Changes between Version 3 and Version 4 of UnifyingTheRenderingInterfaces

Timestamp:

Nov 9, 2007, 4:42:50 AM (16 years ago)

Author:

tbonfort

Comment:

--

UnifyingTheRenderingInterfaces

@@ -1 +1 @@
 = Unifying The Rendering Interfaces =
 page to keep track of ideas and notes concerning "pluggable" renderers, and their interface with the main mapserver program
+
+== Context ==
+Adding new renderers, and maintaining the current ones is getting quite complex due to functional code duplication inside each renderer.
+=== Current way of doing things ===
+{{{
+int msDrawXXX(image, shape, symbol, scalefactor ...) {
+  if renderGD
+    return msDrawXXXGD(image, shape, symbol, scalefactor ...);
+  else if renderAGG
+    return msDrawXXXAGG(image, shape, symbol, scalefactor ...);
+  else if renderPDF
+    return msDrawXXXPDF(image, shape, symbol, scalefactor ...);
+....etc....
+}
+}}}
+and then each msDrawXXXYYY function is
+{{{
+int msDrawXXXYYY(image, shape, symbol, scalefactor ...) {
+ ...
+ do some size, width, etc adjustments with respect to minsize, maxsize, scalefactor, etc
+ ...
+ treat or dispatch off to other functions depending on the symbol type:
+  msDrawXXXpixmapYYY
+  msDrawXXXvectorYYY /*further adjustments in here: vector scaling and rotation*/
+  msDrawXXXtruetypeYYY /*further adjustments in here: font lookup*/
+  msDrawXXXellipseYYY /*further adjustments in here: scaling and rotation*/
+  msDrawXXXhatchYYY
+}
+}}}
+
+=== Proposed way ===
+all (or as much as possible) cartographic treatment is done once, and the renderers only deal with... tada! rendering
+{{{
+int msDrawXXX(image, shape, symbol, scalefactor ...) {
+...
+ do some size, width, etc adjustments with respect to minsize, maxsize, scalefactor, etc
+ ...
+then depending on the symbol type, switch off to a render specific function (possibly pointed at by a vtable structure):
+  if vector symbol
+    return msDrawXXXVector(image, shape, vector points, color, angle ...);
+  else if truetype symbol
+    return msDrawXXXTruetype(image, shape, font file, character, color, angle ...);
+  else 
+....etc....
+}
+}}}
 
 == Desired Functionality ==