mirror of https://github.com/mum4k/termdash.git
94 lines
2.5 KiB
Go
94 lines
2.5 KiB
Go
// Copyright 2018 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package draw
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// rectangle.go draws a rectangle.
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import (
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"fmt"
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"image"
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"github.com/mum4k/termdash/canvas"
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"github.com/mum4k/termdash/cell"
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)
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// RectangleOption is used to provide options to the Rectangle function.
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type RectangleOption interface {
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// set sets the provided option.
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set(*rectOptions)
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}
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// rectOptions stores the provided options.
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type rectOptions struct {
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cellOpts []cell.Option
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char rune
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}
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// rectOption implements RectangleOption.
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type rectOption func(rOpts *rectOptions)
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// set implements RectangleOption.set.
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func (ro rectOption) set(rOpts *rectOptions) {
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ro(rOpts)
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}
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// RectCellOpts sets options on the cells that create the rectangle.
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func RectCellOpts(opts ...cell.Option) RectangleOption {
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return rectOption(func(rOpts *rectOptions) {
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rOpts.cellOpts = append(rOpts.cellOpts, opts...)
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})
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}
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// DefaultRectChar is the default value for the RectChar option.
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const DefaultRectChar = ' '
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// RectChar sets the character used in each of the cells of the rectangle.
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func RectChar(c rune) RectangleOption {
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return rectOption(func(rOpts *rectOptions) {
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rOpts.char = c
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})
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}
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// Rectangle draws a filled rectangle on the canvas.
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func Rectangle(c *canvas.Canvas, r image.Rectangle, opts ...RectangleOption) error {
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opt := &rectOptions{
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char: DefaultRectChar,
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}
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for _, o := range opts {
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o.set(opt)
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}
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if ar := c.Area(); !r.In(ar) {
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return fmt.Errorf("the requested rectangle %v doesn't fit the canvas area %v", r, ar)
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}
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if r.Dx() < 1 || r.Dy() < 1 {
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return fmt.Errorf("the rectangle must be at least 1x1 cell, got %v", r)
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}
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for col := r.Min.X; col < r.Max.X; col++ {
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for row := r.Min.Y; row < r.Max.Y; row++ {
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cells, err := c.SetCell(image.Point{col, row}, opt.char, opt.cellOpts...)
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if err != nil {
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return err
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}
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if cells != 1 {
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return fmt.Errorf("invalid rectangle character %q, this character occupies %d cells, the implementation only supports half-width runes that occupy exactly one cell", opt.char, cells)
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}
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}
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}
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return nil
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}
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