// Encode writes the Image m to w in PNG format. Any Image may be encoded, but
// images that are not image.NRGBA might be encoded lossily.
func Encode(w io.Writer, m image.Image) os.Error {
// Obviously, negative widths and heights are invalid. Furthermore, the PNG
// spec section 11.2.2 says that zero is invalid. Excessively large images are
// also rejected.
mw, mh := int64(m.Width()), int64(m.Height())
if mw <= 0 || mh <= 0 || mw >= 1<<32 || mh >= 1<<32 {
return FormatError("invalid image size: " + strconv.Itoa64(mw) + "x" + strconv.Itoa64(mw))
}
var e encoder
e.w = w
e.m = m
e.colorType = uint8(ctTrueColorAlpha)
pal, _ := m.(*image.Paletted)
if pal != nil {
e.colorType = ctPaletted
} else if opaque(m) {
e.colorType = ctTrueColor
}
_, e.err = io.WriteString(w, pngHeader)
e.writeIHDR()
if pal != nil {
e.writePLTE(pal.Palette)
}
e.writeIDATs()
e.writeIEND()
return e.err
}
func newSampler(img image.Image) *Sampler{
s := new(Sampler);
s.texture = img;
s.tw = img.Width();
s.th = img.Height();
return s;
}
func makeGolden(dst image.Image, t drawTest) image.Image {
// Since golden is a newly allocated image, we don't have to check if the
// input source and mask images and the output golden image overlap.
golden := image.NewRGBA(image.Rect(0, 0, dst.Width(), dst.Height()))
for y := 0; y < golden.Height(); y++ {
my, sy := y, y
for x := 0; x < golden.Width(); x++ {
mx, sx := x, x
const M = 1<<16 - 1
var dr, dg, db, da uint32
if t.op == Over {
dr, dg, db, da = dst.At(x, y).RGBA()
}
sr, sg, sb, sa := t.src.At(sx, sy).RGBA()
ma := uint32(M)
if t.mask != nil {
_, _, _, ma = t.mask.At(mx, my).RGBA()
}
a := M - (sa * ma / M)
golden.Set(x, y, color.RGBA64{
uint16((dr*a + sr*ma) / M),
uint16((dg*a + sg*ma) / M),
uint16((db*a + sb*ma) / M),
uint16((da*a + sa*ma) / M),
})
}
}
return golden
}
// Returns whether or not the image is fully opaque.
func opaque(m image.Image) bool {
for y := 0; y < m.Height(); y++ {
for x := 0; x < m.Width(); x++ {
_, _, _, a := m.At(x, y).RGBA()
if a != 0xffffffff {
return false
}
}
}
return true
}
func diff(m0, m1 image.Image) os.Error {
if m0.Width() != m1.Width() || m0.Height() != m1.Height() {
return os.NewError(fmt.Sprintf("dimensions differ: %dx%d vs %dx%d", m0.Width(), m0.Height(), m1.Width(), m1.Height()))
}
for y := 0; y < m0.Height(); y++ {
for x := 0; x < m0.Width(); x++ {
r0, g0, b0, a0 := m0.At(x, y).RGBA()
r1, g1, b1, a1 := m1.At(x, y).RGBA()
if r0 != r1 || g0 != g1 || b0 != b1 || a0 != a1 {
return os.NewError(fmt.Sprintf("colors differ at (%d, %d): %v vs %v", x, y, m0.At(x, y), m1.At(x, y)))
}
}
}
return nil
}
// Draw aligns r.Min in dst with pt in src and mask
// and then replaces the rectangle r in dst with the
// result of the Porter-Duff compositing operation
// ``(src in mask) over dst.'' If mask is nil, the operation
// simplifies to ``src over dst.''
// The implementation is simple and slow.
func Draw(dst Image, r Rectangle, src, mask image.Image, pt Point) {
// Plenty of room for optimizations here.
dx, dy := src.Width(), src.Height()
if mask != nil {
if dx > mask.Width() {
dx = mask.Width()
}
if dy > mask.Width() {
dy = mask.Width()
}
}
dx -= pt.X
dy -= pt.Y
if r.Dx() > dx {
r.Max.X = r.Min.X + dx
}
if r.Dy() > dy {
r.Max.Y = r.Min.Y + dy
}
x0, x1, dx := r.Min.X, r.Max.X, 1
y0, y1, dy := r.Min.Y, r.Max.Y, 1
if image.Image(dst) == src && r.Overlaps(r.Add(pt.Sub(r.Min))) {
// Rectangles overlap: process backward?
if pt.Y < r.Min.Y || pt.Y == r.Min.Y && pt.X < r.Min.X {
x0, x1, dx = x1-1, x0-1, -1
y0, y1, dy = y1-1, y0-1, -1
}
}
var out *image.RGBA64Color
for y := y0; y != y1; y += dy {
for x := x0; x != x1; x += dx {
sx := pt.X + x - r.Min.X
sy := pt.Y + y - r.Min.Y
if mask == nil {
dst.Set(x, y, src.At(sx, sy))
continue
}
_, _, _, ma := mask.At(sx, sy).RGBA()
switch ma {
case 0:
continue
case 0xFFFFFFFF:
dst.Set(x, y, src.At(sx, sy))
default:
dr, dg, db, da := dst.At(x, y).RGBA()
dr >>= 16
dg >>= 16
db >>= 16
da >>= 16
sr, sg, sb, sa := src.At(sx, sy).RGBA()
sr >>= 16
sg >>= 16
sb >>= 16
sa >>= 16
ma >>= 16
const M = 1<<16 - 1
a := sa * ma / M
dr = (dr*(M-a) + sr*ma) / M
dg = (dg*(M-a) + sg*ma) / M
db = (db*(M-a) + sb*ma) / M
da = (da*(M-a) + sa*ma) / M
if out == nil {
out = new(image.RGBA64Color)
}
out.R = uint16(dr)
out.G = uint16(dg)
out.B = uint16(db)
out.A = uint16(da)
dst.Set(x, y, out)
}
}
}
}
func writeImage(w io.Writer, m image.Image, ct uint8) os.Error {
zw, err := zlib.NewDeflater(w)
if err != nil {
return err
}
defer zw.Close()
bpp := 0 // Bytes per pixel.
var paletted *image.Paletted
switch ct {
case ctTrueColor:
bpp = 3
case ctPaletted:
bpp = 1
paletted = m.(*image.Paletted)
case ctTrueColorAlpha:
bpp = 4
}
// cr[*] and pr are the bytes for the current and previous row.
// cr[0] is unfiltered (or equivalently, filtered with the ftNone filter).
// cr[ft], for non-zero filter types ft, are buffers for transforming cr[0] under the
// other PNG filter types. These buffers are allocated once and re-used for each row.
// The +1 is for the per-row filter type, which is at cr[*][0].
var cr [nFilter][]uint8
for i := 0; i < len(cr); i++ {
cr[i] = make([]uint8, 1+bpp*m.Width())
cr[i][0] = uint8(i)
}
pr := make([]uint8, 1+bpp*m.Width())
for y := 0; y < m.Height(); y++ {
// Convert from colors to bytes.
switch ct {
case ctTrueColor:
for x := 0; x < m.Width(); x++ {
// We have previously verified that the alpha value is fully opaque.
r, g, b, _ := m.At(x, y).RGBA()
cr[0][3*x+1] = uint8(r >> 24)
cr[0][3*x+2] = uint8(g >> 24)
cr[0][3*x+3] = uint8(b >> 24)
}
case ctPaletted:
for x := 0; x < m.Width(); x++ {
cr[0][x+1] = paletted.ColorIndexAt(x, y)
}
case ctTrueColorAlpha:
// Convert from image.Image (which is alpha-premultiplied) to PNG's non-alpha-premultiplied.
for x := 0; x < m.Width(); x++ {
c := image.NRGBAColorModel.Convert(m.At(x, y)).(image.NRGBAColor)
cr[0][4*x+1] = c.R
cr[0][4*x+2] = c.G
cr[0][4*x+3] = c.B
cr[0][4*x+4] = c.A
}
}
// Apply the filter.
f := filter(cr[0:nFilter], pr, bpp)
// Write the compressed bytes.
_, err = zw.Write(cr[f])
if err != nil {
return err
}
// The current row for y is the previous row for y+1.
pr, cr[0] = cr[0], pr
}
return nil
}
// An approximation of the sng command-line tool.
func sng(w io.WriteCloser, filename string, png image.Image) {
defer w.Close()
// For now, the go PNG parser only reads bitdepths of 8.
bitdepth := 8
// Write the filename and IHDR.
io.WriteString(w, "#SNG: from "+filename+".png\nIHDR {\n")
fmt.Fprintf(w, " width: %d; height: %d; bitdepth: %d;\n", png.Width(), png.Height(), bitdepth)
cm := png.ColorModel()
var paletted *image.Paletted
cpm, _ := cm.(image.PalettedColorModel)
switch {
case cm == image.RGBAColorModel:
io.WriteString(w, " using color;\n")
case cm == image.NRGBAColorModel:
io.WriteString(w, " using color alpha;\n")
case cpm != nil:
io.WriteString(w, " using color palette;\n")
paletted = png.(*image.Paletted)
default:
io.WriteString(w, "unknown PNG decoder color model\n")
}
io.WriteString(w, "}\n")
// We fake a gAMA output. The test files have a gAMA chunk but the go PNG parser ignores it
// (the PNG spec section 11.3 says "Ancillary chunks may be ignored by a decoder").
io.WriteString(w, "gAMA {1.0000}\n")
// Write the PLTE (if applicable).
if cpm != nil {
io.WriteString(w, "PLTE {\n")
for i := 0; i < len(cpm); i++ {
r, g, b, _ := cpm[i].RGBA()
r >>= 24
g >>= 24
b >>= 24
fmt.Fprintf(w, " (%3d,%3d,%3d) # rgb = (0x%02x,0x%02x,0x%02x)\n", r, g, b, r, g, b)
}
io.WriteString(w, "}\n")
}
// Write the IMAGE.
io.WriteString(w, "IMAGE {\n pixels hex\n")
for y := 0; y < png.Height(); y++ {
switch {
case cm == image.RGBAColorModel:
for x := 0; x < png.Width(); x++ {
rgba := png.At(x, y).(image.RGBAColor)
fmt.Fprintf(w, "%02x%02x%02x ", rgba.R, rgba.G, rgba.B)
}
case cm == image.NRGBAColorModel:
for x := 0; x < png.Width(); x++ {
nrgba := png.At(x, y).(image.NRGBAColor)
fmt.Fprintf(w, "%02x%02x%02x%02x ", nrgba.R, nrgba.G, nrgba.B, nrgba.A)
}
case cpm != nil:
for x := 0; x < png.Width(); x++ {
fmt.Fprintf(w, "%02x", paletted.ColorIndexAt(x, y))
}
}
io.WriteString(w, "\n")
}
io.WriteString(w, "}\n")
}
// DrawMask aligns r.Min in dst with sp in src and mp in mask and then replaces the rectangle r
// in dst with the result of a Porter-Duff composition. A nil mask is treated as opaque.
// The implementation is simple and slow.
// TODO(nigeltao): Optimize this.
func DrawMask(dst Image, r Rectangle, src image.Image, sp Point, mask image.Image, mp Point, op Op) {
dx, dy := src.Width()-sp.X, src.Height()-sp.Y
if mask != nil {
if dx > mask.Width()-mp.X {
dx = mask.Width() - mp.X
}
if dy > mask.Height()-mp.Y {
dy = mask.Height() - mp.Y
}
}
if r.Dx() > dx {
r.Max.X = r.Min.X + dx
}
if r.Dy() > dy {
r.Max.Y = r.Min.Y + dy
}
// TODO(nigeltao): Clip r to dst's bounding box, and handle the case when sp or mp has negative X or Y.
// TODO(nigeltao): Ensure that r is well formed, i.e. r.Max.X >= r.Min.X and likewise for Y.
// Fast paths for special cases. If none of them apply, then we fall back to a general but slow implementation.
if dst0, ok := dst.(*image.RGBA); ok {
if op == Over {
// TODO(nigeltao): Implement a fast path for font glyphs (i.e. when mask is an image.Alpha).
} else {
if mask == nil {
if src0, ok := src.(image.ColorImage); ok {
drawFill(dst0, r, src0)
return
}
if src0, ok := src.(*image.RGBA); ok {
if dst0 == src0 && r.Overlaps(r.Add(sp.Sub(r.Min))) {
// TODO(nigeltao): Implement a fast path for the overlapping case.
} else {
drawCopy(dst0, r, src0, sp)
return
}
}
}
}
}
x0, x1, dx := r.Min.X, r.Max.X, 1
y0, y1, dy := r.Min.Y, r.Max.Y, 1
if image.Image(dst) == src && r.Overlaps(r.Add(sp.Sub(r.Min))) {
// Rectangles overlap: process backward?
if sp.Y < r.Min.Y || sp.Y == r.Min.Y && sp.X < r.Min.X {
x0, x1, dx = x1-1, x0-1, -1
y0, y1, dy = y1-1, y0-1, -1
}
}
var out *image.RGBA64Color
sy := sp.Y + y0 - r.Min.Y
my := mp.Y + y0 - r.Min.Y
for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
sx := sp.X + x0 - r.Min.X
mx := mp.X + x0 - r.Min.X
for x := x0; x != x1; x, sx, mx = x+dx, sx+dx, mx+dx {
// A nil mask is equivalent to a fully opaque, infinitely large mask.
// We work in 16-bit color, so that multiplying two values does not overflow a uint32.
const M = 1<<16 - 1
ma := uint32(M)
if mask != nil {
_, _, _, ma = mask.At(mx, my).RGBA()
ma >>= 16
}
switch {
case ma == 0:
if op == Over {
// No-op.
} else {
dst.Set(x, y, zeroColor)
}
case ma == M && op == Src:
dst.Set(x, y, src.At(sx, sy))
default:
sr, sg, sb, sa := src.At(sx, sy).RGBA()
sr >>= 16
sg >>= 16
sb >>= 16
sa >>= 16
if out == nil {
out = new(image.RGBA64Color)
}
if op == Over {
dr, dg, db, da := dst.At(x, y).RGBA()
dr >>= 16
dg >>= 16
db >>= 16
da >>= 16
a := M - (sa * ma / M)
out.R = uint16((dr*a + sr*ma) / M)
out.G = uint16((dg*a + sg*ma) / M)
out.B = uint16((db*a + sb*ma) / M)
out.A = uint16((da*a + sa*ma) / M)
} else {
out.R = uint16(sr * ma / M)
out.G = uint16(sg * ma / M)
out.B = uint16(sb * ma / M)
out.A = uint16(sa * ma / M)
}
dst.Set(x, y, out)
}
}
}
}
// DrawMask aligns r.Min in dst with sp in src and mp in mask and then replaces the rectangle r
// in dst with the result of a Porter-Duff composition. A nil mask is treated as opaque.
// The implementation is simple and slow.
// TODO(nigeltao): Optimize this.
func DrawMask(dst Image, r Rectangle, src image.Image, sp Point, mask image.Image, mp Point, op Op) {
dx, dy := src.Width()-sp.X, src.Height()-sp.Y
if mask != nil {
if dx > mask.Width()-mp.X {
dx = mask.Width() - mp.X
}
if dy > mask.Height()-mp.Y {
dy = mask.Height() - mp.Y
}
}
if r.Dx() > dx {
r.Max.X = r.Min.X + dx
}
if r.Dy() > dy {
r.Max.Y = r.Min.Y + dy
}
// TODO(nigeltao): Clip r to dst's bounding box, and handle the case when sp or mp has negative X or Y.
// TODO(nigeltao): Ensure that r is well formed, i.e. r.Max.X >= r.Min.X and likewise for Y.
// Fast paths for special cases. If none of them apply, then we fall back to a general but slow implementation.
switch dst0 := dst.(type) {
case *image.RGBA:
if op == Over {
if mask == nil {
if src0, ok := src.(image.Uniform); ok {
drawFillOver(dst0, r, src0)
return
}
if src0, ok := src.(*image.RGBA); ok {
if dst0 == src0 && r.Overlaps(r.Add(sp.Sub(r.Min))) {
// TODO(nigeltao): Implement a fast path for the overlapping case.
} else {
drawCopyOver(dst0, r, src0, sp)
return
}
}
} else if mask0, ok := mask.(*image.Alpha); ok {
if src0, ok := src.(image.Uniform); ok {
drawGlyphOver(dst0, r, src0, mask0, mp)
return
}
}
} else {
if mask == nil {
if src0, ok := src.(image.Uniform); ok {
drawFillSrc(dst0, r, src0)
return
}
if src0, ok := src.(*image.RGBA); ok {
if dst0 == src0 && r.Overlaps(r.Add(sp.Sub(r.Min))) {
// TODO(nigeltao): Implement a fast path for the overlapping case.
} else {
drawCopySrc(dst0, r, src0, sp)
return
}
}
}
}
drawRGBA(dst0, r, src, sp, mask, mp, op)
return
case DrawMasker:
// Destination might wish to perform the draw operation itself
if dst0.DrawMask(r, src, sp, mask, mp, op) {
return
}
}
x0, x1, dx := r.Min.X, r.Max.X, 1
y0, y1, dy := r.Min.Y, r.Max.Y, 1
if image.Image(dst) == src && r.Overlaps(r.Add(sp.Sub(r.Min))) {
// Rectangles overlap: process backward?
if sp.Y < r.Min.Y || sp.Y == r.Min.Y && sp.X < r.Min.X {
x0, x1, dx = x1-1, x0-1, -1
y0, y1, dy = y1-1, y0-1, -1
}
}
var out *color.RGBA64
sy := sp.Y + y0 - r.Min.Y
my := mp.Y + y0 - r.Min.Y
for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
sx := sp.X + x0 - r.Min.X
mx := mp.X + x0 - r.Min.X
for x := x0; x != x1; x, sx, mx = x+dx, sx+dx, mx+dx {
ma := uint32(m)
if mask != nil {
_, _, _, ma = mask.At(mx, my).RGBA()
}
switch {
case ma == 0:
if op == Over {
// No-op.
} else {
dst.Set(x, y, zeroColor)
}
case ma == m && op == Src:
dst.Set(x, y, src.At(sx, sy))
default:
sr, sg, sb, sa := src.At(sx, sy).RGBA()
if out == nil {
out = new(color.RGBA64)
}
if op == Over {
dr, dg, db, da := dst.At(x, y).RGBA()
a := m - (sa * ma / m)
out.R = uint16((dr*a + sr*ma) / m)
out.G = uint16((dg*a + sg*ma) / m)
out.B = uint16((db*a + sb*ma) / m)
out.A = uint16((da*a + sa*ma) / m)
} else {
out.R = uint16(sr * ma / m)
out.G = uint16(sg * ma / m)
out.B = uint16(sb * ma / m)
out.A = uint16(sa * ma / m)
}
dst.Set(x, y, out)
}
}
}
}