Changes between Version 5 and Version 6 of UnifyingTheRenderingInterfaces

Timestamp:

Nov 21, 2007, 3:52:20 AM (17 years ago)

Author:

tbonfort

Comment:

--

UnifyingTheRenderingInterfaces

@@ -51 +51 @@
 }}}
 
+----------------------------------------------------------------------------------------------------------
+
+== Proposed VTable Approach ==
+I propose we attach a structure containing pointers to rendering function to the outputFormatObj
+{{{
+#!c
+struct renderObj{
+    void (*renderSimpleLine)(imageObj *img, shapeObj *p, colorObj *c, double width, int patternlength, int* pattern);
+    void (*renderVectorSymbol)(imageObj*image, pointObj *location, pointObj **vectorpoints, int nvectorpoints, int/double width,
+                         colorObj *color, colorObj *outlinecolor, colorObj* backgroundcolor);
+    /*
+    ... all the other low level rendering functions
+    */
+
+    /* image i/o */
+    imageObj* (*createImage)(int width, int height, char *imagepath, char* imageurl /*+ format specific args, eg, rgb/rgba, TODO */);
+    int (*saveImage)(imageObj *img /*etc*/);
+    /*...*/
+
+    /* helper functions */
+    void (*getLabelSize)(char* font, int size, char *text /*...*/);
+    /*...*/
+};
+}}}
+
+
+which would be populated when creating the outputFormatObj by
+{{{
+#!c
+
+/*forward declaration of render functions defined in maprenderer.h*/
+#ifdef __cplusplus
+extern "C" {
+#endif
+MS_DLL_EXPORT void msDrawSimpleLineGD(imageObj *img, shapeObj *p, colorObj *c, double width, int patternlength, int* pattern);
+MS_DLL_EXPORT void msDrawSimpleLineAGG(imageObj *img, shapeObj *p, colorObj *c, double width, int patternlength, int* pattern);
+/*....*/
+#ifdef __cplusplus
+}
+#endif
+
+
+renderObj* msCreateRenderer(int type) {
+    renderObj *r = malloc(sizeof(renderObj));
+    switch(type) {
+    case MS_RENDER_WITH_AGG:
+        r->renderSimpleLine=&msDrawSimpleLineAGG;
+        /*....*/
+        return r;
+    case MS_RENDER_WITH_GD:
+        r->renderSimpleLine=&msDrawSimpleLineGD;
+        /*.....*/
+        return r;
+    case MS_RENDER_WITH_PDF:
+    /*...*/
+    default:
+        return NULL;
+    }
+}
+}}}
+
+
+
+the higher level functions in mapdraw.c then become:
+{{{
+#!c
+void msDrawLineSymbol(symbolSetObj *symbolset, imageObj *image, shapeObj *p, styleObj *style, double scalefactor)
+{
+    if (image)
+    {
+        if( image->format->rendererPtr!=NULL) {
+            renderObj *r=image->format->rendererPtr;
+            
+            /* do some common processing of colors, widths, scalefactors, etc
+            ...
+            */
+            
+            if(style->symbol == 0 || symbol->type==MS_SYMBOL_CIRCLE || symbol->type==MS_SYMBOL_SIMPLE) { /*simple line case*/
+                  r->renderSimpleLine(image,p,color,nwidth,symbol->patternlength, symbol->pattern);  
+                  return;
+            }
+            /*continue on with the other line styling possibilities
+            ...
+            */
+       }
+       /* continue using the old style rendering functions for the renderers
+          that haven't been migrated yet to the plugin format, or for those
+          where such an approach isn't feasible
+       */
+       else if( MS_RENDERER_IMAGEMAP(image->format) )
+            msDrawLineSymbolIM(symbolset, image, p, style, scalefactor);
+
+#ifdef USE_MING_FLASH
+        else if( MS_RENDERER_SWF(image->format) )
+            msDrawLineSymbolSWF(symbolset, image, p,  style, scalefactor);
+#endif
+#ifdef USE_PDF
+        else if( MS_RENDERER_PDF(image->format) )
+            msDrawLineSymbolPDF(symbolset, image, p,  style, scalefactor);
+#endif
+        else if( MS_RENDERER_SVG(image->format) )
+            msDrawLineSymbolSVG(symbolset, image, p,  style, scalefactor);
+
+}}}
+
+
+
+----------------------------------------------------------------------------------------------------------
+
+
 == Desired Functionality ==
 === Line Layers ===
@@ -164 +274 @@
 
 '''update''': this won't work out as an inline function is of no use if we're using function pointers (i.e. the vtable)
+
+
+
+
+----------------------------------------------------------------------------------------------------------
+
+
+
 
 == I/O and Pixel Formats ==