Metadata improvements to generate static graph image URL

[mattab]

Improve Metadata output to offer the URL to the graph in the metadata, for Piwik mobile and PDF integration. Notes:

• Metadata will specify the parameters: idSite, period, date, apiModule, apiAction but also:
  • graphType
  • use line graph for "Metadata without dimension" VisitsSummary.get, Goals.get, with default metric
  • use bar graph (or Pie chart) for "Metadata with dimension" (keywords, countries, etc)
  • column, default to the "main" metric for evolution graphs?

So Piwik Mobile will define: $width, $height, $fontSize, $colors, $date, $period, $token_auth, $language.

See #1721

[mattab]

see also #2134

[mattab]

(In [5296]) Fixes #2670

• Metadata output now contains "imageGraphUrl"
• the function used by piwik mobile and others, API.getReportMetadata now accepts period and date parameters
  • for "Evolution graphs" (goals, visitssummary, etc.) we must "plot" multiple days previous to the currently selected date.
    The metadata APi automatically does the $date parameter rewrite, when period != range, and date is not already a range.
    Therefore the imageGraphUrl can be used as is.
• New page available at: index.php?module=ImageGraph&action=index&idSite=1&period=month&date=2011-04-17
  • This page will call metadata APi then display the graph for all existing reports. This is a useful debug/test page to view all graphs as they will be displayed in Piwik Mobile (and PDF reports later refs Display Graphs in scheduled Email reports (PDF / HTML) #2706

Refs #1721

• Showing less vertical bars in graph by default
• Displaying empty graph when there is no data

[mattab]

(In [5298]) Refs #2670

• Fixing few bugs found by integration tests and hopefully fixing build!

[mattab]

(In [5301]) Refs #2670

• Testing for Freetype support otherwise throwing exception

[julienmoumne]

(In [5415]) fixes #2706

• refs Allow Email Reports to be sent in HTML #2318, Plugins reorganization #71 : Graphs now supported
• refs Metadata improvements to generate static graph image URL #2670, Piwik Ecommerce Tracking Plugin #898 : Restoring VisitsSummary report metadata before eCommerce
• refs ImageGraph: export reports as graph #1721 : Additional security, filename fixes and new internal outputType

[julienmoumne]

(In [5582]) * fixes #2706, #2828, #2704, refs #1721, #2637, #2711, #2318, #71 : horizontal static graph implemented

• fixes Static Graph: better graphs when date range period parameter #2788, refs Metadata improvements to generate static graph image URL #2670, ImageGraph: export reports as graph #1721, #2637, #2711 : default graph type logic moved to ImageGraph API, improved date/period logic, new parameter graphs_default_period_to_plot_when_period_range
• fixes Graphs should support Unicode characters & other improvements #2704, graph image cutoff first digits when Y axis has decimals #2804, refs ImageGraph: export reports as graph #1721 : pChart updated to 2.1.3, pChart code removed from Piwik code, OOP refactoring, support for unifont.ttf if present in ImageGraph/fonts, testAllSizes now uses report metadata ImageGraphUrl
• refs Plugin to provide PDF export of data #5491 : space between report title and report table reduced to avoid page overflow
• refs ImageGraph: graphs should display % values #2829 : TODO display percentages
• r5544, r5547, r5549 merged