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// Copyright 2012 The Graphics-Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package interp
import (
"image"
"image/color"
"testing"
)
type interpTest struct {
desc string
src []uint8
srcWidth int
x, y float64
expect uint8
}
func (p *interpTest) newSrc() *image.RGBA {
b := image.Rect(0, 0, p.srcWidth, len(p.src)/p.srcWidth)
src := image.NewRGBA(b)
i := 0
for y := b.Min.Y; y < b.Max.Y; y++ {
for x := b.Min.X; x < b.Max.X; x++ {
src.SetRGBA(x, y, color.RGBA{
R: p.src[i],
G: p.src[i],
B: p.src[i],
A: 0xff,
})
i++
}
}
return src
}
var interpTests = []interpTest{
{
desc: "center of a single white pixel should match that pixel",
src: []uint8{0x00},
srcWidth: 1,
x: 0.5,
y: 0.5,
expect: 0x00,
},
{
desc: "middle of a square is equally weighted",
src: []uint8{
0x00, 0xff,
0xff, 0x00,
},
srcWidth: 2,
x: 1.0,
y: 1.0,
expect: 0x80,
},
{
desc: "center of a pixel is just that pixel",
src: []uint8{
0x00, 0xff,
0xff, 0x00,
},
srcWidth: 2,
x: 1.5,
y: 0.5,
expect: 0xff,
},
{
desc: "asymmetry abounds",
src: []uint8{
0xaa, 0x11, 0x55,
0xff, 0x95, 0xdd,
},
srcWidth: 3,
x: 2.0,
y: 1.0,
expect: 0x76, // (0x11 + 0x55 + 0x95 + 0xdd) / 4
},
}
func TestBilinearRGBA(t *testing.T) {
for _, p := range interpTests {
src := p.newSrc()
// Fast path.
c := Bilinear.(RGBA).RGBA(src, p.x, p.y)
if c.R != c.G || c.R != c.B || c.A != 0xff {
t.Errorf("expect channels to match, got %v", c)
continue
}
if c.R != p.expect {
t.Errorf("%s: got 0x%02x want 0x%02x", p.desc, c.R, p.expect)
continue
}
// Standard Interp should use the fast path.
cStd := Bilinear.Interp(src, p.x, p.y)
if cStd != c {
t.Errorf("%s: standard mismatch got %v want %v", p.desc, cStd, c)
continue
}
// General case should match the fast path.
cGen := color.RGBAModel.Convert(bilinearGeneral(src, p.x, p.y))
r0, g0, b0, a0 := c.RGBA()
r1, g1, b1, a1 := cGen.RGBA()
if r0 != r1 || g0 != g1 || b0 != b1 || a0 != a1 {
t.Errorf("%s: general case mismatch got %v want %v", p.desc, c, cGen)
continue
}
}
}
func TestBilinearSubImage(t *testing.T) {
b0 := image.Rect(0, 0, 4, 4)
src0 := image.NewRGBA(b0)
b1 := image.Rect(1, 1, 3, 3)
src1 := src0.SubImage(b1).(*image.RGBA)
src1.Set(1, 1, color.RGBA{0x11, 0, 0, 0xff})
src1.Set(2, 1, color.RGBA{0x22, 0, 0, 0xff})
src1.Set(1, 2, color.RGBA{0x33, 0, 0, 0xff})
src1.Set(2, 2, color.RGBA{0x44, 0, 0, 0xff})
tests := []struct {
x, y float64
want uint8
}{
{1, 1, 0x11},
{3, 1, 0x22},
{1, 3, 0x33},
{3, 3, 0x44},
{2, 2, 0x2b},
}
for _, p := range tests {
c := Bilinear.(RGBA).RGBA(src1, p.x, p.y)
if c.R != p.want {
t.Errorf("(%.0f, %.0f): got 0x%02x want 0x%02x", p.x, p.y, c.R, p.want)
}
}
}
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