeTCellColorExt(tcell.ColorBlack), gowid.StyleNone))
shadowCanvas.ExtendLeft(gowid.EmptyLine(w.Offset() * 2))
res := gowid.NewCanvasOfSize(shadowCanvas.BoxColumns(), w.Offset())
res.AppendBelow(shadowCanvas, false, false)
res.MergeUnder(innerCanvas, 0, 0, false)
return res
}
func SubWidgetSize(w IOffset, size gowid.IRenderSize, focus gowid.Selector, app gowid.IApp) gowid.IRenderSize {
var newSize gowid.IRenderSize
switch sz := size.(type) {
case gowid.IRenderFixed:
newSize = gowid.RenderFixed{}
case gowid.IRenderBox:
newSize = gowid.RenderBox{C: sz.BoxColumns() - (w.Offset() * 2), R: sz.BoxRows() - w.Offset()}
case gowid.IRenderFlowWith:
newSize = gowid.RenderFlowWith{C: sz.FlowColumns() - 2}
default:
panic(gowid.WidgetSizeError{Widget: w, Size: size})
}
return newSize
}
func RenderSize(w IWidget, size gowid.IRenderSize, focus gowid.Selector, app gowid.IApp) gowid.IRenderBox {
ss := w.SubWidgetSize(size, focus, app)
sdim := w.SubWidget().RenderSize(ss, focus, app)
return gowid.RenderBox{C: sdim.BoxColumns() + (w.Offset() * 2), R: sdim.BoxRows() + w.Offset()}
}
//======================================================================
// Local Variables:
// mode: Go
// fill-column: 110
// End:
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