Question

I am developing an Windows Forms application using VB.NET that offers the user to lookup addresses on Google Maps through a Web Browser. I can also successfully show the directions between two points to the user, as well as allow the user to drag the route as he/she pleases. My question now is – is it possible for me to get the lattitude/longitude information of the route, i.e. the overview_polyline array of encoded lattitude/longitude points and save it to e.g. a text file on my computer? Or is it possible to get a list of all the addresses located both sides of the route over the entire length of the route, and then save the data to a file on my computer? I’m using HTML files to access and display the Google Maps data in the Web Browser item.

Thank you

Answer 1

This is actually pretty simple if your just looking for the screen coordinates.

// this probably should be in your form initialization 
this.MouseClick += new MouseEventHandler(MouseClickEvent); 


    void MouseClickEvent(object sender, MouseEventArgs e) 
    { 
        // do whatever you need with e.Location 
    } 

if your strictly looking for the point in the browser, you need to consider the functions

browser.PointToClient(); 
browser.PointToScreen(); 

So, this method is usable if you know exactly where your form is (easy to get its coords) and where you webbrowser control is (easy to get coords of this as well since it’s just a control in your form) and then, as long as you know how many pixels from the left or right, and from the top or bottom the image will be displayed, once you get the global mouse click coords (which is easy) you can predict where it was clicked on the image.

Alternatively, there are some scarier or uglier ways to do it here…

You can use the ObjectForScripting property to embed code to do this in the webbrowser. It’s ugly to say the least. MSDN has some documentation on the process here: http://msdn.microsoft.com/en-us/library/system.windows.forms.webbrowser.objectforscripting.aspx

Because its really ugly, maybe a better solution is to use AxWebBrowser – it’s ugly too but not so scary.

In addition, I found this post of someone wanting to do it on a pdf document, and a MSFT person saying its not possible, but really what he is trying to say is that it isn’t built in, even with a pdf document its still possible to predict with high to certain accuracy where it was clicked if you use the first method i described. Here is the post anyway: http://social.msdn.microsoft.com/Forums/en/csharpgeneral/thread/2c41b74a-d140-4533-9009-9fcb382dcb60

However, it is possible, and there are a few ways to do it, so don’t get scared from that last link I gave ya.

Also, this post may help if you want to do it in javascript:
http://www.devx.com/tips/Tip/29285

Basically, you can add an attribute on the image through methods available in the webbrowser control, you can add something like onclick=”GetCoords();” so when it is clicked, the JavaScript function will get the coords, and then you can use javascript to place the values in a hidden input field (input type=”hidden”) which you can add through the webbrowser control, or if there is one already on the page, you can use that. So, once you place the coords using javacript into that input field, you can easily grab the value in that using the webbrowser control, eg:

webbrowser1.document.getElementById("myHiddenInputField").value

That will get the value in that field, which you’ve set through JavaScript. Also, the “GetCoords()” function i mentioned is called SetValues() in the javascript method link i provided above (in the devx.com site) but I named it GetCoords because it makes more sense and didn’t want to confuse you with the actual name they used, you can change this to any name you want of course. Here is the javascript they were using, this only gets the coords into a variable, doesn’t put it into a hidden input field, we will need to do that in addition (at the end of the javascript SetValues/GetCoords function).

function SetValues()
{
var s = 'X=' + window.event.clientX + ' Y=' + window.event.clientY ;
document.getElementById('divCoord').innerText = s;
}

These guys are just saving it inside a div element, which is visible to users, but you can make the div invisible if you want to use a div field, there is no advantage or disadvantage in doing that, you would just need to set the visible property to false using javascript or css, but still, it is easier to use a hidden input field so you don’t need to mess with any of that.

Let me know how you get along.