Editing properties which appear in the mfd_meta table for a layout changes the content of that layout. We can exploit that effect to create standardized layouts which are then re-cycled for different content.
Our project contains a drawing and table that shows selected dolmen, relics of stone construction in the Neolithic within the valley of the Loire and its tributary, the Vienne, in France in the region near Angers, the mighty fortress of Saumur, and Chinon, the home fortress of Henry II and Richard the Lionhearted, Plantagenet kings of England and France. The map above shows the dolmen drawing as a layer above a Bing Streets web server background layer. In the lower right corner of the map we see the town of Descartes, where René Descartes was born.
The Project pane above shows the dolmen drawing, the dolmen Table for the drawing, and a Layout.
If we open the dolmen Table we see it has fields that give the common name of each dolmen in the table, a description (in French, of course...), the latitude and longitude location of the dolmen and also the name of a .jpg photo file that shows the dolmen.
The .jpg photo files have been imported into a folder in the project called Photos. They are kept in a folder to avoid cluttering the top level of the project with many components.
We have created a Layout, seen above, that shows the dolmen called Carroir Bon Air.
A typical dolmen consists of one or more horizontal rocks, called the table rock, laid upon vertical rocks. This particular dolmen has collapsed, but when dolmens are not collapsed the effect is to create what appears to be a stone room. Most dolmens in France were constructed from four thousand to six thousand years ago. There are many hundreds of them in France. A photo of a smaller, intact dolmen appears at the end of the Example: Combining Selections using the Select Pane topic.
We can use the Layers pane to see the frames in the layout.
The lowest frame in the stack shows the Carroir Bon Air dolmen image. Above that are two text frames, one of which is clearly the black-background text frame at the top of the layout giving the name of the dolmen, while the other is the white-background text frame giving the text description of the dolmen.
In the Project pane, we click the Layout, press the Copy button in the toolbar, and then we press the Paste button in the toolbar. We could also use Ctrl-C and Ctrl-V in the usual Windows shortcut way. That creates a copy of the layout, called Layout 2 within the Project.
Opening Layout 2, we see that it is, as expected, a copy of Layout.
We will now alter values in the mfd_meta table for properties of Layout 2.
The mfd_meta table stores properties for components within the Project. It provides convenient access to those properties we would like to change manually, using SQL or programmatically with scripts. The mfd_meta table is our gateway to endless fun and time-saving, for example, as shown in the Example: Style Properties in the mfd_meta Table topic. Super!
Double-click on the mfd_meta system table to open it.
As discussed in the Layouts topic, the properties of a layout appear in the mfd_meta table. We scroll down to properties for the Layout 2 component. We will begin by changing the image displayed in the lowest frame, the Item.0 frame. In the illustration above we have Ctrl-clicked that row so it is displayed using red selection color. We are not required to a select a row in the mfd_meta table to edit that row, but we have done so in this example to better illustrate the row which we will edit.
The JSON format used to define the content of frames makes it easy to see that this lowest frame takes content from the Carroir Bon Air dolmen image component. In this example we will change Layout 2 so it shows the Dolmen de Montsabert image and data for that record. To avoid manual keyboarding, we will use Copy and Paste whenever possible.
We begin by slow double-clicking onto the Dolmen de Montsabert image to open the name of the component for editing. We do that so we can Ctrl-C to copy the text of the name.
Next, we double-click into the Value for the Item.0 property and we change the name of the entity to the Dolmen de Montsabert image, being careful when we highlight the old text and then doing a Ctrl-V to paste that we have highlighted all of the text within the square [ ] brackets and only that text. We press Enter to accept the edit.
Like magic, the image shown in Layout 2 changes to the Dolmen de Montsabert image. We see this particular dolmen is located within a town and remains erect, not having collapsed over the millennia. We now will change the content of the text frames, so that the text frame used for the title, for example, does not wrongly identify it as the Dolmen dit le Carroir Bon Air.
In the dolmen Table window we right click the Name of the dolmen and choose Copy.
In the mfd_meta table we right-click the Value cell for the Item.1 property of Layout 2 and we choose Edit. Since the field text is longer we will use the value editing dialog.
In the dialog we highlight the text we wish to replace.
We press Ctrl-V to paste the text we copied from the table and then press OK.
The text in the frame changes to the new text that we pasted. Next we will repeat that procedure in a similar way for the final frame, to change the description. We Copy the text for the Description from the table.
In the mfd_meta table we will right click the Value cell for Item.2 and choose Edit.
In the editing dialog we highlight the text to be changed.
Pressing Ctrl-V pastes the text we copied from the table, the new description we desire. We press OK.
The text frame at the bottom of the layout changes to show the new text.
Changing the values for Z for a frame in a layout's properties allows us to specify where in the display stack the frame should appear. Normally we do that interactively using the Layers pane, but for programmatic manipulation of layouts we can use the Z value in a layout's properties.
See the Z Order discussion in the Layers Pane topic for examples.
This example shows how we can change properties in the mfd_meta table to change the contents of frames in a layout. That opens the door to making mass changes in very many layouts at once. For example, suppose we have a project with two hundred standardized layouts our real estate parcels division in a cadastral office has created and we must change some of the standardized text in each to some new standardized text. Using the Select pane we can select the text frame property to be changed in all of the two hundred layouts, and then using the Transform pane change the text in all of them at once. What might have taken days can be done instantly.
To consider another example, we can have a standardized arrangement of frames, as in this example, and then rapidly populate them with images or text or other content that is copied and pasted into the desired properties to create individualized layouts based on the standard arrangement. We can do that manually, as in this example, or programmatically with scripts or perhaps with SQL.
The following layouts were created very quickly based on layouts used in this example:
A partially fallen dolmen, with interior spaces over five meters in length, with the interior formerly divided into two or three rooms.
The dolmens we illustrate in this topic are exceptionally large and grand dolmens, typically two or more meters high, constructed 4500 to 6000 years ago. France is dotted with many hundreds of smaller dolmens that are only a meter or two high, with thousands more either lost or now visible only as a pile of rocks.
An enormous, typically "Angevin" (the region surrounding Anjou) dolmen, with a table rock that once was a single piece of stone seven meters by seven meters in size, now broken into four pieces since the early 20th century. It was used as a church in 1144.
Throughout time, most cultures have considered it very bad luck to damage a dolmen, but in recent centuries that has not stopped enterprising farmers who were annoyed with having to plow around a multi-ton stone construction from trying to blow them up, especially since the invention of dynamite. More dolmens have been lost in the last 200 years than in the preceding two thousand years.
A smaller dolmen on five supports. Dolmens originally were covered with an earthen mound, long ago eroded away. What we see today would have been the stone chamber underground within the mound.
A typically Angevin dolmen with two interior rooms. The interior dividing slab has a small hole near the bottom.
The immense stone slabs that make up a dolmen were often transported over great distances from quarries where large stone slabs could be split off exposed strata. The slabs often show grooves or holes where ropes might have been attached. Experimental archaeology has shown that even very large stone slabs can be rolled on log rollers over great distances by a crew of no more than a dozen men, easily covering a kilometer or two per day over level ground.
The same small crew of people, with patience, can easily construct a dolmen. Vertical stones are dragged in horizontal position on rollers up a slight ramp and then tipped into vertical position into a deep hole at the end of the ramp (more than half of a vertical support stone is normally underground). Once vertical supports are in place, the crew buries them in an earthen ramp piled slightly higher than the tops of the supports. The horizontal table slab is then rolled into position up the ramp above the vertical supports, and the earth beneath is systematically dug away, allowing the table slab to settle down onto the supports.
A very large dolmen once used as a bakery.
We do not know the original purpose of dolmens. Most likely they were originally intended as tombs for notable individuals or as communal tombs, or perhaps had some religious purpose, but no systematic remains dating back to the time of construction, such as bones, have been found. Remains have been found from later centuries as a result of the reuse of dolmens over thousands of years. Such huge constructions impressed subsequent generations of people, who converted them to their own purposes, using smaller ones as sacrificial altars in Druidic times, and larger ones as storage, as barns, as homes, as churches, and even, as above, bakeries.
Although there are many dolmens in France, such constructions dating to Neolithic times are found across Europe. In most cultures in Europe, dolmens have been revered as places of mystery and magic from an ancient past, so surprisingly many have survived. For an example of finding dolmens near our route when driving through Europe, see the Example: Combining Selections using the Select Pane topic. See also the Example: Create Maps topic for a look at cromlechs, also monuments from the Neolithic.
Example: Style Properties in the mfd_meta Table - Style properties for drawings such as colors for areas are stored in human readable JSON values as properties in the mfd_meta system table. This example shows how we can copy formatting from one drawing to another by simply copying values between records in the mfd_meta table.