Merge pull request #956 from Hardmath123/antialias

Prevent anti-aliasing when merging canvases in paint editor

paint.js

@@ -57,6 +57,7 @@
     June 4 - tweaks (Jens)
     Aug 24 - floodfill alpha-integer issue (Kartik)
     Sep 29 - tweaks (Jens)
+    Sep 28 [of the following year :)] - Try to prevent antialiasing (Kartik)
  */
 
 /*global Point, Rectangle, DialogBoxMorph, fontHeight, AlignmentMorph,
@@ -595,6 +596,7 @@ PaintCanvasMorph.prototype.scale = function (x, y) {
         this.rotationCenter.y
     );
     c.getContext("2d").scale(1 + x, 1 + y);
+    this.disableSmoothing(c.getContext("2d"));
     c.getContext("2d").drawImage(
         this.paper,
         -this.rotationCenter.x,
@@ -622,11 +624,21 @@ PaintCanvasMorph.prototype.undo = function () {
     }
 };
 
+PaintCanvasMorph.prototype.disableSmoothing = function(ctx) {
+    ctx['imageSmoothingEnabled'] = false;       /* standard */
+    ctx['mozImageSmoothingEnabled'] = false;    /* Firefox */
+    ctx['oImageSmoothingEnabled'] = false;      /* Opera */
+    ctx['webkitImageSmoothingEnabled'] = false; /* Safari */
+    ctx['msImageSmoothingEnabled'] = false;     /* IE */
+};
+
 PaintCanvasMorph.prototype.merge = function (a, b) {
+    this.disableSmoothing(b.getContext("2d"));
     b.getContext("2d").drawImage(a, 0, 0);
 };
 
 PaintCanvasMorph.prototype.centermerge = function (a, b) {
+    this.disableSmoothing(b.getContext("2d"));
     b.getContext("2d").drawImage(
         a,
         (b.width - a.width) / 2,
@@ -814,6 +826,9 @@ PaintCanvasMorph.prototype.mouseMove = function (pos) {
     mctx.lineWidth = this.settings.linewidth;
     mctx.clearRect(0, 0, this.bounds.width(), this.bounds.height()); // mask
 
+    // Antialiasing trick.
+    mctx.translate(0.5, 0.5);
+
     this.dragRect.corner = relpos.subtract(this.dragRect.origin); // reset crn
 
     if (this.settings.primarycolor === "transparent" &&