#69 : Determine partial window content size

src/components/Carousel/Carousel.svelte

@@ -18,10 +18,14 @@
     applyClones,
     getPageSizes,
     applyPageSizes,
+    getCurrentPageIndexWithoutClones,
+    getPagesCountWithoutClones,
+    getOneSideClonesCount,
   } from '../../utils/page'
   import { get } from '../../utils/object'
   import { ProgressManager } from '../../utils/ProgressManager'
   import { wait } from '../../utils/interval'
+  import { getIsOdd } from '../../utils/math'
 
   const dispatch = createEventDispatcher()
 
@@ -103,12 +107,12 @@
   /**
    * Number of pages to show 
    */
-  export let pagesToShow = 2 // 2 // 1 // 3
+  export let pagesToShow = 4 // 2 // 2 // 1 // 3
 
   /**
    * Number of pages to scroll 
    */
-  export let pagesToScroll = 2 // 1 // 1  // 2
+  export let pagesToScroll = 3 // 2 // 1 // 1  // 2
 
 
   export async function goTo(pageIndex, options) {
@@ -116,7 +120,7 @@
     if (typeof pageIndex !== 'number') {
       throw new Error('pageIndex should be a number')
     }
-    await showPage(pageIndex + oneSideClonesCount, { animated })
+    await showPage(pageIndex * pagesToScroll + oneSideClonesCount, { animated })
   }
 
   export async function goToPrev(options) {
@@ -130,31 +134,25 @@
   }
 
   let store = createStore()
+  let oneSideClonesCount = getOneSideClonesCount({ pagesToScroll, pagesToShow })
+
   let currentPageIndex = 0
-  $: originalCurrentPageIndex = getOriginalCurrentPageIndex(currentPageIndex, pagesCount, infinite) // index without cloenes
+  $: originalCurrentPageIndex = getCurrentPageIndexWithoutClones({
+    currentPageIndex,
+    pagesCount,
+    oneSideClonesCount,
+    infinite,
+    pagesToScroll
+  })
   $: dispatch('pageChange', originalCurrentPageIndex)
 
-  let oneSideClonesCount = Math.max(pagesToScroll, pagesToShow) // TODO: check 
-  $: pagesItemsClonesCount = oneSideClonesCount * 2
   let pagesCount = 0
-
-  $: originalPagesCount = Math.max(
-    Math.ceil(
-      (
-        pagesCount - (infinite ? pagesItemsClonesCount : 0)
-      ) / pagesToScroll
-    ),
-  1) // without clones
-
-  function getOriginalCurrentPageIndex(currentPageIndex, pagesCount, infinite) {
-    if (infinite) {
-      console.log('currentPageIndex', currentPageIndex)
-      if (currentPageIndex === pagesCount - oneSideClonesCount) return 0
-      if (currentPageIndex === 0) return (pagesCount - oneSideClonesCount)
-      return Math.floor((currentPageIndex-oneSideClonesCount)/pagesToScroll)
-    }
-    return currentPageIndex
-  }
+  $: originalPagesCount = getPagesCountWithoutClones({
+    pagesCount,
+    infinite,
+    oneSideClonesCount,
+    pagesToScroll,
+  })
 
   let pagesWindowWidth = 0
   let pageWidth = 0
@@ -241,6 +239,7 @@
       await tick()
       cleanupFns.push(store.subscribe(value => {
         currentPageIndex = value.currentPageIndex
+        console.log('currentPageIndex', currentPageIndex)
       }))
       cleanupFns.push(() => progressManager.reset())
       if (pagesContainer && pageWindowElement) {
@@ -264,7 +263,7 @@
   })
 
   async function handlePageChange(pageIndex) {
-    await showPage(pageIndex + oneSideClonesCount)
+    await showPage(pageIndex * pagesToScroll + oneSideClonesCount)
   }
 
   function offsetPage(options) {
@@ -285,10 +284,10 @@
   async function jumpIfNeeded() {
     let jumped = false
     if (infinite) {
-      if (currentPageIndex === oneSideClonesCount - 1) {
-        await showPage(pagesCount - oneSideClonesCount - 1, { animated: false })
+      if (currentPageIndex === 0) { // oneSideClonesCount - 1) {
+        await showPage(pagesCount - 2 * oneSideClonesCount, { animated: false })
         jumped = true
-      } else if (currentPageIndex === pagesCount - oneSideClonesCount) {
+      } else if (currentPageIndex === pagesCount - oneSideClonesCount ) {
         await showPage(oneSideClonesCount, { animated: false })
         jumped = true
       }
@@ -313,7 +312,10 @@
 
   async function showPage(pageIndex, options) {
     await changePage(
-      () => store.moveToPage({ pageIndex, pagesCount }),
+      () => store.moveToPage({
+        pageIndex,
+        pagesCount,
+      }),
       options
     )
   }

src/utils/math.js

@@ -4,3 +4,64 @@ export const getDistance = (p1, p2) => {
 
   return Math.sqrt((xDist * xDist) + (yDist * yDist));
 }
+
+// 3 => true
+export function getIsOdd(num) {
+  return Boolean(num % 2)
+}
+
+
+// TODO: determine when partial offset is needed and apply partial offset
+// TODO: determine how many clones should be from both sides
+
+
+// TODO: refactor pagesToShow <= pagesToScroll
+// TODO: think about case if pagesCount < pagesToShow and pagesCount < pagesToScroll
+export function getPartialPageSize({
+  pagesToScroll,
+  pagesToShow,
+  pagesCount
+}) {
+
+  if (pagesToShow <= pagesToScroll) {
+    const overlap = pagesToShow - pagesToScroll
+
+    const d = (Math.max(pagesToShow-pagesToScroll), pagesToShow)
+    // console.log('overlap', overlap)
+    let _pages = d
+    // console.log('pages', _pages)
+  
+    while(true) {
+      // let fp = _pages - overlap
+      _pages = _pages - overlap + d
+      // console.log('pages', _pages)
+      const diff = pagesCount - _pages
+      if (diff < pagesToShow) {
+        // console.log('diff', diff)
+        // console.log('pagesToShow - diff', pagesToShow - Math.abs(diff) - overlap)
+        const res = diff + overlap
+        if (res < 0) {
+          return pagesToShow - overlap + res
+        }
+        console.log(res, diff)
+        return diff !== 0 ? Math.min(res, diff) : res
+      }
+    } 
+  } else {
+    const overlap = pagesToShow - pagesToScroll
+
+    // console.log('overlap', overlap)
+    let _pages = pagesToShow
+    console.log('pages', _pages)
+  
+    while(true) {
+      const diff = pagesCount - _pages + overlap
+      if (diff < pagesToShow) {
+        return diff
+      }
+      _pages += pagesToShow - overlap
+      console.log('pages', _pages)
+    }
+  }
+ 
+}

src/utils/math.test.js

@@ -1,5 +1,6 @@
 import {
   getDistance,
+  getPartialPageSize
 } from './math.js'
 
 describe('getDistance', () => {
@@ -17,3 +18,107 @@ describe('getDistance', () => {
     expect(getDistance(p1, p2)).toBe(5)
   })
 })
+
+describe('getPartialPageSize', () => {
+
+  it('getPartialPageSize', () => {
+    // ==== pagesToShow <= pagesToScroll
+    // const r1 = getPartialPageSize({
+    //   pagesCount: 15,
+    //   pagesToShow: 4,
+    //   pagesToScroll: 5,
+    // })
+    // expect(r1).toBe(0)
+
+    // const r2 = getPartialPageSize({
+    //   pagesCount: 16,
+    //   pagesToShow: 4,
+    //   pagesToScroll: 5,
+    // })
+    // expect(r2).toBe(1)
+
+    // const r3 = getPartialPageSize({
+    //   pagesCount: 17,
+    //   pagesToShow: 4,
+    //   pagesToScroll: 5,
+    // })
+    // expect(r3).toBe(2)
+
+    // const r4 = getPartialPageSize({
+    //   pagesCount: 18,
+    //   pagesToShow: 4,
+    //   pagesToScroll: 5,
+    // })
+    // expect(r4).toBe(3)
+
+    // const r5 = getPartialPageSize({
+    //   pagesCount: 8,
+    //   pagesToShow: 2,
+    //   pagesToScroll: 2,
+    // })
+    // expect(r5).toBe(0)
+
+    // ====== pagesToScroll < pagesToShow
+
+    // const r6 = getPartialPageSize({
+    //   pagesCount: 8,
+    //   pagesToShow: 4,
+    //   pagesToScroll: 2,
+    // })
+    // expect(r6).toBe(2)
+
+    // const r7 = getPartialPageSize({
+    //   pagesCount: 7,
+    //   pagesToShow: 4,
+    //   pagesToScroll: 3,
+    // })
+    // expect(r7).toBe(1)
+
+    // const r8 = getPartialPageSize({
+    //   pagesCount: 8,
+    //   pagesToShow: 4,
+    //   pagesToScroll: 3,
+    // })
+    // expect(r8).toBe(2)
+
+    // const r9 = getPartialPageSize({
+    //   pagesCount: 8,
+    //   pagesToShow: 2,
+    //   pagesToScroll: 2,
+    // })
+    // expect(r9).toBe(0)
+
+    // const r10 = getPartialPageSize({
+    //   pagesCount: 9,
+    //   pagesToShow: 4,
+    //   pagesToScroll: 3,
+    // })
+    // expect(r10).toBe(3)
+
+    // const r11 = getPartialPageSize({
+    //   pagesCount: 8,
+    //   pagesToShow: 3,
+    //   pagesToScroll: 2,
+    // })
+    // expect(r11).toBe(2)
+
+    
+    const r12 = getPartialPageSize({
+      pagesCount: 6,
+      pagesToShow: 3,
+      pagesToScroll: 1,
+    })
+    expect(r12).toBe(2)
+
+    
+    const r13 = getPartialPageSize({
+      pagesCount: 7,
+      pagesToShow: 3,
+      pagesToScroll: 1,
+    })
+    expect(r13).toBe(2)
+
+
+
+  })
+})

src/utils/page.js

@@ -111,3 +111,40 @@ export function applyPageSizes({
     pagesContainerChildren[pageIndex].style.maxWidth = `${pageWidth}px`
   }
 }
+
+export function getCurrentPageIndexWithoutClones({
+  currentPageIndex,
+  pagesCount,
+  oneSideClonesCount,
+  infinite,
+  pagesToScroll,
+}) {
+  if (infinite) {
+    if (currentPageIndex === pagesCount - oneSideClonesCount) return 0
+    if (currentPageIndex === 0) return pagesCount - oneSideClonesCount
+    return Math.floor((currentPageIndex - oneSideClonesCount) / pagesToScroll)
+  }
+  return currentPageIndex
+}
+
+export function getPagesCountWithoutClones({
+  pagesCount,
+  infinite,
+  oneSideClonesCount,
+  pagesToScroll,
+}) {
+  const bothSidesClonesCount = oneSideClonesCount * 2
+  return Math.max(
+    Math.ceil(
+      (pagesCount - (infinite ? bothSidesClonesCount : 0)) / pagesToScroll
+    ),
+  1)
+}
+
+// TODO: check 
+export function getOneSideClonesCount({
+  pagesToScroll,
+  pagesToShow,
+}) {
+  return Math.max(pagesToScroll, pagesToShow) // max - show 4, scroll 3, pages 7
+}