text/v2: add tests

Updates #2454

text/v2/text_test.go

@@ -15,15 +15,25 @@
 package text_test
 
 import (
+	"image"
+	"image/color"
 	"regexp"
 	"strings"
 	"testing"
 
 	"github.com/hajimehoshi/bitmapfont/v3"
+	"golang.org/x/image/font"
+	"golang.org/x/image/math/fixed"
 
+	"github.com/hajimehoshi/ebiten/v2"
+	t "github.com/hajimehoshi/ebiten/v2/internal/testing"
 	"github.com/hajimehoshi/ebiten/v2/text/v2"
 )
 
+func TestMain(m *testing.M) {
+	t.MainWithRunLoop(m)
+}
+
 func TestGlyphIndex(t *testing.T) {
 	const sampleText = `The quick brown fox jumps
 over the lazy dog.`
@@ -38,3 +48,126 @@ over the lazy dog.`
 		t.Errorf("got: %q, want: %q", got, want)
 	}
 }
+
+func TestTextColor(t *testing.T) {
+	clr := color.RGBA{R: 0x80, G: 0x80, B: 0x80, A: 0x80}
+	img := ebiten.NewImage(30, 30)
+	op := &text.DrawOptions{}
+	op.GeoM.Translate(0, 0)
+	op.ColorScale.ScaleWithColor(clr)
+	text.Draw(img, "Hello", text.NewStdFace(bitmapfont.Face), op)
+
+	w, h := img.Bounds().Dx(), img.Bounds().Dy()
+	allTransparent := true
+	for j := 0; j < h; j++ {
+		for i := 0; i < w; i++ {
+			got := img.At(i, j)
+			want1 := color.RGBA{R: 0x80, G: 0x80, B: 0x80, A: 0x80}
+			want2 := color.RGBA{}
+			if got != want1 && got != want2 {
+				t.Errorf("img At(%d, %d): got %v; want %v or %v", i, j, got, want1, want2)
+			}
+			if got == want1 {
+				allTransparent = false
+			}
+		}
+	}
+	if allTransparent {
+		t.Fail()
+	}
+}
+
+const testStdFaceSize = 6
+
+type testStdFace struct{}
+
+func (f *testStdFace) Glyph(dot fixed.Point26_6, r rune) (dr image.Rectangle, mask image.Image, maskp image.Point, advance fixed.Int26_6, ok bool) {
+	dr = image.Rect(0, 0, testStdFaceSize, testStdFaceSize)
+	a := image.NewAlpha(dr)
+	switch r {
+	case 'a':
+		for j := dr.Min.Y; j < dr.Max.Y; j++ {
+			for i := dr.Min.X; i < dr.Max.X; i++ {
+				a.SetAlpha(i, j, color.Alpha{A: 0x80})
+			}
+		}
+	case 'b':
+		for j := dr.Min.Y; j < dr.Max.Y; j++ {
+			for i := dr.Min.X; i < dr.Max.X; i++ {
+				a.SetAlpha(i, j, color.Alpha{A: 0xff})
+			}
+		}
+	}
+	mask = a
+	advance = fixed.I(testStdFaceSize)
+	ok = true
+	return
+}
+
+func (f *testStdFace) GlyphBounds(r rune) (bounds fixed.Rectangle26_6, advance fixed.Int26_6, ok bool) {
+	bounds = fixed.R(0, 0, testStdFaceSize, testStdFaceSize)
+	advance = fixed.I(testStdFaceSize)
+	ok = true
+	return
+}
+
+func (f *testStdFace) GlyphAdvance(r rune) (advance fixed.Int26_6, ok bool) {
+	return fixed.I(testStdFaceSize), true
+}
+
+func (f *testStdFace) Kern(r0, r1 rune) fixed.Int26_6 {
+	if r1 == 'b' {
+		return fixed.I(-testStdFaceSize)
+	}
+	return 0
+}
+
+func (f *testStdFace) Close() error {
+	return nil
+}
+
+func (f *testStdFace) Metrics() font.Metrics {
+	return font.Metrics{
+		Height:     fixed.I(testStdFaceSize),
+		Ascent:     0,
+		Descent:    fixed.I(testStdFaceSize),
+		XHeight:    0,
+		CapHeight:  fixed.I(testStdFaceSize),
+		CaretSlope: image.Pt(0, 1),
+	}
+}
+
+// Issue #1378
+func TestNegativeKern(t *testing.T) {
+	f := text.NewStdFace(&testStdFace{})
+	dst := ebiten.NewImage(testStdFaceSize*2, testStdFaceSize)
+
+	// With testStdFace, 'b' is rendered at the previous position as 0xff.
+	// 'a' is rendered at the current position as 0x80.
+	op := &text.DrawOptions{}
+	op.GeoM.Translate(0, 0)
+	text.Draw(dst, "ab", f, op)
+	for j := 0; j < testStdFaceSize; j++ {
+		for i := 0; i < testStdFaceSize; i++ {
+			got := dst.At(i, j)
+			want := color.RGBA{R: 0xff, G: 0xff, B: 0xff, A: 0xff}
+			if got != want {
+				t.Errorf("At(%d, %d): got: %v, want: %v", i, j, got, want)
+			}
+		}
+	}
+
+	// The glyph 'a' should be treated correctly.
+	op = &text.DrawOptions{}
+	op.GeoM.Translate(testStdFaceSize, 0)
+	text.Draw(dst, "a", f, op)
+	for j := 0; j < testStdFaceSize; j++ {
+		for i := testStdFaceSize; i < testStdFaceSize*2; i++ {
+			got := dst.At(i, j)
+			want := color.RGBA{R: 0x80, G: 0x80, B: 0x80, A: 0x80}
+			if got != want {
+				t.Errorf("At(%d, %d): got: %v, want: %v", i, j, got, want)
+			}
+		}
+	}
+}