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package barcode
import (
"errors"
"fmt"
"image"
"image/color"
"math"
)
type wrapFunc func(x, y int) color.Color
type scaledBarcode struct {
wrapped Barcode
wrapperFunc wrapFunc
rect image.Rectangle
}
func (bc *scaledBarcode) Content() string {
return bc.wrapped.Content()
}
func (bc *scaledBarcode) Metadata() Metadata {
return bc.wrapped.Metadata()
}
func (bc *scaledBarcode) ColorModel() color.Model {
return bc.wrapped.ColorModel()
}
func (bc *scaledBarcode) Bounds() image.Rectangle {
return bc.rect
}
func (bc *scaledBarcode) At(x, y int) color.Color {
return bc.wrapperFunc(x, y)
}
// Scale returns a resized barcode with the given width and height.
func Scale(bc Barcode, width, height int) (Barcode, error) {
switch bc.Metadata().Dimensions {
case 1:
return scale1DCode(bc, width, height)
case 2:
return scale2DCode(bc, width, height)
}
return nil, errors.New("unsupported barcode format")
}
func scale2DCode(bc Barcode, width, height int) (Barcode, error) {
orgBounds := bc.Bounds()
orgWidth := orgBounds.Max.X - orgBounds.Min.X
orgHeight := orgBounds.Max.Y - orgBounds.Min.Y
factor := int(math.Min(float64(width)/float64(orgWidth), float64(height)/float64(orgHeight)))
if factor <= 0 {
return nil, fmt.Errorf("can not scale barcode to an image smaller then %dx%d", orgWidth, orgHeight)
}
offsetX := (width - (orgWidth * factor)) / 2
offsetY := (height - (orgHeight * factor)) / 2
wrap := func(x, y int) color.Color {
if x < offsetX || y < offsetY {
return color.White
}
x = (x - offsetX) / factor
y = (y - offsetY) / factor
if x >= orgWidth || y >= orgHeight {
return color.White
}
return bc.At(x, y)
}
return &scaledBarcode{
bc,
wrap,
image.Rect(0, 0, width, height),
}, nil
}
func scale1DCode(bc Barcode, width, height int) (Barcode, error) {
orgBounds := bc.Bounds()
orgWidth := orgBounds.Max.X - orgBounds.Min.X
factor := int(float64(width) / float64(orgWidth))
if factor <= 0 {
return nil, fmt.Errorf("can not scale barcode to an image smaller then %dx1", orgWidth)
}
offsetX := (width - (orgWidth * factor)) / 2
wrap := func(x, y int) color.Color {
if x < offsetX {
return color.White
}
x = (x - offsetX) / factor
if x >= orgWidth {
return color.White
}
return bc.At(x, 0)
}
return &scaledBarcode{
bc,
wrap,
image.Rect(0, 0, width, height),
}, nil
}
|
