mirror of https://github.com/mum4k/termdash.git
101 lines
3.0 KiB
Go
101 lines
3.0 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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// text.go contains code that prints UTF-8 encoded strings on the canvas.
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import (
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"fmt"
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"image"
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"unicode/utf8"
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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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// OverrunMode represents
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type OverrunMode int
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// String implements fmt.Stringer()
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func (om OverrunMode) String() string {
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if n, ok := overrunModeNames[om]; ok {
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return n
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}
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return "OverrunModeUnknown"
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}
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// overrunModeNames maps OverrunMode values to human readable names.
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var overrunModeNames = map[OverrunMode]string{
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OverrunModeStrict: "OverrunModeStrict",
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}
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const (
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// OverrunModeStrict verifies that the drawn value fits the canvas and
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// returns an error if it doesn't.
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OverrunModeStrict OverrunMode = iota
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// TODO(mum4k): Support other overrun modes, like Trim, ThreeDot or LineWrap.
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)
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// TextBounds specifies the limits (start and end cells) that the text must
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// fall into and the overrun mode when it doesn't.
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type TextBounds struct {
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// Start is the starting point of the drawn text.
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Start image.Point
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// MaxX sets a limit on the X coordinate (column) of the drawn text.
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// The X coordinate of all cells used by the text must be within
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// start.X <= X < MaxX.
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// This is optional, if set to zero, the width of the canvas is used as MaxX.
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// This cannot be negative or greater than the width of the canvas.
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MaxX int
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// Om indicates what to do with text that overruns the MaxX or the width of
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// the canvas if MaxX isn't specified.
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Overrun OverrunMode
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}
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// Text prints the provided text on the canvas.
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func Text(c *canvas.Canvas, text string, tb TextBounds, opts ...cell.Option) error {
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ar := c.Area()
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if !tb.Start.In(ar) {
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return fmt.Errorf("the requested start point %v falls outside of the provided canvas %v", tb.Start, ar)
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}
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if tb.MaxX < 0 || tb.MaxX > ar.Max.X {
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return fmt.Errorf("invalid TextBouds.MaxX %v, must be a positive number that is <= canvas.width %v", tb.MaxX, ar.Dx())
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}
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var wantMaxX int
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if tb.MaxX == 0 {
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wantMaxX = ar.Max.X
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} else {
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wantMaxX = tb.MaxX
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}
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runes := utf8.RuneCountInString(text)
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if maxX := tb.Start.X + runes; maxX > wantMaxX && tb.Overrun == OverrunModeStrict {
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return fmt.Errorf("the requested text %q would end at X coordinate %v which falls outside of the maximum %v", text, maxX, wantMaxX)
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}
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cur := tb.Start
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for _, r := range text {
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if err := c.SetCell(cur, r, opts...); err != nil {
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return err
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}
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cur = image.Point{cur.X + 1, cur.Y}
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}
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return nil
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}
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