Pager

Use pager to display a horizontally scrollable list of pages.

Simple three page pager

The following example displays three predefined pages that occupy all available space within the pager (BrPagerPageElement>>#weight: weight: aNumber weight := aNumber. self requestLayout is set to 1). 

threeFullPagePager
	<gtExample>
	| aPager |
	
	aPager := BrPager new
		matchParent.
	
	aPager addPage: (BrPagerPageElement new
		weight: 1.0;
		layout: BlLinearLayout horizontal alignCenter;
		background: (Color gray alpha: 0.1);
		addChild: (BrLabel new
			aptitude: (BrGlamorousLabelAptitude new fontSize: 30; foreground: Color gray);
			text: 'Page 1')).
			
	aPager addPage: (BrPagerPageElement new
		weight: 1.0;
		layout: BlLinearLayout horizontal alignCenter;
		background: (Color red alpha: 0.1);
		addChild: (BrLabel new
			aptitude: (BrGlamorousLabelAptitude new fontSize: 30; foreground: Color red);
			text: 'Page 2')).

	aPager addPage: (BrPagerPageElement new
		weight: 1.0;
		layout: BlLinearLayout horizontal alignCenter;
		background: (Color blue alpha: 0.1);
		addChild: (BrLabel new
			aptitude: (BrGlamorousLabelAptitude new fontSize: 30; foreground: Color blue);
			text: 'Page 3')).

	^ aPager

Two page pager with custom weight

It is possible, however, to set a different BrPagerPageElement>>#weight: weight: aNumber weight := aNumber. self requestLayout which will make pages share the space within their pager. 

twoHalfPagePager
	<gtExample>
	| aPager |
	
	aPager := BrPager new
		matchParent.
	
	aPager addPage: (BrPagerPageElement new
		weight: 0.5;
		layout: BlLinearLayout horizontal alignCenter;
		background: (Color gray alpha: 0.1);
		addChild: (BrLabel new
			aptitude: (BrGlamorousLabelAptitude new fontSize: 30; foreground: Color gray);
			text: 'Page 1')).
			
	aPager addPage: (BrPagerPageElement new
		weight: 0.5;
		layout: BlLinearLayout horizontal alignCenter;
		background: (Color red alpha: 0.1);
		addChild: (BrLabel new
			aptitude: (BrGlamorousLabelAptitude new fontSize: 30; foreground: Color red);
			text: 'Page 2')).

	^ aPager

Dynamically adding a page

If needed, pages can be added dynamically with the same api as we used in the previous examples BrPager>>#addPage: addPage: aContentElement self viewModel addPage: aContentElement viewModel . However, it is usually required to scroll to a newly created page which can be achieved with the help of the BrPager>>#scrollToLast scrollToLast self scrollTo: self pages size method. 

dynamicPager
	<gtExample>
	| aPager |
	aPager := BrPager new.
	aPager matchParent.
	aPager
		addPage:
			(BrPagerPageElement new
				weight: 1.0;
				layout: BlLinearLayout vertical alignCenter;
				background: (Color gray alpha: 0.1);
				addChild:
					(BrButton new
						beHugeSize;
						aptitude: BrGlamorousButtonWithLabelAptitude new;
						label: 'Next';
						action: [ aPager
								addPage:
									(BrPagerPageElement new
										layout: BlLinearLayout vertical alignCenter;
										background: (Color random alpha: 0.1);
										weight: 1.0;
										addChild:
											(BrLabel new
												aptitude:
													(BrGlamorousLabelAptitude new
														fontSize: 30;
														foreground: Color red);
												text: 'New page')).
							aPager scrollToLast ])).
	^ aPager

Infinite pager

We can build on the previous example to create an "infinite" pager by using a stencil to recursively build new pages: 

infinitePager
	<gtExample>
	| aPager aPageStencil |
	aPager := BrPager new.
	aPager matchParent.
	aPageStencil := nil.
	aPageStencil := [ BrPagerPageElement new
		weight: 1.0;
		layout: BlLinearLayout vertical alignCenter;
		background: (Color random alpha: 0.1);
		addChild:
			(BrLabel new
				aptitude:
					(BrGlamorousLabelAptitude new
						fontSize: 30;
						foreground: Color gray);
				margin: (BlInsets all: 30);
				text: ('Page {1}' format: {(aPager pages size + 1)}));
		addChild:
			(BrButton new
				aptitude: BrGlamorousButtonWithLabelAptitude new;
				beHugeSize;
				label: 'Next';
				action: [ aPager addPage: aPageStencil asElement.
					aPager scrollToLast ]) ] asStencil.
	aPager addPage: aPageStencil asElement.
	^ aPager