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Why are there black pixels left in the drawing area?

April 26, 2017area Black drawing Left pixels

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Why are there black pixels left in the drawing area?

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If you find the pixels droppings disturbing, do a refresh (). If you are not interested in technical details, skip the rest of this question. TCM draws in exclusive or (XOR) mode. In XOR mode, a new destination pixel is produced by the exclusive or of the old destination pixel with the source pixel. In this mode, you can easily draw and erase a figure. You draw a figure to let it appear, and when you redraw it, you erase it. By sequencing drawing and redrawing you can simulating a shape being moved or dragged. Furthermore, in XOR mode, shapes can overlap each other without damaging each other. The overlapping part is rendered white, and when one of the shapes is moved or removed, it will be redrawn, so the overlapping part will then appear black again. For some reason a small rounding error can sometimes occur in drawing some kind of shape and that results in some remaining black pixels. When you do a refresh, these pixels disappear. A feature of TCM is that it maintains a seco