使用方法

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import imageClip from './imageClip.js';

new imageClip({
src: 'data:image/png;base64,',
autoCut: true,
ok: (data) => {
console.log(data);
},
complete: () => {
// 取消或确认操作回调
}
});

封装组件

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// imageClip.js
/**
* 图片裁剪
*/
import cancelIcon from '../tattoo/images/cancel.svg'
import okIcon from '../tattoo/images/ok.svg'

class imageClip {
constructor({ src, autoCut, ok, complete }) {
this.state = {
src,
ok,
complete,
autoCut, // 自动裁剪
cutBox: null,
canvas: null, // 展示画布
scaleRate: 1, // 展示图片缩小的倍数,裁剪时候需要把尺寸还原(裁剪坐标除这个倍数,就是原图的裁剪坐标)
canvasOrigin: null, // 图片原尺寸的画布(最终裁剪的画布)
cutRectCanvas: null, // 裁剪框显示的画布
cutRect: {
x: 0, y: 0, width: 0, height: 0
}, // 裁剪线框
touchPosition: {
value: '',
touch_x: 0,
touch_y: 0,
before_x: 0,
before_y: 0,
before_width: 0,
before_height: 0,
}, // 触摸位置,移动或者缩放裁剪框
};

this.initBox();
}

initBox() {
if (!this.state.cutBox) {
this.state.cutBox = document.createElement('div');
Object.assign(this.state.cutBox.style, {
position: 'fixed',
left: 0,
top: 0,
right: 0,
bottom: '12px',
background: 'rgba(0,0,0,1)'
});

const BottomArea = document.createElement('div');
Object.assign(BottomArea.style, {
position: 'absolute',
left: 0,
bottom: 0,
width: '100%',
height: '72px',
background: 'rgba(255,255,255,1)',
display: 'flex',
flexDirection: 'row',
alignItems: 'center',
justifyContent: 'space-between',
fontSize: '14px',
borderTopLeftRadius: '14px',
borderTopRightRadius: '14px',
});

const BottomAreaCancel = document.createElement('div');
// BottomAreaCancel.innerText = 'Cancel';
BottomAreaCancel.innerHTML = `<img src="${cancelIcon}" alt="icon" style="width: 40px;height: 40px;"/>`;
Object.assign(BottomAreaCancel.style, {
padding: '0 20px',
});

const BottomAreaOk = document.createElement('div');
BottomAreaOk.innerHTML = `<img src="${okIcon}" alt="icon" style="width: 40px;height: 40px;"/>`;
// BottomAreaOk.innerText = 'OK';
Object.assign(BottomAreaOk.style, {
padding: '0 20px',
});

const BottomAreaText = document.createElement('div');
BottomAreaText.innerText = 'Crop';


BottomAreaCancel.addEventListener('click', (e) => {
this.state.complete && this.state.complete();

document.body.removeChild(this.state.cutBox);
});
BottomAreaOk.addEventListener('click', (e) => {
let { x, y, width, height } = this.state.cutRect;
let x_new = x / this.state.scaleRate;
let y_new = y / this.state.scaleRate;
let width_new = width / this.state.scaleRate;
let height_new = height / this.state.scaleRate;
let imgData = this.state.canvasOrigin.getContext('2d').getImageData(x_new, y_new, width_new, height_new);
Object.assign(this.state.canvasOrigin.style, {
width: width_new + 'px',
height: height_new + 'px',
});
this.state.canvasOrigin.width = width_new;
this.state.canvasOrigin.height = height_new;
this.state.canvasOrigin.getContext('2d').putImageData(imgData, 0, 0);
let dataUrl = this.state.canvasOrigin.toDataURL();
this.state.ok && this.state.ok(dataUrl);
this.state.complete && this.state.complete();

document.body.removeChild(this.state.cutBox);
});

this.initCanvas();

BottomArea.appendChild(BottomAreaCancel);
BottomArea.appendChild(BottomAreaText);
BottomArea.appendChild(BottomAreaOk);
this.state.cutBox.appendChild(BottomArea);
document.body.appendChild(this.state.cutBox);
}
}

// 初始化页面展示画布
initCanvas() {
this.state.canvas = document.createElement('canvas');
const canvasWidth = document.body.offsetWidth * 0.8;
const canvasHeight = document.body.offsetHeight - 72 - 60;
const canvasLeft = document.body.offsetWidth * 0.2 / 2;
const canvasTop = 30;
Object.assign(this.state.canvas.style, {
position: 'absolute',
left: canvasLeft + 'px',
top: canvasTop + 'px',
width: canvasWidth + 'px',
height: canvasHeight + 'px',
background: '#fff',
});
this.state.canvas.width = canvasWidth;
this.state.canvas.height = canvasHeight;
this.state.cutBox.appendChild(this.state.canvas);

this.renderImage();
}

// 渲染裁剪图片
renderImage() {
const canvasWidth = this.state.canvas.width;
const canvasHeight = this.state.canvas.height;
const canvasLeft = parseFloat(this.state.canvas.style.left);
const canvasTop = parseFloat(this.state.canvas.style.top);
const img = document.createElement('img');
img.src = this.state.src;
img.onload = () => {
this.state.canvasOrigin = document.createElement('canvas');
Object.assign(this.state.canvasOrigin.style, {
width: img.width + 'px',
height: img.height + 'px',
background: '#fff',
});
this.state.canvasOrigin.width = img.width;
this.state.canvasOrigin.height = img.height;
this.state.canvasOrigin.getContext('2d').drawImage(img, 0, 0, img.width, img.height);

let newWidth = 0, newHeight = 0, newCanvasLeft = 0, newCanvasTop = 0;
if (canvasWidth / canvasHeight > img.width / img.height) {
// 以画布的高度为基准,缩放图片
this.state.scaleRate = canvasHeight / img.height;
newWidth = img.width * (canvasHeight / img.height);
newHeight = canvasHeight;
newCanvasLeft = canvasLeft + (canvasWidth - newWidth) / 2;
newCanvasTop = canvasTop;
} else {
// 以画布的宽度为基准,缩放图片
this.state.scaleRate = canvasWidth / img.width;
newWidth = canvasWidth;
newHeight = img.height * (canvasWidth / img.width);
newCanvasLeft = canvasLeft;
newCanvasTop = canvasTop + (canvasHeight - newHeight) / 2;
}

Object.assign(this.state.canvas.style, {
left: newCanvasLeft + 'px',
top: newCanvasTop + 'px',
width: parseInt(newWidth) + 'px',
height: parseInt(newHeight) + 'px',
});
this.state.canvas.width = parseInt(newWidth);
this.state.canvas.height = parseInt(newHeight);
this.state.canvas.getContext('2d').drawImage(img, 0, 0, parseInt(newWidth), parseInt(newHeight));

this.renderCutRectCanvas();
};
}

// 渲染裁剪线框的画布
renderCutRectCanvas() {
this.state.cutRectCanvas = document.createElement('canvas');
Object.assign(this.state.cutRectCanvas.style, {
position: 'absolute',
left: this.state.canvas.style.left,
top: this.state.canvas.style.top,
width: this.state.canvas.width + 'px',
height: this.state.canvas.height + 'px',
// background: 'rgba(0,0,0,0.4)',
});
this.state.cutRectCanvas.width = this.state.canvas.width;
this.state.cutRectCanvas.height = this.state.canvas.height;
this.state.cutBox.appendChild(this.state.cutRectCanvas);
this.state.cutRect = {
x: 0, y: 0, width: this.state.canvas.width, height: this.state.canvas.height
};
this.renderCutRect();
this.addEvent();
this.state.autoCut && this.autoCut();
}

// 渲染裁剪框
renderCutRect() {
let { x, y, width, height } = this.state.cutRect;
let context = this.state.cutRectCanvas.getContext("2d");
context.clearRect(0, 0, this.state.cutRectCanvas.width, this.state.cutRectCanvas.height); // 清空裁剪框画布

// 设置裁剪框外面部分透明度为0.4
context.globalAlpha = 0.4;
context.fillStyle = 'rgba(0, 0, 0, 1)';
context.fillRect(0, 0, this.state.cutRectCanvas.width, this.state.cutRectCanvas.height);

// 裁剪框内全透明
context.globalAlpha = 1; // 重置透明度为 1
context.clearRect(x, y, width, height); // 清空裁剪框区域

// 裁剪外层框
context.strokeStyle = "#E46F5A";
context.lineWidth = 2;
context.strokeRect(x, y, width, height);

this.addGridlines();
}

// 侧边及顶点线条及网格线
addGridlines() {
let { x, y, width, height } = this.state.cutRect;
let context = this.state.cutRectCanvas.getContext("2d");
// 侧边及顶点线条
context.fillStyle = '#E46F5A';
// 可拖动边角的厚度
let thickness = 3;
// 上
let t_width = width * 0.2;
let t_height = thickness;
let t_left = (width - width * 0.2) / 2 + x;
context.fillRect(t_left, y, t_width, t_height);
// 右
let r_width = thickness;
let r_height = height * 0.2;
let r_top = (height - height * 0.2) / 2 + y;
context.fillRect(x + width - r_width, r_top, r_width, r_height);
// 下
let b_width = width * 0.2;
let b_height = thickness;
let b_left = (width - width * 0.2) / 2 + x;
context.fillRect(b_left, y + height - b_height, b_width, b_height);
// 左
let l_width = thickness;
let l_height = height * 0.2;
let l_top = (height - height * 0.2) / 2 + y;
context.fillRect(x, l_top, l_width, l_height);
// 左上角
let t_l_width = width * 0.1;
let t_l_height = thickness;
context.fillRect(x, y, t_l_width, t_l_height);
let l_t_width = thickness;
let l_t_height = height * 0.1;
context.fillRect(x, y, l_t_width, l_t_height);
// 右上角
let t_r_width = width * 0.1;
let t_r_height = thickness;
context.fillRect(x + width - t_r_width, y, t_r_width, t_r_height);
let r_t_width = thickness;
let r_t_height = height * 0.1;
context.fillRect(x + width - r_t_width, y, r_t_width, r_t_height);
// 右下角
let b_r_width = width * 0.1;
let b_r_height = thickness;
context.fillRect(x + width - t_r_width, y + height - b_r_height, b_r_width, b_r_height);
let r_b_width = thickness;
let r_b_height = height * 0.1;
context.fillRect(x + width - r_t_width, y + height - r_b_height, r_b_width, r_b_height);
// 左下角
let b_l_width = width * 0.1;
let b_l_height = thickness;
context.fillRect(x, y + height - b_l_height, b_l_width, b_l_height);
let l_b_width = thickness;
let l_b_height = height * 0.1;
context.fillRect(x, y + height - l_b_height, l_b_width, l_b_height);

// 网格线
// 竖线
let x1 = width / 3 + x;
let x2 = width / 3 * 2 + x;
context.fillRect(x1, y, 1, height);
context.fillRect(x2, y, 1, height);
// 横线
let y1 = height / 3 + y;
let y2 = height / 3 * 2 + y;
context.fillRect(x, y1, width, 1);
context.fillRect(x, y2, width, 1);
}

// 裁剪画布添加监听事件
addEvent() {
const touch_space = 8; // 触摸留白区域(4个对角)
const touch_space_line = 40; // 触摸留白区域(上下左右)
const cut_space = 60; // 裁剪留白区域(最小尺寸)

this.state.cutRectCanvas.addEventListener('touchstart', e => {
let { x, y, width, height } = this.state.cutRect;

const { clientX, clientY } = e.touches[0];
const touch_x = clientX - parseFloat(this.state.cutRectCanvas.style.left);
const touch_y = clientY - parseFloat(this.state.cutRectCanvas.style.top);

this.state.touchPosition.touch_x = touch_x;
this.state.touchPosition.touch_y = touch_y;
this.state.touchPosition.before_x = this.state.cutRect.x;
this.state.touchPosition.before_y = this.state.cutRect.y;
this.state.touchPosition.before_width = this.state.cutRect.width;
this.state.touchPosition.before_height = this.state.cutRect.height;

if ((touch_x > ((width - width * 0.2) / 2 + x) - touch_space_line) && (touch_x < ((width + width * 0.2) / 2 + x) + touch_space_line) && (touch_y > y - touch_space_line) && (touch_y < y + touch_space_line)) {
// 顶部
this.state.touchPosition.value = 'top';
} else if ((touch_x > x + width - touch_space_line) && (touch_x < x + width + touch_space_line) && ((touch_y > height - height * 0.2) / 2 + y - touch_space_line) && (touch_y < (height + height * 0.2) / 2 + y + touch_space_line)) {
// 右侧
this.state.touchPosition.value = 'right';
} else if ((touch_x > ((width - width * 0.2) / 2 + x) - touch_space_line) && (touch_x < ((width + width * 0.2) / 2 + x) + touch_space_line) && (touch_y > (height + y - touch_space_line)) && (touch_y < (height + y + touch_space_line))) {
// 底部
this.state.touchPosition.value = 'bottom';
} else if ((touch_x > (x - touch_space_line) && (touch_x < (x + touch_space_line)) && (touch_y > (height - height * 0.2) / 2 + y - touch_space_line) && (touch_y < (height + height * 0.2) / 2 + y + touch_space_line))) {
// 左侧
this.state.touchPosition.value = 'left';
} else if ((touch_x > x - width * 0.1 - touch_space && (touch_x < x + width * 0.1 + touch_space) && (touch_y > y - height * 0.1 - touch_space) && (touch_y < y + height * 0.1 + touch_space))) {
// 左上角
this.state.touchPosition.value = 'top_left';
} else if ((touch_x > x + width - width * 0.1 - touch_space && (touch_x < x + width + width * 0.1 + touch_space) && (touch_y > y - height * 0.1 - touch_space) && (touch_y < y + height * 0.1 + touch_space))) {
// 右上角
this.state.touchPosition.value = 'top_right';
} else if ((touch_x > x + width - width * 0.1 - touch_space && (touch_x < x + width + width * 0.1 + touch_space) && (touch_y > y + height - height * 0.1 - touch_space) && (touch_y < y + height + height * 0.1 + touch_space))) {
// 右下角
this.state.touchPosition.value = 'bottom_right';
} else if ((touch_x > x - width * 0.1 - touch_space && (touch_x < x + width * 0.1 + touch_space) && (touch_y > y + height - height * 0.1 - touch_space) && (touch_y < y + height + height * 0.1 + touch_space))) {
// 左下角
this.state.touchPosition.value = 'bottom_left';
} else if ((touch_x > x + touch_space) && (touch_x < x + width - touch_space) && (touch_y > y + touch_space) && (touch_y < y + height - touch_space)) {
// 在裁剪矩形框内
this.state.touchPosition.value = 'inRect';
}
// console.log('touchstart', this.state.touchPosition.value);
});
this.state.cutRectCanvas.addEventListener('touchmove', e => {
const { clientX, clientY } = e.touches[0];
const touch_x = clientX - parseFloat(this.state.cutRectCanvas.style.left);
const touch_y = clientY - parseFloat(this.state.cutRectCanvas.style.top);

const move_x = touch_x - this.state.touchPosition.touch_x;
const move_y = touch_y - this.state.touchPosition.touch_y;

let { x: new_x, y: new_y, width: new_width, height: new_height } = this.state.cutRect;
const { cutRectCanvas, cutRect, touchPosition } = this.state;
const { before_x, before_y, before_width, before_height } = touchPosition;
if (this.state.touchPosition.value === 'inRect') {
// x,y修改
new_x = before_x + move_x;
new_x = Math.max(0, Math.min(new_x, cutRectCanvas.width - cutRect.width));
new_y = before_y + move_y;
new_y = Math.max(0, Math.min(new_y, cutRectCanvas.height - cutRect.height));
} else if (this.state.touchPosition.value === 'top') {
// y,height修改
new_y = before_y + move_y;
new_y = Math.max(0, Math.min(new_y, before_y + before_height - cut_space));
new_height = before_height - move_y;
new_height = Math.max(cut_space, Math.min(new_height, before_y + before_height - new_y));
} else if (this.state.touchPosition.value === 'right') {
// width修改
new_width = before_width + move_x;
new_width = Math.max(cut_space, Math.min(new_width, cutRectCanvas.width - before_x));
} else if (this.state.touchPosition.value === 'bottom') {
// height修改
new_height = touchPosition.before_height + move_y;
new_height = Math.max(cut_space, Math.min(new_height, cutRectCanvas.height - before_y));
} else if (this.state.touchPosition.value === 'left') {
// x,width修改
new_x = before_x + move_x;
new_x = Math.max(0, Math.min(new_x, before_x + before_width - cut_space));
new_width = before_width - move_x;
new_width = Math.max(cut_space, Math.min(new_width, before_x + before_width - new_x));
} else if (this.state.touchPosition.value === 'top_left') {
// x,y,width,height修改
new_x = before_x + move_x;
new_x = Math.max(0, Math.min(new_x, before_x + before_width - cut_space));
new_width = before_width - move_x;
new_width = Math.max(cut_space, Math.min(new_width, before_x + before_width - new_x));
new_y = before_y + move_y;
new_y = Math.max(0, Math.min(new_y, before_y + before_height - cut_space));
new_height = before_height - move_y;
new_height = Math.max(cut_space, Math.min(new_height, before_y + before_height - new_y));
} else if (this.state.touchPosition.value === 'top_right') {
// y,width,height修改
new_width = before_width + move_x;
new_width = Math.max(cut_space, Math.min(new_width, cutRectCanvas.width - before_x));
new_y = before_y + move_y;
new_y = Math.max(0, Math.min(new_y, before_y + before_height - cut_space));
new_height = before_height - move_y;
new_height = Math.max(cut_space, Math.min(new_height, before_y + before_height - new_y));
} else if (this.state.touchPosition.value === 'bottom_right') {
// width,height修改
new_width = before_width + move_x;
new_width = Math.max(cut_space, Math.min(new_width, cutRectCanvas.width - before_x));
new_height = touchPosition.before_height + move_y;
new_height = Math.max(cut_space, Math.min(new_height, cutRectCanvas.height - before_y));
} else if (this.state.touchPosition.value === 'bottom_left') {
// x,width,height修改
new_x = before_x + move_x;
new_x = Math.max(0, Math.min(new_x, before_x + before_width - cut_space));
new_width = before_width - move_x;
new_width = Math.max(cut_space, Math.min(new_width, before_x + before_width - new_x));
new_height = touchPosition.before_height + move_y;
new_height = Math.max(cut_space, Math.min(new_height, cutRectCanvas.height - before_y));
}

// console.log(new_x, new_y, new_width, new_height);
this.state.cutRect.x = new_x;
this.state.cutRect.y = new_y;
this.state.cutRect.width = new_width;
this.state.cutRect.height = new_height;
this.renderCutRect();
// console.log('touchmove', e);
});
this.state.cutRectCanvas.addEventListener('touchend', e => {
this.state.touchPosition.value = '';
// console.log('touchend', e);
});
}

autoCut() {
let ctx = this.state.canvasOrigin.getContext('2d');

let imgData = ctx.getImageData(0, 0, this.state.canvasOrigin.width, this.state.canvasOrigin.height).data; //读取图片数据
let lOffset = this.state.canvasOrigin.width,
rOffset = 0,
tOffset = this.state.canvasOrigin.height,
bOffset = 0;
for (let i = 0; i < this.state.canvasOrigin.width; i++) {
for (let j = 0; j < this.state.canvasOrigin.height; j++) {
let pos = (i + this.state.canvasOrigin.width * j) * 4;
if (
imgData[pos] !== 255 &&
imgData[pos + 1] !== 255 &&
imgData[pos + 2] !== 255 &&
imgData[pos + 3] !== 0
) {
bOffset = Math.max(j, bOffset); // 找到有色彩的最下端
rOffset = Math.max(i, rOffset); // 找到有色彩的最右端
tOffset = Math.min(j, tOffset); // 找到有色彩的最上端
lOffset = Math.min(i, lOffset); // 找到有色彩的最左端
}
}
}
this.state.cutRect.x = lOffset * this.state.scaleRate;
this.state.cutRect.y = tOffset * this.state.scaleRate;
this.state.cutRect.width = rOffset * this.state.scaleRate - lOffset * this.state.scaleRate;
this.state.cutRect.height = bOffset * this.state.scaleRate - tOffset * this.state.scaleRate;
this.renderCutRect();
}
}

export default imageClip;