add toStream() to get a stream from canvas back

add toStream() to get a stream from canvas back
#23

Author: ushelp

demo/demo_node.js

@@ -230,4 +230,33 @@ qrcode5.toSVGText().then(data=>{
 
 qrcode8.saveSVG({
     path: 'qrcode.svg'
-})
+})
+
+
+
+var streamConfig = {
+    // ====== Basic
+    text: "https://github.com/ushelp/EasyQRCodeJS-NodeJS",
+    colorLight: 'transparent',
+    width: 150,
+    height: 150,
+    quietZone: 10,
+    quietZoneColor: 'transparent',
+}
+
+
+async function generate() {
+    var streamQrcode = new QRCode(streamConfig);
+
+    const out = fs.createWriteStream(`qrcode-stream.png`);
+    // const stream = await streamQrcode.toStream();
+    // stream.pipe(out);
+    // out.on('finish', () => console.log('Finsihed'));
+
+    streamQrcode.toStream().then(res=>{
+        res.pipe(out).on('finish', () => console.log('Stream Finsihed'));
+    })
+
+}
+
+generate();

index.d.ts

@@ -14,6 +14,8 @@ declare class QRCode {
     toDataURL(format?: any): any;
 
     toSVGText(format?: any): any;
+    
+    toStream(format?: any): any;
 
     static CorrectLevel: {
         H: number;

index.js

@@ -3,7 +3,7 @@
  *
  * NodeJS QRCode generator. Can save image or svg to file, get standard base64 image data url text or get SVG serialized text. Cross-browser QRCode generator for pure javascript. Support Dot style, Logo, Background image, Colorful, Title etc. settings. support binary mode.(Running without DOM on server side)
  *
- * Version 4.3.5
+ * Version 4.4.0
  *
  * @author [ [email protected] ]
  *
@@ -1543,6 +1543,19 @@ Drawing.prototype.makeImage = function() {
                 })
             }
         }
+    } else if (makeOptions.makeType == 'STREAM') {
+
+        if (this._htOption.onRenderingStart) {
+            this._htOption.onRenderingStart(this._htOption);
+        }
+        
+        if (this._htOption.format == 'PNG') {
+            // dataUrl = this._canvas.toDataURL()
+            t.resolve(this._canvas.createPNGStream());
+        } else {
+            t.resolve(this._canvas.createJPEGStream());
+        }
+  
     }
 };
 
@@ -1813,9 +1826,9 @@ QRCode.prototype.saveSVG = function(saveOptions) {
 };
 
 // Get Base64 or SVG text
-QRCode.prototype._toData = function(drawer) {
+QRCode.prototype._toData = function(drawer, makeType) {
     var defOptions = {
-        makeType: 'URL'
+        makeType: makeType?makeType:'URL'
     }
     this._htOption._drawer = drawer;
 
@@ -1847,7 +1860,12 @@ QRCode.prototype.toDataURL = function() {
 QRCode.prototype.toSVGText = function() {
     return this._toData('svg');
 };
-
+/**
+ * Get SVG data text: '<svg xmlns:xlink="http://www.w3.org/1999/xlink" ...'
+ */
+QRCode.prototype.toStream = function() {
+    return this._toData('canvas', 'STREAM');
+};
 
 /**
  * @name QRCode.CorrectLevel

index.min.js

@@ -1,6 +1,6 @@
 {
 	"name": "easyqrcodejs-nodejs",
-	"version": "4.3.5",
+	"version": "4.4.0",
 	"description": "NodeJS QRCode generator. Can save image or svg to file, get standard base64 image data url text or get SVG serialized text. Cross-browser QRCode generator for pure javascript. Support Dot style, Logo, Background image, Colorful, Title etc. settings. support binary mode.(Running without DOM on server side)",
 	"main": "index.min.js",
 	"scripts": {},

package.json

@@ -42,6 +42,8 @@ EasyQRCodeJS-NodeJS 是一个 NodeJS 环境下的服务端 JavaScript QRCode 图
 	- Support get standard base64 image data url text: `data:image/png;base64, ...`
 
 	- Support get SVG data text: `<svg xmlns:xlink="http://www.w3.org/1999/xlink" ...`
+
+    - Support get a stream from Canvas
 
     - Required Patterns that support dot style
 
@@ -72,6 +74,8 @@ EasyQRCodeJS-NodeJS 是一个 NodeJS 环境下的服务端 JavaScript QRCode 图
 	- 支持获得 Base64 编码的标准图形 URL 字符串：`data:image/png;base64, ...`
 
     - 支持获得 SVG 图形文本: `<svg xmlns:xlink="http://www.w3.org/1999/xlink" ...`
+
+    - 支持从 Canvas 获得图片 Stream
 
     - 支持点形风格的 Required Patterns
 
@@ -377,6 +381,19 @@ var qrcode = new QRCode(options);
 	});
 	```
 
+- **toStream()**
+ 
+	```JS
+    const out = fs.createWriteStream(`qrcode-stream.png`);
+    // const stream = await qrcode.toStream();
+    // stream.pipe(out);
+    // out.on('finish', () => console.log('Finsihed'));
+
+    qrcode.toStream().then(res=>{
+        res.pipe(out).on('finish', () => console.log('Finsihed'));
+    })
+	```
+        
 ## TypeScript Support
 
 Update to version `3.7.1+`.