[gnome-shell/wip/paging-release2: 3/22] iconGrid: Add PaginatedIconGrid and change IconGrid for allow us to use pagination

[Carlos Soriano <csoriano src gnome org>]

commit 580edaa5ebc343856219b6745e2c185eb144addc
Author: Carlos Soriano <carlos soriano89 gmail com>
Date:   Tue Aug 20 10:14:25 2013 +0200

    iconGrid: Add PaginatedIconGrid and change IconGrid for allow us to use pagination
    
    Add a subclass of IconGrid with proper functions to work with
    pagination.
    Also, we change the implementation of IconGrid to use the dynamic
    spacing calculated before allocation of parents which allow us
    to use the PaginationIconGrid, since we need to know before
    the PaginatedIconGrid allocation the parent size to know how many
    pages we need to allocate all the apps items, and therefore, how many
    height we need for the PaginatedIconGrid.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=706081

 js/ui/iconGrid.js |  130 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 130 insertions(+), 0 deletions(-)
---
diff --git a/js/ui/iconGrid.js b/js/ui/iconGrid.js
index 4103a4e..3c9bee8 100644
--- a/js/ui/iconGrid.js
+++ b/js/ui/iconGrid.js
@@ -4,6 +4,7 @@ const Clutter = imports.gi.Clutter;
 const Shell = imports.gi.Shell;
 const St = imports.gi.St;
 
+const Signals = imports.signals;
 const Lang = imports.lang;
 const Params = imports.misc.params;
 
@@ -176,10 +177,14 @@ const IconGrid = new Lang.Class({
     _init: function(params) {
         params = Params.parse(params, { rowLimit: null,
                                         columnLimit: null,
+                                        minRows: 1,
+                                        minColumns: 1,
                                         fillParent: false,
                                         xAlign: St.Align.MIDDLE });
         this._rowLimit = params.rowLimit;
         this._colLimit = params.columnLimit;
+        this._minRows = params.minRows;
+        this._minColumns = params.minColumns;
         this._xAlign = params.xAlign;
         this._fillParent = params.fillParent;
 
@@ -369,6 +374,10 @@ const IconGrid = new Lang.Class({
         this._grid.queue_relayout();
     },
 
+    rowHeight: function() {
+        return this._vItemSize + this._getSpacing();
+    },
+
     removeAll: function() {
         this._grid.destroy_all_children();
     },
@@ -420,5 +429,126 @@ const IconGrid = new Lang.Class({
         let spacingToEnsureMinimums = Math.min(maxSpacingForRows, maxSpacingForColumns);
         let spacingNotTooBig = Math.min(spacingToEnsureMinimums, maxSpacing);
         this.setSpacing(Math.max(this._spacing, spacingNotTooBig));
+    },
+});
+
+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 functions is intended to 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;
+
+        // Take into account when the number of pages changed (then the height of the entire grid changed 
for sure)
+        // and also when the spacing is changed, sure the hegiht per page changed and the entire grid height 
changes, althougt
+        // maybe the number of pages doesn't change
+        if (oldNPages != this._nPages || oldHeightUsedPerPage != this._availableHeightPerPageForItems()) {
+            this.emit('n-pages-changed', this._nPages);
+        }
+    },
+
+    _availableHeightPerPageForItems: function() {
+        return this._rowsPerPage * this.rowHeight() - this._getSpacing();
+    },
+
+    nPages: function() {
+        return this._nPages;
+    },
+
+    getPageYPosition: 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;
     }
 });
+Signals.addSignalMethods(PaginatedIconGrid.prototype);