Changing the cursor from emscripten

You may have an app which needs to change the cursor when you interact with elements in the canvas. In the app I'm working on, I needed the cursor to change when you hover over drawn bars that allow for sizing. To do this I wrote a little javascript code to do the cursor change and then had the c++ call it.

The javascript code:

function changeMouseCursor( type ) {

    if ( type == 0 ) {  
        $('canvas').css( 'cursor', 'default' );  
    }
    else if ( type == 1 ) {
        $('canvas').css('cursor', 'n-resize' );
    }
    else if ( type == 2 ) {
        $('canvas').css('cursor', 's-resize' );
    }
    else if ( type == 4 ) {
        $('canvas').css('cursor', 'e-resize' );
    }
    else if ( type == 5 ) {
        $('canvas').css('cursor', 'se-resize' );
    }
    else if ( type == 6 ) {
        $('canvas').css('cursor', 'ne-resize' );
    }
    else if ( type == 8 ) {
        $('canvas').css('cursor', 'w-resize' );
    }
    else if ( type == 9 ) {
        $('canvas').css('cursor', 'sw-resize' );
    }
    else if ( type == 10 ) {
        $('canvas').css('cursor', 'nw-resize' );
    }
}

Code in emscripten:

int sizeType = IsOverDraggableBorder( m_mouseX, m_mouseY );
                       
 if ( sizeType != m_sizingType )
{
        //change the cursor
        char call[200];
        sprintf(call, "changeMouseCursor(%d)", sizeType );
        emscripten_run_script(call);
                           
         m_sizingType = sizeType;
 }

Here is what it looks like in my app :)

Emscripten speed optimizations

One more important thing I have left off from previous posts is that without these optimization options fed to the compiler it will not be fast! Make sure that you have "-O2 -s ASM_JS=1" as part of your build config. As far as I can tell the "-s ASM_JS=1" doesn't seem to do much, but the first part "-O2" makes a significant difference!

Your build command might look as follows:
~/emscripten/emscripten/emcc -O2 -s ASM_JS=1 main.cpp -o /var/www/html/test.html

Another thing to note is that you most likely should get the beta firefox version (currently 22) to see how your code performs with the latest asm.js optimizations.