multiline-canvas-text - npm Package Compare versions

Comparing version 1.0.3 to 2.0.0

index.d.ts

@@ -11,5 +11,31 @@ export interface IFont {
     canvas: HTMLCanvasElement;
-    lastCharacterPosition: IPoint;
+    cursor: IPoint;
     lines: string[];
 }
-export declare function drawText(text: string, width: number, fontName: string, fontSize: number, lineSpacing?: number, color?: string): IDrawTextResult;
+export declare const TextAlign: {
+    CENTER: string;
+    LEFT: string;
+    RIGHT: string;
+};
+/**
+ * Creates a canvas of the given width and renders the string into it
+ * @param {string} text
+ * @param {number} width
+ * @param {string} fontName
+ * @param {number} fontSize
+ * @param {number} lineSpacing
+ * @param {string} color
+ * @param {boolean} strokeText
+ * @param {string} align
+ * @returns {IDrawTextResult}
+ */
+export declare function drawText(text: string, width: number, fontName: string, fontSize: number, lineSpacing?: number, color?: string, strokeText?: boolean, align?: string): IDrawTextResult;
+/**
+ * Breaks up a string into lines that fit within the supplied width.
+ * @param {string} text
+ * @param {number} width
+ * @param {string} fontName
+ * @param {number} fontSize
+ * @returns {string[]}
+ */
+export declare function fitText(text: string, width: number, fontName: string, fontSize: number): string[];

index.js

@@ -5,5 +5,22 @@ "use strict";
 exports.drawText = drawText;
+exports.fitText = fitText;
+exports.TextAlign = void 0;
 
 var _trimCanvas = require("./trimCanvas");
 
+var TextAlign = {
+  CENTER: 'center',
+  LEFT: 'left',
+  RIGHT: 'right'
+};
+/**
+ * For a given string, returns a new string in which all the separate words (characters divided by a space) fit in the given width. Can add spaces into original words if they are too long.
+ * @param {string} text
+ * @param {number} availableWidth
+ * @param {IFont} font
+ * @returns {string}
+ */
+
+exports.TextAlign = TextAlign;
+
 function splitIntoFittingWords(text, availableWidth, font) {
@@ -37,3 +54,12 @@ var splitResults = [];
 }
+/**
+ * Groups a given string into fitting parts. What a part is is defined by the character to split the original string on.
+ * @param {string} text
+ * @param {string} splitOn
+ * @param {number} availableWidth
+ * @param {IFont} font
+ * @returns {string[]}
+ */
 
+
 function groupText(text, splitOn, availableWidth, font) {
@@ -61,4 +87,17 @@ return text.split(splitOn).reduce(function (resultingLines, currentItem) {
 }
+/**
+ * Creates a canvas of the given width and renders the string into it
+ * @param {string} text
+ * @param {number} width
+ * @param {string} fontName
+ * @param {number} fontSize
+ * @param {number} lineSpacing
+ * @param {string} color
+ * @param {boolean} strokeText
+ * @param {string} align
+ * @returns {IDrawTextResult}
+ */
 
-function drawText(text, width, fontName, fontSize, lineSpacing, color) {
+
+function drawText(text, width, fontName, fontSize, lineSpacing, color, strokeText, align) {
   if (lineSpacing === void 0) {
@@ -72,25 +111,61 @@ lineSpacing = 0;
 
-  // for now, just add spacing to fix fonts falling ut of view sometimes (at the bottom specifically)
+  if (strokeText === void 0) {
+    strokeText = false;
+  }
+
+  if (align === void 0) {
+    align = 'center';
+  }
+
+  var alignModes = [TextAlign.LEFT, TextAlign.CENTER, TextAlign.RIGHT];
+
+  if (alignModes.indexOf(align) === -1) {
+    throw new Error("Invalid alignMode (possible options: " + alignModes.join(',') + ")");
+  } // for now, just add spacing to fix fonts falling ut of view sometimes (at the bottom specifically)
   // padding will be removed by trimming canvas at the end
+
+
   var padding = {
-    x: 10,
-    y: 15
-  };
-  var font = {
-    size: fontSize,
-    name: fontName
-  };
-  var lines = fitText(text, width, font); // create and init canvas
+    x: 20,
+    y: fontSize * 2
+  }; // todo this needs a better fix
 
+  var font = createFont(fontName, fontSize);
+  var lines = fitText(text, width - 2 * padding.x, fontName, fontSize); // create and init canvas
+
   var canvas = document.createElement('canvas');
-  canvas.width = width + 2 * padding.x;
+  canvas.width = width; // + 2 * padding.x;
+
   canvas.height = lines.length * fontSize + (lines.length - 1) * lineSpacing + 2 * padding.y;
   var context = canvas.getContext('2d');
   context.font = getCanvasFontProperty(font);
-  context.textAlign = 'center';
-  context.textBaseline = 'top'; // draw lines
+  context.textAlign = align;
+  context.textBaseline = 'top';
+  context.fillStyle = color;
+  context.strokeStyle = color; // draw lines
 
-  var centerX = canvas.width * 0.5;
+  var baseX;
+
+  switch (align) {
+    case TextAlign.RIGHT:
+      {
+        baseX = canvas.width - padding.x;
+        break;
+      }
+
+    case TextAlign.LEFT:
+      {
+        baseX = padding.x;
+        break;
+      }
+
+    case TextAlign.CENTER:
+      {
+        baseX = canvas.width * 0.5;
+        break;
+      }
+  }
+
   var yOffset = 0;
-  var lastCharacterPosition = {
+  var cursor = {
     x: canvas.width * 0.5,
@@ -100,5 +175,9 @@ y: yOffset
   lines.forEach(function (line) {
-    context.fillStyle = color;
-    context.fillText(line, centerX, yOffset);
-    lastCharacterPosition = {
+    if (strokeText) {
+      context.strokeText(line, baseX, yOffset);
+    } else {
+      context.fillText(line, baseX, yOffset);
+    }
+
+    cursor = {
       x: canvas.width * 0.5 + 0.5 * getTextWidth(line, font).width,
@@ -110,15 +189,45 @@ y: yOffset
   return {
-    lastCharacterPosition: lastCharacterPosition,
-    lines: [],
+    lines: lines,
+    cursor: cursor,
     canvas: (0, _trimCanvas.trimCanvas)(canvas)
   };
 }
+/**
+ * Breaks up a string into lines that fit within the supplied width.
+ * @param {string} text
+ * @param {number} width
+ * @param {string} fontName
+ * @param {number} fontSize
+ * @returns {string[]}
+ */
 
-function fitText(text, width, font) {
+
+function fitText(text, width, fontName, fontSize) {
+  var font = createFont(fontName, fontSize);
   var fittingWords = splitIntoFittingWords(text, width, font);
   return groupText(fittingWords, ' ', width, font);
 }
+/**
+ * Formats fontName and fontSize into a css string for canvas.
+ * @param {IFont} font
+ * @returns {string}
+ */
 
+
 function getCanvasFontProperty(font) {
   return font.size + "px " + font.name;
-}
+}
+/**
+ * Create IFont object
+ * @param {string} name
+ * @param {number} size
+ * @returns {IFont}
+ */
+
+
+var createFont = function createFont(name, size) {
+  return {
+    size: size,
+    name: name
+  };
+};

package.json

 {
   "name": "multiline-canvas-text",
-  "version": "1.0.3",
-  "description": "Render multiline text to canvas",
+  "version": "2.0.0",
+  "description": "Render a string to canvas, breaking it up into multiple lines to fit the given width.",
   "main": "./index.js",
@@ -6,0 +6,0 @@ "types": "./index.d.ts",

README.md

 # multiline-canvas-text
+Render a string to canvas, breaking it up into multiple lines to fit the given width.
+
+## install
+```sh
+npm install multiline-canvas-text
+```
+
+## demo
+Check out the [interactive example](https://petervdn.github.io/multiline-canvas-text/example/).
+
+## usage
+```javascript
+import { drawText } from "multiline-canvas-text";
+
+const text = 'The quick brown fox jumps over the lazy dog';
+const width = 40;         // width in pixels to fit the text
+const font = 'Arial';     // font should be available in the page
+const fontSize = 20;      // in pixels
+const lineSpacing = 1;    // vertical spacing between the lines
+const color = 'white';    // can be any valid css color string: 'black', #FFF', 'rgba(0,0,0,0.5)', etc
+const strokeText = false; // true results in calling strokeText instead of fillText
+
+const result = drawText(text, width, font, fontSize, lineSpacing, color, strokeText);
+
+element.appendChild(result.canvas);
+```
+
+The result object contains 3 properties:
+* `canvas`: The generated canvas element with the rendered text. This canvas has the width that was given to the `drawText` method, but can obviously vary in height.
+* `lines`: An array that shows how the string was broken up into multiple lines, for example: `["The quick brown", "fox jumps over", "the lazy dog"]`
+* `cursor`: if you are replicating an interactive textfield in canvas, you may want to add a blinking cursor to increase the user experience. The `cursor` property holds `x` and `y` values for where to draw it. **This value is not correct at the moment!**

trimCanvas.js

@@ -8,14 +8,6 @@ "use strict";
 function trimCanvas(canvas) {
-  var ctx = canvas.getContext('2d'); // create a temporary canvas in which we will draw back the trimmed text
-
-  var copy = document.createElement('canvas').getContext('2d'); // Use the Canvas Image Data API, in order to get all the
-  // underlying pixels data of that canvas. This will basically
-  // return an array (Uint8ClampedArray) containing the data in the
-  // RGBA order. Every 4 items represent one pixel.
-
-  var pixels = ctx.getImageData(0, 0, canvas.width, canvas.height); // total pixels
-
-  var l = pixels.data.length; // main loop counter and pixels coordinates
-
-  var x;
+  var ctx = canvas.getContext('2d');
+  var copy = document.createElement('canvas').getContext('2d');
+  var pixels = ctx.getImageData(0, 0, canvas.width, canvas.height);
+  var l = pixels.data.length;
   var y; // an object that will store the area that isn't transparent
@@ -33,4 +25,3 @@
     if (pixels.data[i + 3] !== 0) {
-      // find it's coordinates
-      x = i / 4 % canvas.width;
+      // find its coordinates
       y = ~~(i / 4 / canvas.width); // store/update those coordinates
@@ -41,16 +32,15 @@ // inside our bounding box Object
         bound.top = y;
-      }
+      } // if (bound.left === null) {
+      //   bound.left = x;
+      // } else if (x < bound.left) {
+      //   bound.left = x;
+      // }
+      //
+      // if (bound.right === null) {
+      //   bound.right = x;
+      // } else if (bound.right < x) {
+      //   bound.right = x;
+      // }
 
-      if (bound.left === null) {
-        bound.left = x;
-      } else if (x < bound.left) {
-        bound.left = x;
-      }
 
-      if (bound.right === null) {
-        bound.right = x;
-      } else if (bound.right < x) {
-        bound.right = x;
-      }
-
       if (bound.bottom === null) {
@@ -67,6 +57,7 @@ bound.bottom = y;
   var trimHeight = bound.bottom - bound.top;
-  var trimWidth = bound.right - bound.left; // get the zone (trimWidth x trimHeight) as an ImageData
+  var trimWidth = canvas.width; // do not trim horizontally
+  // get the zone (trimWidth x trimHeight) as an ImageData
   // (Uint8ClampedArray of pixels) from our canvas
 
-  var trimmed = ctx.getImageData(bound.left, bound.top, trimWidth, trimHeight); // Draw back the ImageData into the canvas
+  var trimmed = ctx.getImageData(0, bound.top, trimWidth, trimHeight); // Draw back the ImageData into the canvas
 
@@ -73,0 +64,0 @@ copy.canvas.width = trimWidth;

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Improved metrics

Total package byte prevSize

177101

increased by2.52%

Lines of code

291

increased by61.67%

Number of lines in readme file

33

increased by1550%

No dependency changes