code-boxx/0-JS-CROP-IMG.MD

## 0-JS-CROP-IMG.MD

      
    Raw
  

              0-JS-CROP-IMG.MD
            
          
    JAVASCRIPT CROP IMAGES

https://code-boxx.com/crop-images-javascript/
IMAGE


LICENSE

Copyright by Code Boxx
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

  
## 1-simple.html
<!DOCTYPE html>
<html>
  <head>
    <title>JS Canvas Crop</title>
  </head>
  <body>
    <!-- (A) HTML CANVAS -->
    <canvas id="demo" width="300" height="300"></canvas>

    <script>
    // (B) IMAGE OBJECT
    var img = new Image();

    // (C) CROP ON LOAD
    img.onload = () => {
      // (C1) GET CANVAS + 2D CONTEXT
      let canvas = document.getElementById("demo"),
          ctx = canvas.getContext("2d");

      // (C2) CROP BY COPYING PART OF SOURCE IMAGE TO CANVAS
      ctx.drawImage(img,
        // SOURCE X, Y, WIDTH, HEIGHT
        50, 100, 300, 300,
        // DESTINATION X, Y, WIDTH, HEIGHT
        0, 0, 300, 300
      );
    };

    // (D) GO!
    img.src = "easter.png";
    </script>
  </body>
</html>

## 2-pick-crop.html
<!DOCTYPE html>
<html>
  <head>
    <title>JS Canvas Crop</title>
  </head>
  <body>
    <!-- (A) FILE PICKER -->
    <input type="file" id="picker" accept="image/jpeg,image/png,image/webp">

    <script>
    // (B) AUTO START ON SELECT FILE
    let picker = document.getElementById("picker");
    picker.onchange = () => {
      // (C) CREATE CANVAS
      let canvas = document.createElement("canvas"),
          ctx = canvas.getContext("2d");
      canvas.width = 300;
      canvas.height = 300;

      // (D) CREATE ANCHOR + SELECTED IMAGE URL
      let anchor = document.createElement("a"),
          surl = URL.createObjectURL(picker.files[0]);

      // (E) CREATE IMAGE + CROP
      let img = new Image();
      img.onload = () => {
        // (E1) DO YOUR OWN CROP CALCULATIONS...
        ctx.drawImage(img, 50, 100, 300, 300, 0, 0, 300, 300);

        // (E2) "FORCE DOWNLOAD"
        anchor.href = canvas.toDataURL("image/png");
        anchor.download = "cropped.png";
        anchor.click(); // MAY NOT WORK - BETTER TO LET USER CLICK

        // (E3) CLEAN UP
        anchor.remove();
        canvas.remove();
        img.remove();
        URL.revokeObjectURL(surl);
      };

      // (F) GO!
      img.src = surl;
    };
    </script>
  </body>
</html>
	<!DOCTYPE html>
	<html>
	<head>
	<title>JS Canvas Crop</title>
	</head>
	<body>
	<!-- (A) HTML CANVAS -->
	<canvas id="demo" width="300" height="300"></canvas>

	<script>
	// (B) IMAGE OBJECT
	var img = new Image();

	// (C) CROP ON LOAD
	img.onload = () => {
	// (C1) GET CANVAS + 2D CONTEXT
	let canvas = document.getElementById("demo"),
	ctx = canvas.getContext("2d");

	// (C2) CROP BY COPYING PART OF SOURCE IMAGE TO CANVAS
	ctx.drawImage(img,
	// SOURCE X, Y, WIDTH, HEIGHT
	50, 100, 300, 300,
	// DESTINATION X, Y, WIDTH, HEIGHT
	0, 0, 300, 300
	);
	};

	// (D) GO!
	img.src = "easter.png";
	</script>
	</body>
	</html>