134 lines
3.4 KiB
Go
134 lines
3.4 KiB
Go
package xcanvas
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import "image"
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import "image/color"
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import "github.com/jezek/xgbutil"
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import "github.com/jezek/xgb/xproto"
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import "github.com/jezek/xgbutil/xgraphics"
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import "git.tebibyte.media/tomo/tomo/canvas"
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// Canvas satisfies the canvas.Canvas interface. It draws to an xgraphics.Image.
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// It must be closed after use.
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type Canvas struct {
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*xgraphics.Image
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}
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// NewCanvas creates a new canvas from a bounding rectangle.
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func NewCanvas (x *xgbutil.XUtil, bounds image.Rectangle) *Canvas {
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return NewCanvasFrom(xgraphics.New(x, bounds))
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}
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// NewCanvasFrom creates a new canvas from an existing xgraphics.Image. Note
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// that calling Close() on the resulting canvas will destroy this image.
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func NewCanvasFrom (image *xgraphics.Image) *Canvas {
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if image == nil { return nil }
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return &Canvas { image }
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}
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// Pen returns a new drawing context.
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func (this *Canvas) Pen () canvas.Pen {
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return &pen {
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image: this.Image,
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}
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}
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// Clip returns a sub-canvas of this canvas.
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func (this *Canvas) Clip (bounds image.Rectangle) canvas.Canvas {
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this.assert()
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subImage := this.Image.SubImage(bounds)
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if subImage == nil { return nil }
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xImage := subImage.(*xgraphics.Image)
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return &Canvas { xImage }
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}
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// Push pushes this canvas to the screen.
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func (this *Canvas) Push (window xproto.Window) {
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this.assert()
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this.XDraw()
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this.XExpPaint(window, this.Bounds().Min.X, this.Bounds().Min.Y)
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}
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// Close frees this canvas from the X server.
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func (this *Canvas) Close () {
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this.assert()
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this.Image.Destroy()
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}
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func (this *Canvas) assert () {
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if this == nil { panic("nil canvas") }
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}
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// TODO: we need to implement:
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// - cap
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// - joint
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// - align
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type pen struct {
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image *xgraphics.Image
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closed bool
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endCap canvas.Cap
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joint canvas.Joint
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weight int
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align canvas.StrokeAlign
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stroke xgraphics.BGRA
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fill xgraphics.BGRA
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texture *Texture
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}
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func (this *pen) Rectangle (bounds image.Rectangle) {
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bounds = bounds.Canon()
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if this.weight == 0 {
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if this.fill.A > 0 && !this.textureObscures() {
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this.fillRectangle(this.fill, bounds)
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}
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if this.texture != nil {
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this.textureRectangle(bounds)
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}
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} else {
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if this.stroke.A > 0 {
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this.strokeRectangle(this.stroke, bounds)
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}
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}
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}
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func (this *pen) Path (points ...image.Point) {
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if this.weight == 0 {
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if this.fill.A > 0 {
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this.fillPolygon(this.fill, points...)
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}
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} else if this.closed && len(points) > 2 {
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if this.stroke.A > 0 {
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this.strokePolygon(this.stroke, points...)
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}
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} else {
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if this.stroke.A > 0 {
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this.polyLine(this.stroke, points...)
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}
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}
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}
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func (this *pen) Closed (closed bool) { this.closed = closed }
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func (this *pen) Cap (endCap canvas.Cap) { this.endCap = endCap }
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func (this *pen) Joint (joint canvas.Joint) { this.joint = joint }
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func (this *pen) StrokeWeight (weight int) { this.weight = weight }
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func (this *pen) StrokeAlign (align canvas.StrokeAlign) { this.align = align }
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func (this *pen) Stroke (stroke color.Color) { this.stroke = convertColor(stroke) }
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func (this *pen) Fill (fill color.Color) { this.fill = convertColor(fill) }
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func (this *pen) Texture (texture canvas.Texture) { this.texture = AssertTexture(texture) }
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func (this *pen) textureObscures () bool {
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return this.texture != nil && this.texture.Opaque()
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}
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func convertColor (c color.Color) xgraphics.BGRA {
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r, g, b, a := c.RGBA()
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return xgraphics.BGRA {
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B: uint8(b >> 8),
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G: uint8(g >> 8),
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R: uint8(r >> 8),
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A: uint8(a >> 8),
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}
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}
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