From e0741dcd9495c79ba37a38b21f6c92ba467997f3 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sat, 9 Dec 2023 22:01:28 +0900
Subject: [PATCH] text/v2: refactoring

---
 text/v2/export_test.go |  35 +++++++++++++
 text/v2/text.go        |  13 ++---
 text/v2/text_test.go   | 116 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 155 insertions(+), 9 deletions(-)
 create mode 100644 text/v2/export_test.go

diff --git a/text/v2/export_test.go b/text/v2/export_test.go
new file mode 100644
index 000000000..3f42d202a
--- /dev/null
+++ b/text/v2/export_test.go
@@ -0,0 +1,35 @@
+// Copyright 2023 The Ebitengine 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 text
+
+import (
+	"golang.org/x/image/math/fixed"
+)
+
+func Fixed26_6ToFloat32(x fixed.Int26_6) float32 {
+	return fixed26_6ToFloat32(x)
+}
+
+func Fixed26_6ToFloat64(x fixed.Int26_6) float64 {
+	return fixed26_6ToFloat64(x)
+}
+
+func Float32ToFixed26_6(x float32) fixed.Int26_6 {
+	return float32ToFixed26_6(x)
+}
+
+func Float64ToFixed26_6(x float64) fixed.Int26_6 {
+	return float64ToFixed26_6(x)
+}
diff --git a/text/v2/text.go b/text/v2/text.go
index 9d133435b..3e47aa770 100644
--- a/text/v2/text.go
+++ b/text/v2/text.go
@@ -18,7 +18,6 @@
 package text
 
 import (
-	"math"
 	"strings"
 
 	"golang.org/x/image/math/fixed"
@@ -72,23 +71,19 @@ type Metrics struct {
 }
 
 func fixed26_6ToFloat32(x fixed.Int26_6) float32 {
-	return float32(x>>6) + float32(x&((1<<6)-1))/float32(1<<6)
+	return float32(x) / (1 << 6)
 }
 
 func fixed26_6ToFloat64(x fixed.Int26_6) float64 {
-	return float64(x>>6) + float64(x&((1<<6)-1))/float64(1<<6)
+	return float64(x) / (1 << 6)
 }
 
 func float32ToFixed26_6(x float32) fixed.Int26_6 {
-	i := float32(math.Floor(float64(x)))
-	frac := x - i
-	return fixed.Int26_6(i)<<6 + fixed.Int26_6(frac*(1<<6))
+	return fixed.Int26_6(x * (1 << 6))
 }
 
 func float64ToFixed26_6(x float64) fixed.Int26_6 {
-	i := math.Floor(x)
-	frac := x - i
-	return fixed.Int26_6(i)<<6 + fixed.Int26_6(frac*(1<<6))
+	return fixed.Int26_6(x * (1 << 6))
 }
 
 func glyphVariationCount(face Face) int {
diff --git a/text/v2/text_test.go b/text/v2/text_test.go
index 21b258012..fb7aa6089 100644
--- a/text/v2/text_test.go
+++ b/text/v2/text_test.go
@@ -240,3 +240,119 @@ func TestUnhashableFace(t *testing.T) {
 		}
 	}
 }
+
+func TestConvertToFixed26_6(t *testing.T) {
+	testCases := []struct {
+		In  float64
+		Out fixed.Int26_6
+	}{
+		{
+			In:  0,
+			Out: 0,
+		},
+		{
+			In:  0.25,
+			Out: fixed.I(1) / 4,
+		},
+		{
+			In:  0.5,
+			Out: fixed.I(1) / 2,
+		},
+		{
+			In:  1.25,
+			Out: fixed.I(1) * 5 / 4,
+		},
+		{
+			In:  1,
+			Out: fixed.I(1),
+		},
+		{
+			In:  -0.25,
+			Out: fixed.I(-1) / 4,
+		},
+		{
+			In:  -0.5,
+			Out: fixed.I(-1) / 2,
+		},
+		{
+			In:  -1,
+			Out: fixed.I(-1),
+		},
+		{
+			In:  -1.25,
+			Out: fixed.I(-1) * 5 / 4,
+		},
+	}
+
+	for _, tc := range testCases {
+		got := text.Float32ToFixed26_6(float32(tc.In))
+		want := tc.Out
+		if got != want {
+			t.Errorf("Float32ToFixed26_6(%v): got: %v, want: %v", tc.In, got, want)
+		}
+
+		got = text.Float64ToFixed26_6(tc.In)
+		want = tc.Out
+		if got != want {
+			t.Errorf("Float32ToFixed26_6(%v): got: %v, want: %v", tc.In, got, want)
+		}
+	}
+}
+
+func TestConvertToFloat(t *testing.T) {
+	testCases := []struct {
+		In  fixed.Int26_6
+		Out float64
+	}{
+		{
+			In:  0,
+			Out: 0,
+		},
+		{
+			In:  fixed.I(1) / 4,
+			Out: 0.25,
+		},
+		{
+			In:  fixed.I(1) / 2,
+			Out: 0.5,
+		},
+		{
+			In:  fixed.I(1) * 5 / 4,
+			Out: 1.25,
+		},
+		{
+			In:  fixed.I(1),
+			Out: 1,
+		},
+		{
+			In:  fixed.I(-1) / 4,
+			Out: -0.25,
+		},
+		{
+			In:  fixed.I(-1) / 2,
+			Out: -0.5,
+		},
+		{
+			In:  fixed.I(-1),
+			Out: -1,
+		},
+		{
+			In:  fixed.I(-1) * 5 / 4,
+			Out: -1.25,
+		},
+	}
+
+	for _, tc := range testCases {
+		got := text.Fixed26_6ToFloat32(tc.In)
+		want := float32(tc.Out)
+		if got != want {
+			t.Errorf("Fixed26_6ToFloat32(%v): got: %v, want: %v", tc.In, got, want)
+		}
+
+		got64 := text.Fixed26_6ToFloat64(tc.In)
+		want64 := tc.Out
+		if got64 != want64 {
+			t.Errorf("Fixed26_6ToFloat64(%v): got: %v, want: %v", tc.In, got64, want64)
+		}
+	}
+}