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Fix blur when drawing selection after rotation 

Note tradeoff in code comment
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Isaiah Odhner 2018-01-13 16:57:19 -05:00
parent b736695741
commit 36d8b7a2b1
1 changed files with 11 additions and 4 deletions
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15
src/Selection.js
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@ -127,13 +127,20 @@ Selection.prototype.resize = function(){
Selection.prototype.replace_canvas = function(new_canvas){
var sel = this;
var cx = sel.x + sel.width/2;
var cy = sel.y + sel.height/2;
var center_x = sel.x + sel.width/2;
var center_y = sel.y + sel.height/2;
var new_width = new_canvas.width;
var new_height = new_canvas.height;
sel.x = cx - new_width/2;
sel.y = cy - new_height/2;
// NOTE: flooring the coordinates to integers avoids blurring
// but it introduces "inching", where the selection can move along by pixels if you rotate it repeatedly
// could introduce an "error offset" just to avoid this but that seems overkill
// and then that would be weird hidden behavior, probably not worth it
// Math.round() might make it do it on fewer occasions(?),
// but then it goes down *and* to the right, 2 directions vs One Direction
// and Math.ceil() is the worst of both worlds
sel.x = ~~(center_x - new_width/2);
sel.y = ~~(center_y - new_height/2);
sel.width = new_width;
sel.height = new_height;