bitmap-ts

Library built in Typescript to load/handle a bitmap file. Support 1, 2, 4, 8, 16(no tested) and 24 bpp. The following functions are available:

• read(File)
• negative()
• rotate90CW()
• rotate90CCW()
• rotate180()
• rotate270CW()
• rotate270CCW()
• horizontalFlip()
• verticalFlip()
• drawOnCanvas(canvas)
• drawHistogram(canvas_r, canvas_g, canvas_b, canvas_avg)
• brightness(value)
• contrast(value)
• equalization()
• umbralization(min, max)
• saveFile(callback)
• scale(width, height, 'interpolation|neighbor')
• drawOnCanvasWithZoom (canvas, zoomValue, 'interpolation|neighbor')
• rotate(angle)
• kernel(width, height, customKernel?)
• blur('box|gauss')
• edge('prewitt|sobel')
• outline(boolean)
• customFilter()
• undo() : boolean
• redo() : boolean

How to use

I prepared a code to interact with library, you only need to clone the repository, and open index.html in src/views/, using a modern browser. The same view is located on github repository page, mentioned in the end of this markdown.

To use the library in your own context, only need:

Import in your typescript file the library:

import {Bitmap} from "./bitmap";

Call the constructor and read:

let bmp: Bitmap = new Bitmap(file);
// file is a File Type
bmp.read(file, (b: Bitmap) => {
  // bmp and b is the same instance
  // The file was read. Now, you can use the functions
});

And that's all.

Drawing on Canvas:

Every time that you want to see the changes on your canvas, you have to call drawOnCanvas(canvas)

let canvas = document.getElementById("canvas_id");
let bmp: Bitmap = new Bitmap(file);
bmp.read(file, (b: Bitmap) => {
  b.drawOnCanvas(canvas);
});

Also, is important to specify a size of you canvas:

<canvas id="canvas_id" width="500" height="500">

NOTE: Canvas can be very slow for big files, it is not the best solution to display a bmp file in HTML. Open a issue if found a faster solution.

Drawing Histogram:

Now is possible draw image's histogram, for the moments you have to pass 4 canvas, the first three are for RED, GREEN and BLUE. The last is the average between 3 channels (R, G, B). If the image is grayscale type, only average histogram will be shown. If is the image has color, R,G,B histograms will be shown.

Dependencies

RequireJS in needed to allow exports and import Bitmap module.

<script data-main="../../build/main.js" src="../../lib/require.js"></script>

FileSaver is required, it allows to write a DataView in Blob.

<script src="../../lib/FileSaver.min.js"></script>

Demo

Visit the github repository page to see a demo.

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Leonardo Testa & Carlos Abreu