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