Rip out refCounted from the driver.

Instead, use a mark-and-sweep per context.
Removes the horrible Release() interface method from Texture and Canvas.

GXUI seems a lot snappier, probably because we're not ref-twiddling
everything any more.

Fixes #111

canvas.go

@@ -23,5 +23,4 @@ type Canvas interface {
 	DrawPolygon(Polygon, Pen, Brush)
 	DrawRect(math.Rect, Brush)
 	DrawRoundedRect(rect math.Rect, tl, tr, bl, br float32, p Pen, b Brush)
-	Release()
 }

drivers/gl/blitter.go

@@ -119,7 +119,6 @@ func newBlitter(ctx *context, stats *contextStats) *blitter {
 }
 
 func (b *blitter) destroy(ctx *context) {
-	b.quad.release()
 	b.copyShader.destroy(ctx)
 	b.colorShader.destroy(ctx)
 	b.fontShader.destroy(ctx)
@@ -297,7 +296,6 @@ func (b *blitter) commitGlyphs(ctx *context) {
 		"mSrc":   mSrc,
 	})
 	gl.Enable(gl.SCISSOR_TEST)
-	s.release()
 	b.glyphBatch.GlyphPage = nil
 	b.glyphBatch.DstRects = b.glyphBatch.DstRects[:0]
 	b.glyphBatch.SrcRects = b.glyphBatch.SrcRects[:0]

drivers/gl/canvas.go

@@ -32,15 +32,8 @@ type drawState struct {
 	OriginPixels math.Point
 }
 
-type resource interface {
-	addRef()
-	release() bool
-}
-
 type canvas struct {
-	refCounted
 	sizeDips          math.Size
-	resources         []resource
 	ops               []canvasOp
 	built             bool
 	buildingPushCount int
@@ -53,13 +46,10 @@ func newCanvas(sizeDips math.Size) *canvas {
 	c := &canvas{
 		sizeDips: sizeDips,
 	}
-	c.init()
-	globalStats.canvasCount.inc()
 	return c
 }
 
 func (c *canvas) draw(ctx *context, dss *drawStateStack) {
-	c.assertAlive("draw")
 	ds := dss.head()
 	ctx.apply(ds)
 
@@ -69,31 +59,12 @@ func (c *canvas) draw(ctx *context, dss *drawStateStack) {
 }
 
 func (c *canvas) appendOp(name string, op canvasOp) {
-	c.assertAlive(name)
 	if c.built {
 		panic(fmt.Errorf("%s() called after Complete()", name))
 	}
 	c.ops = append(c.ops, op)
 }
 
-func (c *canvas) appendResource(r resource) {
-	r.addRef()
-	c.resources = append(c.resources, r)
-}
-
-func (c *canvas) release() bool {
-	if !c.refCounted.release() {
-		return false
-	}
-	for _, r := range c.resources {
-		r.release()
-	}
-	c.ops = nil
-	c.resources = nil
-	globalStats.canvasCount.dec()
-	return true
-}
-
 // gxui.Canvas compliance
 func (c *canvas) Size() math.Size {
 	return c.sizeDips
@@ -164,7 +135,6 @@ func (c *canvas) DrawCanvas(cc gxui.Canvas, offsetDips math.Point) {
 		dss.pop()
 		ctx.apply(dss.head())
 	})
-	c.appendResource(childCanvas)
 }
 
 func (c *canvas) DrawRunes(f gxui.Font, r []rune, p []math.Point, col gxui.Color) {
@@ -186,10 +156,6 @@ func (c *canvas) DrawLines(lines gxui.Polygon, pen gxui.Pen) {
 			ctx.blitter.blitShape(ctx, *edge, pen.Color, ds)
 		}
 	})
-	if edge != nil {
-		c.appendResource(edge)
-		edge.release()
-	}
 }
 
 func (c *canvas) DrawPolygon(poly gxui.Polygon, pen gxui.Pen, brush gxui.Brush) {
@@ -203,14 +169,6 @@ func (c *canvas) DrawPolygon(poly gxui.Polygon, pen gxui.Pen, brush gxui.Brush)
 			ctx.blitter.blitShape(ctx, *edge, pen.Color, ds)
 		}
 	})
-	if fill != nil {
-		c.appendResource(fill)
-		fill.release()
-	}
-	if edge != nil {
-		c.appendResource(edge)
-		edge.release()
-	}
 }
 
 func (c *canvas) DrawRect(r math.Rect, brush gxui.Brush) {
@@ -242,9 +200,4 @@ func (c *canvas) DrawTexture(t gxui.Texture, r math.Rect) {
 		tc := ctx.getOrCreateTextureContext(t.(*texture))
 		ctx.blitter.blit(ctx, tc, tc.sizePixels.Rect(), ctx.resolution.rectDipsToPixels(r), dss.head())
 	})
-	c.appendResource(t.(*texture))
-}
-
-func (c *canvas) Release() {
-	c.release()
 }

drivers/gl/context.go

@@ -10,6 +10,12 @@ import (
 	"github.com/goxjs/gl"
 )
 
+// contextResource is used as an anonymous field by types that are constructed
+// per context.
+type contextResource struct {
+	lastContextUse int // used for mark-and-sweeping the resource.
+}
+
 type context struct {
 	blitter              *blitter
 	resolution           resolution
@@ -19,6 +25,7 @@ type context struct {
 	indexBufferContexts  map[*indexBuffer]*indexBufferContext
 	sizeDips, sizePixels math.Size
 	clip                 math.Rect
+	frame                int
 }
 
 func newContext() *context {
@@ -52,42 +59,43 @@ func (c *context) destroy() {
 }
 
 func (c *context) beginDraw(sizeDips, sizePixels math.Size) {
-	// Reap any dead textures
+	dipsToPixels := float32(sizePixels.W) / float32(sizeDips.W)
+
+	c.sizeDips = sizeDips
+	c.sizePixels = sizePixels
+	c.resolution = resolution(dipsToPixels*65536 + 0.5)
+
+	c.stats.drawCallCount = 0
+	c.stats.timer("Frame").start()
+}
+
+func (c *context) endDraw() {
+	// Reap any unused resources
 	for texture, tc := range c.textureContexts {
-		if !texture.alive() {
+		if tc.lastContextUse != c.frame {
 			delete(c.textureContexts, texture)
 			tc.destroy()
 			c.stats.textureCount--
 		}
 	}
 	for stream, sc := range c.vertexStreamContexts {
-		if !stream.alive() {
+		if sc.lastContextUse != c.frame {
 			delete(c.vertexStreamContexts, stream)
 			sc.destroy()
 			c.stats.vertexStreamCount--
 		}
 	}
 	for buffer, ic := range c.indexBufferContexts {
-		if !buffer.alive() {
+		if ic.lastContextUse != c.frame {
 			delete(c.indexBufferContexts, buffer)
 			ic.destroy()
 			c.stats.indexBufferCount--
 		}
 	}
 
-	dipsToPixels := float32(sizePixels.W) / float32(sizeDips.W)
-
-	c.sizeDips = sizeDips
-	c.sizePixels = sizePixels
-	c.resolution = resolution(dipsToPixels*65536 + 0.5)
-
-	c.stats.drawCallCount = 0
-	c.stats.timer("Frame").start()
-}
-
-func (c *context) endDraw() {
 	c.stats.timer("Frame").stop()
 	c.stats.frameCount++
+	c.frame++
 }
 
 func (c *context) getOrCreateTextureContext(t *texture) *textureContext {
@@ -97,6 +105,7 @@ func (c *context) getOrCreateTextureContext(t *texture) *textureContext {
 		c.textureContexts[t] = tc
 		c.stats.textureCount++
 	}
+	tc.lastContextUse = c.frame
 	return tc
 }
 
@@ -107,6 +116,7 @@ func (c *context) getOrCreateVertexStreamContext(vs *vertexStream) *vertexStream
 		c.vertexStreamContexts[vs] = vc
 		c.stats.vertexStreamCount++
 	}
+	vc.lastContextUse = c.frame
 	return vc
 }
 
@@ -117,6 +127,7 @@ func (c *context) getOrCreateIndexBufferContext(ib *indexBuffer) *indexBufferCon
 		c.indexBufferContexts[ib] = ic
 		c.stats.indexBufferCount++
 	}
+	ic.lastContextUse = c.frame
 	return ic
 }
 

drivers/gl/glyph_page.go

@@ -5,11 +5,12 @@
 package gl
 
 import (
-	"github.com/google/gxui/math"
 	"image"
 	"image/png"
 	"os"
 
+	"github.com/google/gxui/math"
+
 	"code.google.com/p/freetype-go/freetype/raster"
 	"code.google.com/p/freetype-go/freetype/truetype"
 )
@@ -158,11 +159,7 @@ func (p *glyphPage) add(rune rune, g *glyph) bool {
 	if h > p.rowHeight {
 		p.rowHeight = h
 	}
-
-	if p.tex != nil {
-		p.tex.Release()
-		p.tex = nil
-	}
+	p.tex = nil
 
 	return true
 }

drivers/gl/index_buffer.go

@@ -12,17 +12,10 @@ import (
 )
 
 type indexBuffer struct {
-	refCounted
 	data []byte
 	ty   primitiveType
 }
 
-type indexBufferContext struct {
-	buffer gl.Buffer
-	ty     primitiveType
-	length int
-}
-
 func newIndexBuffer(ty primitiveType, data16 []uint16) *indexBuffer {
 	switch ty {
 	case ptUbyte, ptUshort, ptUint:
@@ -44,19 +37,9 @@ func newIndexBuffer(ty primitiveType, data16 []uint16) *indexBuffer {
 		data: data,
 		ty:   ty,
 	}
-	ib.init()
-	globalStats.indexBufferCount.inc()
 	return ib
 }
 
-func (b *indexBuffer) release() bool {
-	if !b.refCounted.release() {
-		return false
-	}
-	globalStats.indexBufferCount.dec()
-	return true
-}
-
 func (b *indexBuffer) newContext() *indexBufferContext {
 	dataVal := reflect.ValueOf(b.data)
 	length := dataVal.Len() / 2 // HACK: Hardcode support for only ptUshort.
@@ -67,14 +50,23 @@ func (b *indexBuffer) newContext() *indexBufferContext {
 	gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, gl.Buffer{})
 	checkError()
 
+	globalStats.indexBufferContextCount.inc()
 	return &indexBufferContext{
 		buffer: buffer,
 		ty:     b.ty,
 		length: length,
 	}
 }
 
+type indexBufferContext struct {
+	contextResource
+	buffer gl.Buffer
+	ty     primitiveType
+	length int
+}
+
 func (c *indexBufferContext) destroy() {
+	globalStats.indexBufferContextCount.dec()
 	gl.DeleteBuffer(c.buffer)
 	c.buffer = gl.Buffer{}
 }

drivers/gl/refcounted.go

@@ -4,6 +4,7 @@
 
 package gl
 
+/*
 import (
 	"fmt"
 	"runtime"
@@ -72,3 +73,4 @@ func (r *refCounted) assertAlive(funcName string) {
 		}
 	}
 }
+*/

drivers/gl/shape.go

@@ -7,7 +7,6 @@ package gl
 import "github.com/goxjs/gl"
 
 type shape struct {
-	refCounted
 	vb       *vertexBuffer
 	ib       *indexBuffer
 	drawMode drawMode
@@ -23,27 +22,9 @@ func newShape(vb *vertexBuffer, ib *indexBuffer, drawMode drawMode) *shape {
 		ib:       ib,
 		drawMode: drawMode,
 	}
-	s.init()
-	globalStats.shapeCount.inc()
 	return s
 }
 
-func (s *shape) release() bool {
-	if !s.refCounted.release() {
-		return false
-	}
-	if s.vb != nil {
-		s.vb.release()
-		s.vb = nil
-	}
-	if s.ib != nil {
-		s.ib.release()
-		s.ib = nil
-	}
-	globalStats.shapeCount.dec()
-	return true
-}
-
 func newQuadShape() *shape {
 	pos := newVertexStream("aPosition", stFloatVec2, []float32{
 		0.0, 0.0,
@@ -60,8 +41,6 @@ func newQuadShape() *shape {
 }
 
 func (s shape) draw(ctx *context, shader *shaderProgram, ub uniformBindings) {
-	s.assertAlive("draw")
-
 	shader.bind(ctx, s.vb, ub)
 	if s.ib != nil {
 		ctx.getOrCreateIndexBufferContext(s.ib).render(s.drawMode)