Revert "Revert 2 commits using ColorM cache"

This reverts commit dd7a8bc497.

Reason: DrawTriangles worked fine for the reporter's purpose.

Updates #1655

ebitenutil/shapes.go

@@ -20,7 +20,6 @@ import (
 	"math"
 
 	"github.com/hajimehoshi/ebiten/v2"
-	"github.com/hajimehoshi/ebiten/v2/internal/colormcache"
 )
 
 var (
@@ -32,11 +31,17 @@ 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)
 
@@ -44,7 +49,7 @@ 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 = colormcache.ColorToColorM(clr)
+	op.ColorM.Scale(colorToScale(clr))
 	// Filter must be 'nearest' filter (default).
 	// Linear filtering would make edges blurred.
 	dst.DrawImage(emptySubImage, op)
@@ -53,13 +58,11 @@ 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 = colormcache.ColorToColorM(clr)
+	op.ColorM.Scale(colorToScale(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

@@ -17,6 +17,7 @@ package affine
 import (
 	"image/color"
 	"math"
+	"sync"
 )
 
 // ColorMDim is a dimension of a ColorM.
@@ -441,15 +442,16 @@ 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 &ColorM{
-			body: []float32{
-				r, 0, 0, 0,
-				0, g, 0, 0,
-				0, 0, b, 0,
-				0, 0, 0, a,
-			},
-		}
+		return getCachedScalingColorM(r, g, b, 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)
@@ -549,3 +551,62 @@ 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

@@ -22,6 +22,33 @@ 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

@@ -1,96 +0,0 @@
-// 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

@@ -27,7 +27,6 @@ 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"
 )
 
@@ -177,13 +176,19 @@ 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)