mirror of https://github.com/mum4k/termdash.git
119 lines
3.1 KiB
Go
119 lines
3.1 KiB
Go
// Copyright 2019 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 donut
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// circle.go assists in calculation of points and angles on a circle.
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import (
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"image"
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"math"
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"github.com/mum4k/termdash/private/canvas/braille"
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)
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// startEndAngles given progress indicators and the desired start angle and
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// direction, returns the starting and the ending angle of the partial circle
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// that represents this progress.
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func startEndAngles(current, total, startAngle, direction int) (start, end int) {
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const fullCircle = 360
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if total == 0 {
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return startAngle, startAngle
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}
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mult := float64(current) / float64(total)
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angleSize := math.Round(float64(360) * mult)
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if angleSize == fullCircle {
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return 0, fullCircle
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}
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end = startAngle + int(math.Round(float64(direction)*angleSize))
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if end < 0 {
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end += fullCircle
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if startAngle == 0 {
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startAngle = fullCircle
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}
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return end, startAngle
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}
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if end < startAngle {
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return end, startAngle
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}
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if end > fullCircle {
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end = end % fullCircle
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}
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return startAngle, end
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}
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// midAndRadius given an area of a braille canvas, determines the mid point in
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// pixels and radius to draw the largest circle that fits.
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// The circle's mid point is always positioned on the {0,1} pixel in the chosen
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// cell so that any text inside of it can be visually centered.
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func midAndRadius(ar image.Rectangle) (image.Point, int) {
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mid := image.Point{ar.Dx() / 2, ar.Dy() / 2}
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if mid.X%2 != 0 {
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mid.X--
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}
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switch mid.Y % 4 {
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case 0:
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mid.Y++
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case 1:
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case 2:
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mid.Y--
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case 3:
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mid.Y -= 2
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}
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// Calculate radius based on the smaller axis.
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var radius int
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if ar.Dx() < ar.Dy() {
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if mid.X < ar.Dx()/2 {
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radius = mid.X
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} else {
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radius = ar.Dx() - mid.X - 1
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}
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} else {
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if mid.Y < ar.Dy()/2 {
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radius = mid.Y
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} else {
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radius = ar.Dy() - mid.Y - 1
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}
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}
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return mid, radius
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}
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// availableCells given a radius returns the number of cells that are available
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// within the circle and the coordinates of the first cell.
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// These coordinates are for a normal (non-braille) canvas.
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// That is the cells that do not contain any of the circle points. This is
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// important since normal characters and braille characters cannot share the
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// same cell.
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func availableCells(mid image.Point, radius int) (int, image.Point) {
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if radius < 3 {
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return 0, image.Point{0, 0}
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}
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// Pixels available for the text only.
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// Subtract one for the circle itself.
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pixels := radius*2 - 1
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startPixel := image.Point{mid.X - pixels/2, mid.Y}
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startCell := image.Point{
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startPixel.X / braille.ColMult,
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mid.Y / braille.RowMult,
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}
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return pixels / braille.ColMult, startCell
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}
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