aerc/lib/ui/context.go
Ben Burwell bcd03c4c4a Add popovers
A popover is a special UI element which can be layered over the rest of
the UI (i.e. it is painted last) and can fall anywhere on the screen,
not just with the bounds of its parent's viewport/context. With these
special abilities comes the restriction that only one popover may be
visible on screen at once.

Popovers are requested from the UI context passed to Draw calls and
specify the anchor point and the desired dimensions. The popover is then
fit to the available space and placed relative to the anchor point.
2019-12-21 09:23:20 -05:00

126 lines
2.8 KiB
Go

package ui
import (
"fmt"
"github.com/gdamore/tcell"
"github.com/gdamore/tcell/views"
"github.com/mattn/go-runewidth"
)
// A context allows you to draw in a sub-region of the terminal
type Context struct {
screen tcell.Screen
viewport *views.ViewPort
x, y int
onPopover func(*Popover)
}
func (ctx *Context) X() int {
x, _, _, _ := ctx.viewport.GetPhysical()
return x
}
func (ctx *Context) Y() int {
_, y, _, _ := ctx.viewport.GetPhysical()
return y
}
func (ctx *Context) Width() int {
width, _ := ctx.viewport.Size()
return width
}
func (ctx *Context) Height() int {
_, height := ctx.viewport.Size()
return height
}
func NewContext(width, height int, screen tcell.Screen, p func(*Popover)) *Context {
vp := views.NewViewPort(screen, 0, 0, width, height)
return &Context{screen, vp, 0, 0, p}
}
func (ctx *Context) Subcontext(x, y, width, height int) *Context {
vp_width, vp_height := ctx.viewport.Size()
if x < 0 || y < 0 {
panic(fmt.Errorf("Attempted to create context with negative offset"))
}
if x+width > vp_width || y+height > vp_height {
panic(fmt.Errorf("Attempted to create context larger than parent"))
}
vp := views.NewViewPort(ctx.viewport, x, y, width, height)
return &Context{ctx.screen, vp, ctx.x + x, ctx.y + y, ctx.onPopover}
}
func (ctx *Context) SetCell(x, y int, ch rune, style tcell.Style) {
width, height := ctx.viewport.Size()
if x >= width || y >= height {
panic(fmt.Errorf("Attempted to draw outside of context"))
}
crunes := []rune{}
ctx.viewport.SetContent(x, y, ch, crunes, style)
}
func (ctx *Context) Printf(x, y int, style tcell.Style,
format string, a ...interface{}) int {
width, height := ctx.viewport.Size()
if x >= width || y >= height {
panic(fmt.Errorf("Attempted to draw outside of context"))
}
str := fmt.Sprintf(format, a...)
old_x := x
newline := func() bool {
x = old_x
y++
return y < height
}
for _, ch := range str {
switch ch {
case '\n':
if !newline() {
return runewidth.StringWidth(str)
}
case '\r':
x = old_x
default:
crunes := []rune{}
ctx.viewport.SetContent(x, y, ch, crunes, style)
x += runewidth.RuneWidth(ch)
if x == old_x+width {
if !newline() {
return runewidth.StringWidth(str)
}
}
}
}
return runewidth.StringWidth(str)
}
func (ctx *Context) Fill(x, y, width, height int, rune rune, style tcell.Style) {
vp := views.NewViewPort(ctx.viewport, x, y, width, height)
vp.Fill(rune, style)
}
func (ctx *Context) SetCursor(x, y int) {
ctx.screen.ShowCursor(ctx.x+x, ctx.y+y)
}
func (ctx *Context) HideCursor() {
ctx.screen.HideCursor()
}
func (ctx *Context) Popover(x, y, width, height int, d Drawable) {
ctx.onPopover(&Popover{
x: ctx.x + x,
y: ctx.y + y,
width: width,
height: height,
content: d,
})
}