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// Copyright 2021 The Hugo Authors. All rights reserved.
//
// 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 images
import (
"image"
"image/color"
"image/draw"
"io"
"strings"
"github.com/disintegration/gift"
"github.com/gohugoio/hugo/common/hugio"
"golang.org/x/image/font"
"golang.org/x/image/font/gofont/goregular"
"golang.org/x/image/font/opentype"
"golang.org/x/image/math/fixed"
)
var _ gift.Filter = (*textFilter)(nil)
type textFilter struct {
text string
color color.Color
x, y int
alignx string
aligny string
size float64
linespacing int
fontSource hugio.ReadSeekCloserProvider
}
func (f textFilter) Draw(dst draw.Image, src image.Image, options *gift.Options) {
// Load and parse font
ttf := goregular.TTF
if f.fontSource != nil {
rs, err := f.fontSource.ReadSeekCloser()
if err != nil {
panic(err)
}
defer rs.Close()
ttf, err = io.ReadAll(rs)
if err != nil {
panic(err)
}
}
otf, err := opentype.Parse(ttf)
if err != nil {
panic(err)
}
// Set font options
face, err := opentype.NewFace(otf, &opentype.FaceOptions{
Size: f.size,
DPI: 72,
Hinting: font.HintingNone,
})
if err != nil {
panic(err)
}
d := font.Drawer{
Dst: dst,
Src: image.NewUniform(f.color),
Face: face,
}
gift.New().Draw(dst, src)
maxWidth := dst.Bounds().Dx() - 20
var availableWidth int
switch f.alignx {
case "right":
availableWidth = f.x
case "center":
availableWidth = min((maxWidth-f.x), f.x) * 2
case "left":
availableWidth = maxWidth - f.x
}
fontHeight := face.Metrics().Ascent.Ceil()
// Calculate lines, consider and include linebreaks
finalLines := []string{}
f.text = strings.ReplaceAll(f.text, "\r", "")
for _, line := range strings.Split(f.text, "\n") {
currentLine := ""
// Break each line at the maximum width.
for _, str := range strings.Fields(line) {
fieldStrWidth := font.MeasureString(face, str)
currentLineStrWidth := font.MeasureString(face, currentLine)
if (currentLineStrWidth.Ceil() + fieldStrWidth.Ceil()) >= availableWidth {
finalLines = append(finalLines, currentLine)
currentLine = ""
}
currentLine += str + " "
}
finalLines = append(finalLines, currentLine)
}
// Total height of the text from the top of the first line to the baseline of the last line
totalHeight := len(finalLines)*fontHeight + (len(finalLines)-1)*f.linespacing
// Correct y position based on font and size
y := f.y + fontHeight
switch f.aligny {
case "top":
// Do nothing
case "center":
y = y - totalHeight/2
case "bottom":
y = y - totalHeight
}
// Draw text line by line
for _, line := range finalLines {
line = strings.TrimSpace(line)
strWidth := font.MeasureString(face, line)
var x int
switch f.alignx {
case "right":
x = f.x - strWidth.Ceil()
case "center":
x = f.x - (strWidth.Ceil() / 2)
case "left":
x = f.x
}
d.Dot = fixed.P(x, y)
d.DrawString(line)
y = y + fontHeight + f.linespacing
}
}
func (f textFilter) Bounds(srcBounds image.Rectangle) image.Rectangle {
return image.Rect(0, 0, srcBounds.Dx(), srcBounds.Dy())
}
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