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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/draw"
"strings"
"github.com/disintegration/gift"
"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, color string
x, y int
size float64
linespacing int
}
func (f textFilter) Draw(dst draw.Image, src image.Image, options *gift.Options) {
color, err := hexStringToColor(f.color)
if err != nil {
panic(err)
}
// Load and parse font
ttf := goregular.TTF
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(color),
Face: face,
}
gift.New().Draw(dst, src)
// Draw text, consider and include linebreaks
maxWidth := dst.Bounds().Dx() - 20
fontHeight := face.Metrics().Ascent.Ceil()
// Correct y position based on font and size
f.y = f.y + fontHeight
// Start position
y := f.y
d.Dot = fixed.P(f.x, f.y)
// Draw text and break line at max width
parts := strings.Fields(f.text)
for _, str := range parts {
strWith := font.MeasureString(face, str)
if (d.Dot.X.Ceil() + strWith.Ceil()) >= maxWidth {
y = y + fontHeight + f.linespacing
d.Dot = fixed.P(f.x, y)
}
d.DrawString(str + " ")
}
}
func (f textFilter) Bounds(srcBounds image.Rectangle) image.Rectangle {
return image.Rect(0, 0, srcBounds.Dx(), srcBounds.Dy())
}
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