[Pkg] The Trunk: Graphics-tpr.225.mcz
commits at source.squeak.org
commits at source.squeak.org
Tue Sep 17 22:45:56 UTC 2013
tim Rowledge uploaded a new version of Graphics to project The Trunk:
http://source.squeak.org/trunk/Graphics-tpr.225.mcz
==================== Summary ====================
Name: Graphics-tpr.225
Author: tpr
Time: 17 September 2013, 3:44:03.769 pm
UUID: 43697020-933c-4e07-a3db-c81d40fd8015
Ancestors: Graphics-nice.224
An attempt to improve the comment for BitBlt; it was very out of date (no Patterns or MAskedForms in image now) and more than a bit confusing in places. Hopefully this is less so.
=============== Diff against Graphics-nice.224 ===============
Item was changed:
Object subclass: #BitBlt
instanceVariableNames: 'destForm sourceForm halftoneForm combinationRule destX destY width height sourceX sourceY clipX clipY clipWidth clipHeight colorMap'
classVariableNames: 'CachedFontColorMaps ColorConvertingMaps SubPixelRenderColorFonts SubPixelRenderFonts'
poolDictionaries: ''
category: 'Graphics-Primitives'!
+ !BitBlt commentStamp: 'tpr 9/17/2013 15:42' prior: 0!
+ WARNING: BitBlt's shape cannot be modified since WarpBlt relies on the exact layout. Important primitives will break if you fail to heed this warning.
- !BitBlt commentStamp: 'ar 8/4/2009 20:19' prior: 0!
- WARNING: BitBlt's shape cannot be modified since WarpBlt relies on the exact layout.
+ I represent a block transfer (BLT) of pixels from one Form ( the sourceForm) into a rectangle (destX, destY, width, height) of the destinationForm, as modified by a combination rule, a possible halftoneForm and a possible color map.
- I represent a block transfer (BLT) of pixels into a rectangle (destX, destY, width, height) of the destinationForm. The source of pixels may be a similar rectangle (at sourceX, sourceY) in the sourceForm, or a constant color, currently called halftoneForm. If both are specified, their pixel values are combined with a logical AND function prior to transfer. In any case, the pixels from the source are combined with those of the destination by as specified by the combinationRule.
+ The source of pixels may be a similar rectangle (at sourceX, sourceY) in the sourceForm, or the halftoneForm, or both. If both are specified, their pixel values are combined by a logical AND function prior to any further combination rule processing. The halftoneForm may be an actual Form or a simple WordArray of 32 bit values usually intended to represent Color values. In either case the 'top' of the form is effectively aligned with the top of the destinationForm and for each scanline the destination y modulo the size of the halftoneForm gives the index of the word to use. This makes it easy to make horizontal stripes, for example.
- The combination rule whose value is 0 through 15 programs the transfer to produce 1 or 0 according to its 4-bit representation as follows:
- 8: if source is 0 and destination is 0
- 4: if source is 0 and destination is 1
- 2: if source is 1 and destination is 0
- 1: if source is 1 and destination is 1.
- At each pixel the corresponding bits of the source and destination pixel values determine one of these conditions; if the combination rule has a 1 in the corresponding bit position, then the new destination value will be 1, otherwise it will be zero. Forms may be of different depths, see the comment in class Form.
+ In any case, the pixels from the source (AND'd with the halftone, remember) are combined with those of the destination by as specified by the combinationRules below-
+ name rule result
- In addition to the original 16 combination rules, this BitBlt supports
- 16 fails (to simulate paint bits)
- 17 fails (to simulate erase bits)
- 18 sourceWord + destinationWord
- 19 sourceWord - destinationWord
- 20 rgbAdd: sourceWord with: destinationWord. Sum of color components
- 21 rgbSub: sourceWord with: destinationWord. Difference of color components
- 22 OLDrgbDiff: sourceWord with: destinationWord. Sum of abs of differences in components
- 23 OLDtallyIntoMap: destinationWord. Tallies pixValues into a colorMap
- these old versions don't do bitwise dest clipping. Use 32 and 33 now.
- 24 alphaBlend: sourceWord with: destinationWord. 32-bit source and dest only
- 25 pixPaint: sourceWord with: destinationWord. Wherever the sourceForm is non-zero, it replaces the destination. Can be used with a 1-bit source color mapped to (0, FFFFFFFF), and a fillColor to fill the dest with that color wherever the source is 1.
- 26 pixMask: sourceWord with: destinationWord. Like pixPaint, but fills with 0.
- 27 rgbMax: sourceWord with: destinationWord. Max of each color component.
- 28 rgbMin: sourceWord with: destinationWord. Min of each color component.
- 29 rgbMin: sourceWord bitInvert32 with: destinationWord. Min with (max-source)
- 30 alphaBlendConst: sourceWord with: destinationWord. alpha is an arg. works in 16 bits.
- 31 alphaPaintConst: sourceWord with: destinationWord. alpha is an arg. works in 16 bits.
- 32 rgbDiff: sourceWord with: destinationWord. Sum of abs of differences in components
- 33 tallyIntoMap: destinationWord. Tallies pixValues into a colorMap
- 34 alphaBlendScaled: srcWord with: dstWord. Alpha blend of scaled srcWord and destWord.
+ 0 always 0
+ and 1 src AND dst
+ 2 src AND not(dst)
+ over 3 src only
+ erase 4 not(src) AND& dst
+ 5 dst only
+ reverse 6 src XOR dst
+ under 7 src OR dst
+ 8 not(src) AND not(dst)
+ 9 not(src) XOR dst
+ 10 not(dst)
+ 11 src OR not(dst)
+ 12 not(src)
+ 13 not(src) OR dst
+ 14 not(src) OR not(dst)
+ 15 always 1
+ (You can find an interesting explanation of how this comes to be in http://dev-docs.atariforge.org/files/BLiTTER_1-25-1990.pdf - which interestingly fails to mention any connection to Smalltalk and PARC.)
+ Forms may be of different depths, see the comment in class Form.
- The color specified by halftoneForm may be either a Color or a Pattern. A Color is converted to a pixelValue for the depth of the destinationForm. If a Pattern, BitBlt will simply interpret its bitmap as an array of Color pixelValues. BitBlt aligns the first element of this array with the top scanline of the destinationForm, the second with the second, and so on, cycling through the color array as necessary. Within each scan line the 32-bit value is repeated from left to right across the form. If the value repeats on pixels boudaries, the effect will be a constant color; if not, it will produce a halftone that repeats on 32-bit boundaries.
+ In addition to the original 16 combination rules invented for monochrome Forms, this BitBlt supports
+ 16 fails (to simulate paint bits)
+ 17 fails (to simulate erase bits)
+ 18 sourceWord + destinationWord
+ 19 sourceWord - destinationWord
+ 20 rgbAdd: sourceWord with: destinationWord. Sum of color components
+ 21 rgbSub: sourceWord with: destinationWord. Difference of color components
+ 22 OLDrgbDiff: sourceWord with: destinationWord. Sum of abs of differences in components
+ 23 OLDtallyIntoMap: destinationWord. Tallies pixValues into a colorMap
+ these old versions don't do bitwise dest clipping. Use 32 and 33 now.
+ blend 24 alphaBlend: sourceWord with: destinationWord. 32-bit source and dest only. Blend sourceWord
+ with destinationWord, assuming both are 32-bit pixels. The source is assumed to have 255*alpha
+ in the high 8 bits of each pixel, while the high 8 bits of the destinationWord will be ignored.
+ The blend produced is alpha*source + (1-alpha)*dest, with the computation being performed
+ independently on each color component. The high byte of the result will be 0.
+ paint 25 pixPaint: sourceWord with: destinationWord. Wherever the sourceForm is non-zero, it replaces
+ the destination. Can be used with a 1-bit source color mapped to (0, FFFFFFFF), and a fillColor
+ to fill the dest with that color wherever the source is 1.
+ erase1BitShape 26 pixMask: sourceWord with: destinationWord. Like pixPaint, but fills with 0.
+ 27 rgbMax: sourceWord with: destinationWord. Max of each color component.
+ 28 rgbMin: sourceWord with: destinationWord. Min of each color component.
+ 29 rgbMin: sourceWord bitInvert32 with: destinationWord. Min with (max-source)
+ blendAlpha 30 alphaBlendConst: sourceWord with: destinationWord. alpha is an arg. works in 16 bits. Blend
+ sourceWord with destinationWord using a constant alpha. Alpha is encoded as 0 meaning
+ 0.0, and 255 meaning 1.0. The blend produced is alpha*source + (1.0-alpha)*dest, with
+ the computation being performed independently on each color component.
+ paintAlpha 31 alphaPaintConst: sourceWord with: destinationWord. alpha is an arg. works in 16 bits.
+ 32 rgbDiff: sourceWord with: destinationWord. Sum of abs of differences in components
+ 33 tallyIntoMap: destinationWord. Tallies pixValues into a colorMap - Those tallied are exactly
+ those in the destination rectangle. Note that the source should be specified == destination,
+ in order for the proper color map checks be performed at setup.
+ blendAlphaScaled 34 alphaBlendScaled: srcWord with: dstWord. Alpha blend of scaled srcWord and destWord. In contrast
+ to alphaBlend:with: the color produced is srcColor + (1-srcAlpha) * dstColor
+ 35 & 36 not used
+ rgbMul 37 rgbMul: srcWord with: dstWord.
+ 38 pixSwap: srcWord with: dstWord.
+ 39 pixClear: srcWord with: dstWord. Clear all pixels in destinationWord for which the pixels of
+ sourceWord have the same values. Used to clear areas of some constant color to zero.
+ 40 fixAlpha: srcWord with: dstWord. For any non-zero pixel value in destinationWord with zero alpha
+ channel take the alpha from sourceWord and fill it in. Intended for fixing alpha channels left at
+ zero during 16->32 bpp conversions.
+ 41 rgbComponentAlpha: srcWord with: dstWord.
+
+ Any transfer specified is further clipped by the specified clipping rectangle (clipX, clipY, clipWidth, clipHeight), and also by the bounds of the source and destination forms.
- Any transfer specified is further clipped by the specified rectangle (clipX, clipY, clipWidth, clipHeight), and also by the bounds of the source and destination forms.
To make a small Form repeat and fill a big form, use an InfiniteForm as the source.
- To write on a form and leave with both transparent and opapue areas, use a MaskedForm as the source.
+ Pixels copied from a source to a destination whose pixels have a different depth are converted based on the optional colorMap. If colorMap is nil, then conversion to more bits is done by filling the new high-order bits with zero, and conversion to fewer bits is done by truncating the lost high-order bits.
- Pixels from a source to a destination whose pixels have a different depth are converted based on the optional colorMap. If colorMap is nil, then conversion to more bits is done by filling the new high-order bits with zero, and conversion to fewer bits is done by truncating the lost high-order bits.
The colorMap, if specified, must be a either word array (ie Bitmap) with 2^n elements, where n is the pixel depth of the source, or a fully specified ColorMap which may contain a lookup table (ie Bitmap) and/or four separate masks and shifts which are applied to the pixels. For every source pixel, BitBlt will first perform masking and shifting and then index the lookup table, and select the corresponding pixelValue and mask it to the destination pixel size before storing.
When blitting from a 32 or 16 bit deep Form to one 8 bits or less, the default is truncation. This will produce very strange colors, since truncation of the high bits does not produce the nearest encoded color. Supply a 512 long colorMap, and red, green, and blue will be shifted down to 3 bits each, and mapped. The message copybits...stdColors will use the best map to the standard colors for destinations of depths 8, 4, 2 and 1. Two other sized of colorMaps are allowed, 4096 (4 bits per color) and 32786 (five bits per color).
Normal blits between 16 and 32 bit forms truncates or pads the colors automatically to provide the best preservation of colors.
+ Colors can be remapped at the same depth. Sometimes a Form is in terms of colors that are not the standard colors for this depth, for example in a GIF file. Convert the Form to a MaskedForm and send colorMap: the list of colors that the picture is in terms of. (Note also that a Form can be copied to itself, and transformed in the process, if a non-nil colorMap is supplied.)!
- Colors can be remapped at the same depth. Sometimes a Form is in terms of colors that are not the standard colors for this depth, for example in a GIF file. Convert the Form to a MaskedForm and send colorMap: the list of colors that the picture is in terms of. MaskedForm will use the colorMap when copying to the display or another Form. (Note also that a Form can be copied to itself, and transformed in the process, if a non-nil colorMap is supplied.)!
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