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Simplfy component ordering.

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treeform 2022-05-07 12:03:03 -07:00
parent a2b6540f89
commit a6ea5fe6c2
2 changed files with 19 additions and 31 deletions
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50
src/pixie/fileformats/jpeg.nim
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@ -344,7 +344,7 @@ proc decodeSOS(state: var DecoderState) =
if state.scanComponents notin [1, 3]: if state.scanComponents notin [1, 3]:
failInvalid("unsupported scan component count") failInvalid("unsupported scan component count")
state.componentOrder = @[] state.componentOrder.setLen(0)
for i in 0 ..< state.scanComponents: for i in 0 ..< state.scanComponents:
let let
@ -799,40 +799,28 @@ template checkReset(state: var DecoderState) =
proc decodeBlocks(state: var DecoderState) = proc decodeBlocks(state: var DecoderState) =
## Decodes scan data blocks that follow a SOS block. ## Decodes scan data blocks that follow a SOS block.
if state.progressive: if state.scanComponents == 1:
if state.scanComponents == 1: # Single component pass.
# Single component pass.
let let
comp = state.componentOrder[0] comp = state.componentOrder[0]
w = (state.components[comp].width + 7) shr 3 w = (state.components[comp].width + 7) shr 3
h = (state.components[comp].height + 7) shr 3 h = (state.components[comp].height + 7) shr 3
for column in 0 ..< h: for column in 0 ..< h:
for row in 0 ..< w: for row in 0 ..< w:
state.decodeBlock(comp, row, column) state.decodeBlock(comp, row, column)
state.checkReset() state.checkReset()
else:
# Interleaved component pass.
for y in 0 ..< state.numMcuHigh:
for x in 0 ..< state.numMcuWide:
for comp in state.componentOrder:
for j in 0 ..< state.components[comp].yScale:
for i in 0 ..< state.components[comp].xScale:
let
row = (x * state.components[comp].xScale + i)
column = (y * state.components[comp].yScale + j)
state.decodeBlock(comp, row, column)
state.checkReset()
else: else:
# Interleaved regular component pass. # Interleaved regular component pass.
for y in 0 ..< state.numMcuHigh: for mcuY in 0 ..< state.numMcuHigh:
for x in 0 ..< state.numMcuWide: for mcuX in 0 ..< state.numMcuWide:
for comp in state.componentOrder: for comp in state.componentOrder:
for j in 0 ..< state.components[comp].xScale: for compY in 0 ..< state.components[comp].xScale:
for i in 0 ..< state.components[comp].yScale: for compX in 0 ..< state.components[comp].yScale:
let let
row = (x * state.components[comp].yScale + i) row = (mcuX * state.components[comp].yScale + compX)
column = (y * state.components[comp].xScale + j) col = (mcuY * state.components[comp].xScale + compY)
state.decodeBlock(comp, row, column) state.decodeBlock(comp, row, col)
state.checkReset() state.checkReset()
proc quantizationAndIDCTPass(state: var DecoderState) = proc quantizationAndIDCTPass(state: var DecoderState) =

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