add context2d setLineDash() and lineDashOffset.

Author: flyskyko

src/jspdf.js

@@ -2001,7 +2001,7 @@ function jsPDF(options) {
       font: font,
       out: out,
       newObject: newObject,
-      putStream: putStream,
+      putStream: putStream
     });
 
     if (font.isAlreadyPutted !== true) {

src/libs/FileSaver.js

@@ -90,7 +90,8 @@ var saveAs =
         /* noop */
       }
     : // Use download attribute first if possible (#193 Lumia mobile) unless this is a native app
-    (typeof HTMLAnchorElement !== "undefined" && "download" in HTMLAnchorElement.prototype)
+    typeof HTMLAnchorElement !== "undefined" &&
+      "download" in HTMLAnchorElement.prototype
     ? function saveAs(blob, name, opts) {
         var URL = _global.URL || _global.webkitURL;
         var a = document.createElement("a");

src/libs/pdfname.js

@@ -5,8 +5,11 @@
  */
 function toPDFName(str) {
   // eslint-disable-next-line no-control-regex
-  if(/[^\u0000-\u00ff]/.test(str)){ // non ascii string
-    throw new Error('Invalid PDF Name Object: ' + str + ', Only accept ASCII characters.');
+  if (/[^\u0000-\u00ff]/.test(str)) {
+    // non ascii string
+    throw new Error(
+      "Invalid PDF Name Object: " + str + ", Only accept ASCII characters."
+    );
   }
   var result = "",
     strLength = str.length;

src/modules/cell.js

@@ -442,7 +442,10 @@ import { jsPDF } from "../jspdf.js";
       });
     }
 
-    if (autoSize || (Array.isArray(headers) && typeof headers[0] === "string")) {
+    if (
+      autoSize ||
+      (Array.isArray(headers) && typeof headers[0] === "string")
+    ) {
       var headerName;
       for (i = 0; i < headerNames.length; i += 1) {
         headerName = headerNames[i];

src/modules/context2d.js

@@ -51,6 +51,8 @@ import {
     this.currentPoint = ctx.currentPoint || new Point();
     this.miterLimit = ctx.miterLimit || 10.0;
     this.lastPoint = ctx.lastPoint || new Point();
+    this.lineDashOffset = ctx.lineDashOffset || 0.0;
+    this.lineDash = ctx.lineDash || [];
 
     this.ignoreClearRect =
       typeof ctx.ignoreClearRect === "boolean" ? ctx.ignoreClearRect : true;
@@ -641,6 +643,32 @@ import {
       }
     });
 
+    /**
+     * A float specifying the amount of the line dash offset. The default value is 0.0.
+     *
+     * @name lineDashOffset
+     * @default 0.0
+     */
+    Object.defineProperty(this, "lineDashOffset", {
+      get: function() {
+        return this.ctx.lineDashOffset;
+      },
+      set: function(value) {
+        this.ctx.lineDashOffset = value;
+        setLineDash.call(this);
+      }
+    });
+
+    Object.defineProperty(this, "lineDash", {
+      get: function() {
+        return this.ctx.lineDash;
+      },
+      set: function(value) {
+        this.ctx.lineDash = value;
+        setLineDash.call(this);
+      }
+    });
+
     // Not HTML API
     Object.defineProperty(this, "ignoreClearRect", {
       get: function() {
@@ -652,6 +680,16 @@ import {
     });
   };
 
+  /**
+   * Sets the line dash pattern used when stroking lines.
+   * @name setLineDash
+   * @function
+   * @description It uses an array of values that specify alternating lengths of lines and gaps which describe the pattern.
+   */
+  Context2D.prototype.setLineDash = function(dashArray) {
+    this.lineDash = dashArray;
+  };
+
   Context2D.prototype.fill = function() {
     pathPreProcess.call(this, "fill", false);
   };
@@ -1105,6 +1143,8 @@ import {
       this.lineCap = this.ctx.lineCap;
       this.lineWidth = this.ctx.lineWidth;
       this.lineJoin = this.ctx.lineJoin;
+      this.lineDash = this.ctx.lineDash;
+      this.lineDashOffset = this.ctx.lineDashOffset;
     }
   };
 
@@ -2383,4 +2423,32 @@ import {
       Math.round(maxy - miny)
     );
   };
+
+  var getPrevLineDashValue = function(lineDash, lineDashOffset) {
+    return JSON.stringify({
+      lineDash: lineDash,
+      lineDashOffset: lineDashOffset
+    });
+  };
+
+  var setLineDash = function() {
+    // Avoid unnecessary line dash declarations.
+    if (
+      !this.prevLineDash &&
+      !this.ctx.lineDash.length &&
+      !this.ctx.lineDashOffset
+    ) {
+      return;
+    }
+
+    // Avoid unnecessary line dash declarations.
+    const nextLineDash = getPrevLineDashValue(
+      this.ctx.lineDash,
+      this.ctx.lineDashOffset
+    );
+    if (this.prevLineDash !== nextLineDash) {
+      this.pdf.setLineDash(this.ctx.lineDash, this.ctx.lineDashOffset);
+      this.prevLineDash = nextLineDash;
+    }
+  };
 })(jsPDF.API);

test/reference/lineDash.pdf

@@ -485,6 +485,81 @@ describe("Context2D: standard tests", () => {
     comparePdf(doc.output(), "moveTo_lineTo_stroke_fill.pdf", "context2d");
   });
 
+  fit("context2d: setLineDash(), lineDashOffset", () => {
+    var doc = new jsPDF({
+      orientation: "p",
+      unit: "pt",
+      format: "a4",
+      floatPrecision: 2
+    });
+    var ctx = doc.context2d;
+
+    var y = 20;
+    var pad = 20;
+
+    ctx.lineWidth = 5;
+    ctx.beginPath();
+    ctx.moveTo(20, y);
+    ctx.lineTo(200, y);
+    ctx.stroke();
+    y += pad;
+    ctx.save();
+    ctx.beginPath();
+    ctx.setLineDash([10, 20]);
+    ctx.lineDashOffset = 10;
+    ctx.moveTo(20, y);
+    ctx.lineTo(200, y);
+    ctx.stroke();
+    y += pad;
+    ctx.beginPath();
+    ctx.setLineDash([]);
+    ctx.lineDashOffset = 0;
+    ctx.moveTo(20, y);
+    ctx.lineTo(200, y);
+    ctx.stroke();
+    y += pad;
+    ctx.beginPath();
+    ctx.setLineDash([10, 20]);
+    ctx.lineDashOffset = 10;
+    ctx.moveTo(20, y);
+    ctx.lineTo(200, y);
+    ctx.stroke();
+    y += pad;
+    ctx.save();
+    ctx.beginPath();
+    ctx.setLineDash([]);
+    ctx.lineDashOffset = 0;
+    ctx.moveTo(20, y);
+    ctx.lineTo(200, y);
+    ctx.stroke();
+    y += pad;
+    ctx.restore();
+    ctx.beginPath();
+    ctx.moveTo(20, y);
+    ctx.lineTo(200, y);
+    ctx.stroke();
+    y += pad;
+    ctx.save();
+    ctx.beginPath();
+    ctx.moveTo(20, y);
+    ctx.lineTo(200, y);
+    ctx.stroke();
+    y += pad;
+    ctx.restore();
+    ctx.beginPath();
+    ctx.moveTo(20, y);
+    ctx.lineTo(200, y);
+    ctx.stroke();
+    y += pad;
+    ctx.restore();
+    ctx.beginPath();
+    ctx.moveTo(20, y);
+    ctx.lineTo(200, y);
+    ctx.stroke();
+
+    comparePdf(doc.output(), "lineDash.pdf", "context2d");
+  });
+
   it("context2d: textBaseline", () => {
     var doc = new jsPDF({
       orientation: "p",