In some ways, android.graphics renders more like Quartz/PostScript than like QuickDraw/AWT
On Sep 11, 2008, at 9:41 AM, sahn0 wrote: Thanks for the explanation. Now I need to comprehend it :) On 11 сент, 20:28, Mike Reed <[EMAIL PROTECTED]> wrote: > /* oops, the rect example I gave is for (0,0) (2,0) */ > > On Sep 11, 2008, at 9:27 AM, Mike Reed wrote: > > The general confusion is that the android graphics geometry is center- > line based, and consistent at all matrix transformations, while J2ME > linedrawing is more "pen" based. > > As an example, when android draws a line, it basically constructs a > rectangle about the line, by moving parallel to the line by 1/2 the > strokeWidth. If there is no fancy Join (e.g. Square or Round), no > outset is performed on the line's ends. So for the line (0,0) (0,2), > it constructs the rectangle > > // assuming the strokeWidth is 1.0 > left = 0 > top = -1/2 > right = 2 > bottom = 1/2 > > and then tries to fill the rectangle, using the standard of rounding > each coordinate to an int via (int)(coord + 0.5) // for positive > coords > > That said, in your example, the strokeWidth is 0, which is a special > value meaning hairline. This is pretty close to 1.0, but will draw > slightly differently at times, but much faster. (aside: hairline > stroking always draws 1-pixel wide, regardless of the matrix on the > canvas). > > Stroking rectangles in hairline mode does a little extra work to be > nice to try to hit all of the corners, even if the normal hairline > drawLine path would have missed it. > > But back to center-line geometry. The upshot really is, if you want to > trivially predict what pixels will be hit for stroking, put your > geometry on 1/2 pixel boundaries. Then when I outset by 1/2 the > strokeWidth, the center-line pixel will always get hit. > > mike > > On Sep 11, 2008, at 9:12 AM, sahn0 wrote: > > Yes, p is Paint object set up as follows: > > Paint p=new Paint(); > p.setColor(0xFF800000); > p.setStyle(Paint.Style.STROKE); > > Style.STROKE is needed for drawRect to actually draw rect, issue with > right-bottom pixel shows itself independently of Style. > > On 11 сент, 19:48, Mike Reed <[EMAIL PROTECTED]> wrote: > >> Might be a bug. Can you put a more complete code snippet (including >> how the paint (p) was setup) into the bug? > >> thanks, >> mike --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
