This is an attempt to summarize the types of scaling behaviour that can occur, and to highlight a few remaining unresolved issues. Only the behaviour of the visual bbox will be discussed. In Inkscape 0.48.4 there were two types of stretching behaviour, depending on the choice of the preference for Scale Stroke Width. The choice of the preference for Optimized/Preserved Transforms did not affect the visual appearance in Inkscape, although it did in other renderers. With the implementation of the new Cairo renderer both of these preferences now affect the visual appearance, as they should. So there are now 4 possible results. The attached file 4boxes.svg has four identical boxes in a horizontal row. After stretching vertically with the Select tool (F1) we get file 4boxes_12851.svg. The four types of stretch used here were, from left to right: scale/optimized, no scale/optimized, scale/preserved, no scale/preserved. The first three cases scale more or less as expected, the fourth case is a bit unexpected. Since the idea of a constant (apparent) stroke width is meaningless in the case of a preserved transform, what has happened here is that the geometric mean of the apparent horizontal stroke and the apparent vertical stroke has been kept constant during the stretch, which is why the stroke along the horizontal axis is so narrow. Upon looking closer, case 3, scaled/preserved, has a few minor inconsistencies: it is too narrow and there is a vertical offset. These have been addressed in rev 12852. The result is shown in the file 4boxes_12852.svg. There are two remaining issues which may be more difficult to solve. In case 4, no scale/preserved, there is a remaining vertical offset. The offset is actually more serious than it appears to be, because it is persistent, it does not go away even after performing a round trip by contracting the shape again. It appears to be related to the fact that the stretching was asymmetric. If you drag at a 45 degree angle, then there is no offset. This will be reported elsewhere as a bug. The second unresolved issue is that the appearance during the drag is not the same as the appearance after releasing the object (Bug 1258271). Hoping to raise the visibility of this behaviour because this has provoked some discussion in the past, Bug 805392, Bug 805793; and since I have no idea how to fix the remaining issues.
4boxes.svg http://inkscape.13.x6.nabble.com/file/n4969050/4boxes.svg 4boxes_12851.svg http://inkscape.13.x6.nabble.com/file/n4969050/4boxes_12851.svg 4boxes_12852.svg http://inkscape.13.x6.nabble.com/file/n4969050/4boxes_12852.svg
Cheers, Alvin
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