85 lines
2.0 KiB
Markdown
85 lines
2.0 KiB
Markdown
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## How to use custom shape
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[Source Code](../../example/with-custom-shape/main.go)
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first step, you must define your own shape to QRCode, which consists of two part:
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* normal cell (of course, there are many types, separator, timing, alignment patter, data, format and version etc)
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* finder cell (to help recognizer to locate the matrix's position)
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<img src="../../assets/qrcode_structure.png" align="center" width="50%" />
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```go
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type IShape interface {
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// Draw to fill the IShape of qrcode.
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Draw(ctx *DrawContext)
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// DrawFinder to fill the finder pattern of QRCode, what's finder? google it for more information.
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DrawFinder(ctx *DrawContext)
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}
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```
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> Notice:
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>
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> if you must be careful to design finder's shape, otherwise qrcode could not be recognized.
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>
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Now, if you're define your shape like this:
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```go
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func newShape(radiusPercent float64) qrcode.IShape {
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return &smallerCircle{smallerPercent: radiusPercent}
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}
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// smallerCircle use smaller circle to qrcode.
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type smallerCircle struct {
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smallerPercent float64
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}
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func (sc *smallerCircle) DrawFinder(ctx *qrcode.DrawContext) {
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// use normal radius to draw finder for that qrcode image can be recognized.
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backup := sc.smallerPercent
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sc.smallerPercent = 1.0
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sc.Draw(ctx)
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sc.smallerPercent = backup
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}
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func (sc *smallerCircle) Draw(ctx *qrcode.DrawContext) {
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w, h := ctx.Edge()
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upperLeft := ctx.UpperLeft()
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color := ctx.Color()
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// choose a proper radius values
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radius := w / 2
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r2 := h / 2
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if r2 <= radius {
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radius = r2
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}
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// 80 percent smaller
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radius = int(float64(radius) * sc.smallerPercent)
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cx, cy := upperLeft.X+w/2, upperLeft.Y+h/2 // get center point
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ctx.DrawCircle(float64(cx), float64(cy), float64(radius))
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ctx.SetColor(color)
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ctx.Fill()
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}
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```
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Finally, you can use your shape.
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```go
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func main() {
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shape := newShape(0.7)
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qrc, err := qrcode.New("with-custom-shape", qrcode.WithCustomShape(shape))
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if err != nil {
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panic(err)
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}
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err = qrc.Save("./smaller.png")
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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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```
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