HTML Canvas Image access the first pixel

Description

HTML Canvas Image access the first pixel

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<!DOCTYPE html>

<html>
  <head>
    <title>Manipulating images and video</title>
    <meta charset="utf-8">
    /*  w ww  .  j a v a2 s. c o m*/
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
    
    <script type="text/javascript">
      $(document).ready(function() {  
        var canvas = $("#myCanvas");
        var context = canvas.get(0).getContext("2d");
        

        // Accessing the first pixel
        var image = new Image();
        image.src = "image1.png";
        $(image).load(function() {
          context.drawImage(image, 0, 0, 500, 333);
          
          var imageData = context.getImageData(0, 0, 3, 3); // 3x3 grid
          var pixel = imageData.data; // CanvasPixelArray
          
          var red = pixel[0];
          var green = pixel[1];
          var blue = pixel[2];
          var alpha = pixel[3];
        });

        
        var image = new Image();
        image.src = "image1.png";
        
        $(image).load(function() {
          context.drawImage(image, 0, 0, 500, 333);
        });
        
        canvas.click(function(e) {
          var canvasOffset = canvas.offset();
          var canvasX = Math.floor(e.pageX-canvasOffset.left);
          var canvasY = Math.floor(e.pageY-canvasOffset.top);
          
          var imageData = context.getImageData(canvasX, canvasY, 1, 1);
          var pixel = imageData.data;
          var pixelColour = "rgba("+pixel[0]+", "+pixel[1]+", "+pixel[2]+", "+pixel[3]+")";
          
          $("body").css("backgroundColor", pixelColour);
        });
      });
    </script>
  </head>
  
  <body>
    <canvas id="myCanvas" width="500" height="500">
      <!-- Insert fallback content here -->
    </canvas>
  </body>
</html>



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