How to scale GraphicsPathCommand data? - actionscript-3

Question

Context: For a legacy Flex/Actionscript drawing app, I need to add scaling of simple symbols. The app uses the Graffiti lib for drawing and the resulting shape data is stored as GraphicsPathCommands serialized to XML using the Degrafa lib for save and reload. I need to enable the user to scale these graphics and then get updated path data which can be serialized. The symbols are simple but more complicated than simple geometry. For example:
Question: I converted the SVG data for this symbol to Actionscript GraphicsPathCommands and am able to draw it, and of course translation is easy – but I don't know how I would scale it, given a bounding box defined by a user dragging out a marquee rectangle in the app.
Does anyone know of either an Actionscript way of transforming the command data, or a Javascript snippet for scaling SVG which I can port to Actionscript?
For reference, an example of the Actionscript GraphicsPathCommands for drawing a star is below.
public function DrawPathExample()
{
var star_commands:Vector.<int> = new Vector.<int>(5, true);
star_commands[0] = GraphicsPathCommand.MOVE_TO;
star_commands[1] = GraphicsPathCommand.LINE_TO;
star_commands[2] = GraphicsPathCommand.LINE_TO;
star_commands[3] = GraphicsPathCommand.LINE_TO;
star_commands[4] = GraphicsPathCommand.LINE_TO;
var star_coord:Vector.<Number> = new Vector.<Number>(10, true);
star_coord[0] = 66; //x
star_coord[1] = 10; //y
star_coord[2] = 23;
star_coord[3] = 127;
star_coord[4] = 122;
star_coord[5] = 50;
star_coord[6] = 10;
star_coord[7] = 49;
star_coord[8] = 109;
star_coord[9] = 127;
graphics.beginFill(0x003366);
graphics.drawPath(star_commands, star_coord);
}
Solution
A full solution for interactively scaling GraphicsPathCommand data is below. The path data was derived from an SVG put through this SVGParser. It generates path drawing commands in the form of graphics.lineTo(28.4,16.8);. A couple of utility functions separate the data from the commands and store them in Vectors so the data can be serialized. I don't need to use arbitrary SWGs so I just hardcoded the data.
package classes
{
import flash.display.GraphicsPathCommand;
import flash.display.Shape;
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.geom.Point;
import flash.geom.Rectangle;
public class DrawSVG extends Sprite
{
private var startPt:Point = new Point();
private var selectRect:Rectangle = new Rectangle();
private var viewBox:Rectangle = new Rectangle();
protected var commands:Vector.<int> = new Vector.<int>();
protected var drawingData:Vector.<Number> = new Vector.<Number>();
protected var sourceDrawingData:Vector.<Number> = new Vector.<Number>();
public function DrawSVG()
{
super();
this.addEventListener(Event.ADDED_TO_STAGE, setup);
setupWomanData();
}
private function setup(event:Event):void
{
stage.addEventListener(MouseEvent.MOUSE_DOWN, onMouseDown);
}
private function onMouseDown(event:MouseEvent):void
{
stage.addEventListener(MouseEvent.MOUSE_UP, onMouseUp);
stage.addEventListener(MouseEvent.MOUSE_MOVE, onMouseMove);
this.graphics.clear();
// offset so graphic draws centered on click point
startPt = new Point(event.stageX - (viewBox.width /2), event.stageY - (viewBox.height /2));
selectRect = new Rectangle(startPt.x, startPt.y, viewBox.width, viewBox.height);
var kx:Number = selectRect.width / (viewBox.width);
var ky:Number = selectRect.height / (viewBox.height);
var scaleFactor:Number = kx < ky ? kx : ky;
drawSymbol(scaleFactor);
this.graphics.lineStyle(1, 0x000000);
this.graphics.drawRect(selectRect.x, selectRect.y, selectRect.width, selectRect.height);
}
private function onMouseMove(event:MouseEvent):void
{
selectRect.width = Math.max(viewBox.width, Math.abs(event.stageX - startPt.x));
selectRect.height = Math.max(viewBox.height, Math.abs(event.stageY - startPt.y));
var kx:Number = selectRect.width / (viewBox.width);
var ky:Number = selectRect.height / (viewBox.height);
var scaleFactor:Number = kx < ky ? kx : ky;
this.graphics.clear();
drawSymbol(scaleFactor);
this.graphics.lineStyle(1, 0x000000);
this.graphics.drawRect(selectRect.x, selectRect.y, viewBox.width * scaleFactor, viewBox.height * scaleFactor);
}
private function onMouseUp(event:MouseEvent):void
{
stage.removeEventListener(MouseEvent.MOUSE_UP, onMouseUp);
stage.removeEventListener(MouseEvent.MOUSE_MOVE, onMouseMove);
this.graphics.clear();
createSprite(commands, drawingData);
}
private function drawSymbol(toScale:Number):void
{
drawingData.length = 0;
for (var i:int = 0; i < sourceDrawingData.length; i++) {
drawingData[i] = Math.max(sourceDrawingData[i], sourceDrawingData[i] * toScale);
drawingData[i] += i % 2 == 0 ? startPt.x : startPt.y ;
}
this.graphics.clear();
this.graphics.lineStyle();
this.graphics.beginFill(0xff0000);
this.graphics.drawPath(commands, drawingData);
this.graphics.endFill();
}
private function createSprite(command:Vector.<int>, coord:Vector.<Number>):Shape{
var s:Shape = new Shape();
addChild(s);
s.graphics.beginFill(0xff);
s.graphics.drawPath(command, coord);
s.graphics.endFill();
return s;
}
private function setupWomanData():void
{
commands = new Vector.<int>();
drawingData = new Vector.<Number>();
viewBox= new Rectangle(0, 0, 24.629, 52.336);
addMoveToCmd(12.31,10.3);
addCurveToCmd(13.37,10.3,14.3,9.89);
addCurveToCmd(15.24,9.48,15.94,8.78);
addCurveToCmd(16.64,8.08,17.05,7.14);
addCurveToCmd(17.46,6.2,17.46,5.15);
addCurveToCmd(17.46,4.1,17.05,3.16);
addCurveToCmd(16.64,2.23,15.94,1.52);
addCurveToCmd(15.24,0.82,14.3,0.41);
addCurveToCmd(13.37,0,12.31,0);
addCurveToCmd(11.26,0,10.33,0.41);
addCurveToCmd(9.39,0.82,8.69,1.52);
addCurveToCmd(7.98,2.23,7.57,3.16);
addCurveToCmd(7.16,4.1,7.16,5.15);
addCurveToCmd(7.16,6.2,7.57,7.14);
addCurveToCmd(7.98,8.08,8.69,8.78);
addCurveToCmd(9.39,9.48,10.33,9.89);
addCurveToCmd(11.26,10.3,12.31,10.3);
addLineToCmd(12.314,10.304);
addMoveToCmd(24.6,26.36);
addLineToCmd(20.7,12.77);
addCurveToCmd(20.62,12.3,20.39,11.91);
addCurveToCmd(20.15,11.51,19.81,11.23);
addCurveToCmd(19.47,10.94,19.04,10.78);
addCurveToCmd(18.61,10.62,18.14,10.62);
addLineToCmd(6.49,10.62);
addCurveToCmd(6.02,10.62,5.59,10.78);
addCurveToCmd(5.16,10.94,4.82,11.23);
addCurveToCmd(4.48,11.51,4.24,11.91);
addCurveToCmd(4.01,12.3,3.93,12.77);
addLineToCmd(0.03,26.36);
addCurveToCmd(0.01,26.4,0.01,26.45);
addCurveToCmd(-0.01,26.5,-0.01,26.55);
addCurveToCmd(0.01,26.6,0.01,26.65);
addCurveToCmd(0.02,26.69,0.03,26.74);
addCurveToCmd(-0.15,27.95,0.55,28.69);
addCurveToCmd(1.25,29.44,2.2,29.6);
addCurveToCmd(3.15,29.77,4.05,29.3);
addCurveToCmd(4.95,28.84,5.17,27.63);
addLineToCmd(6.85,21.37);
addLineToCmd(4.07,34.88);
addCurveToCmd(3.81,35.51,3.91,36.15);
addCurveToCmd(4,36.78,4.35,37.3);
addCurveToCmd(4.7,37.81,5.26,38.13);
addCurveToCmd(5.81,38.45,6.49,38.45);
addLineToCmd(6.78,38.45);
addLineToCmd(6.78,49.72);
addCurveToCmd(6.78,50.99,7.59,51.62);
addCurveToCmd(8.41,52.25,9.39,52.25);
addCurveToCmd(10.37,52.25,11.19,51.62);
addCurveToCmd(12,50.99,12,49.72);
addLineToCmd(12,38.45);
addLineToCmd(12.63,38.45);
addLineToCmd(12.63,49.72);
addCurveToCmd(12.63,50.99,13.44,51.62);
addCurveToCmd(14.26,52.25,15.24,52.25);
addCurveToCmd(16.22,52.25,17.04,51.62);
addCurveToCmd(17.85,50.99,17.85,49.72);
addLineToCmd(17.85,38.45);
addLineToCmd(18.14,38.45);
addCurveToCmd(18.82,38.45,19.38,38.13);
addCurveToCmd(19.93,37.81,20.28,37.3);
addCurveToCmd(20.63,36.78,20.72,36.14);
addCurveToCmd(20.81,35.51,20.56,34.87);
addLineToCmd(17.78,21.37);
addLineToCmd(19.45,27.58);
addCurveToCmd(19.67,28.79,20.57,29.27);
addCurveToCmd(21.47,29.75,22.43,29.6);
addCurveToCmd(23.38,29.45,24.08,28.7);
addCurveToCmd(24.78,27.96,24.6,26.74);
addCurveToCmd(24.61,26.69,24.62,26.65);
addCurveToCmd(24.63,26.6,24.63,26.55);
addCurveToCmd(24.63,26.5,24.62,26.45);
addCurveToCmd(24.62,26.4,24.6,26.36);
addLineToCmd(24.601,26.356);
}
protected function addCurveToCmd(p1:Number, p2:Number, p3:Number, p4:Number):void
{
commands.push(GraphicsPathCommand.CURVE_TO);
sourceDrawingData.push(p1);
sourceDrawingData.push(p2);
sourceDrawingData.push(p3);
sourceDrawingData.push(p4);
}
protected function addMoveToCmd(p1:Number, p2:Number):void
{
commands.push(GraphicsPathCommand.MOVE_TO);
sourceDrawingData.push(p1);
sourceDrawingData.push(p2);
}
protected function addLineToCmd(p1:Number, p2:Number):void
{
commands.push(GraphicsPathCommand.LINE_TO);
sourceDrawingData.push(p1);
sourceDrawingData.push(p2);
}
}
}

Answer 1

Seems like there is a pretty straightforward way to do this. It looks like the only thing to scale are the coordinates themselves, so you may just apply a scale factor.
Based on your example:
public function ASEntryPoint() {
var star_commands:Vector.<int> = new Vector.<int>(5, true);
star_commands[0] = GraphicsPathCommand.MOVE_TO;
star_commands[1] = GraphicsPathCommand.LINE_TO;
star_commands[2] = GraphicsPathCommand.LINE_TO;
star_commands[3] = GraphicsPathCommand.LINE_TO;
star_commands[4] = GraphicsPathCommand.LINE_TO;
var star_coord:Vector.<Number> = new Vector.<Number>(10, true);
star_coord[0] = 66; //x
star_coord[1] = 10; //y
star_coord[2] = 23;
star_coord[3] = 127;
star_coord[4] = 122;
star_coord[5] = 50;
star_coord[6] = 10;
star_coord[7] = 49;
star_coord[8] = 109;
star_coord[9] = 127;
//reference shape to detect initial size
var s:Shape = shapeInRect(star_commands, star_coord);
var bounds:Rectangle = s.getBounds(s);
s.graphics.lineStyle(1);
s.graphics.drawRect(bounds.x, bounds.y, bounds.width, bounds.height);
addChild(s);
//fit to target
var targetSize:Rectangle = new Rectangle(150, 100, 75, 60);
//detect lesser factor - assuming you need to preserve proportions
var kx:Number = targetSize.width / (bounds.width);
var ky:Number = targetSize.height / (bounds.height);
var toUse:Number = kx < ky ? kx : ky;
//apply to coords
for (var i:int = 0; i < star_coord.length; i++) {
//size
star_coord[i] *= toUse;
//fix initial offset
star_coord[i] -= i % 2 == 0 ? bounds.x * toUse : bounds.y * toUse;
}
//draw
addChild(shapeInRect(star_commands, star_coord, targetSize));
}
private function shapeInRect(command:Vector.<int>, coord:Vector.<Number>, rect:Rectangle = null):Shape{
var s:Shape = new Shape();
addChild(s);
s.graphics.beginFill(0x003366);
s.graphics.drawPath(command, coord);
s.graphics.endFill();
if (rect){
s.graphics.lineStyle(1);
s.graphics.drawRect(0, 0, rect.width, rect.height);
s.x = rect.x;
s.y = rect.y;
}
return s;
}