原理來自Justany_WhiteSnow的Javascript影象處理——虛擬邊緣一文。
/* * BORDER_REPLICATE: aaaaaaaa|abcdefgh|hhhhhhhh * BORDER_REFLECT: hgfedcba|abcdefgh|hgfedcba * BORDER_REFLECT_101: hgfedcb|abcdefgh|gfedcba * BORDER_WRAP: efgh|abcdefgh|abcd * BORDER_CONSTANT: iiiiiiii|abcdefgh|iiiiiiii with some specified 'i'(default value [0, 0, 0, 255]) */ (function () { function imageVariousBorder(iCanvas, url, borderType, orientation, value) { this.canvas = iCanvas; this.iCtx = this.canvas.getContext("2d"); this.url = url; this.borderType = borderType; this.orientation = orientation || "bottom"; this.value = value || [0, 0, 0, 255]; } imageVariousBorder.prototype = { imread: function (_image) { var width = _image.width, height = _image.height; this.iResize(width, height); this.iCtx.drawImage(_image, 0, 0); var imageData = this.iCtx.getImageData(0, 0, width, height), tempMat = new Mat(height, width, imageData.data); imageData = null; this.iCtx.clearRect(0, 0, width, height); return tempMat; }, iResize: function (_width, _height) { this.canvas.width = _width; this.canvas.height = _height; }, RGBA2ImageData: function (_imgMat) { var width = _imgMat.col, height = _imgMat.row; var imageData = this.iCtx.createImageData(width, height); imageData.data.set(_imgMat.data); return imageData; }, render: function () { var img = new Image(); var _this = this; img.onload = function () { var myMat = _this.imread(img); var width = myMat.col; var height = myMat.row; if (_this.borderType == "BORDER_WRAP") { width = width/2; height = height/2; } var strOrientation = { "left": [0, width, 0, 0], "right": [0, 0, 0, width], "bottom": [0, 0, height, 0], "top": [height, 0, 0, 0], "left_right": [0, width, 0, width] }; var newImage = copyMakeBorder(myMat, strOrientation[_this.orientation][0], strOrientation[_this.orientation][1], strOrientation[_this.orientation][2], strOrientation[_this.orientation][3], _this.borderType, _this.value); var newIamgeData = _this.RGBA2ImageData(newImage); var newWidth = newImage.col; var newHeight = newImage.row; _this.iResize(newWidth, newHeight); _this.iCtx.putImageData(newIamgeData, 0, 0); }; img.src = this.url; } }; function Mat(_row, _col, _data, _buffer) { this.row = _row || 0; this.col = _col || 0; this.channel = 4; this.buffer = _buffer || new ArrayBuffer(_row * _col * 4); this.data = new Uint8ClampedArray(this.buffer); _data && this.data.set(_data); this.bytes = 1; this.type = "CV_RGBA"; } function copyMakeBorder(_src, _top, _left, _bottom, _right, _borderType, _value) { if (_src.type != "CV_RGBA") { console.log("not support this type"); } else if (_borderType == "BORDER_CONSTANT") { return copyMakeConstBorder_8U(_src, _top, _left, _bottom, _right, _value); } else { return copyMakeBorder_8U(_src, _top, _left, _bottom, _right, _borderType); } } function borderInterpolate(_p, _len, _borderType) { if (_p < 0 || _p >= _len) { switch (_borderType) { case "BORDER_REPLICATE": _p = _p < 0 ? 0 : _len - 1; break; case "BORDER_REFLECT": case "BORDER_REFLECT_101": var delta = (_borderType == "BORDER_REFLECT_101"); if (_len == 1) { return 0; } do { if (_p < 0) { _p = -_p - 1 + delta; } else { _p = _len - 1 - (_p - _len) - delta; } } while (_p < 0 || _p >= _len); break; case "BORDER_WRAP": if (_p < 0) { _p -= ((_p - _len + 1) / _len | 0) * _len; } if (_p >= _len) { _p %= _len; } break; case "BORDER_CONSTANT": _p = -1; default: console.log(arguments.callee, "UNSPPORT_BORDER_TYPE"); } } return _p; } function copyMakeBorder_8U(_src, _top, _left, _bottom, _right, _borderType) { var i, j; var width = _src.col, height = _src.row; var top = _top, left = _left || _top, right = _right || left, bottom = _bottom || top, dstWidth = width + left + right, dstHeight = height + top + bottom, borderType = _borderType || "BORDER_REFLECT"; var buffer = new ArrayBuffer(dstHeight * dstWidth * 4), tab = new Uint32Array(left + right); for (i = 0; i < left; i++) { tab[i] = borderInterpolate(i - left, width, borderType); } for (i = 0; i < right; i++) { tab[i + left] = borderInterpolate(width + i, width, borderType); } var tempArray, data; for (i = 0; i < height; i++) { tempArray = new Uint32Array(buffer, (i + top) * dstWidth * 4, dstWidth); data = new Uint32Array(_src.buffer, i * width * 4, width); for (j = 0; j < left; j++) tempArray[j] = data[tab[j]]; for (j = 0; j < right; j++) tempArray[j + width + left] = data[tab[j + left]]; tempArray.set(data, left); } var allArray = new Uint32Array(buffer); for (i = 0; i < top; i++) { j = borderInterpolate(i - top, height, _borderType); tempArray = new Uint32Array(buffer, i * dstWidth * 4, dstWidth); tempArray.set(allArray.subarray((j + top) * dstWidth, (j + top + 1) * dstWidth)); } for (i = 0; i < bottom; i++) { j = borderInterpolate(i + height, height, borderType); tempArray = new Uint32Array(buffer, (i + top + height) * dstWidth * 4, dstWidth); tempArray.set(allArray.subarray((j + top) * dstWidth, (j + top + 1) * dstWidth)); } return new Mat(dstHeight, dstWidth, new Uint8ClampedArray(buffer)); } function copyMakeConstBorder_8U(_src, _top, _left, _bottom, _right, _value) { var i, j; var width = _src.col, height = _src.row; var top = _top, left = _left || _top, right = _right || left, bottom = _bottom || top, dstWidth = width + left + right, dstHeight = height + top + bottom, value = _value || [0, 0, 0, 255]; var constBuf = new ArrayBuffer(dstWidth * 4), constArray = new Uint8ClampedArray(constBuf); buffer = new ArrayBuffer(dstHeight * dstWidth * 4); for (i = 0; i < dstWidth; i++) { for (j = 0; j < 4; j++) { constArray[i * 4 + j] = value[j]; } } constArray = new Uint32Array(constBuf); var tempArray; for (i = 0; i < height; i++) { tempArray = new Uint32Array(buffer, (i + top) * dstWidth * 4, left); tempArray.set(constArray.subarray(0, left)); tempArray = new Uint32Array(buffer, ((i + top + 1) * dstWidth - right) * 4, right); tempArray.set(constArray.subarray(0, right)); tempArray = new Uint32Array(buffer, ((i + top) * dstWidth + left) * 4, width); tempArray.set(new Uint32Array(_src.buffer, i * width * 4, width)); } for (i = 0; i < top; i++) { tempArray = new Uint32Array(buffer, i * dstWidth * 4, dstWidth); tempArray.set(constArray); } for (i = 0; i < bottom; i++) { tempArray = new Uint32Array(buffer, (i + top + height) * dstWidth * 4, dstWidth); tempArray.set(constArray); } return new Mat(dstHeight, dstWidth, new Uint8ClampedArray(buffer)); } window.imageVariousBorder = imageVariousBorder; })();
呼叫示例：
var iCanvas = document.getElementById("variousBorder_replicate"); var imgVariousBorder = new imageVariousBorder(iCanvas, "images/1.jpg", "BORDER_REPLICATE", "right"); imgVariousBorder.render();
效果：
