Simplewaita/source/common/buttons.scss

//auxiliary functions for buttons first

$_default_button_c: $button_bg;

@function _border_color($c, $darker: false) {
  @if $darker == true { @return darken($c, 20%); }
  @else { @return darken($c, 10%); }
}

@function _text_shadow_color ($tc: $fg_color, $bg: $bg_color) {
//
// calculate the color of text shadows
//
// $tc is the text color
// $bg is the background color
//
  $_lbg: lightness($bg)/100%;
  @if lightness($tc)<50% { @return transparentize(white, 1-$_lbg/($_lbg*1.3)); }
  @else { @return transparentize(black, $_lbg*0.8); }
}

@function _button_hilight_color($c) {
//
// calculate the right top hilight color for buttons
//
// $c: base color;
//
  @if lightness($c)>95% { @return white; }
  @else if lightness($c)>90% { @return transparentize(white, 0.15); }
  @else if lightness($c)>80% { @return transparentize(white, 0.35); }
  @else if lightness($c)>50% { @return transparentize(white, 0.5); }
  @else if lightness($c)>40% { @return transparentize(white, 0.65); }
  @else { @return transparentize(white, 0.7); }
  //@return $top_hilight;
}

@mixin _button_text_shadow ($tc:$fg_color, $bg:$bg_color) {
//
// helper function for the text emboss effect
//
// $tc is the optional text color, not the shadow color
//
// TODO: this functions needs a way to deal with special cases
//

  $_shadow: _text_shadow_color($tc, $bg);

  @if lightness($tc)<50% {
    text-shadow: 0 1px _button_hilight_color($tc);//$_shadow;
    -gtk-icon-shadow: 0 1px _button_hilight_color($tc);//$_shadow;
  }
  @else {
    text-shadow: 0 -1px $_shadow;
    -gtk-icon-shadow: 0 -1px $_shadow;
  }
}





@mixin button($t, $c:$button_bg, $tc:$button_fg, $edge: none, $backimage: null) {

	//
	// Button drawing function
	//
	// $t:    button type,
	// $c:    base button color for colored* types
	// $tc:   optional text color for colored* types
	// $edge: set to none to not draw the bottom edge or specify a color to not
	//        use the default one
	// $backimage: additional background-image behind the default one
	//             (for the button.circular hack)
	//
	// possible $t values (gtk3):
	// normal, hover, active, insensitive, insensitive-active,
	// backdrop, backdrop-active, backdrop-insensitive, backdrop-insensitive-active,
	// osd, osd-hover, osd-active, osd-insensitive, osd-backdrop, undecorated
	
	// possible $t values (gtk4):
	// normal, hover, active, checked-hover, checked-active, insensitive, insensitive-active,
	// backdrop, backdrop-active, backdrop-insensitive, backdrop-insensitive-active,
	// osd, osd-hover, osd-active, osd-insensitive, osd-backdrop, undecorated

	// this mixin needs to cover both gtk3 and gtk4 cases in order to work.
	// gtk4 mixin calls only include $t, $c and $tc, therefore it should be safe to use in both.

	//TODO: gtk3 add cases in common.scss to separate active from checked-active

  	$_hilight_color: _button_hilight_color($c);
	$_button_edge: if($edge == none, none, _widget_edge($edge));
	$_blank_edge: if($edge == none, none, _widget_edge(transparentize($edge,1)));
	$_button_shadow: 0 1px 2px transparentize($shadow_hard_color, 0.6);
	
	$button_clickable_image: linear-gradient(
						to bottom, 
						transparentize($_hilight_color, if($variant == 'light', 0.2 ,0.3 )), 
						transparentize($_hilight_color, 1) 50%,
						transparentize($shadow_hard_color, 1) 50%,
						transparentize($shadow_hard_color, if($variant == 'light',0.85,0.7)) );
	
	@if $t==normal or $t==normal-alt  {
	//
	// normal button
	//
	
	color: $tc;
	background-color: $c;
	outline-color: $focus_border_color;
	background-image: $button_clickable_image;
	@include _button_text_shadow($tc, $c);
    @include _shadows(inset 0 1px $_hilight_color, $_button_edge, $_button_shadow);
    
	}
	@else if $t==hover or $t==hover-alt or $t==undecorated-hover  {
	//
	// hovered button
	//
  	background-color: shade($c, 1.1)
	}

	
  	
  	@else if ($t==active)  {
	  //
	  // pushed button
	  //
	  //color: $button_checked_fg;
	  //background-color: $button_checked_bg;
		@include _shadows(0 1px $_hilight_color, $_button_edge, inset $_button_shadow);
	}
	
	@else if ($t==checked-active ) {
	  //
	  // pushed and toggled button
	  //
	  color: $button_checked_fg;
	  background-color: $button_checked_bg;
	  @include _button_text_shadow($button_checked_fg, $button_checked_bg);
	  @include _shadows(0 1px $_hilight_color, $_button_edge, inset $_button_shadow);
	
	}
	
	@else if ($t==checked-hover) {
	  //
	  // toggled button and hover
	  //
	  color: $button_checked_fg;
	  background-color: shade($button_checked_bg, 1.1);
	  @include _button_text_shadow($button_checked_fg, $button_checked_bg);
	  @include _shadows(0 1px $_hilight_color, $_button_edge, inset $_button_shadow);
	
	}

	
	 @else if $t==insensitive {
  //
  // insensitive button
  //
  		color: $insensitive_fg_color;
  		background-color: $insensitive_bg_color;
  		background-image: if($backimage==null, none, $backimage);
  	}
  	@else if $t==insensitive-active {
  	  //
 	 // insensitive pushed button
  	//
  		color: $insensitive_fg_color;
  		background-color: mix($insensitive_bg_color, $button_checked_bg, 85%);
  	}
  	
  	@else if $t==backdrop  {
	  //
	  // backdrop button
	  //
	  background-image: if($backimage==null, none, $backimage);
	  }
	@else if $t==backdrop-active {
  //
  // backdrop pushed button
  //
  }
  @else if $t==backdrop-insensitive {
  //
  // backdrop insensitive button
  //
  }
  
  @else if $t==backdrop-insensitive-active {
  //
  // backdrop insensitive pushed button
  //
  }
  
  //TODO: what happens with OSDs? Is it necessary to redefine them?
  
  @else if $t==undecorated {
  //
  // reset
  //
    border-color: transparent;
    background-color: transparent;
    background-image: none;

    @include _shadows(inset 0 1px transparentize(white, 1), $_blank_edge);

    text-shadow: none;
    -gtk-icon-shadow: none;
  }
  
}