rotated-image.go

package main

import "github.com/fogleman/gg"

func main() {
	const W = 400
	const H = 500
	im, err := gg.LoadPNG("examples/gopher.png")
	if err != nil {
		panic(err)
	}
	iw, ih := im.Bounds().Dx(), im.Bounds().Dy()
	dc := gg.NewContext(W, H)
	// draw outline
	dc.SetHexColor("#ff0000")
	dc.SetLineWidth(1)
	dc.DrawRectangle(0, 0, float64(W), float64(H))
	dc.Stroke()
	// draw full image
	dc.SetHexColor("#0000ff")
	dc.SetLineWidth(2)
	dc.DrawRectangle(100, 210, float64(iw), float64(ih))
	dc.Stroke()
	dc.DrawImage(im, 100, 210)
	// draw image with current matrix applied
	dc.SetHexColor("#0000ff")
	dc.SetLineWidth(2)
	dc.Rotate(gg.Radians(10))
	dc.DrawRectangle(100, 0, float64(iw), float64(ih)/2+20.0)
	dc.StrokePreserve()
	dc.Clip()
	dc.DrawImageAnchored(im, 100, 0, 0.0, 0.0)
	dc.SavePNG("out.png")
}