canvas
此腳本不應該直接安裝，它是一個供其他腳本使用的函式庫。欲使用本函式庫，請在腳本 metadata 寫上： // @require https://update.cn-greasyfork.org/scripts/39480/258533/bv7_canvas.js
// ==UserScript==
// @name bv7_canvas
// @namespace bv7
// @version 0.3
// @description canvas
// @author bv7
// @require https://greasyfork.org/scripts/39476-bv7-jpeg-encoder/code/bv7_jpeg_encoder.js
// @require https://greasyfork.org/scripts/39479-bv7-jpeg2array/code/bv7_jpeg2array.js
// ==/UserScript==
class Canvas {
constructor() {
this.domCanvas = document.createElement('canvas');
this.jpegEncoder = new JpegEncoder();
}
set width(v) {
this.domCanvas.width = v;
this.onresize();
}
set height(v) {
this.domCanvas.height = v;
this.onresize();
}
get width () {
return this.domCanvas.width;
}
get height() {
return this.domCanvas.height;
}
onresize() {
}
getContext(_id) {
switch (_id) {
case '2d':
this.context = new class {
constructor(canvas) {
this.canvas = canvas;
this.domContext = this.canvas.domCanvas.getContext('2d');
this.imageData = this.domContext.getImageData(0, 0, this.canvas.domCanvas.width, this.canvas.domCanvas.height);
}
drawImage(image, sx, sy, sWidth, sHeight, dx, dy, dWidth, dHeight, then) {
let myImage;
let draw = () => {
if (dWidth && sWidth && dHeight && sHeight) {
let syStep = sHeight / dHeight;
let sxStep = sWidth / dWidth;
let dyStep = dHeight / sHeight;
let dxStep = dWidth / sWidth ;
let syStart = Math.max(0, sy, sy - dy / dyStep);
let sxStart = Math.max(0, sx, sx - dx / dxStep);
let syEnd = Math.min(myImage.height, sy + sHeight, sy + (this.imageData.height - dy) / dyStep);
let sxEnd = Math.min(myImage.width , sx + sWidth , sx + (this.imageData.width - dx) / dxStep);
let dyStart = dy + (syStart - sy) * dyStep;
let dxStart = dx + (sxStart - sx) * dxStep;
let dyEnd = dy + (syEnd - sy) * dyStep;
let dxEnd = dx + (sxEnd - sx) * dxStep;
let sh1 = Math.max(1, syStep);
let sw1 = Math.max(1, sxStep);
let dh1 = Math.max(1, dyStep);
let dw1 = Math.max(1, dxStep);
let siPerLine, siStartLine, siStart;
let diPerLine, diStartLine, diStart;
let sy1, sy1Next, sy2Start, sy2End;
let sx1, sx1Next, sx2Start, sx2End;
let dy1, dy1Next, dy2Start, dy2End;
let dx1, dx1Next, dx2Start, dx2End;
let s2count;
let r, g, b, a;
siPerLine = myImage.imageData.width * 4;
diPerLine = this.imageData.width * 4;
sy2Start = Math.round(sy1 = syStart);
dy2Start = Math.round(dy1 = dyStart);
while (sy1 < syEnd) {
sy2End = Math.round(sy1Next = sy1 + sh1);
dy2End = Math.round(dy1Next = dy1 + dh1);
sx2Start = Math.round(sx1 = sxStart);
dx2Start = Math.round(dx1 = dxStart);
siStartLine = sy2Start * siPerLine;
diStartLine = dy2Start * diPerLine;
while (sx1 < sxEnd) {
sx2End = Math.round(sx1Next = sx1 + sw1);
dx2End = Math.round(dx1Next = dx1 + dw1);
siStart = siStartLine + sx2Start * 4;
diStart = diStartLine + dx2Start * 4;
s2count = (sy2End - sy2Start) * (sx2End - sx2Start);
r = g = b = a = 0;
for (let sy2 = sy2Start; sy2 < sy2End; sy2++, siStart += siPerLine) for (let sx2 = sx2Start, si = siStart; sx2 < sx2End; sx2++) {
r += myImage.imageData.data[si++];
g += myImage.imageData.data[si++];
b += myImage.imageData.data[si++];
a += myImage.imageData.data[si++];
}
for (let dy2 = dy2Start; dy2 < dy2End; dy2++, diStart += diPerLine) for (let dx2 = dx2Start, di = diStart; dx2 < dx2End; dx2++) {
this.imageData.data[di++] = (r - r % s2count) / s2count;
this.imageData.data[di++] = (g - g % s2count) / s2count;
this.imageData.data[di++] = (b - b % s2count) / s2count;
this.imageData.data[di++] = (a - a % s2count) / s2count;
}
sx1 = sx1Next;
dx1 = dx1Next;
sx2Start = sx2End;
dx2Start = dx2End;
}
sy1 = sy1Next;
dy1 = dy1Next;
sy2Start = sy2End;
dy2Start = dy2End;
}
this.domContext.putImageData(this.imageData, 0, 0);
}
if (then) then();
};
if (Canvas.images.some((v) => (myImage = v).src == image.src))
draw();
else {
myImage = new JpegImage();
myImage.onload = () => {
myImage.imageData = this.domContext.createImageData(myImage.width, myImage.height);
myImage.copyToImageData(myImage.imageData);
Canvas.images.push(myImage);
draw();
};
myImage.src = image.src;
}
};
} (this);
break;
}
return this.context;
}
toDataUrl(type = 'image/png', encoderOptions = 0.92) {
let r;
switch (type) {
case 'image/jpeg':
r = this.jpegEncoder.encode(this.context.imageData, encoderOptions);
break;
default:
r = '';
}
return r;
}
}
Canvas.images = [];