refactor: bitmap package
This commit is contained in:
Ilia Denisov
@@ -0,0 +1,121 @@
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package bitmap
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import (
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"fmt"
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"math"
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)
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const intSize = 32
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type bitmap struct {
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width uint32
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height uint32
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bitVector []uint32
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}
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func NewBitmap(width uint32, height uint32) bitmap {
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return bitmap{width: width, height: height, bitVector: make([]uint32, int(math.Ceil(float64(width*height)/intSize)))}
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}
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func (p bitmap) Set(x, y int) {
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boundX := (p.width + uint32(x)) % p.width
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boundY := (p.height + uint32(y)) % p.height
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p.set(boundX + boundY*p.width)
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}
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func (p bitmap) set(number uint32) {
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p.bitVector[number/intSize] |= (0b1 << (number % intSize))
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}
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func (p bitmap) IsSet(x, y int) bool {
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return p.isSet(uint32(x) + uint32(y)*p.width)
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}
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func (p bitmap) isSet(number uint32) bool {
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return p.bitVector[number/intSize]&(0b1<<(number%intSize)) > 0
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}
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func (p bitmap) Circle(x, y int, r float64) {
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plotX := 0
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plotY := int(math.Ceil(r))
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delta := 3 - 2*plotY
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lastY := plotY
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for plotX <= plotY {
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p.octant(x, y, plotX, plotY)
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if plotY < lastY {
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for lineX := 0; lineX < plotX; lineX++ {
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p.octant(x, y, lineX, plotY)
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}
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lastY = plotY
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}
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if delta < 0 {
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delta += 4*plotX + 6
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} else {
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delta += 4*(plotX-plotY) + 10
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plotY -= 1
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}
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plotX += 1
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}
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for fillX := 0; fillX < plotX; fillX++ {
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for fillY := 0; fillY <= fillX; fillY++ {
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p.octant(x, y, fillX, fillY)
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}
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}
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}
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func (p bitmap) CircleAdjacent(x, y int, r float64) {
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plotX := 0
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plotY := int(math.Ceil(r))
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delta := 1 - 2*plotY
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err := 0
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for plotX <= plotY {
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p.octant(x, y, plotX, plotY)
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err = 2*(delta+plotY) - 1
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if delta < 0 && err <= 0 {
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plotX += 1
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delta += 2*plotX + 1
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continue
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}
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if delta > 0 && err > 0 {
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plotY -= 1
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delta -= 2*plotY + 1
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continue
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}
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plotX += 1
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plotY -= 1
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delta += 2 * (plotX - plotY)
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}
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}
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func (p bitmap) octant(x, y int, plotX, plotY int) {
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p.Set(x+plotX, y+plotY)
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p.Set(x+plotX, y-plotY)
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p.Set(x-plotX, y+plotY)
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p.Set(x-plotX, y-plotY)
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p.Set(x+plotY, y+plotX)
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p.Set(x+plotY, y-plotX)
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p.Set(x-plotY, y+plotX)
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p.Set(x-plotY, y-plotX)
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}
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func (p bitmap) Clear() {
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for i := range p.bitVector {
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p.bitVector[i] &= 0
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}
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}
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func (p bitmap) String() string {
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px := map[bool]string{true: "██", false: "░░"}
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var result string
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cnt := 0
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for i := 0; i < len(p.bitVector); i++ {
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for bit := 0; bit < intSize && cnt < int(p.width*p.height); bit++ {
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result += fmt.Sprintf("%s", px[p.bitVector[i]&(0b1<<bit) > 0])
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cnt++
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if cnt%int(p.width) == 0 {
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result += "\n"
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}
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}
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}
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return result
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}
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@@ -0,0 +1,184 @@
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package bitmap_test
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import (
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"fmt"
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"math/rand"
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"os"
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"strings"
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"testing"
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"bitmap"
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)
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func TestBitVectorSize(t *testing.T) {
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type testCase struct {
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width, height uint32
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expectSize int
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}
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for _, tc := range []testCase{
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{
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width: 10,
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height: 10,
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expectSize: 4,
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},
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{
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width: 1,
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height: 1,
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expectSize: 1,
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},
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{
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width: 32,
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height: 32,
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expectSize: 32,
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},
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} {
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t.Run(fmt.Sprintf("w=%d h=%d s=%d", tc.width, tc.height, tc.expectSize), func(t *testing.T) {
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bm := bitmap.NewBitmap(tc.width, tc.height)
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l := len(bitmap.Value(bm))
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if tc.expectSize != l {
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t.Errorf("expected bitmap size: %d, got: %d", tc.expectSize, l)
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}
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})
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}
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}
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func TestSetPixel(t *testing.T) {
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type coord struct {
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x, y int
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}
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type testCase struct {
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width, height uint32
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pixels []coord
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bits []int
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}
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asMap := func(bits []int) map[int]bool {
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result := make(map[int]bool)
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for i := range bits {
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if _, ok := result[bits[i]]; ok {
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t.Fatalf("source bits duplicate at idx=%d", i)
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} else {
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result[bits[i]] = true
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}
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}
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return result
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}
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asUint32 := func(v bool) uint32 { return map[bool]uint32{true: 1, false: 0}[v] }
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for i, tc := range []testCase{
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{
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width: 5,
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height: 5,
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pixels: []coord{{0, 0}},
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bits: []int{0},
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},
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{
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width: 5,
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height: 5,
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pixels: []coord{{1, 0}},
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bits: []int{1},
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},
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{
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width: 5,
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height: 5,
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pixels: []coord{{2, 0}},
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bits: []int{2},
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},
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{
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width: 5,
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height: 5,
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pixels: []coord{{0, 1}},
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bits: []int{5},
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},
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{
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width: 5,
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height: 5,
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pixels: []coord{{4, 4}},
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bits: []int{24},
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},
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{
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width: 8,
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height: 8,
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pixels: []coord{{7, 7}},
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bits: []int{63},
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},
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} {
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t.Run(fmt.Sprintf("tc#%d", i), func(t *testing.T) {
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bm := bitmap.NewBitmap(tc.width, tc.height)
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for _, c := range tc.pixels {
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if bm.IsSet(c.x, c.y) {
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t.Errorf("expected pixel to be clear at x=%d y=%d", c.x, c.y)
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}
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bm.Set(c.x, c.y)
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if !bm.IsSet(c.x, c.y) {
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t.Errorf("expected pixel to be set at x=%d y=%d", c.x, c.y)
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}
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}
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bitVector := bitmap.Value(bm)
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bitNum := 0
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expected := asMap(tc.bits)
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for bi := range bitVector {
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for ; bitNum < (bi+1)*32; bitNum++ {
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if (bitVector[bi]>>(bitNum%32))&1 != asUint32(expected[bitNum]) {
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t.Errorf("expected: bit #%d to be %t, got %v", bitNum, expected[bitNum], uint32(1<<(bitNum%32)))
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}
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}
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}
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})
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}
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}
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func TestClear(t *testing.T) {
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var bm = bitmap.NewBitmap(10, 10)
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for range 50 {
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bm.Set(rand.Intn(10), rand.Intn(10))
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}
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var acc uint32
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for _, holder := range bitmap.Value(bm) {
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acc |= holder
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}
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if acc == 0 {
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t.Errorf("some pixels should be set")
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}
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bm.Clear()
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acc = 0
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for _, holder := range bitmap.Value(bm) {
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acc |= holder
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}
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if acc != 0 {
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t.Errorf("all pixels should be clear")
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}
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}
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func TestCircle5x5(t *testing.T) {
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type testCase struct {
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x, y int
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r float64
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filled bool
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}
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bm := bitmap.NewBitmap(80, 80)
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for i, tc := range []testCase{
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{3, 3, 0.9, false},
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} {
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file := fmt.Sprintf("assets_test/circle_case_%02d.txt", i)
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_ = file
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t.Run(file, func(t *testing.T) {
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bm.CircleAdjacent(tc.x, tc.y, tc.r)
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b, err := os.ReadFile(file)
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if err != nil {
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t.Fatal(err)
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}
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expect := strings.TrimSpace(string(b))
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if expect != bm.String() {
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t.Errorf("expect:\n%s\ngot:\n%s\n", expect, bm.String())
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}
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})
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}
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}
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func TestCircle(t *testing.T) {
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var size int = 40
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var bm1 = bitmap.NewBitmap(uint32(size), uint32(size))
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bm1.Circle(size/2+5, size/2-5, float64(size/2)-3)
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fmt.Println(bm1)
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var bm2 = bitmap.NewBitmap(uint32(size), uint32(size))
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bm2.CircleAdjacent(size/2+20, size/2, float64(size/2)-5)
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}
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@@ -0,0 +1,9 @@
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package bitmap
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import "slices"
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func (p bitmap) value() []uint32 {
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return slices.Clone(p.bitVector)
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}
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var Value = (bitmap).value
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@@ -0,0 +1,3 @@
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module bitmap
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go 1.24.5
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