Saving Map in Image at specific extent

[shabbirsiddiqui2]

Hi,

I am using the function of snapshot to save the map in .PNG on button click at the time of submission of form.

I want this function to always save the map at specific extent, i use this function but not useful on single click.

Can any one guide me how to achieve this.


            private var quality:Number;
            private var logovis:Boolean;   
            private var sbvis:Boolean;
            private var zoomslidevis:Boolean;
            private var mapbg:uint;           
            private var ImageData:ByteArray;
            private var strEncodedString:String;       
            private var myEncoder:Base64Encoder = new Base64Encoder();

            protected function saveMapImage():void
            {
               
                // for zooming at at spacific location before saving(but not useful)
                var offset:int=300;
                var graphicsExtent:Extent;
                if (geom)
                {
                    graphicsExtent = geom.extent;
                    graphicsExtent.xmax=graphicsExtent.xmax+offset;
                    graphicsExtent.xmin=graphicsExtent.xmin-offset;
                    graphicsExtent.ymax=graphicsExtent.ymax+offset;
                    graphicsExtent.ymin=graphicsExtent.ymin-offset;
                    map.extent = graphicsExtent
                }
                // for saving the map..               
                map.infoWindow.hide();
                map.infoWindowContent = null;
                const encoder: JPEGEncoder = new JPEGEncoder(quality);
                map.scaleBarVisible=sbvis;
                map.zoomSliderVisible = zoomslidevis;
                map.opaqueBackground = mapbg;
                map.validateNow();
                const imageSnapshot:ImageSnapshot = ImageSnapshot.captureImage(map,0,encoder);
                map.scaleBarVisible=true;
                map.opaqueBackground = null;
                map.validateNow();
                ImageData = new ByteArray(); // To send through webservices to ASP.Net
                ImageData = imageSnapshot.data;   
            }

[IvanBespalov]

You must handle map zoom end handler, or any other way handle (listen each layer update end) map fully updated after you change extent.

In this code look at: map.addEventListener(ZoomEvent.ZOOM_END, onMapZoomEnd);
If map extent not changed - call function exports map image.
If map extent changed - wait until map zoomed, call function exports map image.

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
      xmlns:s="library://ns.adobe.com/flex/spark"
      xmlns:esri="http://www.esri.com/2008/ags" 
      xmlns:mx="library://ns.adobe.com/flex/mx">
 
 <!-- ArcGIS API for FLEX 3.0 -->
 <!-- Adobe SDK 4.6 -->
 
 <s:layout>
  <s:VerticalLayout paddingBottom="20"
        paddingLeft="20"
        paddingRight="20"
        paddingTop="20"/>
 </s:layout>
 
 <fx:Script>
  <![CDATA[
   import com.esri.ags.Graphic;
   import com.esri.ags.events.DrawEvent;
   import com.esri.ags.events.ZoomEvent;
   import com.esri.ags.geometry.Extent;
   import com.esri.ags.geometry.Geometry;
   import com.esri.ags.symbols.SimpleFillSymbol;
   import com.esri.ags.symbols.SimpleLineSymbol;
   
   import mx.collections.ArrayCollection;
   import mx.controls.Alert;
   import mx.core.UIComponent;
   import mx.events.CloseEvent;
   import mx.graphics.codec.PNGEncoder;
   
   private const FILE_NAME:String = "screen.png";
   
   private var mapExtent:Extent;
   private var bitmapData:BitmapData;   
   private var logoBitmapData:BitmapData;
   
   /**
    * Save as png clicked
    */
   protected function onSaveAsPng(event:MouseEvent):void
   {
    trace("Save button clicked");
    
    var printableExtent:Extent = getDrawnExtent();
    var readyToPrint:Boolean = true;
    
    if (printableExtent)
    {
     mapExtent = map.extent;
     map.extent = printableExtent;
     
     map.addEventListener(ZoomEvent.ZOOM_END, onMapZoomEnd);
    }
    else
    {
     saveMapImage();
    }
   }
   
   /**
    * Map zoom endend
    */
   protected function onMapZoomEnd(event:ZoomEvent):void
   {
    trace("Map zoom ended")
    map.removeEventListener(ZoomEvent.ZOOM_END, onMapZoomEnd);
    
    // user action needed (mouse click or key press) to call FileReference.save() method
    Alert.show("Do you really want to print?", "Ready to print", Alert.YES | Alert.NO, null, onAlertClose);
   }
   
   /**
    * Confirmation dialog close handler
    */
   protected function onAlertClose(event:CloseEvent):void
   {
    trace("Confirmation dialog closed");
    if (event.detail == Alert.YES)
    {
     saveMapImage();
    }
    else
    {
     // restore map state
     showComponents();
    }
   }
   
   /**
    * @private
    */
   private function saveMapImage():void
   {
    trace("Image export started");
    var fileReference:FileReference = new FileReference();
    
    hideComponents();
    
    // add listeners to show zoom slider after execution
    fileReference.addEventListener(Event.COMPLETE, fileSaveComplete);
    fileReference.addEventListener(Event.CANCEL, fileSaveCancel);
    
    try
    {
     var mapComponent:UIComponent = map as UIComponent;
     var exportData:BitmapData = getBitmapData(mapComponent);
     if (exportData)
     {
      // encode to PNG format
      var pngEncoder:PNGEncoder = new PNGEncoder();
      var byteArray:ByteArray = pngEncoder.encode(exportData);
      // open dialog box
      fileReference.save(byteArray, FILE_NAME);
      
      exportData = null;
      bitmapData = null;
     }
    }
    catch (ioError:IllegalOperationError)
    { 
     trace(ioError.getStackTrace());
    }
    catch (error:Error)
    { 
     trace(error.getStackTrace());
    }
   }
   
   /**
    * get bitmap data from IBitmapDrawable component
    */
   private function getBitmapData(uiComponent:UIComponent):BitmapData
   {
    try
    {
     // map image size
     var mapWidth:Number = uiComponent.width;
     var mapHeigth:Number = uiComponent.height;
     // get flash map bitmap data
     bitmapData = new BitmapData(mapWidth, mapHeigth);
     var matrix:Matrix = new Matrix();
     bitmapData.draw(uiComponent, matrix);
     
     // logo image size
     var logoWidth:Number = logo.width;
     var logoHeigth:Number = logo.height;
     // get logo bitmap data
     logoBitmapData = new BitmapData(logoWidth, logoHeigth);
     logoBitmapData.draw(logo, matrix);
     
     // calculate logo left-top position on map
     var logoX:Number = mapWidth - logoWidth - 10;
     var logoY:Number = 10;
     var point:Point = new Point(logoX, logoY);
     var mult:uint = 0x100; // 100% (256) RGBA channels multipliers
     bitmapData.merge(logoBitmapData, logoBitmapData.rect, point, mult, mult, mult, mult);
    }
    catch (error:Error)
    {
     trace(error.getStackTrace()); 
    }
    return bitmapData;
   }
   
   /**
    * Hide crosshair, logo, scalebar ...
    */
   private function hideComponents():void
   {
    // TODO: complete code
    
    // force UIComponent update/redraw
    map.validateNow();
   }
   
   /**
    * Restore hidden map components: crosshair, logo, scalebar ...
    * Restore map extent.
    */
   private function showComponents():void
   {
    // TODO: complete code
    
    // restore map extent
    map.extent = mapExtent;
    mapExtent = null;
   }
   
   /**
    * @return extent of drawn graphic
    */
   private function getDrawnExtent():Extent
   {
    var graphicProvider:ArrayCollection = graphicsLayer.graphicProvider as ArrayCollection;
    if (graphicProvider && graphicProvider.length > 0)
    {
     var graphic:Graphic = graphicProvider.getItemAt(0) as Graphic;
     var geometry:Geometry = graphic.geometry;
     
     graphicsLayer.clear();
     return geometry.extent;
    }
    else
    {
     trace("Graphics provider is empty");
     return null;
    }
   }
   
   /**
    * Draw button clicked
    */
   protected function onActivateDrawTool(event:MouseEvent):void
   {
    trace("Draw button clicked");
    
    graphicsLayer.clear();
    
    drawTool.activate(DrawTool.EXTENT);
    drawTool.fillSymbol = new SimpleFillSymbol(SimpleFillSymbol.STYLE_NULL, 0, 0, new SimpleLineSymbol(SimpleLineSymbol.STYLE_SOLID, 0, 1, 2));
   }
   
   /**
    * Drawing ended
    */
   protected function onDrawEnd(event:DrawEvent):void
   {
    trace("Drawing ended");
    
    drawTool.deactivate();
   }
   
   /**
    * File upload/download canceled by user
    */
   protected function fileSaveCancel(event:Event):void
   {
    showComponents();
   }
   
   /**
    * File upload/download completed
    */
   protected function fileSaveComplete(event:Event):void
   {
    showComponents();
   }
   
  ]]>
 </fx:Script>
 
 <fx:Declarations>
  <esri:DrawTool id="drawTool"
        drawEnd="onDrawEnd(event)"
        graphicsLayer="{graphicsLayer}"
        map="{map}"/>
 </fx:Declarations>
 
 <s:HGroup width="100%">
  
  <mx:Image id="logo"
      source="http://edn.esri.com/common/style/images/esriLogoSm.gif" />
  
  <s:Button label="Save as PNG"
      click="onSaveAsPng(event)" />
  
  <s:Button label="Draw printable Extent"
      click="onActivateDrawTool(event)" />
  
 </s:HGroup>
 
 <esri:Map id="map"> 
  
  <esri:ArcGISTiledMapServiceLayer url="http://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer"/>
  
  <esri:GraphicsLayer id="graphicsLayer" />
  
 </esri:Map>
 
 
</s:Application>

Good luck