Saturday, January 28, 2012

Creating a Flex AIR Screenshot app: Part 7

In this tutorial we are going to start adding functionality to the screenshot feature.

The screenshot feature is our program's main feature, and the crop feature will later work based on the functions we'll make during creating this screenshot functionality, so it is wise to start with it before we go any deeper into the crop functionality. This doesn't mean that everything we've done for the crop stage window is for nothing - no, on the contrary, we will use it in the future, when we return to coding it.

Anyway, let's start now. Go to the loadpage NavigatorContent container and swap the image buttons (the Screenshot button should stand first, since it really is the main attraction of the program). Add a click event listener for the screenshot button, set the handler to goScreenshot() function:

<s:NavigatorContent id="loadpage">
<s:VGroup width="100%" horizontalAlign="center" paddingTop="20">
<s:Label styleName="descriptionText">Enter the link to the page:</s:Label>
<s:HGroup>
<s:TextInput width="250" id="urlInput" text="http://" /><s:Button label="Browse local..." click="doBrowse();" />
</s:HGroup>
<s:HGroup>
<custom:ImageButton img="@Embed('../lib/b_screenshot.png')" over="@Embed('../lib/b_screenshot_over.png')" toolTip="Take screenshot" click="goScreenshot();" buttonMode="true" enabled="{urlInput.text!=''}" />
<custom:ImageButton img="@Embed('../lib/b_cut.png')" over="@Embed('../lib/b_cut_over.png')" toolTip="Crop area" click="goCrop();" buttonMode="true" enabled="{urlInput.text!=''}" />
</s:HGroup>
</s:VGroup>
</s:NavigatorContent>

When the user clicks on this button, according to our scheme - the user should be taken to export settings. However, there is a process to be made before that - and that is loading the actual site to later take picture of it. To do that, we'll need to create another state for our application - so create a new NavigatorContent with an id of "screenshotloading". It should contain text saying that the user should wait until the page is loaded, and a button to cancel loading. Set the button's click event handler to cancelLoading().

<s:NavigatorContent id="loadpage">
<s:VGroup width="100%" horizontalAlign="center" paddingTop="20">
<s:Label styleName="descriptionText">Enter the link to the page:</s:Label>
<s:HGroup>
<s:TextInput width="250" id="urlInput" text="http://" /><s:Button label="Browse local..." click="doBrowse();" />
</s:HGroup>
<s:HGroup>
<custom:ImageButton img="@Embed('../lib/b_screenshot.png')" over="@Embed('../lib/b_screenshot_over.png')" toolTip="Take screenshot" click="goScreenshot();" buttonMode="true" enabled="{urlInput.text!=''}" />
<custom:ImageButton img="@Embed('../lib/b_cut.png')" over="@Embed('../lib/b_cut_over.png')" toolTip="Crop area" click="goCrop();" buttonMode="true" enabled="{urlInput.text!=''}" />
</s:HGroup>
</s:VGroup>
</s:NavigatorContent>

Add this NavigatorContent after loadpage one. This way it is second in the stack.

Go to declarations and add a new object for the headings for this stack item, place it as the second item:

<fx:Declarations>
<mx:ArrayCollection id="headerTitles">
<fx:Object step="Step one:" description="load a web page." />
<fx:Object step="Loading..." description="please wait." />
<fx:Object step="Step two:" description="set your export preferences." />
<fx:Object step="Step two:" description="select the area you wish to crop." />
<fx:Object step="Step three:" description="set your export preferences for the cropped image." />
<fx:Object step="Final step:" description="please wait while your images are being expored." />
</mx:ArrayCollection>
</fx:Declarations>

The loading process is like this - we create a temporary HTML object somewhere (without displaying it to the user) and load the content inside of it. Listen to its COMPLETE event, when that is dispatched - go to next view stack item.

First declare this HTML object:

private var tempHTML:HTML = new HTML();

Create a goScreenshot() function. Inside of it, set the stack's selectedChild to screenshotloading page, set urlString to the input text field's text value. Add the HTML object using addElement() method, set its visibility to false, add an event listener and load the page.

private function goScreenshot():void {
stack.selectedChild = screenshotloading;
urlString = urlInput.text;

addElement(tempHTML);
tempHTML.visible = false;
tempHTML.addEventListener(Event.COMPLETE, onTempLoad);
tempHTML.htmlLoader.load(new URLRequest(urlString));
}

In the onTempLoad() function, set selectedChild of the stack to screenshotsettings:

private function onTempLoad(evt:Event):void {
stack.selectedChild = screenshotsettings;
}

When the user cancels the loading, cancelLoading() is called. Inside of it, remove the event listener for the COMPLETE event, cancel loading usign cancelLoad() method and return to loadpage. Remove tempHTML using removeElement:

private function cancelLoading():void {
tempHTML.removeEventListener(Event.COMPLETE, onTempLoad);
tempHTML.cancelLoad();
stack.selectedChild = loadpage;
removeElement(tempHTML);
}

And we're done.

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:custom="*"
                       xmlns:mx="library://ns.adobe.com/flex/mx" showStatusBar="false"
   width="550" height="300" creationComplete="init();">
   
   
<fx:Declarations>
<mx:ArrayCollection id="headerTitles">
<fx:Object step="Step one:" description="load a web page." />
<fx:Object step="Loading..." description="please wait." />
<fx:Object step="Step two:" description="set your export preferences." />
<fx:Object step="Step two:" description="select the area you wish to crop." />
<fx:Object step="Step three:" description="set your export preferences for the cropped image." />
<fx:Object step="Final step:" description="please wait while your images are being expored." />
</mx:ArrayCollection>
</fx:Declarations>

<fx:Style>
@namespace s "library://ns.adobe.com/flex/spark";
@namespace mx "library://ns.adobe.com/flex/mx";

.descriptionText{
fontSize: 24;
color: #fff;
}

#headStep{
fontSize: 30;
fontWeight: bold;
color: #ffffbb;
}

#headDesc{
fontSize: 30;
color: #ffffff;
}
</fx:Style>

<fx:Script>
<![CDATA[
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.filesystem.File;
import flash.geom.Rectangle;
import flash.net.URLRequest;
import mx.controls.HTML;
import mx.core.FlexHTMLLoader;
import mx.events.FlexNativeWindowBoundsEvent;
import mx.controls.Alert;
import mx.graphics.ImageSnapshot;
import spark.primitives.BitmapImage;

[Bindable]
private var urlString:String;
[Bindable]
private var canSelect:Boolean = true;
private var tempHTML:HTML = new HTML();

private function init():void {
addEventListener(FlexNativeWindowBoundsEvent.WINDOW_RESIZE, onResize);
}

private function doBrowse():void{
var file:File = new File();
file.addEventListener(Event.SELECT, browseSelect);
file.browseForOpen("Load a webpage");

function browseSelect(evt:Event):void {
urlInput.text = file.nativePath;
}
}

private function goCrop():void {
stack.selectedChild = crop;
urlString = urlInput.text;
}

private function goScreenshot():void {
stack.selectedChild = screenshotloading;
urlString = urlInput.text;

addElement(tempHTML);
tempHTML.visible = false;
tempHTML.addEventListener(Event.COMPLETE, onTempLoad);
tempHTML.htmlLoader.load(new URLRequest(urlString));
}

private function onTempLoad(evt:Event):void {
stack.selectedChild = screenshotsettings;
}

private function cancelLoading():void {
tempHTML.removeEventListener(Event.COMPLETE, onTempLoad);
tempHTML.cancelLoad();
stack.selectedChild = loadpage;
removeElement(tempHTML);
}

private function changeState():void {
if (stack.selectedChild == loadpage) {
contentBox.setStyle("horizontalAlign", "center");
urlInput.text = urlString;
}
if (stack.selectedChild == crop) {
maximize();
canSelect = true;
contentBox.setStyle("horizontalAlign", "left");
cropHTML.htmlLoader.load(new URLRequest(urlString));
cropHTML.width = contentBox.width;
cropHTML.height = contentBox.height - 24;
cropStatus.text = "Loading";
cropStatus.setStyle("color", "#ffff00");
cropHTML.addEventListener(Event.COMPLETE, onCropLoad);
}
}

private function onCropLoad(evt:Event):void {
cropStatus.text = "Loaded";
cropStatus.setStyle("color", "#ffffff");
}

private function onResize(evt:Event):void {
if (stack.selectedChild == crop) {
cropHTML.width = contentBox.width;
cropHTML.height = contentBox.height - 24;
}
}
]]>
</fx:Script>
   
<s:VGroup width="100%" height="100%" gap="0">
<mx:HBox backgroundColor="#333333" height="46" width="100%" paddingTop="10" paddingLeft="10">
<s:Label id="headStep" text="{headerTitles.getItemAt(stack.selectedIndex).step}" />
<s:Label id="headDesc" text="{headerTitles.getItemAt(stack.selectedIndex).description}" />
</mx:HBox>
<mx:Box backgroundColor="#666666" width="100%" height="100%" id="contentBox" horizontalAlign="center">
<mx:ViewStack id="stack" change="changeState();">
<s:NavigatorContent id="loadpage">
<s:VGroup width="100%" horizontalAlign="center" paddingTop="20">
<s:Label styleName="descriptionText">Enter the link to the page:</s:Label>
<s:HGroup>
<s:TextInput width="250" id="urlInput" text="http://" /><s:Button label="Browse local..." click="doBrowse();" />
</s:HGroup>
<s:HGroup>
<custom:ImageButton img="@Embed('../lib/b_screenshot.png')" over="@Embed('../lib/b_screenshot_over.png')" toolTip="Take screenshot" click="goScreenshot();" buttonMode="true" enabled="{urlInput.text!=''}" />
<custom:ImageButton img="@Embed('../lib/b_cut.png')" over="@Embed('../lib/b_cut_over.png')" toolTip="Crop area" click="goCrop();" buttonMode="true" enabled="{urlInput.text!=''}" />
</s:HGroup>
</s:VGroup>
</s:NavigatorContent>

<s:NavigatorContent id="screenshotloading">
<s:VGroup width="100%" horizontalAlign="center" paddingTop="20">
<s:Label styleName="descriptionText">The page is being loaded...</s:Label>
<s:Button label="Cancel" click="cancelLoading();" />
</s:VGroup>
</s:NavigatorContent>

<s:NavigatorContent id="screenshotsettings">

</s:NavigatorContent>

<s:NavigatorContent id="crop">
<s:VGroup width="100%" height="100%" gap="0">
<mx:HBox backgroundColor="#999999" width="100%" height="24" verticalScrollPolicy="off" verticalAlign="middle" paddingLeft="2">
<s:Button label="Back" click="{cropHTML.htmlLoader.loadString(''); stack.selectedChild = loadpage;}" />
<s:Button label="Export selection" enabled="false" />
<s:Label id="cropStatus" />
<s:Label text="{urlString}" />
</mx:HBox>
<mx:HTML id="cropHTML" horizontalScrollPolicy="on" verticalScrollPolicy="on" />
</s:VGroup>
</s:NavigatorContent>

<s:NavigatorContent id="cropsettings">

</s:NavigatorContent>

<s:NavigatorContent id="export">

</s:NavigatorContent>
</mx:ViewStack>
</mx:Box>
</s:VGroup>

</s:WindowedApplication>

Thanks for reading!

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