Revert 2 commits using ColorM cache

This reverts commit 87c8625692.
This reverts commit a6dd6196b4.

Reason: Performance regression (#1655)

Closes #1655

ebitenutil/shapes.go

@@ -20,6 +20,7 @@ import (
 	"math"
 
 	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/internal/colormcache"
 )
 
 var (
@@ -31,17 +32,11 @@ func init() {
 	emptyImage.Fill(color.White)
 }
 
-func colorToScale(clr color.Color) (float64, float64, float64, float64) {
-	cr, cg, cb, ca := clr.RGBA()
-	if ca == 0 {
-		return 0, 0, 0, 0
-	}
-	return float64(cr) / float64(ca), float64(cg) / float64(ca), float64(cb) / float64(ca), float64(ca) / 0xffff
-}
-
 // DrawLine draws a line segment on the given destination dst.
 //
 // DrawLine is intended to be used mainly for debugging or prototyping purpose.
+//
+// DrawLine is not concurrent-safe.
 func DrawLine(dst *ebiten.Image, x1, y1, x2, y2 float64, clr color.Color) {
 	length := math.Hypot(x2-x1, y2-y1)
 
@@ -49,7 +44,7 @@ func DrawLine(dst *ebiten.Image, x1, y1, x2, y2 float64, clr color.Color) {
 	op.GeoM.Scale(length, 1)
 	op.GeoM.Rotate(math.Atan2(y2-y1, x2-x1))
 	op.GeoM.Translate(x1, y1)
-	op.ColorM.Scale(colorToScale(clr))
+	op.ColorM = colormcache.ColorToColorM(clr)
 	// Filter must be 'nearest' filter (default).
 	// Linear filtering would make edges blurred.
 	dst.DrawImage(emptySubImage, op)
@@ -58,11 +53,13 @@ func DrawLine(dst *ebiten.Image, x1, y1, x2, y2 float64, clr color.Color) {
 // DrawRect draws a rectangle on the given destination dst.
 //
 // DrawRect is intended to be used mainly for debugging or prototyping purpose.
+//
+// DrawRect is not concurrent-safe.
 func DrawRect(dst *ebiten.Image, x, y, width, height float64, clr color.Color) {
 	op := &ebiten.DrawImageOptions{}
 	op.GeoM.Scale(width, height)
 	op.GeoM.Translate(x, y)
-	op.ColorM.Scale(colorToScale(clr))
+	op.ColorM = colormcache.ColorToColorM(clr)
 	// Filter must be 'nearest' filter (default).
 	// Linear filtering would make edges blurred.
 	dst.DrawImage(emptyImage.SubImage(image.Rect(1, 1, 2, 2)).(*ebiten.Image), op)

internal/affine/colorm.go

@@ -17,7 +17,6 @@ package affine
 import (
 	"image/color"
 	"math"
-	"sync"
 )
 
 // ColorMDim is a dimension of a ColorM.
@@ -442,16 +441,15 @@ func (c *ColorM) Concat(other *ColorM) *ColorM {
 // Scale scales the matrix by (r, g, b, a).
 func (c *ColorM) Scale(r, g, b, a float32) *ColorM {
 	if !c.isInited() {
-		return getCachedScalingColorM(r, g, b, a)
+		return &ColorM{
+			body: []float32{
+				r, 0, 0, 0,
+				0, g, 0, 0,
+				0, 0, b, 0,
+				0, 0, 0, a,
+			},
 		}
-
-	if c.ScaleOnly() {
-		if c.body == nil {
-			return getCachedScalingColorM(r, g, b, a)
 	}
-		return getCachedScalingColorM(r*c.body[0], g*c.body[5], b*c.body[10], a*c.body[15])
-	}
-
 	eb := make([]float32, len(colorMIdentityBody))
 	if c.body != nil {
 		copy(eb, c.body)
@@ -551,62 +549,3 @@ func (c *ColorM) ChangeHSV(hueTheta float64, saturationScale float32, valueScale
 	c = c.Concat(yCbCrToRgb)
 	return c
 }
-
-type cachedScalingColorMKey struct {
-	r, g, b, a float32
-}
-
-type cachedScalingColorMValue struct {
-	c     *ColorM
-	atime uint64
-}
-
-var (
-	cachedScalingColorM  = map[cachedScalingColorMKey]*cachedScalingColorMValue{}
-	cachedScalingColorMM sync.Mutex
-	cacheMonotonicClock  uint64
-)
-
-func getCachedScalingColorM(r, g, b, a float32) *ColorM {
-	key := cachedScalingColorMKey{r, g, b, a}
-
-	cachedScalingColorMM.Lock()
-	defer cachedScalingColorMM.Unlock()
-
-	cacheMonotonicClock++
-	now := cacheMonotonicClock
-
-	if v, ok := cachedScalingColorM[key]; ok {
-		v.atime = now
-		return v.c
-	}
-
-	const maxCacheSize = 512 // An arbitrary number
-
-	for len(cachedScalingColorM) >= maxCacheSize {
-		var oldest uint64 = math.MaxUint64
-		var oldestKey cachedScalingColorMKey
-		for k, v := range cachedScalingColorM {
-			if v.atime < oldest {
-				oldestKey = k
-				oldest = v.atime
-			}
-		}
-		delete(cachedScalingColorM, oldestKey)
-	}
-
-	v := &cachedScalingColorMValue{
-		c: &ColorM{
-			body: []float32{
-				r, 0, 0, 0,
-				0, g, 0, 0,
-				0, 0, b, 0,
-				0, 0, 0, a,
-			},
-		},
-		atime: now,
-	}
-	cachedScalingColorM[key] = v
-
-	return v.c
-}

internal/affine/colorm_test.go

@@ -22,33 +22,6 @@ import (
 	. "github.com/hajimehoshi/ebiten/v2/internal/affine"
 )
 
-func TestColorMScale(t *testing.T) {
-	cases := []struct {
-		In  *ColorM
-		Out *ColorM
-	}{
-		{
-			nil,
-			(*ColorM)(nil).Scale(0.25, 0.5, 0.75, 1),
-		},
-		{
-			(*ColorM)(nil).Scale(0.5, 0.5, 0.5, 0.8),
-			(*ColorM)(nil).Scale(0.125, 0.25, 0.375, 0.8),
-		},
-		{
-			(*ColorM)(nil).Translate(0, 0, 0, 0),
-			(*ColorM)(nil).Scale(0.25, 0.5, 0.75, 1),
-		},
-	}
-	for _, c := range cases {
-		got := c.In.Scale(0.25, 0.5, 0.75, 1)
-		want := c.Out
-		if got != want {
-			t.Errorf("%v.Scale(): got: %v, want: %v", c.In, got, want)
-		}
-	}
-}
-
 func TestColorMScaleOnly(t *testing.T) {
 	cases := []struct {
 		In  *ColorM

internal/colormcache/cache.go

@@ -0,0 +1,96 @@
+// Copyright 2020 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package colormcache
+
+import (
+	"image/color"
+	"math"
+
+	"github.com/hajimehoshi/ebiten/v2"
+)
+
+var (
+	monotonicClock int64
+)
+
+func now() int64 {
+	monotonicClock++
+	return monotonicClock
+}
+
+const (
+	cacheLimit = 512 // This is an arbitrary number.
+)
+
+type colorMCacheKey uint32
+
+type colorMCacheEntry struct {
+	m     ebiten.ColorM
+	atime int64
+}
+
+var (
+	colorMCache = map[colorMCacheKey]*colorMCacheEntry{}
+	emptyColorM ebiten.ColorM
+)
+
+func init() {
+	emptyColorM.Scale(0, 0, 0, 0)
+}
+
+func ColorToColorM(clr color.Color) ebiten.ColorM {
+	// RGBA() is in [0 - 0xffff]. Adjust them in [0 - 0xff].
+	cr, cg, cb, ca := clr.RGBA()
+	cr /= 0x101
+	cg /= 0x101
+	cb /= 0x101
+	ca /= 0x101
+	if ca == 0 {
+		return emptyColorM
+	}
+
+	key := colorMCacheKey(uint32(cr) | (uint32(cg) << 8) | (uint32(cb) << 16) | (uint32(ca) << 24))
+	e, ok := colorMCache[key]
+	if ok {
+		e.atime = now()
+		return e.m
+	}
+
+	if len(colorMCache) > cacheLimit {
+		oldest := int64(math.MaxInt64)
+		oldestKey := colorMCacheKey(0)
+		for key, c := range colorMCache {
+			if c.atime < oldest {
+				oldestKey = key
+				oldest = c.atime
+			}
+		}
+		delete(colorMCache, oldestKey)
+	}
+
+	cm := ebiten.ColorM{}
+	rf := float64(cr) / float64(ca)
+	gf := float64(cg) / float64(ca)
+	bf := float64(cb) / float64(ca)
+	af := float64(ca) / 0xff
+	cm.Scale(rf, gf, bf, af)
+	e = &colorMCacheEntry{
+		m:     cm,
+		atime: now(),
+	}
+	colorMCache[key] = e
+
+	return e.m
+}

text/text.go

@@ -27,6 +27,7 @@ import (
 	"golang.org/x/image/math/fixed"
 
 	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/internal/colormcache"
 	"github.com/hajimehoshi/ebiten/v2/internal/hooks"
 )
 
@@ -176,19 +177,13 @@ func Draw(dst *ebiten.Image, text string, face font.Face, x, y int, clr color.Co
 	textM.Lock()
 	defer textM.Unlock()
 
-	cr, cg, cb, ca := clr.RGBA()
-	if ca == 0 {
-		return
-	}
-
-	var colorm ebiten.ColorM
-	colorm.Scale(float64(cr)/float64(ca), float64(cg)/float64(ca), float64(cb)/float64(ca), float64(ca)/0xffff)
-
 	fx, fy := fixed.I(x), fixed.I(y)
 	prevR := rune(-1)
 
 	faceHeight := face.Metrics().Height
 
+	colorm := colormcache.ColorToColorM(clr)
+
 	for _, r := range text {
 		if prevR >= 0 {
 			fx += face.Kern(prevR, r)