class CqTools {

 /// Returns if the userAgent of the browser belong to a mobile browser.
 static final bool mobile = window.navigator.userAgent.contains(r'Android|webOS|iPhone|iPad|iPod|BlackBerry|Windows Phone');

 /**
  * Blends [below] with [above] using [blendingFunction].
  */
 static void blend(CanvasElement below, var above, BlendFunction blendingFunction, [num mix = 1]) {
   _initBlend(below, above, mix, (pixels, belowPixels, abovePixels, mix) {
     _blend(pixels, belowPixels, abovePixels, mix, blendingFunction);
   });
 }

 /**
  * Blends [below] with [above] using [blendingFunction].
  */
 static void blendSpecial(CanvasElement below, var above, SpecialBlendFunction blendingFunction, [num mix = 1]) {
   _initBlend(below, above, mix, (pixels, belowPixels, abovePixels, mix) {
     _blendSpecial(pixels, belowPixels, abovePixels, mix, blendingFunction);
   });
 }

 static CanvasElement _initBlend(CanvasElement below, var above, num mix, Function blendingFunction(Uint8ClampedArray pixels, Uint8ClampedArray belowPixels, Uint8ClampedArray abovePixels, num mix)) {
   var belowCtx = below.context2d;
   var aboveCtx = cq(above).canvas.context2d;

   var belowData = belowCtx.getImageData(0, 0, below.width, below.height);
   var aboveData = aboveCtx.getImageData(0, 0, above.width, above.height);

   var imageData = createImageData(below.width, below.height);

   blendingFunction(imageData.data, belowData.data, aboveData.data, mix);

   below.context2d.putImageData(imageData, 0, 0);
 }

 static _blendSpecial(List<int> pixels, List<int> belowPixels, List<int> abovePixels, num mix, SpecialBlendFunction blendingFunction) {
   for(int i = 0; i < belowPixels.length; i += 4) {
     var rgb = blendingFunction([belowPixels[i + 0], belowPixels[i + 1], belowPixels[i + 2]], [abovePixels[i + 0], abovePixels[i + 1], abovePixels[i + 2]]);

     pixels[i + 0] = belowPixels[i + 0] + ((rgb[0] - belowPixels[i + 0]) * mix).toInt();
     pixels[i + 1] = belowPixels[i + 1] + ((rgb[1] - belowPixels[i + 1]) * mix).toInt();
     pixels[i + 2] = belowPixels[i + 2] + ((rgb[2] - belowPixels[i + 2]) * mix).toInt();

     pixels[i + 3] = belowPixels[i + 3];
   }
 }

 static _blend(List<int> pixels, List<int> belowPixels, List<int> abovePixels, num mix, BlendFunction blendingFunction) {
   for(int i = 0; i < belowPixels.length; i += 4) {
     int r = blendingFunction(belowPixels[i + 0], abovePixels[i + 0]);
     int g = blendingFunction(belowPixels[i + 1], abovePixels[i + 1]);
     int b = blendingFunction(belowPixels[i + 2], abovePixels[i + 2]);

     pixels[i + 0] = belowPixels[i + 0] + ((r - belowPixels[i + 0]) * mix).toInt();
     pixels[i + 1] = belowPixels[i + 1] + ((g - belowPixels[i + 1]) * mix).toInt();
     pixels[i + 2] = belowPixels[i + 2] + ((b - belowPixels[i + 2]) * mix).toInt();

     pixels[i + 3] = belowPixels[i + 3];
   }
 }

 /**
  * Draws an [img] on a [CanvasElement] and returns the canvas.
  */
 static CanvasElement createCanvas(ImageElement img) {
   var result = new CanvasElement(width: img.width, height: img.height);
   result.context2d.drawImage(img, 0, 0);
   return result;
 }

 /**
  * Creates an [ImageData] object for the size of [width] and [height].
  */
 static ImageData createImageData(int width, int height) {
   return new CanvasElement().context2d.createImageData(width, height);
 }

 /**
  * Calculates the position of the mouse.
  *
  * See <https://gist.github.com/3781251>
  */
 static Point mousePosition(UIEvent event) {
   var totalOffsetX = 0,
       totalOffsetY = 0,
       coordX = 0,
       coordY = 0,
       mouseX = 0,
       mouseY = 0;

   Element currentElement = event.currentTarget;

   // Traversing the parents to get the total offset
   do {
     totalOffsetX += currentElement.offset.left;
     totalOffsetY += currentElement.offset.top;
   }
   while (null != (currentElement = currentElement.offsetParent));
   // Use pageX to get the mouse coordinates
   if(null != event.page.x || null != event.page.y) {
     mouseX = event.page.x;
     mouseY = event.page.y;
   }
   // IE8 and below doesn't support event.pageX
   else if (event is MouseEvent) {
     if (null != event.client.x || null != event.client.y) {
       mouseX = event.client.x + document.body.scrollLeft + document.documentElement.scrollLeft;
       mouseY = event.client.y + document.body.scrollTop + document.documentElement.scrollTop;
     }
   }
   // Subtract the offset from the mouse coordinates
   coordX = mouseX - totalOffsetX;
   coordY = mouseY - totalOffsetY;

   return new Point(coordX, coordY);
 }
}