[gnome-shell/wip/paging-release2: 3/23] iconGrid: Add PaginatedIconGrid

[Carlos Soriano <csoriano src gnome org>]

commit 3d864a69db536bd5bd8470ca6174e8b944f6653b
Author: Carlos Soriano <carlos soriano89 gmail com>
Date:   Tue Aug 20 10:14:25 2013 +0200

    iconGrid: Add PaginatedIconGrid
    
    The new PaginatedIconGrid class acts as a container for pages.
    So the new class provides  the container behaviour and some
    useful functions like positions of pages, number of pages, etc.
    But, it doesn't add indicators of the pages and doesn't manage
    the scroll of the pages, neither any management of the pages
    like in which page currently it is, etc.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=706081

 js/ui/iconGrid.js |  117 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 117 insertions(+), 0 deletions(-)
---
diff --git a/js/ui/iconGrid.js b/js/ui/iconGrid.js
index 0d8f8da..ccd5e76 100644
--- a/js/ui/iconGrid.js
+++ b/js/ui/iconGrid.js
@@ -363,6 +363,10 @@ const IconGrid = new Lang.Class({
         this._grid.queue_relayout();
     },
 
+    rowHeight: function() {
+        return this._vItemSize + this._getSpacing();
+    },
+
     removeAll: function() {
         this._grid.destroy_all_children();
     },
@@ -404,5 +408,118 @@ const IconGrid = new Lang.Class({
             spacing = Math.round(spacing);
         }
         this.setSpacing(spacing);
+    },
+});
+
+const PaginatedIconGrid = new Lang.Class({
+    Name: 'PaginatedIconGrid',
+    Extends: IconGrid,
+
+    _init: function(params) {
+        this.parent(params);
+        this._nPages = 0;
+    },
+
+    _getPreferredHeight: function (grid, forWidth, alloc) {
+        if(!this._nPages) {
+            alloc.min_size = 0;
+            alloc.natural_size = 0;
+            return;
+        }
+        alloc.min_size = this._availableHeightPerPageForItems() * this._nPages + this._spaceBetweenPages * 
this._nPages;
+        alloc.natural_size = this._availableHeightPerPageForItems() * this._nPages + this._spaceBetweenPages 
* this._nPages;
+    },
+
+    _allocate: function (grid, box, flags) {
+        if (this._fillParent) {
+            // Reset the passed in box to fill the parent
+            let parentBox = this.actor.get_parent().allocation;
+            let gridBox = this.actor.get_theme_node().get_content_box(parentBox);
+            box = this._grid.get_theme_node().get_content_box(gridBox);
+        }
+        let children = this._getVisibleChildren();
+        let availWidth = box.x2 - box.x1;
+        let availHeight = box.y2 - box.y1;
+        let spacing = this._getSpacing();
+        let [nColumns, usedWidth] = this._computeLayout(availWidth);
+
+        let leftPadding;
+        switch(this._xAlign) {
+            case St.Align.START:
+                leftPadding = 0;
+                break;
+            case St.Align.MIDDLE:
+                leftPadding = Math.floor((availWidth - usedWidth) / 2);
+                break;
+            case St.Align.END:
+                leftPadding = availWidth - usedWidth;
+        }
+
+        let x = box.x1 + leftPadding;
+        let y = box.y1;
+        let columnIndex = 0;
+        let rowIndex = 0;
+
+        for (let i = 0; i < children.length; i++) {
+            let childBox = this._calculateChildBox(children[i], x, y, box);
+            children[i].allocate(childBox, flags);
+            this._grid.set_skip_paint(children[i], false);
+
+            columnIndex++;
+            if (columnIndex == nColumns) {
+                columnIndex = 0;
+                rowIndex++;
+            }
+            if (columnIndex == 0) {
+                y += this._vItemSize + spacing;
+                if((i + 1) % this._childrenPerPage == 0)
+                    y += this._spaceBetweenPages - spacing;
+                x = box.x1 + leftPadding;
+            } else
+                x += this._hItemSize + spacing;
+        }
+    },
+    /**
+    * Compute the pagination values. This function must be called
+    * before allocation of the grid.
+    */
+    computePages: function (availWidthPerPage, availHeightPerPage) {
+        let [nColumns, usedWidth] = this._computeLayout(availWidthPerPage);
+        let nRows;
+        let children = this._getVisibleChildren();
+        if (nColumns > 0)
+            nRows = Math.ceil(children.length / nColumns);
+        else
+            nRows = 0;
+        if (this._rowLimit)
+            nRows = Math.min(nRows, this._rowLimit);
+        let oldHeightUsedPerPage = this._availableHeightPerPageForItems();
+        let oldNPages = this._nPages;
+
+        let spacing = this._getSpacing();
+        this._rowsPerPage = Math.floor((availHeightPerPage + spacing) / (this._vItemSize + spacing));
+        this._nPages = Math.ceil(nRows / this._rowsPerPage);
+        this._spaceBetweenPages = availHeightPerPage - (this._rowsPerPage * (this._vItemSize + spacing) - 
spacing);
+        this._childrenPerPage = nColumns * this._rowsPerPage;
+    },
+
+    _availableHeightPerPageForItems: function() {
+        return this._rowsPerPage * this.rowHeight() - this._getSpacing();
+    },
+
+    nPages: function() {
+        return this._nPages;
+    },
+
+    getPageY: function(pageNumber) {
+        if (!this._nPages)
+            return 0;
+        if(pageNumber < 0  || pageNumber > this._nPages) {
+            throw new Error('Invalid page number ' + pageNumber + ' requested, ' + this._nPages + ' computed 
pages');
+            return 0;
+        }
+        let firstPageItem = pageNumber * this._childrenPerPage
+        let childBox = this._getVisibleChildren()[firstPageItem].get_allocation_box();
+        return childBox.y1;
     }
 });