ArcGIS API for Android case study 8

I. Client element client element layer

ArcGIS Android provides a client element layer graphicslayer. With ArcGIS's previous web development experience, we can know that this layer is used to draw client elements. Let's try to add another graphicslayer in mapview:

<? XML version ="1.0"Encoding ="UTF-8"?>

<Linearlayout xmlns: Android =Http://schemas.android.com/apk/res/android"

Android: Orientation ="Vertical"Android: layout_width ="Fill_parent"

Android: layout_height ="Fill_parent">

<Button Android: Id ="@ + ID/buttonaddgraphic"Android: layout_width ="Fill_parent"

Android: layout_height ="Wrap_content"Android: text ="Add client elements"/>

<Com. ESRI. Android. Map. mapview Android: Id ="@ + ID/Map"

Android: layout_width ="Fill_parent"Android: layout_height ="Fill_parent">

<Com. ESRI. Android. Map. AGS. arcgistiledmapservicelayer
Url =Http://server.arcgisonline.com/ArcGIS/rest/services
/World_imagery/mapserver"/>

<Com. ESRI. Android. Map. graphicslayer Android: Id ="@ + ID/glayer"/>

</COM. ESRI. Android. Map. mapview>

</Linearlayout>

Here, I also added a button "add client elements". I hope that when you click this button, the program can add a client element in the center of the map, that is, add a graphic on graphicslayer. Therefore, I added the following code when creating this activity:

Glayer = (graphicslayer) findviewbyid (R. Id.Glayer);

Glayer. setrenderer (NewSimplerenderer (NewSimplemarkersymbol (color.Red,

20, simplemarkersymbol. style.Square)));

Buttonaddgraphic = (button) findviewbyid (R. Id.Buttonaddgraphic);

Buttonaddgraphic. setonclicklistener (NewOnclicklistener (){

Public VoidOnclick (view v ){

Graphic G =NewGraphic ();

G. setgeometry (agsgraphicslayer.This. Map. getcenter ());

Agsgraphicslayer.This. Glayer. addgraphic (g );

Agsgraphicslayer.This. Glayer. postinvalidate ();

}

});

Pay attention to the lines of code highlighted above. The rendering style of graphicslayer is defined above, indicating that the client element layer must display a point element of 20 pixels and a square shape; the following code adds a client element through the button and notifies the program to update the display immediately. These codes run as follows:

Figure 22 Add a client element by clicking the button

Now let's change the rendering method. I want to use a small image to render these elements. For example, I want to use the icon of the current program. How should I modify it? You can check the API to find the familiar picturemarkersymbol symbol class. Let's modify the above Code a bit:

Drawable image = agsgraphicslayer.This. Getbasecontext (). getresources ()

. Getdrawable (R. drawable.Icon);

Glayer. setrenderer (NewSimplerenderer (NewPicturemarkersymbol (image )));

Here, we obtain the program's icon resource and use it as a picturemarkersymbol symbol, so that the modified Code runs like this:

Figure 23 use images to display client Elements

Similarly, we can also perform classification rendering or unique value rendering on the client layer. For example, if I want to show the red half of the elements and the green half of the elements, I can use the classification rendering implementation:

Classbreaksrenderer Renderer =NewClassbreaksrenderer ();

Renderer. setfield ("class ");

Renderer. setminvalue (0 );

Classbreak class1 =NewClassbreak ();

Class1.setclassmaxvalue (0.5 );

Class1.setsymbol (NewSimplemarkersymbol (color.Red, 20,

Simplemarkersymbol. style.Circle));

Renderer. addclassbreak (class1 );

Classbreak class2 =NewClassbreak ();

Class2.setclassmaxvalue (1 );

Class2.setsymbol (NewSimplemarkersymbol (color.Green, 20,

Simplemarkersymbol. style.Circle));

Renderer. addclassbreak (class2 );

Glayer. setrenderer (Renderer );

Buttonaddgraphic = (button) findviewbyid (R. Id.Buttonaddgraphic);

Buttonaddgraphic. setonclicklistener (NewOnclicklistener (){

Public VoidOnclick (view v ){

Graphic G =NewGraphic ();

G. setattributevalue ("class", math.Random());

G. setgeometry (agsgraphicslayer.This. Map. getcenter ());

Agsgraphicslayer.This. Glayer. addgraphic (g );

Agsgraphicslayer.This. Glayer. postinvalidate ();

}

});

In this way, all client elements are displayed in different colors based on the randomly assigned attribute "class", as shown in Figure 24.

Figure 24 display client elements using classification Rendering