Howto:Extend the Canvas SVG module: Difference between revisions

Howto:Extend the Canvas SVG module (view source)

1,221 bytes added , 19 April 2016

20,741

edits

@@ Line 49: / Line 49: @@
       xlink:href="https://forum.flightgear.org/styles/flightgear/theme/images/logoF.png" />
 </svg>
+</syntaxhighlight>
+By default, the svg parser will bail out with a message saying '''Skipping unknown element image'''. Thus, we need to open $FG_ROOT/Nasal/canvas/svg.nas and navigate to the line where that error is triggered:
+<syntaxhighlight lang="nasal">
+else
+    {
+      printlog("info", "Skipping unknown element '" ~ name ~ "'");
+      skip = level;
+      return;
+    }
+</syntaxhighlight>
+So, the next step is prepending a new conditional block that looks specifically for the new tag that we'd like to see supported, e.g.:
+<syntaxhighlight lang="nasal">
+else if (name == "image")
+    {
+        printlog("alert", "image tag encountered (not yet implemented)");
+    }
+</syntaxhighlight>
+Or as a diff/patch:
+<syntaxhighlight lang="diff">
+diff --git a/Nasal/canvas/svg.nas b/Nasal/canvas/svg.nas
+index d7fe570..c1b4a90 100644
+--- a/Nasal/canvas/svg.nas
++++ b/Nasal/canvas/svg.nas
+@@ -578,6 +578,10 @@ var parsesvg = func(group, path, options = nil)
+       append(defs_stack, "defs");
+       return;
+     }
++    else if (name == "image")
++    {
++       printlog("alert", "image tag encountered (not yet implemented)");
++    }
+     else
+     {
+       printlog("info", "Skipping unknown element '" ~ name ~ "'");
 </syntaxhighlight>