Posts Tagged ‘scroll’

Patch for GLUT on Mac OS X for horizontal scrolling and command key modifier

Thursday, October 24th, 2013

I recently found out about a patch for the GLUT framework on Mac OS X to provide support for mouse wheel scrolling. This is great, because I was really getting tired of the X11 windows that freeGLUT uses.

I followed these instructions for building from source: grab the source from Apple and apply the 3 patches.

Unfortunately I still got compilation errors on Mac OS X 10.7.5 with Xcode 4.

Type 'id <NSMenuItem>' does not conform to the 'NSCopying' protocol

I fixed this, I changed the line in GLUTApplication.m that looks like:

- (BOOL)validateMenuItem:(id <NSMenuItem>)menuItem


- (BOOL)validateMenuItem:(NSMenuItem *)menuItem

Now it compiles. These patches only add support for vertical scrolling. To add horizontal scrolling I changed the scrollWheel function in GLUTView.m to this:

- (void)scrollWheel: (NSEvent *)theEvent
   if(_mouseFunc) {
      NSPoint location = [self convertMouseLocationToBacking: [theEvent locationInWindow]];

      float deltaY = [theEvent deltaY];
      float deltaX = [theEvent deltaX];
      int buttonID = GLUT_WHEEL_UP;
      if(deltaY < 0) {
         deltaY = -deltaY;
         buttonID = GLUT_WHEEL_DOWN;
      }else if(deltaY > 0)
         buttonID = GLUT_WHEEL_UP;
      }else if(deltaX < 0)
         deltaY = -deltaX;
         buttonID = GLUT_WHEEL_RIGHT;
      }else if(deltaX > 0)
         deltaY = deltaX;
         buttonID = GLUT_WHEEL_LEFT;

      int x = rint(location.x);
      int y = rint(location.y);

      int i;
      for(i = 0; i < deltaY; i++) {
//       (*_mouseFunc)(buttonID, GLUT_DOWN, x, y);
         (*_mouseFunc)(buttonID, GLUT_UP, x, y);

and add the following definitions in glut.h:


While I was at it, I also added support for catching the command (aka apple, aka ⌘) key. To do this I add the following lines to glutGetModifiers in macx_modifier.m:

   if(__glutModifierMask & NSCommandKeyMask)
      modifiers |= GLUT_ACTIVE_COMMAND;

and again added a respective definition in glut.h:

#define GLUT_ACTIVE_COMMAND             8

Now I compile and replace the GLUT.framework directory in /System/Library/Frameworks/ and I’m reading to go!

Download xcodeproject of patched glut

Update: On 10.9 OS X Mavericks, I’m getting complaints from Xcode that garbage collection is no longer supported and that I should switch to ARC. I chose “Not now”, but then got a compile error complaining:

error: garbage collection is no longer supported

I fixed this, following this advice, by removing lines like

                           GCC_ENABLE_OBJC_GC = supported;

from GLUT_External.xcodeproj/project.pbxproj. I’ve updated the zipped project appropriately.

Update: On 10.10 OS X Yosemite my hack for getting modifier keys during mouse move and scroll events with Carbon “expired”. Rather than figure out how to continue using Carbon, I’ve patched Glut again to reveal modifier flags during mouse move and mouse scroll events. This means that you can call glutGetModifiers during your glutPassiveMotionFunc, glutMotionFunc and when glutMouseFunc fires on a scroll event. I’ve updated the zipped project by appropriately enclosing these function calls between:

__glutModifierMask = [theEvent modifierFlags];
... // call func
__glutModifierMask = ~0;

**Update: ** Based on another patch I’ve updated mine to enable easy access to the core profile.

**Update: ** I’ve basically been tracking my changes via a .zip file hosted on this blog. That’s not very safe. Now, I’ve uploaded all of the code to a github repo. You can still download everything as a zip or just clone the repo.

Scroll a bit in safari window, take screenshot repeat

Friday, February 22nd, 2013

Here’s an applescript I used to make a series of screen captures of scrolling through a web page in safari:

tell application "Safari"
	set sc to 0
		set thescript to "if((window.pageYOffset + window.innerHeight)<document.body.clientHeight)
    	window.scrollBy(0,10); // horizontal and vertical scroll increments
		do JavaScript thescript in current tab of first window
		set imagePath to (path to desktop as text) & "screenCapture_" & my zero_pad(sc, 6) & ".png"
		delay 1.5
		do shell script "screencapture -o -mx -T0 " & quoted form of POSIX path of imagePath
		delay 0.5
		set sc to sc + 1
	end repeat
end tell

on zero_pad(value, string_length)
	set string_zeroes to ""
	set digits_to_pad to string_length - (length of (value as string))
	if digits_to_pad > 0 then
		repeat digits_to_pad times
			set string_zeroes to string_zeroes & "0" as string
		end repeat
	end if
	set padded_value to string_zeroes & value as string
	return padded_value
end zero_pad