I just attempted to draw a rectangle with dimensions 3@3 corner: 9@3. Nothing gets drawn. The reason that nothing is drawn is that the width of the rectangle is 0. This makes sense for real numbers but for a pixelated screen or other display medium the dimensions of the rectangle should be 1 x 7 not 0 x 6!?. This is 7 pixels needed to draw, not 0.
The same issues occur for the height of the rectangles.
I would think that the way things work would cause all kinds of problems but since Rectangles are pretty basic, either I am wrong, or every bit of Squeak code using rectangles has adjusted accordingly.
Please clarify.
How do Java and other languages handle this?
Ralph Boland
How would that work for horizontal bar charts in which bars with no hits would be displayed the same as bars with a single hit?
On Wed, May 24, 2017 at 11:19 PM, Ralph Boland rpboland@gmail.com wrote:
I just attempted to draw a rectangle with dimensions 3@3 corner: 9@3. Nothing gets drawn. The reason that nothing is drawn is that the width of the rectangle is 0. This makes sense for real numbers but for a pixelated screen or other display medium the dimensions of the rectangle should be 1 x 7 not 0 x 6!?. This is 7 pixels needed to draw, not 0.
The same issues occur for the height of the rectangles.
I would think that the way things work would cause all kinds of problems but since Rectangles are pretty basic, either I am wrong, or every bit of Squeak code using rectangles has adjusted accordingly.
Please clarify.
How do Java and other languages handle this?
Ralph Boland _______________________________________________ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
On Thu, May 25, 2017 at 5:19 AM, Ralph Boland rpboland@gmail.com wrote:
I just attempted to draw a rectangle with dimensions 3@3 corner: 9@3. Nothing gets drawn. The reason that nothing is drawn is that the width of the rectangle is 0. This makes sense for real numbers but for a pixelated screen or other display medium the dimensions of the rectangle should be 1 x 7 not 0 x 6!?. This is 7 pixels needed to draw, not 0.
The same issues occur for the height of the rectangles.
I would think that the way things work would cause all kinds of problems but since Rectangles are pretty basic, either I am wrong, or every bit of Squeak code using rectangles has adjusted accordingly.
Please clarify.
The coordinates refer to the imaginary lines between pixels. Thus, if you draw a rectangle from x=4 to x=5 its width is 1. This is so that if you draw multiple rectangles, they do not overlap (imagine drawing from 5 to 12 and from 12 to 19).
How do Java and other languages handle this?
Same. There's a nice illustration on this page: http://math.hws.edu/~bridgeman/courses/124/f13/doc/paint/paint.html%E2%80%8B
- Bert -
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