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canvas_blur_rect.js
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canvas_blur_rect.js
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!function(window) {
'use strict';
var blurCanvas = document.createElement('canvas');
blurCanvas.width = screen.width;
blurCanvas.height = screen.height;
var blurCtx = blurCanvas.getContext('2d');
function saturate(src, w, h, sv) {
var len = w * h;
var pos, i, j, offset;
var lumR = (1 - sv) * 0.3086;
var lumG = (1 - sv) * 0.6094;
var lumB = (1 - sv) * 0.0820;
var r, g, b;
var shiftW = w << 2;
for(j = 0; j < h; j++) {
offset = j * shiftW;
for(i = 0; i < w; i++) {
pos = offset + (i << 2);
r = src[pos];
g = src[pos + 1];
b = src[pos + 2];
src[pos] = ((lumR + sv) * r) +
(lumG * g) +
(lumB * b);
src[pos + 1] = (lumR * r) +
((lumG + sv) * g) +
(lumB * b);
src[pos + 2] = (lumR * r) +
(lumG * g) +
((lumB + sv) * b);
}
}
};
function boxBlur(src, w, h, r, sv) {
var tmp = new Uint8Array(w * h * 4);
blurRight(src, tmp, w, h, r);
blurDown(tmp, src, w, h, r);
blurLeft(src, tmp, w, h, r);
blurUp(tmp, src, w, h, r);
(sv !== undefined && sv !== 1) && saturate(src, w, h, sv);
};
function blurRight(src, dest, w, h, r) {
var i, j, offset, pos, posR;
var shiftR = r << 2;
var shiftW = w << 2;
var weightR, weightG, weightB, weightA;
for(j = 0; j < h; j++) {
weightR = 0;
weightG = 0;
weightB = 0;
weightA = 0;
offset = j * shiftW;
for(i = 0; i < r; i++) {
pos = offset + (i << 2);
weightR += src[pos];
weightG += src[pos + 1];
weightB += src[pos + 2];
weightA += src[pos + 3];
dest[pos] = (weightR / (i + 1)) | 0;
dest[pos + 1] = (weightG / (i + 1)) | 0;
dest[pos + 2] = (weightB / (i + 1)) | 0;
dest[pos + 3] = (weightA / (i + 1)) | 0;
}
for(; i < w; i++) {
pos = offset + (i << 2);
posR = pos - shiftR;
dest[pos] = (weightR / r) | 0;
dest[pos + 1] = (weightG / r) | 0;
dest[pos + 2] = (weightB / r) | 0;
dest[pos + 3] = (weightA / r) | 0;
weightR += src[pos] - src[posR];
weightG += src[pos + 1] - src[posR + 1];
weightB += src[pos + 2] - src[posR + 2];
weightA += src[pos + 3] - src[posR + 3];
}
}
};
function blurLeft(src, dest, w, h, r) {
var i, j, offset, pos, posR;
var shiftR = r << 2;
var shiftW = w << 2;
var weightR, weightG, weightB, weightA;
for(j = 0; j < h; j++) {
weightR = 0;
weightG = 0;
weightB = 0;
weightA = 0;
offset = j * shiftW;
for(i = w - 1; i >= w - r; i--) {
pos = offset + (i << 2);
weightR += src[pos];
weightG += src[pos + 1];
weightB += src[pos + 2];
weightA += src[pos + 3];
dest[pos] = (weightR / (w - i)) | 0;
dest[pos + 1] = (weightG / (w - i)) | 0;
dest[pos + 2] = (weightB / (w - i)) | 0;
dest[pos + 3] = (weightA / (w - i)) | 0;
}
for(; i >= 0; i--) {
pos = offset + (i << 2);
posR = pos + shiftR;
dest[pos] = (weightR / r) | 0;
dest[pos + 1] = (weightG / r) | 0;
dest[pos + 2] = (weightB / r) | 0;
dest[pos + 3] = (weightA / r) | 0;
weightR += src[pos] - src[posR];
weightG += src[pos + 1] - src[posR + 1];
weightB += src[pos + 2] - src[posR + 2];
weightA += src[pos + 3] - src[posR + 3];
}
}
};
function blurDown(src, dest, w, h, r) {
var i, j, offset, pos, posR;
var shiftR = r << 2;
var shiftW = w << 2;
var offsetR = shiftW * r;
var weightR, weightG, weightB, weightA;
for(i = 0; i < w; i++) {
weightR = 0;
weightG = 0;
weightB = 0;
weightA = 0;
offset = i << 2;
for(j = 0; j < r; j++) {
pos = offset + (j * shiftW);
weightR += src[pos];
weightG += src[pos + 1];
weightB += src[pos + 2];
weightA += src[pos + 3];
dest[pos] = (weightR / (j + 1)) | 0;
dest[pos + 1] = (weightG / (j + 1)) | 0;
dest[pos + 2] = (weightB / (j + 1)) | 0;
dest[pos + 3] = (weightA / (j + 1)) | 0;
}
for(; j < h; j++) {
pos = offset + (j * shiftW);
posR = pos - offsetR;
dest[pos] = (weightR / r) | 0;
dest[pos + 1] = (weightG / r) | 0;
dest[pos + 2] = (weightB / r) | 0;
dest[pos + 3] = (weightA / r) | 0;
weightR += src[pos] - src[posR];
weightG += src[pos + 1] - src[posR + 1];
weightB += src[pos + 2] - src[posR + 2];
weightA += src[pos + 3] - src[posR + 3];
}
}
};
function blurUp(src, dest, w, h, r) {
var i, j, offset, pos, posR;
var shiftR = r << 2;
var shiftW = w << 2;
var offsetR = shiftW * r;
var weightR, weightG, weightB, weightA;
for(i = 0; i < w; i++) {
weightR = 0;
weightG = 0;
weightB = 0;
weightA = 0;
offset = i << 2;
for(j = h - 1; j >= h - r; j--) {
pos = offset + (j * shiftW);
weightR += src[pos];
weightG += src[pos + 1];
weightB += src[pos + 2];
weightA += src[pos + 3];
dest[pos] = (weightR / (h - j)) | 0;
dest[pos + 1] = (weightG / (h - j)) | 0;
dest[pos + 2] = (weightB / (h - j)) | 0;
dest[pos + 3] = (weightA / (h - j)) | 0;
}
for(; j >= 0; j--) {
pos = offset + (j * shiftW);
posR = pos + offsetR;
dest[pos] = (weightR / r) | 0;
dest[pos + 1] = (weightG / r) | 0;
dest[pos + 2] = (weightB / r) | 0;
dest[pos + 3] = (weightA / r) | 0;
weightR += src[pos] - src[posR];
weightG += src[pos + 1] - src[posR + 1];
weightB += src[pos + 2] - src[posR + 2];
weightA += src[pos + 3] - src[posR + 3];
}
}
};
function blurRect(x, y, w, h, r, sv) {
var ctx = this;
var canvas = ctx.canvas;
var srcW = w | 0;
var srcH = h | 0;
var srcX = x | 0;
var srcY = y | 0;
r = (r | 0) * 32;
r = Math.min(Math.max(r, 32), 256);
var resizeFactor = Math.max(0, ((Math.log(r) / Math.log(2)) - 3) | 0);
var radius = r >>> resizeFactor;
var resizeWidth = canvas.width >>> resizeFactor;
var resizeHeight = canvas.height >>> resizeFactor;
blurCtx.drawImage(canvas, 0, 0, resizeWidth, resizeHeight);
var imageData = blurCtx.getImageData(0, 0, resizeWidth, resizeHeight);
boxBlur(imageData.data, resizeWidth, resizeHeight, radius, sv);
blurCtx.putImageData(imageData, 0, 0);
blurCtx.drawImage(
blurCanvas,
0, 0,
resizeWidth, resizeHeight,
0, 0,
canvas.width, canvas.height
);
ctx.drawImage(
blurCanvas,
srcX, srcY,
srcW, srcH,
srcX, srcY,
srcW, srcH
);
return ctx;
};
window.CanvasRenderingContext2D.prototype._blurRect = blurRect;
}(window);