138 lines
4.3 KiB
JavaScript
138 lines
4.3 KiB
JavaScript
/*
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* @provide pskl.drawingtools.SimplePen
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*
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* @require pskl.utils
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*/
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(function() {
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var ns = $.namespace("pskl.drawingtools");
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ns.Stroke = function() {
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this.toolId = "tool-stroke"
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// Stroke's first point coordinates (set in applyToolAt)
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this.startCol = null;
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this.startRow = null;
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// Stroke's second point coordinates (changing dynamically in moveToolAt)
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this.endCol = null;
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this.endRow = null;
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this.canvasOverlay = null;
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};
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pskl.utils.inherit(ns.Stroke, ns.BaseTool);
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/**
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* @override
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*/
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ns.Stroke.prototype.applyToolAt = function(col, row, frame, color, canvas, dpi) {
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this.startCol = col;
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this.startRow = row;
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// When drawing a stroke we don't change the model instantly, since the
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// user can move his cursor to change the stroke direction and length
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// dynamically. Instead we draw the (preview) stroke in a fake canvas that
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// overlay the drawing canvas.
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// We wait for the releaseToolAt callback to impact both the
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// frame model and canvas rendering.
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// The fake canvas where we will draw the preview of the stroke:
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this.canvasOverlay = this.createCanvasOverlay(canvas);
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// Drawing the first point of the stroke in the fake overlay canvas:
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this.drawPixelInCanvas(col, row, this.canvasOverlay, color, dpi);
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};
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ns.Stroke.prototype.moveToolAt = function(col, row, frame, color, canvas, dpi) {
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this.endCol = col;
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this.endRow = row;
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// When the user moussemove (before releasing), we dynamically compute the
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// pixel to draw the line and draw this line in the overlay canvas:
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var strokePoints = this.getLinePixels_(this.startCol, this.endCol, this.startRow, this.endRow);
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// Clean overlay canvas:
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this.canvasOverlay.getContext("2d").clearRect(
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0, 0, this.canvasOverlay.width, this.canvasOverlay.height);
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// Drawing current stroke:
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for(var i = 0; i< strokePoints.length; i++) {
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if(color == Constants.TRANSPARENT_COLOR) {
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// When mousemoving the stroke tool, we draw in the canvas overlay above the drawing canvas.
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// If the stroke color is transparent, we won't be
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// able to see it during the movement.
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// We set it to a semi-opaque white during the tool mousemove allowing to see colors below the stroke.
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// When the stroke tool will be released, It will draw a transparent stroke,
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// eg deleting the equivalent of a stroke.
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color = "rgba(255, 255, 255, 0.6)";
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}
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this.drawPixelInCanvas(strokePoints[i].col, strokePoints[i].row, this.canvasOverlay, color, dpi);
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}
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};
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/**
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* @override
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*/
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ns.Stroke.prototype.releaseToolAt = function(col, row, frame, color, canvas, dpi) {
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this.endCol = col;
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this.endRow = row;
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// If the stroke tool is released outside of the canvas, we cancel the stroke:
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if(col < 0 || row < 0 || col > frame.length || row > frame[0].length) {
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this.removeCanvasOverlays();
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return;
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}
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// The user released the tool to draw a line. We will compute the pixel coordinate, impact
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// the model and draw them in the drawing canvas (not the fake overlay anymore)
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var strokePoints = this.getLinePixels_(this.startCol, this.endCol, this.startRow, this.endRow);
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for(var i = 0; i< strokePoints.length; i++) {
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// Change model:
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frame[strokePoints[i].col][strokePoints[i].row] = color;
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// Draw in canvas:
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// TODO: Remove that when we have the centralized redraw loop
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this.drawPixelInCanvas(strokePoints[i].col, strokePoints[i].row, canvas, color, dpi);
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}
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// For now, we are done with the stroke tool and don't need an overlay anymore:
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this.removeCanvasOverlays();
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};
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/**
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* Bresenham line algorihtm: Get an array of pixels from
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* start and end coordinates.
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*
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* http://en.wikipedia.org/wiki/Bresenham's_line_algorithm
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* http://stackoverflow.com/questions/4672279/bresenham-algorithm-in-javascript
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*
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* @private
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*/
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ns.Stroke.prototype.getLinePixels_ = function(x0, x1, y0, y1) {
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var pixels = [];
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var dx = Math.abs(x1-x0);
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var dy = Math.abs(y1-y0);
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var sx = (x0 < x1) ? 1 : -1;
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var sy = (y0 < y1) ? 1 : -1;
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var err = dx-dy;
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while(true){
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// Do what you need to for this
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pixels.push({"col": x0, "row": y0});
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if ((x0==x1) && (y0==y1)) break;
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var e2 = 2*err;
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if (e2>-dy){
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err -= dy;
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x0 += sx;
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}
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if (e2 < dx) {
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err += dx;
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y0 += sy;
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}
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}
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return pixels;
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};
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})();
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