Add area support for dot, for generating treemaps

There is another Graphviz command called "patchwork",
that can generate treemaps when given a digraph .dot.

The area is scaled to megabytes, which seems to work.
It shouldn't have any ill effects, for regular "dot".

README.md

@@ -50,6 +50,16 @@ $ dockviz images --dot --only-labelled | dot -Tpng -o images.png
 
 ![](sample/images_only_labelled.png "Image")
 
+Or as a treemap:
+
+```
+$ dockviz images -d | patchwork -Tpng -o treemap.png
+OR
+$ dockviz images --dot | patchwork -Tpng -o treemap.png
+```
+
+![](sample/treemap.png "Image")
+
 Or in short form:
 
 ```

images.go

@@ -405,6 +405,10 @@ func PrintTreeNode(buffer *bytes.Buffer, image Image, dispOpts DisplayOpts, pref
 	}
 }
 
+func megabytes(bytes int64) float64 {
+	return float64(bytes) / (1024 * 1024)
+}
+
 func humanSize(raw int64) string {
 	sizes := []string{"B", "KB", "MB", "GB", "TB"}
 
@@ -461,9 +465,9 @@ func imagesToDot(buffer *bytes.Buffer, images []Image, byParent map[string][]Ima
 			buffer.WriteString(fmt.Sprintf(" \"%s\" -> \"%s\"\n", truncate(image.ParentId, 12), truncate(image.Id, 12)))
 		}
 		if image.RepoTags[0] != "<none>:<none>" {
-			buffer.WriteString(fmt.Sprintf(" \"%s\" [label=\"%s\\n%s\",shape=box,fillcolor=\"paleturquoise\",style=\"filled,rounded\"];\n", truncate(image.Id, 12), truncate(stripPrefix(image.OrigId), 12), strings.Join(image.RepoTags, "\\n")))
+			buffer.WriteString(fmt.Sprintf(" \"%s\" [label=\"%s\\n%s\",area=%f,shape=box,fillcolor=\"paleturquoise\",style=\"filled,rounded\"];\n", truncate(image.Id, 12), truncate(stripPrefix(image.OrigId), 12), strings.Join(image.RepoTags, "\\n"), megabytes(image.Size)))
 		} else {
-			buffer.WriteString(fmt.Sprintf(" \"%s\" [label=\"%s\"]\n", truncate(image.Id, 12), truncate(stripPrefix(image.OrigId), 12)))
+			buffer.WriteString(fmt.Sprintf(" \"%s\" [label=\"%s\",area=%f]\n", truncate(image.Id, 12), truncate(stripPrefix(image.OrigId), 12), megabytes(image.Size)))
 		}
 		if subimages, exists := byParent[image.Id]; exists {
 			imagesToDot(buffer, subimages, byParent)

sample/images.dot

@@ -1,37 +1,61 @@
 digraph docker {
- "0fe9a2bc50fe" -> "8c32832f07ba"
- "cc4e1358bc80" -> "5c0d04fba9df"
- "5c0d04fba9df" [label="5c0d04fba9df\nnate/mongodb:latest",shape=box,fillcolor="paleturquoise",style="filled,rounded"];
- "67b8b7262a67" -> "0fe9a2bc50fe"
- "2f96171d2098" -> "67b8b7262a67"
- "8c32832f07ba" -> "cc4e1358bc80"
- "89541b3b35f2" -> "7dac4e98548e"
- "341d0cc3fac8" -> "2f96171d2098"
- "7dac4e98548e" -> "341d0cc3fac8"
- "59dac4bae93b" -> "89541b3b35f2"
- "d0525208a46c" -> "59dac4bae93b"
- "e18d8001204e" -> "d0525208a46c"
- "a7cf8ae4e998" -> "e18d8001204e"
- "0cd8e7f50270" -> "594b6f8e6f92"
- "594b6f8e6f92" -> "f832a63e87a4"
- "f832a63e87a4" [label="f832a63e87a4\nredis:latest",shape=box,fillcolor="paleturquoise",style="filled,rounded"];
- "398d592f2009" -> "0cd8e7f50270"
- "a7cf8ae4e998" -> "398d592f2009"
- "5dbd9cb5a02f" -> "74fe38d11401"
- "74fe38d11401" [label="74fe38d11401\nubuntu:12.04\nubuntu:precise",shape=box,fillcolor="paleturquoise",style="filled,rounded"];
- "82cdea7ab5b5" -> "5dbd9cb5a02f"
- "f10ebce2c0e1" -> "82cdea7ab5b5"
- "511136ea3c5a" -> "f10ebce2c0e1"
- "cf8dc907452c" -> "a7cf8ae4e998"
- "a7cf8ae4e998" [label="a7cf8ae4e998\nubuntu:12.10\nubuntu:quantal",shape=box,fillcolor="paleturquoise",style="filled,rounded"];
- "ef519c9ee91a" -> "07302703becc"
- "07302703becc" -> "cf8dc907452c"
- "511136ea3c5a" -> "ef519c9ee91a"
- "cb12405ee8fa" -> "316b678ddf48"
- "316b678ddf48" [label="316b678ddf48\nubuntu:13.04\nubuntu:raring",shape=box,fillcolor="paleturquoise",style="filled,rounded"];
- "e7206bfc66aa" -> "cb12405ee8fa"
- "02dae1c13f51" -> "e7206bfc66aa"
- "511136ea3c5a" -> "02dae1c13f51"
  base -> "511136ea3c5a" [style=invis]
+ "511136ea3c5a" [label="511136ea3c5a",area=0.000000]
+ "511136ea3c5a" -> "f10ebce2c0e1"
+ "f10ebce2c0e1" [label="f10ebce2c0e1",area=98.872495]
+ "f10ebce2c0e1" -> "82cdea7ab5b5"
+ "82cdea7ab5b5" [label="82cdea7ab5b5",area=0.243621]
+ "82cdea7ab5b5" -> "5dbd9cb5a02f"
+ "5dbd9cb5a02f" [label="5dbd9cb5a02f",area=0.001830]
+ "5dbd9cb5a02f" -> "74fe38d11401"
+ "74fe38d11401" [label="74fe38d11401\nubuntu:12.04\nubuntu:precise",area=100.772088,shape=box,fillcolor="paleturquoise",style="filled,rounded"];
+ "511136ea3c5a" -> "ef519c9ee91a"
+ "ef519c9ee91a" [label="ef519c9ee91a",area=96.254996]
+ "ef519c9ee91a" -> "07302703becc"
+ "07302703becc" [label="07302703becc",area=0.239370]
+ "07302703becc" -> "cf8dc907452c"
+ "cf8dc907452c" [label="cf8dc907452c",area=0.001830]
+ "cf8dc907452c" -> "a7cf8ae4e998"
+ "a7cf8ae4e998" [label="a7cf8ae4e998\nubuntu:12.10\nubuntu:quantal",area=66.847105,shape=box,fillcolor="paleturquoise",style="filled,rounded"];
+ "a7cf8ae4e998" -> "e18d8001204e"
+ "e18d8001204e" [label="e18d8001204e",area=0.027992]
+ "e18d8001204e" -> "d0525208a46c"
+ "d0525208a46c" [label="d0525208a46c",area=0.000068]
+ "d0525208a46c" -> "59dac4bae93b"
+ "59dac4bae93b" [label="59dac4bae93b",area=67.854815]
+ "59dac4bae93b" -> "89541b3b35f2"
+ "89541b3b35f2" [label="89541b3b35f2",area=256.858793]
+ "89541b3b35f2" -> "7dac4e98548e"
+ "7dac4e98548e" [label="7dac4e98548e",area=0.000000]
+ "7dac4e98548e" -> "341d0cc3fac8"
+ "341d0cc3fac8" [label="341d0cc3fac8",area=0.000000]
+ "341d0cc3fac8" -> "2f96171d2098"
+ "2f96171d2098" [label="2f96171d2098",area=0.000000]
+ "2f96171d2098" -> "67b8b7262a67"
+ "67b8b7262a67" [label="67b8b7262a67",area=1.779918]
+ "67b8b7262a67" -> "0fe9a2bc50fe"
+ "0fe9a2bc50fe" [label="0fe9a2bc50fe",area=0.000626]
+ "0fe9a2bc50fe" -> "8c32832f07ba"
+ "8c32832f07ba" [label="8c32832f07ba",area=0.000365]
+ "8c32832f07ba" -> "cc4e1358bc80"
+ "cc4e1358bc80" [label="cc4e1358bc80",area=0.000000]
+ "cc4e1358bc80" -> "5c0d04fba9df"
+ "5c0d04fba9df" [label="5c0d04fba9df\nnate/mongodb:latest",area=0.000000,shape=box,fillcolor="paleturquoise",style="filled,rounded"];
+ "a7cf8ae4e998" -> "398d592f2009"
+ "398d592f2009" [label="398d592f2009",area=67.632430]
+ "398d592f2009" -> "0cd8e7f50270"
+ "0cd8e7f50270" [label="0cd8e7f50270",area=1.352684]
+ "0cd8e7f50270" -> "594b6f8e6f92"
+ "594b6f8e6f92" [label="594b6f8e6f92",area=0.000000]
+ "594b6f8e6f92" -> "f832a63e87a4"
+ "f832a63e87a4" [label="f832a63e87a4\nredis:latest",area=0.000000,shape=box,fillcolor="paleturquoise",style="filled,rounded"];
+ "511136ea3c5a" -> "02dae1c13f51"
+ "02dae1c13f51" [label="02dae1c13f51",area=93.792276]
+ "02dae1c13f51" -> "e7206bfc66aa"
+ "e7206bfc66aa" [label="e7206bfc66aa",area=0.181205]
+ "e7206bfc66aa" -> "cb12405ee8fa"
+ "cb12405ee8fa" [label="cb12405ee8fa",area=0.001815]
+ "cb12405ee8fa" -> "316b678ddf48"
+ "316b678ddf48" [label="316b678ddf48\nubuntu:13.04\nubuntu:raring",area=67.541988,shape=box,fillcolor="paleturquoise",style="filled,rounded"];
  base [style=invisible]
 }