[GUI] [linux] Support creating fullscreen window by "ti.GUI(fullscreen=True)"

[archibate]

Related issue = taichi-dev/taichi_three#20 (comment)

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This PR use the method in https://stackoverflow.com/questions/9083273/x11-fullscreen-window-opengl to support fullscreen on X11. We'd add this to Win32 and Cocoa too iapr.

[codecov]

Codecov Report

Merging #1921 into master will increase coverage by 0.92%.
The diff coverage is 16.66%.

@@            Coverage Diff             @@
##           master    #1921      +/-   ##
==========================================
+ Coverage   42.80%   43.72%   +0.92%     
==========================================
  Files          45       45              
  Lines        6413     6207     -206     
  Branches     1101     1103       +2     
==========================================
- Hits         2745     2714      -31     
+ Misses       3498     3322     -176     
- Partials      170      171       +1     

Impacted Files	Coverage Δ
python/taichi/misc/gui.py	8.68% <16.66%> (ø)
.../build/taichi-dev/taichi/python/taichi/__init__.py
.../build/taichi-dev/taichi/python/taichi/lang/ops.py
...d/taichi-dev/taichi/python/taichi/core/settings.py
...build/taichi-dev/taichi/python/taichi/lang/tape.py
...build/taichi-dev/taichi/python/taichi/lang/util.py
...uild/taichi-dev/taichi/python/taichi/lang/shell.py
...taichi-dev/taichi/python/taichi/lang/common_ops.py
...uild/taichi-dev/taichi/python/taichi/misc/image.py
...ild/taichi-dev/taichi/python/taichi/tools/video.py
... and 81 more

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[archibate]

@JYLeeLYJ Would you confirm if this part works? many thanks!

[thinking-tower]

LGTM! I ran it on Ubuntu 18.04 and tried it on fractals, nbody_oscillator and taichi_logo and it works. Not all of the examples listen for an escape key, so it was a bit of an issue for me to minimize the window until I found the keyboard shortcut.

For MacOS:

Add

  if (fullscreen) {
    call(window, "toggleFullScreen:");
  }

to the end of GUI::create_window() in taichi/gui/cocoa.cpp and it should start in full screen.

taichi/taichi/gui/cocoa.cpp

Lines 268 to 311 in 094baad

	void GUI::create_window() {
	clscall("NSApplication", "sharedApplication");
	if (NSApp == nullptr) {
	fprintf(stderr, "Failed to initialized NSApplication.\nterminating.\n");
	return;
	}
	// I finally found how to bring the NSWindow to the front and to handle
	// keyboard events in these posts:
	// https://stackoverflow.com/a/11010614/12003165
	// http://www.cocoawithlove.com/2010/09/minimalist-cocoa-programming.html
	//
	// The problem was that, a Cocoa app without NIB files (app bundle,
	// info.plist, whatever the meta files are) by default has a policy of
	// NSApplicationActivationPolicyProhibited.
	// (https://developer.apple.com/documentation/appkit/nsapplicationactivationpolicy/nsapplicationactivationpolicyprohibited?language=objc)
	call(NSApp, "setActivationPolicy:", NSApplicationActivationPolicyRegular);
	// This doesn't seem necessary, but in case there's some weird bug causing the
	// Window not to be brought to the front, try enable this.
	// https://stackoverflow.com/a/7460187/12003165
	// call(NSApp, "activateIgnoringOtherApps:", YES);
	img_data_length = width * height * 4;
	img_data.resize(img_data_length);
	auto appDelObj = clscall("AppDelegate", "alloc");
	appDelObj = call(appDelObj, "init");
	call(NSApp, "setDelegate:", appDelObj);
	window = clscall("NSWindow", "alloc");
	auto rect = (CGRect){{0, 0}, {CGFloat(width), CGFloat(height)}};
	call(window, "initWithContentRect:styleMask:backing:defer:", rect,
	(NSTitledWindowMask | NSClosableWindowMask | NSResizableWindowMask |
	NSMiniaturizableWindowMask),
	0, false);
	view = call(clscall(kTaichiViewClassName, "alloc"), "initWithFrame:", rect);
	gui_from_id[view] = this;
	// Needed by NSWindowDelegate
	gui_from_id[window] = this;
	// Use layer to speed up the draw
	// https://developer.apple.com/documentation/appkit/nsview/1483695-wantslayer?language=objc
	call(view, "setWantsLayer:", YES);
	call(window, "setDelegate:", appDelObj);
	call(window, "setContentView:", view);
	call(window, "becomeFirstResponder");
	call(window, "setAcceptsMouseMovedEvents:", YES);
	call(window, "makeKeyAndOrderFront:", window);
	}

[k-ye]

LGTM!