| |
| function LinearCanvasGradient(x1, y1, x2, y2) { |
| this._shader = null; |
| this._colors = []; |
| this._pos = []; |
| |
| this.addColorStop = function(offset, color) { |
| if (offset < 0 || offset > 1 || !isFinite(offset)) { |
| throw 'offset must be between 0 and 1 inclusively'; |
| } |
| |
| color = parseColor(color); |
| // From the spec: If multiple stops are added at the same offset on a |
| // gradient, then they must be placed in the order added, with the first |
| // one closest to the start of the gradient, and each subsequent one |
| // infinitesimally further along towards the end point (in effect |
| // causing all but the first and last stop added at each point to be |
| // ignored). |
| // To implement that, if an offset is already in the list, |
| // we just overwrite its color (since the user can't remove Color stops |
| // after the fact). |
| var idx = this._pos.indexOf(offset); |
| if (idx !== -1) { |
| this._colors[idx] = color; |
| } else { |
| // insert it in sorted order |
| for (idx = 0; idx < this._pos.length; idx++) { |
| if (this._pos[idx] > offset) { |
| break; |
| } |
| } |
| this._pos .splice(idx, 0, offset); |
| this._colors.splice(idx, 0, color); |
| } |
| } |
| |
| this._copy = function() { |
| var lcg = new LinearCanvasGradient(x1, y1, x2, y2); |
| lcg._colors = this._colors.slice(); |
| lcg._pos = this._pos.slice(); |
| return lcg; |
| } |
| |
| this._dispose = function() { |
| if (this._shader) { |
| this._shader.delete(); |
| this._shader = null; |
| } |
| } |
| |
| this._getShader = function(currentTransform) { |
| // From the spec: "The points in the linear gradient must be transformed |
| // as described by the current transformation matrix when rendering." |
| var pts = [x1, y1, x2, y2]; |
| CanvasKit.SkMatrix.mapPoints(currentTransform, pts); |
| var sx1 = pts[0]; |
| var sy1 = pts[1]; |
| var sx2 = pts[2]; |
| var sy2 = pts[3]; |
| |
| this._dispose(); |
| this._shader = CanvasKit.MakeLinearGradientShader([sx1, sy1], [sx2, sy2], |
| this._colors, this._pos, CanvasKit.TileMode.Clamp); |
| return this._shader; |
| } |
| } |