package roundimage import ( "math" "github.com/diamondburned/cchat-gtk/internal/gts/httputil" "github.com/diamondburned/cchat-gtk/internal/ui/primitives" "github.com/gotk3/gotk3/cairo" "github.com/gotk3/gotk3/gdk" "github.com/gotk3/gotk3/gtk" ) const ( pi = math.Pi circle = 2 * math.Pi ) type RadiusSetter interface { SetRadius(float64) } type Connector interface { ConnectHandlers(connector primitives.Connector) } type Imager interface { gtk.IWidget RadiusSetter // Embed setters. httputil.ImageContainerSizer GetPixbuf() *gdk.Pixbuf GetAnimation() *gdk.PixbufAnimation GetImage() *gtk.Image } type Image struct { *gtk.Image Radius float64 } var _ Imager = (*Image)(nil) // NewImage creates a new round image. If radius is 0, then it will be half the // dimensions. If the radius is less than 0, then nothing is rounded. func NewImage(radius float64) (*Image, error) { i, err := gtk.ImageNew() if err != nil { return nil, err } image := &Image{Image: i, Radius: radius} // Connect to the draw callback and clip the context. i.Connect("draw", image.drawer) return image, nil } func (i *Image) GetImage() *gtk.Image { return i.Image } func (i *Image) SetRadius(r float64) { i.Radius = r } func (i *Image) drawer(widget gtk.IWidget, cc *cairo.Context) bool { var w = float64(i.GetAllocatedWidth()) var h = float64(i.GetAllocatedHeight()) var min = w // Use the smallest side for radius calculation. if h < w { min = h } // Copy the variables in case we need to change them. var r = i.Radius switch { // If radius is less than 0, then don't round. case r < 0: return false // If radius is 0, then we have to calculate our own radius.:This only // works if the image is a square. case r == 0: // Calculate the radius by dividing a side by 2. r = (min / 2) // Draw an arc from 0deg to 360deg. cc.Arc(w/2, h/2, r, 0, circle) // We have to do this so the arc paint doesn't leave back a black // background instead of the usual alpha. cc.SetSourceRGBA(255, 255, 255, 0) // Clip the image with the arc we drew. cc.Clip() // If radius is more than 0, then we have to calculate the radius from // the edges. case r > 0: // StackOverflow is godly. // https://stackoverflow.com/a/6959843. // Radius should be largest a single side divided by 2. if max := min / 2; r > max { r = max } // Draw 4 arcs at 4 corners. cc.Arc(0+r, 0+r, r, 2*(pi/2), 3*(pi/2)) // top left cc.Arc(w-r, 0+r, r, 3*(pi/2), 4*(pi/2)) // top right cc.Arc(w-r, h-r, r, 0*(pi/2), 1*(pi/2)) // bottom right cc.Arc(0+r, h-r, r, 1*(pi/2), 2*(pi/2)) // bottom left // Close the created path. cc.ClosePath() cc.SetSourceRGBA(255, 255, 255, 0) // Clip the image with the arc we drew. cc.Clip() } // Paint the changes. cc.Paint() return false }