termdash/draw/box.go

78 lines
2.2 KiB
Go

// Copyright 2018 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package draw
// box.go contains code that draws boxes.
import (
"fmt"
"image"
"github.com/mum4k/termdash/canvas"
"github.com/mum4k/termdash/cell"
)
// boxChar returns the correct box character from the parts for the use at the
// specified point of the box. Returns -1 if no character should be at this point.
func boxChar(p image.Point, box image.Rectangle, parts map[linePart]rune) rune {
switch {
case p.X == box.Min.X && p.Y == box.Min.Y:
return parts[topLeftCorner]
case p.X == box.Max.X-1 && p.Y == box.Min.Y:
return parts[topRightCorner]
case p.X == box.Min.X && p.Y == box.Max.Y-1:
return parts[bottomLeftCorner]
case p.X == box.Max.X-1 && p.Y == box.Max.Y-1:
return parts[bottomRightCorner]
case p.X == box.Min.X || p.X == box.Max.X-1:
return parts[vLine]
case p.Y == box.Min.Y || p.Y == box.Max.Y-1:
return parts[hLine]
}
return -1
}
// Box draws a box on the canvas.
func Box(c *canvas.Canvas, box image.Rectangle, ls LineStyle, opts ...cell.Option) error {
if ar := c.Area(); !box.In(ar) {
return fmt.Errorf("the requested box %+v falls outside of the provided canvas %+v", box, ar)
}
const minSize = 2
if box.Dx() < minSize || box.Dy() < minSize {
return fmt.Errorf("the smallest supported box is %dx%d, got: %dx%d", minSize, minSize, box.Dx(), box.Dy())
}
parts, err := lineParts(ls)
if err != nil {
return err
}
for col := box.Min.X; col < box.Max.X; col++ {
for row := box.Min.Y; row < box.Max.Y; row++ {
p := image.Point{col, row}
r := boxChar(p, box, parts)
if r == -1 {
continue
}
if err := c.SetCell(p, r, opts...); err != nil {
return err
}
}
}
return nil
}