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NanoJpeg.pas
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NanoJpeg.pas
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{Copyright (c) 2012 Ville Krumlinde
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.}
unit NanoJpeg;
interface
{.$define USE_CHROMA_FILTER}
type
//Original code by Martin Fiedler http://keyj.s2000.ws/?p=137
//Delphi port by Ville Krumlinde
TNjDecoder = class
strict private
type ErrorCodes = (
OK = 0, // decoding successful
NotAJpeg, // not a JPEG file
Unsupported, // unsupported format
OutOfMemory, // out of memory
InternalError, // internal error
SyntaxError, // syntax error
Internal_Finished); // used internally, will never be reported
type VlcCode = packed record
bits,code : byte;
end;
type PVlcCode = ^VlcCode;
type Component = record
cid,
ssx, ssy,
width, height,
stride,
qtsel,
actabsel, dctabsel,
dcpred : integer;
pixels : PByte;
end;
type PComponent = ^Component;
type Context = record
error : ErrorCodes;
pos : PByte;
size,
length,
width, height,
mbwidth, mbheight,
mbsizex, mbsizey,
ncomp : integer;
comp : array[0..2] of Component;
qtused, qtavail : integer;
qtab : array[0..3,0..63] of byte;
vlctab : array[0..3,0..65535] of VlcCode;
buf, bufbits : integer;
block : array[0..63] of integer;
rstinterval : integer;
rgb : PByte;
end;
var
ctx : Context;
const
ZZ : array[0..63] of byte = (0, 1, 8, 16, 9, 2, 3, 10, 17, 24, 32, 25, 18,
11, 4, 5, 12, 19, 26, 33, 40, 48, 41, 34, 27, 20, 13, 6, 7, 14, 21, 28, 35,
42, 49, 56, 57, 50, 43, 36, 29, 22, 15, 23, 30, 37, 44, 51, 58, 59, 52, 45,
38, 31, 39, 46, 53, 60, 61, 54, 47, 55, 62, 63);
W1 = 2841;
W2 = 2676;
W3 = 2408;
W5 = 1609;
W6 = 1108;
W7 = 565;
procedure RowIDCT(blk : PInteger);
procedure ColIDCT(blk : PInteger; pout : PByte; stride : integer);
function ShowBits(bits : integer) : integer;
procedure ByteAlign;
function Decode16(pos: PByte): word;
procedure DecodeLength;
function GetBits(bits: integer): integer;
procedure njThrow(const E: ErrorCodes);
procedure Skip(count: integer);
procedure SkipBits(bits: integer);
procedure SkipMarker;
procedure DecodeSOF;
procedure DecodeDHT;
procedure DecodeBlock(c: PComponent; pout: PByte);
procedure DecodeDQT;
procedure DecodeDRI;
function GetVLC(vlc: PVlcCode; code: PByte): integer;
procedure DecodeScan;
{$ifdef USE_CHROMA_FILTER}
procedure UpsampleV(c: PComponent);
procedure UpsampleH(c: PComponent);
{$else}
procedure Upsample(c: PComponent);
{$endif}
procedure Convert;
private
class function Clip(const X : integer) : byte;
public
function Decode(jpeg: pointer; const size: integer): boolean;
destructor Destroy; override;
function GetWidth : integer;
function GetHeight : integer;
function GetImage : pointer;
end;
implementation
{$POINTERMATH ON}
//Delphi shr does not work with negative values, use this instead
function cshr(const i : integer; const j : byte) : integer;
{$if defined(CPU386)}
asm
mov cl,j
sar eax,cl
end;
{$elseif defined(CPUX64)}
asm
mov eax,i
mov cl,j
sar eax,cl
end;
{$elseif defined(Android)}
asm
asr r0,r0,r1
end;
{$ifend}
{ TNjDecoder }
class function TNjDecoder.Clip(const X: integer): byte;
begin
if X<0 then
Result := 0
else if X>$FF then
Result := $FF
else
Result := X;
end;
procedure TNjDecoder.RowIDCT(blk: PInteger);
var
x0, x1, x2, x3, x4, x5, x6, x7, x8 : integer;
begin
x1 := blk[4] shl 11;
x2 := blk[6];
x3 := blk[2];
x4 := blk[1];
x5 := blk[7];
x6 := blk[5];
x7 := blk[3];
if (x1 or x2 or x3 or x4 or x5 or x6 or x7) = 0 then
begin
blk[0] := blk[0] shl 3;
blk[1] := blk[0];
blk[2] := blk[0];
blk[3] := blk[0];
blk[4] := blk[0];
blk[5] := blk[0];
blk[6] := blk[0];
blk[7] := blk[0];
Exit;
end;
x0 := (blk[0] shl 11) + 128;
x8 := W7 * (x4 + x5);
x4 := x8 + (W1 - W7) * x4;
x5 := x8 - (W1 + W7) * x5;
x8 := W3 * (x6 + x7);
x6 := x8 - (W3 - W5) * x6;
x7 := x8 - (W3 + W5) * x7;
x8 := x0 + x1;
x0 := x0 - x1;
x1 := W6 * (x3 + x2);
x2 := x1 - (W2 + W6) * x2;
x3 := x1 + (W2 - W6) * x3;
x1 := x4 + x6;
x4 := x4 - x6;
x6 := x5 + x7;
x5 := x5 - x7;
x7 := x8 + x3;
x8 := x8 - x3;
x3 := x0 + x2;
x0 := x0 - x2;
x2 := cshr((181 * (x4 + x5) + 128), 8);
x4 := cshr((181 * (x4 - x5) + 128), 8);
blk[0] := cshr((x7 + x1), 8);
blk[1] := cshr((x3 + x2), 8);
blk[2] := cshr((x0 + x4), 8);
blk[3] := cshr((x8 + x6), 8);
blk[4] := cshr((x8 - x6), 8);
blk[5] := cshr((x0 - x4), 8);
blk[6] := cshr((x3 - x2), 8);
blk[7] := cshr((x7 - x1), 8);
end;
procedure TNjDecoder.ColIDCT(blk : PInteger; pout : PByte; stride : integer);
var
x0, x1, x2, x3, x4, x5, x6, x7, x8 : integer;
begin
x1 := blk[8*4] shl 8;
x2 := blk[8*6];
x3 := blk[8*2];
x4 := blk[8*1];
x5 := blk[8*7];
x6 := blk[8*5];
x7 := blk[8*3];
if (x1 or x2 or x3 or x4 or x5 or x6 or x7) = 0 then
begin
x1 := Clip( cshr((blk[0] + 32), 6) + 128);
for x0 := 8 downto 1 do
begin
pout^ := x1;
Inc(pout,stride);
end;
Exit;
end;
x0 := (blk[0] shl 8) + 8192;
x8 := W7 * (x4 + x5) + 4;
x4 := cshr((x8 + (W1 - W7) * x4), 3);
x5 := cshr((x8 - (W1 + W7) * x5), 3);
x8 := W3 * (x6 + x7) + 4;
x6 := cshr((x8 - (W3 - W5) * x6), 3);
x7 := cshr((x8 - (W3 + W5) * x7), 3);
x8 := x0 + x1;
x0 := x0 - x1;
x1 := W6 * (x3 + x2) + 4;
x2 := cshr((x1 - (W2 + W6) * x2), 3);
x3 := cshr((x1 + (W2 - W6) * x3), 3);
x1 := x4 + x6;
x4 := x4 - x6;
x6 := x5 + x7;
x5 := x5 - x7;
x7 := x8 + x3;
x8 := x8 - x3;
x3 := x0 + x2;
x0 := x0 - x2;
x2 := cshr((181 * (x4 + x5) + 128), 8);
x4 := cshr((181 * (x4 - x5) + 128), 8);
pout^ := Clip((cshr((x7 + x1), 14)) + 128); Inc(pout,stride);
pout^ := Clip((cshr((x3 + x2), 14)) + 128); Inc(pout,stride);
pout^ := Clip((cshr((x0 + x4), 14)) + 128); Inc(pout,stride);
pout^ := Clip((cshr((x8 + x6), 14)) + 128); Inc(pout,stride);
pout^ := Clip((cshr((x8 - x6), 14)) + 128); Inc(pout,stride);
pout^ := Clip((cshr((x0 - x4), 14)) + 128); Inc(pout,stride);
pout^ := Clip((cshr((x3 - x2), 14)) + 128); Inc(pout,stride);
pout^ := Clip((cshr((x7 - x1), 14)) + 128);
end;
function TNjDecoder.ShowBits(bits : integer) : integer;
var
newbyte,marker : byte;
begin
if Bits=0 then
Exit(0);
while (ctx.bufbits < bits) do
begin
if (ctx.size <= 0) then
begin
ctx.buf := (ctx.buf shl 8) or $FF;
ctx.bufbits := ctx.bufbits + 8;
continue;
end;
newbyte := ctx.pos^; Inc(ctx.pos);
Dec(ctx.size);
ctx.bufbits := ctx.bufbits + 8;
ctx.buf := (ctx.buf shl 8) or newbyte;
if (newbyte = $FF) then
begin
if (ctx.size<>0) then
begin
marker := ctx.pos^; Inc(ctx.pos);
Dec(ctx.size);
case marker of
0 : ;
$D9 : ctx.Size:=0;
else
begin
if (marker and $f8)<>$d0 then
ctx.error := SyntaxError
else
begin
ctx.buf := (ctx.buf shl 8) or marker;
ctx.bufbits := ctx.bufbits + 8;
end;
end;
end;
end else
ctx.error := SyntaxError;
end;
end;
Result := (ctx.buf shr (ctx.bufbits - bits)) and ((1 shl bits) - 1);
end;
procedure TNjDecoder.SkipBits(bits : integer);
begin
if (ctx.bufbits < bits) then
ShowBits(bits);
ctx.bufbits := ctx.bufbits-bits;
end;
function TNjDecoder.GetBits(bits : integer) : integer;
begin
Result := ShowBits(bits);
SkipBits(bits);
end;
function TNjDecoder.GetHeight: integer;
begin
Result := Ctx.height;
end;
function TNjDecoder.GetImage: pointer;
begin
if ctx.ncomp = 1 then
Result := ctx.comp[0].pixels
else
Result := ctx.rgb;
end;
procedure TNjDecoder.ByteAlign;
begin
ctx.bufbits := ctx.bufbits and $F8;
end;
procedure TNjDecoder.Skip(count : integer);
begin
ctx.pos := ctx.pos + count;
ctx.size := ctx.size - count;
ctx.length := ctx.length - count;
if (ctx.size < 0) then
ctx.error := SyntaxError;
end;
function TNjDecoder.Decode16(pos : PByte) : word;
begin
Result := (pos[0] shl 8) or pos[1];
end;
procedure TNjDecoder.njThrow(const E : ErrorCodes);
begin
ctx.Error := E;
end;
procedure TNjDecoder.DecodeLength;
begin
if (ctx.size < 2) then
njThrow(SyntaxError);
ctx.length := Decode16(ctx.pos);
if (ctx.length > ctx.size) then
njThrow(SyntaxError);
Skip(2);
end;
procedure TNjDecoder.SkipMarker;
begin
DecodeLength();
Skip(ctx.length);
end;
procedure TNjDecoder.DecodeSOF;
var
i, ssxmax, ssymax : integer;
c : ^Component;
begin
ssxmax := 0; ssymax :=0;
DecodeLength();
if (ctx.length < 9) then
njThrow(SyntaxError);
if (ctx.pos[0] <> 8) then
njThrow(Unsupported);
ctx.height := Decode16(ctx.pos+1);
ctx.width := Decode16(ctx.pos+3);
ctx.ncomp := ctx.pos[5];
Skip(6);
case (ctx.ncomp) of
1,3 : ;
else
njThrow(Unsupported);
end;
if (ctx.length < (ctx.ncomp * 3)) then
njThrow(SyntaxError);
c := @ctx.comp;
for i := 0 to ctx.ncomp-1 do
begin
c.cid := ctx.pos[0];
c.ssx := ctx.pos[1] shr 4;
if c.ssx=0 then
njThrow(SyntaxError);
if (c.ssx and (c.ssx - 1))<>0 then
njThrow(Unsupported); // non-power of two
c.ssy := ctx.pos[1] and 15;
if c.ssy=0 then
njThrow(SyntaxError);
if (c.ssy and (c.ssy - 1))<>0 then
njThrow(Unsupported); // non-power of two
c.qtsel := ctx.pos[2];
if ((c.qtsel) and $FC)<>0 then
njThrow(SyntaxError);
Skip(3);
ctx.qtused := ctx.qtused or (1 shl c.qtsel);
if (c.ssx > ssxmax) then ssxmax := c.ssx;
if (c.ssy > ssymax) then ssymax := c.ssy;
Inc(C);
end;
ctx.mbsizex := ssxmax shl 3;
ctx.mbsizey := ssymax shl 3;
ctx.mbwidth := (ctx.width + ctx.mbsizex - 1) div ctx.mbsizex;
ctx.mbheight := (ctx.height + ctx.mbsizey - 1) div ctx.mbsizey;
c := @ctx.comp;
for i := 0 to ctx.ncomp-1 do
begin
c.width := (ctx.width * c.ssx + ssxmax - 1) div ssxmax;
c.stride := (c.width + 7) and $7FFFFFF8;
c.height := (ctx.height * c.ssy + ssymax - 1) div ssymax;
c.stride := ctx.mbwidth * ctx.mbsizex * c.ssx div ssxmax;
if (((c.width < 3) and (c.ssx <> ssxmax)) or ((c.height < 3) and (c.ssy <> ssymax))) then
njThrow(Unsupported);
GetMem(c.pixels,c.stride * (ctx.mbheight * ctx.mbsizey * c.ssy div ssymax));
if c.pixels=nil then
njThrow(OutOfMemory);
Inc(C);
end;
if (ctx.ncomp = 3) then
begin
GetMem(ctx.rgb, ctx.width * ctx.height * ctx.ncomp);
if ctx.rgb=nil then
njThrow(OutOfMemory);
end;
Skip(ctx.length);
end;
destructor TNjDecoder.Destroy;
var
i : integer;
begin
for i := 0 to 3-1 do
if (ctx.comp[i].pixels<>nil) then
FreeMem(ctx.comp[i].pixels);
if (ctx.rgb<>nil) then
FreeMem(ctx.rgb);
inherited;
end;
procedure TNjDecoder.DecodeDHT;
var
codelen, currcnt, remain, spread, i, j : integer;
vlc : PVlcCode;
counts : array[0..15] of byte;
code : byte;
begin
DecodeLength();
while (ctx.length >= 17) do
begin
i := ctx.pos[0];
if (i and $EC)<>0 then njThrow(SyntaxError);
if (i and $02)<>0 then njThrow(Unsupported);
i := (i or (i shr 3)) and 3; // combined DC/AC + tableid value
for codelen := 1 to 16 do
counts[codelen - 1] := ctx.pos[codelen];
Skip(17);
vlc := @ctx.vlctab[i][0];
spread := 65536;
remain := spread;
for codelen := 1 to 16 do
begin
spread := spread div (1 shl 1);
currcnt := counts[codelen - 1];
if (currcnt=0) then
Continue;
if (ctx.length < currcnt) then
njThrow(SyntaxError);
remain := remain - (currcnt shl (16 - codelen));
if (remain < 0) then
njThrow(SyntaxError);
for i := 0 to currcnt-1 do
begin
code := ctx.pos[i];
for j := spread downto 1 do
begin
vlc.bits := codelen;
vlc.code := code;
Inc(vlc);
end;
end;
Skip(currcnt);
end;
while (remain>0) do
begin
vlc.bits := 0;
Inc(vlc);
Dec(Remain);
end;
end;
if (ctx.length<>0) then
njThrow(SyntaxError);
end;
procedure TNjDecoder.DecodeDQT;
var
i : integer;
t : PByte;
begin
DecodeLength();
while (ctx.length >= 65) do
begin
i := ctx.pos[0];
if (i and $FC)<>0 then
njThrow(SyntaxError);
ctx.qtavail := ctx.qtavail or (1 shl i);
t := @ctx.qtab[i][0];
for i := 0 to 64-1 do
t[i] := ctx.pos[i + 1];
Skip(65);
end;
if (ctx.length<>0) then
njThrow(SyntaxError);
end;
procedure TNjDecoder.DecodeDRI;
begin
DecodeLength();
if (ctx.length < 2) then
njThrow(SyntaxError);
ctx.rstinterval := Decode16(ctx.pos);
Skip(ctx.length);
end;
function TNjDecoder.GetVLC(vlc : PVlcCode; code : PByte) : integer;
var
value,bits : integer;
begin
value := ShowBits(16);
bits := vlc[value].bits;
if bits=0 then
begin
ctx.error := SyntaxError;
Exit(0);
end;
SkipBits(bits);
value := vlc[value].code;
if (code<>nil) then
code^ := value;
bits := value and 15;
if (bits=0) then
Exit(0);
value := GetBits(bits);
if (value < (1 shl (bits - 1))) then
value := value + (((-1) shl bits) + 1);
Result := value;
end;
function TNjDecoder.GetWidth: integer;
begin
Result := Ctx.width;
end;
procedure TNjDecoder.DecodeBlock(c : PComponent; pout : PByte);
var
Code : byte;
Value, Coef : integer;
begin
code := 0;
coef := 0;
FillChar(ctx.block, SizeOf(Ctx.Block), 0);
c.dcpred := c.dcpred + GetVLC(@ctx.vlctab[c.dctabsel][0], nil);
ctx.block[0] := (c.dcpred) * ctx.qtab[c.qtsel][0];
repeat
value := GetVLC(@ctx.vlctab[c.actabsel][0], @code);
if (code=0) then
break; // EOB
if ( ((code and $0F)=0) and (code <> $F0)) then
njThrow(SyntaxError);
coef := coef + (code shr 4) + 1;
if (coef > 63) then
njThrow(SyntaxError);
ctx.block[ ZZ[coef] ] := value * ctx.qtab[c.qtsel][coef];
until Coef>=63;
coef := 0;
while Coef<64 do
begin
RowIDCT(@ctx.block[coef]);
Inc(Coef,8);
end;
for coef := 0 to 8-1 do
begin
ColIDCT(@ctx.block[coef], @pout[coef], c.stride);
end;
end;
procedure TNjDecoder.DecodeScan;
var
i, mbx, mby, sbx, sby, rstcount, nextrst : integer;
c : PComponent;
begin
rstcount := ctx.rstinterval;
nextrst := 0;
DecodeLength();
if (ctx.length < (4 + 2 * ctx.ncomp)) then
njThrow(SyntaxError);
if (ctx.pos[0] <> ctx.ncomp) then
njThrow(Unsupported);
Skip(1);
c := @ctx.comp;
for i := 0 to ctx.ncomp-1 do
begin
if (ctx.pos[0] <> c.cid) then
njThrow(SyntaxError);
if (ctx.pos[1] and $EE)<>0 then
njThrow(SyntaxError);
c.dctabsel := (ctx.pos[1] shr 4);
c.actabsel := (ctx.pos[1] and 1) or 2;
Skip(2);
Inc(C);
end;
if ((ctx.pos[0]<>0) or (ctx.pos[1] <> 63) or (ctx.pos[2]<>0)) then
njThrow(Unsupported);
Skip(ctx.length);
mbx := 0; mby := 0;
while True do
begin
c := @ctx.comp;
for i := 0 to ctx.ncomp-1 do
begin
for sby := 0 to c.ssy-1 do
for sbx := 0 to c.ssx-1 do
begin
DecodeBlock(c, @c.pixels[((mby * c.ssy + sby) * c.stride + mbx * c.ssx + sbx) shl 3]);
if ctx.error>OK then
Exit;
end;
Inc(C);
end;
Inc(mbx);
if (mbx >= ctx.mbwidth) then
begin
mbx := 0;
Inc(mby);
if mby >= ctx.mbheight then
Break;
end;
Dec(rstcount);
if (ctx.rstinterval<>0) and (rstcount=0) then
begin
ByteAlign();
i := GetBits(16);
if (((i and $FFF8) <> $FFD0) or ((i and 7) <> nextrst)) then
njThrow(SyntaxError);
nextrst := (nextrst + 1) and 7;
rstcount := ctx.rstinterval;
for i := 0 to 3-1 do
ctx.comp[i].dcpred := 0;
end;
end;
ctx.error := Internal_Finished;
end;
{$ifdef USE_CHROMA_FILTER}
const
CF4A = (-9);
CF4B = (111);
CF4C = (29);
CF4D = (-3);
CF3A = (28);
CF3B = (109);
CF3C = (-9);
CF3X = (104);
CF3Y = (27);
CF3Z = (-3);
CF2A = (139);
CF2B = (-11);
function CF(const X : integer) : integer;
begin
Result := TNjDecoder.clip( cshr((x + 64), 7) );
end;
procedure TNjDecoder.UpsampleH(c : PComponent);
var
xmax,x,y : integer;
pout,lin,lout : PByte;
begin
xmax := c.width - 3;
GetMem(pout, (c.width * c.height) shl 1);
if (pout=nil) then
njThrow(OutOfMemory);
lin := c.pixels;
lout := pout;
for y := c.height downto 1 do
begin
lout[0] := CF(CF2A * lin[0] + CF2B * lin[1]);
lout[1] := CF(CF3X * lin[0] + CF3Y * lin[1] + CF3Z * lin[2]);
lout[2] := CF(CF3A * lin[0] + CF3B * lin[1] + CF3C * lin[2]);
for x := 0 to xmax-1 do
begin
lout[(x shl 1) + 3] := CF(CF4A * lin[x] + CF4B * lin[x + 1] + CF4C * lin[x + 2] + CF4D * lin[x + 3]);
lout[(x shl 1) + 4] := CF(CF4D * lin[x] + CF4C * lin[x + 1] + CF4B * lin[x + 2] + CF4A * lin[x + 3]);
end;
lin := lin + c.stride;
lout := lout + (c.width shl 1);
lout[-3] := CF(CF3A * lin[-1] + CF3B * lin[-2] + CF3C * lin[-3]);
lout[-2] := CF(CF3X * lin[-1] + CF3Y * lin[-2] + CF3Z * lin[-3]);
lout[-1] := CF(CF2A * lin[-1] + CF2B * lin[-2]);
end;
c.width := c.width shl 1;
c.stride := c.width;
FreeMem(c.pixels);
c.pixels := pout;
end;
procedure TNjDecoder.UpsampleV(c : PComponent);
var
w,s1,s2,x,y : integer;
pout,cin,cout : PByte;
begin
w := c.width;
s1 := c.stride;
s2 := s1 + s1;
GetMem(pout,(c.width * c.height) shl 1);
if (pout=nil) then
njThrow(OutOfMemory);
for x := 0 to w-1 do
begin
cin := @c.pixels[x];
cout := @pout[x];
cout^ := CF(CF2A * cin[0] + CF2B * cin[s1]); cout := cout + w;
cout^ := CF(CF3X * cin[0] + CF3Y * cin[s1] + CF3Z * cin[s2]); cout := cout + w;
cout^ := CF(CF3A * cin[0] + CF3B * cin[s1] + CF3C * cin[s2]); cout := cout + w;
cin := cin + s1;
for y := c.height - 3 downto 1 do
begin
cout^ := CF(CF4A * cin[-s1] + CF4B * cin[0] + CF4C * cin[s1] + CF4D * cin[s2]); cout := cout + w;
cout^ := CF(CF4D * cin[-s1] + CF4C * cin[0] + CF4B * cin[s1] + CF4A * cin[s2]); cout := cout + w;
cin := cin + s1;
end;
cin := cin + s1;
cout^ := CF(CF3A * cin[0] + CF3B * cin[-s1] + CF3C * cin[-s2]); cout := cout + w;
cout^ := CF(CF3X * cin[0] + CF3Y * cin[-s1] + CF3Z * cin[-s2]); cout := cout + w;
cout^ := CF(CF2A * cin[0] + CF2B * cin[-s1]);
end;
c.height := c.height shl 1;
c.stride := c.width;
FreeMem(c.pixels);
c.pixels := pout;
end;
{$else}
procedure TNjDecoder.Upsample(c : PComponent);
var
x, y, xshift, yshift : integer;
pout, lin, lout : PByte;
begin
xshift := 0; yshift := 0;
while (c.width < ctx.width) do
begin
c.width := c.width shl 1;
Inc(xshift);
end;
while (c.height < ctx.height) do
begin
c.height := c.height shl 1;
Inc(yshift);
end;
GetMem(pout, c.width * c.height);
if pout=nil then
njThrow(OutOfMemory);
lout := pout;
for y := 0 to c.height-1 do
begin
lin := @c.pixels[(y shr yshift) * c.stride];
for x := 0 to c.width-1 do
lout[x] := lin[(x shr xshift)];
lout := lout + c.width;
end;
c.stride := c.width;
FreeMem(c.pixels);
c.pixels := pout;
end;
{$endif}
procedure TNjDecoder.Convert;
var
i : integer;
c : PComponent;
x, yy : integer;
prgb,py,pcb,pcr,pin,pout : PByte;
y,cb,cr : integer;
begin
c := @ctx.comp;
for i := 0 to ctx.ncomp-1 do
begin
{$ifdef USE_CHROMA_FILTER}
while (c.width < ctx.width) or (c.height < ctx.height) do
begin
if (c.width < ctx.width) then UpsampleH(c);
// if (ctx.error>OK) then Exit;
if (c.height < ctx.height) then UpsampleV(c);
// if (ctx.error>OK) then Exit;
end;
{$else}
if ((c.width < ctx.width) or (c.height < ctx.height)) then
Upsample(c);
{$endif}
if ((c.width < ctx.width) or (c.height < ctx.height)) then
njThrow(InternalError);
Inc(c);
end;
if (ctx.ncomp = 3) then
begin
// convert to RGB (and flip vertical)
prgb := ctx.rgb;
py := ctx.comp[0].pixels + (ctx.height-1)*ctx.comp[0].stride;
pcb := ctx.comp[1].pixels + (ctx.height-1)*ctx.comp[1].stride;
pcr := ctx.comp[2].pixels + (ctx.height-1)*ctx.comp[2].stride;
for yy := ctx.height downto 1 do
begin
for x := 0 to ctx.width-1 do
begin
y := py[x] shl 8;
cb := pcb[x] - 128;
cr := pcr[x] - 128;
prgb^ := Clip(cshr((y + 359 * cr + 128), 8)); Inc(prgb);
prgb^ := Clip(cshr((y - 88 * cb - 183 * cr + 128), 8)); Inc(prgb);
prgb^ := Clip(cshr((y + 454 * cb + 128), 8)); Inc(prgb);
end;
py := py - ctx.comp[0].stride;
pcb := pcb - ctx.comp[1].stride;
pcr := pcr - ctx.comp[2].stride;
end;
end else if (ctx.comp[0].width <> ctx.comp[0].stride) then
begin
// grayscale -> only remove stride
pin := @ctx.comp[0].pixels[ctx.comp[0].stride];
pout := @ctx.comp[0].pixels[ctx.comp[0].width];
for y := ctx.comp[0].height - 1 downto 1 do
begin
Move(pout^, pin^, ctx.comp[0].width);
Inc(pin,ctx.comp[0].stride);
Inc(pout,ctx.comp[0].width);
end;
ctx.comp[0].stride := ctx.comp[0].width;
end;
end;
function TNjDecoder.Decode(jpeg : pointer; const size : integer) : boolean;
begin
ctx.pos := jpeg;
ctx.size := size and $7FFFFFFF;
if (ctx.size < 2) then
Exit(False);//return NJ_NO_JPEG;
if (((ctx.pos[0] xor $FF)<>0) or ((ctx.pos[1] xor $D8)<>0)) then
Exit(False);//return NJ_NO_JPEG;
Skip(2);
while ctx.error=OK do
begin
if ((ctx.size < 2) or (ctx.pos[0] <> $FF)) then
Exit(False);//return NJ_SYNTAX_ERROR;
Skip(2);
case (ctx.pos[-1]) of
$C0: DecodeSOF();
$C4: DecodeDHT();
$DB: DecodeDQT();
$DD: DecodeDRI();
$DA: DecodeScan();
$FE: SkipMarker();
else
begin
if ((ctx.pos[-1] and $F0) = $E0) then
SkipMarker()
else
Exit(False);//return NJ_UNSUPPORTED;
end;
end;
end;
if (ctx.error<>Internal_Finished) then
Exit(False);
Convert();
Result := True;
end;
end.