Friday, February 24, 2012

Creating a Flex AIR Annotator app: Part 5

Today we will add a cursor and pen drawing functionality.

First of all, find the Canvas container and make some changes to it - add a Box object with an id of drawHitArea, alpha 0, mouseDown and mouseMove event handlers drawDown() and drawMove(). Also, move th drawGroup object under imgHolder (so that it actually appears on top of imgHolder. I also changed drawGroup's class to Box and drawSprite's to Group. Also add event listeners for the canvas for rollOver and rollOut events, with handlers canvasOver() and canvasOut():

<mx:Canvas width="100%" height="100%" horizontalScrollPolicy="on" verticalScrollPolicy="on" rollOver="canvasOver();" rollOut="canvasOut();">
<mx:Box backgroundColor="#eeeeee" width="100%" height="100%" verticalAlign="middle" horizontalAlign="center" horizontalScrollPolicy="off" verticalScrollPolicy="off">
<mx:Box id="drawArea" backgroundColor="#ffffff" width="300" height="200" horizontalScrollPolicy="off" verticalScrollPolicy="off">
<mx:ViewStack id="stack" change="stackChange();">
<s:NavigatorContent>
<custom:BigButton icon="@Embed('../lib/folder.png')" subtext="Import picture" toolTip="Open file" enabled="true" buttonMode="true" bWidth="300" bHeight="200" click="importPicture();" />
</s:NavigatorContent>
<s:NavigatorContent>
<mx:Image id="imgHolder" />
<mx:Box id="drawGroup">
<s:Group id="drawSprite" />
</mx:Box>
<mx:Box id="drawHitArea" alpha="0" backgroundColor="#000000" mouseDown="drawDown();" mouseMove="drawMove();"/>
</s:NavigatorContent>
</mx:ViewStack>
</mx:Box>
</mx:Box>
</mx:Canvas>

Now, let's add a cursor. Here's a cross cursor picture I made for KirShot, I am going to use it for this annotator application too:


Put it in the lib directory of the project, call the file "cursor_cross.png". Declare a variable crossCursor with this image embedded:

[Embed(source="../lib/cursor_cross.png")]
private var crossCursor:Class;

Now create the canvasOver and canvasOut functions. In the first one, check if the drawing mode is selected, and if it is - set cursor to crossCursor. In the second function remove the cursors.

private function canvasOver():void {
if (toolbarStack.selectedIndex == 2) {
cursorManager.setCursor(crossCursor, 2, -9, -9);
}
}

private function canvasOut():void {
cursorManager.removeAllCursors();
}

Declare a new variable drawMode:

private var drawMode:String = "";

We have listeners for mouseDown and mouseMove events for the drawHitArea object, with handlers drawDown() and drawMove(). We need to listen for mouseUp as well, but globally. Add the listener in init() and set its handler to drawUp.

private function init():void{
drawArea.filters = [new DropShadowFilter(4, 60, 0, 0.7, 10, 10, 1, 3)];
addEventListener(MouseEvent.MOUSE_UP, drawUp);
}

The drawDown() function checks if the drawing mode is on, and if the pen is selected. If it is, set drawMode to pen and use drawSprite's graphic property's moveTo() method to move to mouse coordinates.

private function drawDown():void {
if (toolbarStack.selectedIndex == 2 && drawTools.selectedIndex == 0) {
drawMode = "pen";
drawSprite.graphics.moveTo(drawArea.mouseX, drawArea.mouseY);
}
}

In drawUp(), just set drawMode to blank:

private function drawUp(evt:MouseEvent):void {
drawMode = "";
}

In drawMove, check if drawMode is pen, and if it is - draw line to current mouse coordinates.

private function drawMove():void {
if (drawMode == "pen") {
drawSprite.graphics.lineStyle(lineThickness, lineColor);
drawSprite.graphics.lineTo(drawArea.mouseX, drawArea.mouseY);
}
}

The drawing works fine now, however, if we draw with bigger thickness and really close to the edge of the drawing area - because of the big radius, the line can cross the boundaries of the drawing area. To prevent this, we set drawHitArea's coordinates and size according to lineThickness to prevent the line from going out of the frame.

private function updateLineExample():void{
lineExample.graphics.clear();
lineExample.graphics.lineStyle(lineThickness, lineColor);
lineExample.graphics.moveTo(10, 10);
lineExample.graphics.lineTo(30, 10);

drawHitArea.width = content.width - lineThickness;
drawHitArea.height = content.height - lineThickness;
drawHitArea.x = lineThickness / 2;
drawHitArea.y = lineThickness / 2;
}

And that's all!

Full code:

<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009"
   xmlns:s="library://ns.adobe.com/flex/spark"
   xmlns:mx="library://ns.adobe.com/flex/mx" 
   xmlns:custom="*"
   showStatusBar="false"
   creationComplete="init();" minWidth="700" minHeight="400"
   width="700" height="500">

<fx:Script>
<![CDATA[
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.FocusDirection;
import flash.display.Loader;
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.filesystem.File;
import flash.filesystem.FileStream;
import flash.filters.DropShadowFilter;
import flash.geom.Matrix;
import flash.net.FileFilter;
import flash.net.URLRequest;
import flash.utils.ByteArray;
import mx.controls.Alert;
import flash.filesystem.FileMode;

private var bitmapData:BitmapData;
private var content:*;
[Bindable]
private var buttonsEnabled:Boolean = false;
[Bindable]
private var lineThickness:int = 5;
[Bindable]
private var lineColor:uint = 0xff0000;

[Embed(source="../lib/cursor_cross.png")]
private var crossCursor:Class;

private var drawMode:String = "";

private function init():void{
drawArea.filters = [new DropShadowFilter(4, 60, 0, 0.7, 10, 10, 1, 3)];
addEventListener(MouseEvent.MOUSE_UP, drawUp);
}

private function canvasOver():void {
if (toolbarStack.selectedIndex == 2) {
cursorManager.setCursor(crossCursor, 2, -9, -9);
}
}

private function canvasOut():void {
cursorManager.removeAllCursors();
}

private function drawDown():void {
if (toolbarStack.selectedIndex == 2 && drawTools.selectedIndex == 0) {
drawMode = "pen";
drawSprite.graphics.moveTo(drawArea.mouseX, drawArea.mouseY);
}
}

private function drawUp(evt:MouseEvent):void {
drawMode = "";
}

private function drawMove():void {
if (drawMode == "pen") {
drawSprite.graphics.lineStyle(lineThickness, lineColor);
drawSprite.graphics.lineTo(drawArea.mouseX, drawArea.mouseY);
}
}

private function importPicture():void {
var file:File = new File();
var imageFilter:FileFilter = new FileFilter("Images", "*.jpg;*jpeg;*.gif;*.png");
file.browseForOpen("Import picture", [imageFilter]);
file.addEventListener(Event.SELECT, fileSelect);
}

private function fileSelect(evt:Event):void {
var file:File = evt.target as File;
var loader:Loader = new Loader();
loader.contentLoaderInfo.addEventListener(Event.COMPLETE, loadComplete);
loader.load(new URLRequest(file.url));
}

private function loadComplete(evt:Event):void {
content = evt.target.content;
bitmapData = new BitmapData(content.width, content.height, false);
bitmapData.draw(content, new Matrix(), null, null, null, true);
stackChange(); // needed if selectedIndex was already 1 when the function was called
stack.selectedIndex = 1;
}

private function stackChange():void {
if (stack.selectedIndex == 1) {
imgHolder.source = new Bitmap(bitmapData);
drawArea.width = content.width;
drawArea.height = content.height;
drawGroup.width = content.width;
drawGroup.height = content.height;
buttonsEnabled = true;
}
}

private function toolbarChange():void {
if (toolbarStack.selectedIndex == 2) {
updateLineExample();
}
}

private function updateLineExample():void{
lineExample.graphics.clear();
lineExample.graphics.lineStyle(lineThickness, lineColor);
lineExample.graphics.moveTo(10, 10);
lineExample.graphics.lineTo(30, 10);

drawHitArea.width = content.width - lineThickness;
drawHitArea.height = content.height - lineThickness;
drawHitArea.x = lineThickness / 2;
drawHitArea.y = lineThickness / 2;
}
]]>
</fx:Script>

<fx:Declarations>
<mx:ArrayCollection id="toolbarToggle">
<fx:Object icon="@Embed('../lib/ic_pen.png')" />
<fx:Object icon="@Embed('../lib/ic_ellipse.png')"/>
<fx:Object icon="@Embed('../lib/ic_rect.png')"/>
<fx:Object icon="@Embed('../lib/ic_line.png')"/>
</mx:ArrayCollection>
</fx:Declarations>

<s:VGroup width="100%" height="100%" gap="0">
<mx:HBox backgroundColor="#ccccdd" width="100%" height="52">
<custom:IconButton icon="@Embed('../lib/new.png')" toolTip="New" enabled="{buttonsEnabled}" buttonMode="true" click="importPicture();" />
<custom:IconButton icon="@Embed('../lib/move.png')" toolTip="Move" enabled="{buttonsEnabled}" buttonMode="true" click="toolbarStack.selectedIndex=1;" />
<custom:IconButton icon="@Embed('../lib/draw.png')" toolTip="Draw" enabled="{buttonsEnabled}" buttonMode="true" click="toolbarStack.selectedIndex=2;" />
<custom:IconButton icon="@Embed('../lib/bubble.png')" toolTip="Annotation" enabled="{buttonsEnabled}" buttonMode="true" click="toolbarStack.selectedIndex=3;" />
<custom:IconButton icon="@Embed('../lib/cut.png')" toolTip="Cut" enabled="{buttonsEnabled}" buttonMode="true" click="toolbarStack.selectedIndex=4;" />
<custom:IconButton icon="@Embed('../lib/save.png')" toolTip="Save" enabled="{buttonsEnabled}" buttonMode="true" />
<mx:ViewStack id="toolbarStack" width="100%" height="100%" change="toolbarChange();">
<s:NavigatorContent>

</s:NavigatorContent>
<s:NavigatorContent>
<s:VGroup width="100%" height="44" top="4">
<s:Label fontSize="18" color="#333333">Selected: Move</s:Label>
<s:Label>Click and hold your mouse on annotations to move them.</s:Label>
</s:VGroup>
</s:NavigatorContent>
<s:NavigatorContent>
<s:VGroup width="100%" height="44" top="4">
<s:Label fontSize="18" color="#333333">Selected: Draw</s:Label>
<s:HGroup>
<mx:ToggleButtonBar dataProvider="{toolbarToggle}" width="100" id="drawTools" />
<mx:ColorPicker selectedColor="@{lineColor}" change="updateLineExample();" />
<mx:Slider minimum="1" maximum="15" change="updateLineExample();" value="@{lineThickness}" width="80" liveDragging="true"/>
<s:SpriteVisualElement width="40" height="20" id="lineExample"/>
<s:Button click="drawSprite.graphics.clear();" label="Clear all" />
</s:HGroup>
</s:VGroup>
</s:NavigatorContent>
<s:NavigatorContent>
<s:VGroup width="100%" height="44" top="4">
<s:Label fontSize="18" color="#333333">Selected: Annotation</s:Label>
<s:HGroup>
<s:TextInput width="180" text="Insert text here" />
<mx:ColorPicker />
</s:HGroup>
</s:VGroup>
</s:NavigatorContent>
<s:NavigatorContent>
<s:VGroup width="100%" height="44" top="4">
<s:Label fontSize="18" color="#333333">Selected: Cut</s:Label>
<s:HGroup>
<s:Label>Select an area to crop.</s:Label>
<s:Button label="Crop selected area" />
</s:HGroup>
</s:VGroup>
</s:NavigatorContent>
</mx:ViewStack>
</mx:HBox>
<mx:Canvas width="100%" height="100%" horizontalScrollPolicy="on" verticalScrollPolicy="on" rollOver="canvasOver();" rollOut="canvasOut();">
<mx:Box backgroundColor="#eeeeee" width="100%" height="100%" verticalAlign="middle" horizontalAlign="center" horizontalScrollPolicy="off" verticalScrollPolicy="off">
<mx:Box id="drawArea" backgroundColor="#ffffff" width="300" height="200" horizontalScrollPolicy="off" verticalScrollPolicy="off">
<mx:ViewStack id="stack" change="stackChange();">
<s:NavigatorContent>
<custom:BigButton icon="@Embed('../lib/folder.png')" subtext="Import picture" toolTip="Open file" enabled="true" buttonMode="true" bWidth="300" bHeight="200" click="importPicture();" />
</s:NavigatorContent>
<s:NavigatorContent>
<mx:Image id="imgHolder" />
<mx:Box id="drawGroup">
<s:Group id="drawSprite" />
</mx:Box>
<mx:Box id="drawHitArea" alpha="0" backgroundColor="#000000" mouseDown="drawDown();" mouseMove="drawMove();"/>
</s:NavigatorContent>
</mx:ViewStack>
</mx:Box>
</mx:Box>
</mx:Canvas>
</s:VGroup>

</s:WindowedApplication>

Thanks for reading!

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