mirror of https://github.com/gohugoio/hugo
143 lines
3.3 KiB
Go
143 lines
3.3 KiB
Go
// Copyright 2021 The Hugo Authors. All rights reserved.
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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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// 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 images
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import (
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"image"
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"image/color"
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"image/draw"
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"io"
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"strings"
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"github.com/disintegration/gift"
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"github.com/gohugoio/hugo/common/hugio"
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"golang.org/x/image/font"
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"golang.org/x/image/font/gofont/goregular"
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"golang.org/x/image/font/opentype"
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"golang.org/x/image/math/fixed"
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)
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var _ gift.Filter = (*textFilter)(nil)
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type textFilter struct {
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text string
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color color.Color
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x, y int
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alignx string
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size float64
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linespacing int
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fontSource hugio.ReadSeekCloserProvider
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}
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func (f textFilter) Draw(dst draw.Image, src image.Image, options *gift.Options) {
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// Load and parse font
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ttf := goregular.TTF
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if f.fontSource != nil {
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rs, err := f.fontSource.ReadSeekCloser()
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if err != nil {
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panic(err)
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}
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defer rs.Close()
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ttf, err = io.ReadAll(rs)
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if err != nil {
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panic(err)
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}
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}
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otf, err := opentype.Parse(ttf)
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if err != nil {
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panic(err)
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}
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// Set font options
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face, err := opentype.NewFace(otf, &opentype.FaceOptions{
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Size: f.size,
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DPI: 72,
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Hinting: font.HintingNone,
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})
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if err != nil {
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panic(err)
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}
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d := font.Drawer{
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Dst: dst,
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Src: image.NewUniform(f.color),
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Face: face,
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}
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gift.New().Draw(dst, src)
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maxWidth := dst.Bounds().Dx() - 20
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var availableWidth int
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switch f.alignx {
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case "right":
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availableWidth = f.x
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case "center":
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availableWidth = min((maxWidth-f.x), f.x) * 2
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case "left":
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availableWidth = maxWidth - f.x
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}
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fontHeight := face.Metrics().Ascent.Ceil()
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// Calculate lines, consider and include linebreaks
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finalLines := []string{}
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f.text = strings.ReplaceAll(f.text, "\r", "")
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for _, line := range strings.Split(f.text, "\n") {
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currentLine := ""
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// Break each line at the maximum width.
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for _, str := range strings.Fields(line) {
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fieldStrWidth := font.MeasureString(face, str)
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currentLineStrWidth := font.MeasureString(face, currentLine)
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if (currentLineStrWidth.Ceil() + fieldStrWidth.Ceil()) >= availableWidth {
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finalLines = append(finalLines, currentLine)
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currentLine = ""
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}
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currentLine += str + " "
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}
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finalLines = append(finalLines, currentLine)
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}
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// Correct y position based on font and size
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f.y = f.y + fontHeight
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// Start position
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y := f.y
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// Draw text line by line
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for _, line := range finalLines {
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line = strings.TrimSpace(line)
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strWidth := font.MeasureString(face, line)
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var x int
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switch f.alignx {
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case "right":
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x = f.x - strWidth.Ceil()
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case "center":
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x = f.x - (strWidth.Ceil() / 2)
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case "left":
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x = f.x
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}
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d.Dot = fixed.P(x, y)
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d.DrawString(line)
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y = y + fontHeight + f.linespacing
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}
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}
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func (f textFilter) Bounds(srcBounds image.Rectangle) image.Rectangle {
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return image.Rect(0, 0, srcBounds.Dx(), srcBounds.Dy())
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}
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