[squeak-dev] The Trunk: Graphics-ul.175.mcz

commits at source.squeak.org commits at source.squeak.org
Wed Jan 12 17:17:50 UTC 2011


Levente Uzonyi uploaded a new version of Graphics to project The Trunk:
http://source.squeak.org/trunk/Graphics-ul.175.mcz

==================== Summary ====================

Name: Graphics-ul.175
Author: ul
Time: 9 January 2011, 3:01:23.719 pm
UUID: ecdffa9c-6063-d44c-9c86-ac5387806de3
Ancestors: Graphics-cmm.174

- a naive fix for PNGReadWriterTest >> #testGrayScale

=============== Diff against Graphics-cmm.174 ===============

Item was changed:
  ----- Method: PNGReadWriter>>copyPixelsGray: (in category 'pixel copies') -----
  copyPixelsGray: y 
  	"Handle non-interlaced grayscale color mode (colorType = 0)"
  
+ 	| base bits bytesLeft word |
- 	| base bits |
  	bitsPerChannel = 16 ifTrue: [
  		"Warning: This is extremely slow. Besides we are downsampling to 8 bits!!"
  		| blitter |
  		blitter := BitBlt current bitPokerToForm: form.
  		0 to: width - 1 do: [ :x |
  			blitter pixelAt: x @ y put: 255 - (thisScanline at: x * 2 + 1) ].
  			^self ].
  
  	"Just copy the bits"
  
  	"This Smalltalk version might be easier to understand than the others below."
  	base := y * form width * bitsPerChannel // 32 + 1.
  	bits := form bits.
+ 	0 to: thisScanline size // 4 - 1 do: [ :i |
+ 		| ii |
- 	0 to: thisScanline size - 1 // 4 do: [ :i |
- 		| ii word |
  		ii := i * 4.
  		"This somewhat weird mixture of (#* and #+) with (#bitShift: and #bitOr:) 
  		is to make use of faster arithmetic bytecodes, but not of slow largeintegers."
  		word :=
  			(((thisScanline at: ii + 1) * 256 + 
  			(thisScanline at: ii + 2) * 256 + 
  			(thisScanline at: ii + 3)) bitShift: 8) bitOr: 
  			(thisScanline at: ii + 4).
  		bits at: base + i put: word ].	
+ 	(bytesLeft := thisScanline size bitAnd: 3) = 0 ifFalse: [
+ 		word := 0.
+ 		thisScanline size - bytesLeft + 1 to: thisScanline size do: [ :ii |
+ 			word := word * 256 + (thisScanline at: ii) ].
+ 		word := word bitShift: 8 * (4 - bytesLeft).
+ 		bits at: base + (thisScanline size // 4) put: word ].
+ 
- 	
  	"This interesting technique (By Andreas Raab) is faster for very large images, but might be slower for small ones"
  	"^self copyPixelsGrayWeirdBitBltHack: y ".
  	"It uses the following method:
  	PNGReadWriter >> copyPixelsGrayWeirdBitBltHack: y 
  	""Handle non-interlaced black and white color mode (colorType = 0)
  	By Andreas Raab""
  	
  	| source dest cmap |
  	source := Form extent: 1 @ (thisScanline size // 4) depth: 32 bits: thisScanline.
  	dest := Form extent: 1 @ (form bits size) depth: 32 bits: form bits.
  	cmap := Smalltalk isLittleEndian
  		ifTrue:[ColorMap 
  					shifts: #(-24 -8 8 24) 
  					masks: #(16rFF000000 16r00FF0000 16r0000FF00 16r000000FF)].
  	(BitBlt toForm: dest)
  		sourceForm: source;
  		destX: 0 destY: (y * form width*bitsPerChannel//32) width: 1 height: (form width+31*bitsPerChannel//32);
  		colorMap: cmap;
  		combinationRule: 3;
  		copyBits."
  		
  	"This interesting technique  (By Yoshiki Ohshima) is faster for very large images, but might be slower for small ones"
  	"form bits copyFromByteArray2: thisScanline to: y * (form width* bitsPerChannel // 32)".
  	"It uses the following method:
  	BitMap >> copyFromByteArray2: byteArray to: i
  	""This method should work with either byte orderings""
  
  	| myHack byteHack |
  	myHack := Form new hackBits: self.
  	byteHack := Form new hackBits: byteArray.
  	Smalltalk  isLittleEndian ifTrue: [byteHack swapEndianness].
  	byteHack displayOn: myHack at:  0 at i"!




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