gecko/browser/devtools/shared/widgets/CSSTransformPreviewer.js

390 lines
12 KiB
JavaScript

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
/**
* The CSSTransformPreview module displays, using a <canvas> a rectangle, with
* a given width and height and its transformed version, given a css transform
* property and origin. It also displays arrows from/to each corner.
*
* It is useful to visualize how a css transform affected an element. It can
* help debug tricky transformations. It is used today in a tooltip, and this
* tooltip is shown when hovering over a css transform declaration in the rule
* and computed view panels.
*
* TODO: For now, it multiplies matrices itself to calculate the coordinates of
* the transformed box, but that should be removed as soon as we can get access
* to getQuads().
*/
const HTML_NS = "http://www.w3.org/1999/xhtml";
/**
* The TransformPreview needs an element to output a canvas tag.
*
* Usage example:
*
* let t = new CSSTransformPreviewer(myRootElement);
* t.preview("rotate(45deg)", "top left", 200, 400);
* t.preview("skew(19deg)", "center", 100, 500);
* t.preview("matrix(1, -0.2, 0, 1, 0, 0)");
* t.destroy();
*
* @param {nsIDOMElement} parentEl
* Where the canvas will go
*/
function CSSTransformPreviewer(parentEl) {
this.parentEl = parentEl;
this.doc = this.parentEl.ownerDocument;
this.canvas = null;
this.ctx = null;
}
module.exports.CSSTransformPreviewer = CSSTransformPreviewer;
CSSTransformPreviewer.prototype = {
/**
* The preview look-and-feel can be changed using these properties
*/
MAX_DIM: 250,
PAD: 5,
ORIGINAL_FILL: "#1F303F",
ORIGINAL_STROKE: "#B2D8FF",
TRANSFORMED_FILL: "rgba(200, 200, 200, .5)",
TRANSFORMED_STROKE: "#B2D8FF",
ARROW_STROKE: "#329AFF",
ORIGIN_STROKE: "#329AFF",
ARROW_TIP_HEIGHT: 10,
ARROW_TIP_WIDTH: 8,
CORNER_SIZE_RATIO: 6,
/**
* Destroy removes the canvas from the parentelement passed in the constructor
*/
destroy: function() {
if (this.canvas) {
this.parentEl.removeChild(this.canvas);
}
if (this._hiddenDiv) {
this.parentEl.removeChild(this._hiddenDiv);
}
this.parentEl = this.canvas = this.ctx = this.doc = null;
},
_createMarkup: function() {
this.canvas = this.doc.createElementNS(HTML_NS, "canvas");
this.canvas.setAttribute("id", "canvas");
this.canvas.setAttribute("width", this.MAX_DIM);
this.canvas.setAttribute("height", this.MAX_DIM);
this.canvas.style.position = "relative";
this.parentEl.appendChild(this.canvas);
this.ctx = this.canvas.getContext("2d");
},
_getComputed: function(name, value, width, height) {
if (!this._hiddenDiv) {
// Create a hidden element to apply the style to
this._hiddenDiv = this.doc.createElementNS(HTML_NS, "div");
this._hiddenDiv.style.visibility = "hidden";
this._hiddenDiv.style.position = "absolute";
this.parentEl.appendChild(this._hiddenDiv);
}
// Camelcase the name
name = name.replace(/-([a-z]{1})/g, (m, letter) => letter.toUpperCase());
// Apply width and height to make sure computation is made correctly
this._hiddenDiv.style.width = width + "px";
this._hiddenDiv.style.height = height + "px";
// Show the hidden div, apply the style, read the computed style, hide the
// hidden div again
this._hiddenDiv.style.display = "block";
this._hiddenDiv.style[name] = value;
let computed = this.doc.defaultView.getComputedStyle(this._hiddenDiv);
let computedValue = computed[name];
this._hiddenDiv.style.display = "none";
return computedValue;
},
_getMatrixFromTransformString: function(transformStr) {
let matrix = transformStr.substring(0, transformStr.length - 1).
substring(transformStr.indexOf("(") + 1).split(",");
matrix.forEach(function(value, index) {
matrix[index] = parseFloat(value, 10);
});
let transformMatrix = null;
if (matrix.length === 6) {
// 2d transform
transformMatrix = [
[matrix[0], matrix[2], matrix[4], 0],
[matrix[1], matrix[3], matrix[5], 0],
[0, 0, 1, 0],
[0, 0, 0, 1]
];
} else {
// 3d transform
transformMatrix = [
[matrix[0], matrix[4], matrix[8], matrix[12]],
[matrix[1], matrix[5], matrix[9], matrix[13]],
[matrix[2], matrix[6], matrix[10], matrix[14]],
[matrix[3], matrix[7], matrix[11], matrix[15]]
];
}
return transformMatrix;
},
_getOriginFromOriginString: function(originStr) {
let offsets = originStr.split(" ");
offsets.forEach(function(item, index) {
offsets[index] = parseInt(item, 10);
});
return offsets;
},
_multiply: function(m1, m2) {
let m = [];
for (let m1Line = 0; m1Line < m1.length; m1Line++) {
m[m1Line] = 0;
for (let m2Col = 0; m2Col < m2.length; m2Col++) {
m[m1Line] += m1[m1Line][m2Col] * m2[m2Col];
}
}
return [m[0], m[1]];
},
_getTransformedPoint: function(matrix, point, origin) {
let pointMatrix = [point[0] - origin[0], point[1] - origin[1], 1, 1];
return this._multiply(matrix, pointMatrix);
},
_getTransformedPoints: function(matrix, rect, origin) {
return rect.map(point => {
let tPoint = this._getTransformedPoint(matrix, [point[0], point[1]], origin);
return [tPoint[0] + origin[0], tPoint[1] + origin[1]];
});
},
/**
* For canvas to avoid anti-aliasing
*/
_round: x => Math.round(x) + .5,
_drawShape: function(points, fillStyle, strokeStyle) {
this.ctx.save();
this.ctx.lineWidth = 1;
this.ctx.strokeStyle = strokeStyle;
this.ctx.fillStyle = fillStyle;
this.ctx.beginPath();
this.ctx.moveTo(this._round(points[0][0]), this._round(points[0][1]));
for (var i = 1; i < points.length; i++) {
this.ctx.lineTo(this._round(points[i][0]), this._round(points[i][1]));
}
this.ctx.lineTo(this._round(points[0][0]), this._round(points[0][1]));
this.ctx.fill();
this.ctx.stroke();
this.ctx.restore();
},
_drawArrow: function(x1, y1, x2, y2) {
// do not draw if the line is too small
if (Math.abs(x2-x1) < 20 && Math.abs(y2-y1) < 20) {
return;
}
this.ctx.save();
this.ctx.strokeStyle = this.ARROW_STROKE;
this.ctx.fillStyle = this.ARROW_STROKE;
this.ctx.lineWidth = 1;
this.ctx.beginPath();
this.ctx.moveTo(this._round(x1), this._round(y1));
this.ctx.lineTo(this._round(x2), this._round(y2));
this.ctx.stroke();
this.ctx.beginPath();
this.ctx.translate(x2, y2);
let radians = Math.atan((y1 - y2) / (x1 - x2));
radians += ((x1 >= x2) ? -90 : 90) * Math.PI / 180;
this.ctx.rotate(radians);
this.ctx.moveTo(0, 0);
this.ctx.lineTo(this.ARROW_TIP_WIDTH / 2, this.ARROW_TIP_HEIGHT);
this.ctx.lineTo(-this.ARROW_TIP_WIDTH / 2, this.ARROW_TIP_HEIGHT);
this.ctx.closePath();
this.ctx.fill();
this.ctx.restore();
},
_drawOrigin: function(x, y) {
this.ctx.save();
this.ctx.strokeStyle = this.ORIGIN_STROKE;
this.ctx.fillStyle = this.ORIGIN_STROKE;
this.ctx.beginPath();
this.ctx.arc(x, y, 4, 0, 2 * Math.PI, false);
this.ctx.stroke();
this.ctx.fill();
this.ctx.restore();
},
/**
* Computes the largest width and height of all the given shapes and changes
* all of the shapes' points (by reference) so they fit into the configured
* MAX_DIM - 2*PAD area.
* @return {Object} A {w, h} giving the size the canvas should be
*/
_fitAllShapes: function(allShapes) {
let allXs = [], allYs = [];
for (let shape of allShapes) {
for (let point of shape) {
allXs.push(point[0]);
allYs.push(point[1]);
}
}
let minX = Math.min.apply(Math, allXs);
let maxX = Math.max.apply(Math, allXs);
let minY = Math.min.apply(Math, allYs);
let maxY = Math.max.apply(Math, allYs);
let spanX = maxX - minX;
let spanY = maxY - minY;
let isWide = spanX > spanY;
let cw = isWide ? this.MAX_DIM :
this.MAX_DIM * Math.min(spanX, spanY) / Math.max(spanX, spanY);
let ch = !isWide ? this.MAX_DIM :
this.MAX_DIM * Math.min(spanX, spanY) / Math.max(spanX, spanY);
let mapX = x => this.PAD + ((cw - 2 * this.PAD) / (maxX - minX)) * (x - minX);
let mapY = y => this.PAD + ((ch - 2 * this.PAD) / (maxY - minY)) * (y - minY);
for (let shape of allShapes) {
for (let point of shape) {
point[0] = mapX(point[0]);
point[1] = mapY(point[1]);
}
}
return {w: cw, h: ch};
},
_drawShapes: function(shape, corner, transformed, transformedCorner) {
this._drawOriginal(shape);
this._drawOriginalCorner(corner);
this._drawTransformed(transformed);
this._drawTransformedCorner(transformedCorner);
},
_drawOriginal: function(points) {
this._drawShape(points, this.ORIGINAL_FILL, this.ORIGINAL_STROKE);
},
_drawTransformed: function(points) {
this._drawShape(points, this.TRANSFORMED_FILL, this.TRANSFORMED_STROKE);
},
_drawOriginalCorner: function(points) {
this._drawShape(points, this.ORIGINAL_STROKE, this.ORIGINAL_STROKE);
},
_drawTransformedCorner: function(points) {
this._drawShape(points, this.TRANSFORMED_STROKE, this.TRANSFORMED_STROKE);
},
_drawArrows: function(shape, transformed) {
this._drawArrow(shape[0][0], shape[0][1], transformed[0][0], transformed[0][1]);
this._drawArrow(shape[1][0], shape[1][1], transformed[1][0], transformed[1][1]);
this._drawArrow(shape[2][0], shape[2][1], transformed[2][0], transformed[2][1]);
this._drawArrow(shape[3][0], shape[3][1], transformed[3][0], transformed[3][1]);
},
/**
* Draw a transform preview
*
* @param {String} transform
* The css transform value as a string, as typed by the user, as long
* as it can be computed by the browser
* @param {String} origin
* Same as above for the transform-origin value. Defaults to "center"
* @param {Number} width
* The width of the container. Defaults to 200
* @param {Number} height
* The height of the container. Defaults to 200
* @return {Boolean} Whether or not the preview could be created. Will return
* false for instance if the transform is invalid
*/
preview: function(transform, origin="center", width=200, height=200) {
// Create/clear the canvas
if (!this.canvas) {
this._createMarkup();
}
this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
// Get computed versions of transform and origin
transform = this._getComputed("transform", transform, width, height);
if (transform && transform !== "none") {
origin = this._getComputed("transform-origin", origin, width, height);
// Get the matrix, origin and width height data for the previewed element
let originData = this._getOriginFromOriginString(origin);
let matrixData = this._getMatrixFromTransformString(transform);
// Compute the original box rect and transformed box rect
let shapePoints = [
[0, 0],
[width, 0],
[width, height],
[0, height]
];
let transformedPoints = this._getTransformedPoints(matrixData, shapePoints, originData);
// Do the same for the corner triangle shape
let cornerSize = Math.min(shapePoints[2][1] - shapePoints[1][1],
shapePoints[1][0] - shapePoints[0][0]) / this.CORNER_SIZE_RATIO;
let cornerPoints = [
[shapePoints[1][0], shapePoints[1][1]],
[shapePoints[1][0], shapePoints[1][1] + cornerSize],
[shapePoints[1][0] - cornerSize, shapePoints[1][1]]
];
let transformedCornerPoints = this._getTransformedPoints(matrixData, cornerPoints, originData);
// Resize points to fit everything in the canvas
let {w, h} = this._fitAllShapes([
shapePoints,
transformedPoints,
cornerPoints,
transformedCornerPoints,
[originData]
]);
this.canvas.setAttribute("width", w);
this.canvas.setAttribute("height", h);
this._drawShapes(shapePoints, cornerPoints, transformedPoints, transformedCornerPoints)
this._drawArrows(shapePoints, transformedPoints);
this._drawOrigin(originData[0], originData[1]);
return true;
} else {
return false;
}
}
};