report more info in agg_capture

Author: thomasp85

NEWS.md

@@ -3,6 +3,9 @@
 * Fix support for the default symbol font on many linux distros
   (StandardSymbolPS) by ensuring proper fallback during character metric
   calculation (#136, #201)
+* `agg_capture()` now reports the current "page number" as well as whether any
+  drawing has occured since the last time the capture was taken as attributes
+  in the return value (but only if you request native raster) (#204)
 
 # ragg 1.5.0
 

src/AggDevice.h

@@ -69,6 +69,7 @@ class AggDevice {
   unsigned char* buffer;
 
   int pageno;
+  bool changed;
   std::string file;
   R_COLOR background;
   int background_int;
@@ -356,6 +357,7 @@ class AggDevice {
       if (evenodd) ras.filling_rule(agg::fill_even_odd);
 
       if (recording_mask == NULL && recording_raster == NULL) {
+        changed = true;
         solid_renderer.color(convertColour(fill));
         if (current_mask == NULL) {
           render<agg::scanline_p8>(ras, ras_clip, slp, solid_renderer, current_clip != NULL);
@@ -411,6 +413,7 @@ class AggDevice {
     agg::scanline_u8 slu;
     setStroke(ras, path, lty, lwd, lend, ljoin, lmitre);
     if (recording_mask == NULL && recording_raster == NULL) {
+      changed = true;
       solid_renderer.color(convertColour(col));
       if (current_mask == NULL) {
         render<agg::scanline_u8>(ras, ras_clip, slu, solid_renderer, current_clip != NULL);
@@ -537,6 +540,7 @@ void AggDevice<PIXFMT, R_COLOR, BLNDFMT>::newPage(unsigned int bg) {
     renderer.clear(background);
   }
   pageno++;
+  changed = true;
 }
 template<class PIXFMT, class R_COLOR, typename BLNDFMT>
 void AggDevice<PIXFMT, R_COLOR, BLNDFMT>::close() {
@@ -1044,6 +1048,7 @@ void AggDevice<PIXFMT, R_COLOR, BLNDFMT>::useGroup(SEXP ref, SEXP trans) {
 
   agg::scanline_u8 sl;
   if (recording_mask == NULL && recording_raster == NULL) {
+    changed = true;
     if (current_mask == NULL) {
       it->second->draw(mtx, ras, ras_clip, sl, renderer, clip);
     } else {
@@ -1366,6 +1371,7 @@ void AggDevice<PIXFMT, R_COLOR, BLNDFMT>::drawRaster(unsigned int *raster, int w
 
   agg::scanline_u8 slu;
   if (recording_mask == NULL && recording_raster == NULL) {
+    changed = true;
     if (current_mask == NULL) {
       render_raster<pixfmt_r_raster, BLNDFMT>(rbuf, w, h, ras, ras_clip, slu, interpolator, renderer, interpolate, current_clip != NULL, false);
     } else {
@@ -1446,6 +1452,7 @@ void AggDevice<PIXFMT, R_COLOR, BLNDFMT>::drawText(double x, double y, const cha
 
   agg::scanline_u8 slu;
   if (recording_mask == NULL && recording_raster == NULL) {
+    changed = true;
     solid_renderer.color(convertColour(col));
     if (current_mask == NULL) {
       t_ren.template plot_text<BLNDFMT>(x, y, str, rot, hadj, solid_renderer, renderer, slu, device_id, ras_clip, current_clip != NULL, recording_path);
@@ -1535,6 +1542,7 @@ void AggDevice<PIXFMT, R_COLOR, BLNDFMT>::drawGlyph(int n, int *glyphs,
 
   agg::scanline_u8 slu;
   if (recording_mask == NULL && recording_raster == NULL) {
+    changed = true;
     solid_renderer.color(convertColour(colour));
     if (current_mask == NULL) {
       t_ren.template plot_glyphs<BLNDFMT>(n, glyphs, x, y, rot, solid_renderer, renderer, slu, ras_clip, current_clip != NULL, recording_path);

src/AggDeviceCapture.h

@@ -1,18 +1,19 @@
 #pragma once
 
+#include "Rinternals.h"
 #include "ragg.h"
 #include "AggDevice.h"
 
 template<class PIXFMT>
 class AggDeviceCapture : public AggDevice<PIXFMT> {
 public:
   bool can_capture = true;
-  
+
   AggDeviceCapture(const char* fp, int w, int h, double ps, int bg, double res,
                    double scaling, bool snap) :
     AggDevice<PIXFMT>(fp, w, h, ps, bg, res, scaling, snap)
   {
-    
+
   }
   // Behaviour
   bool savePage() {
@@ -27,6 +28,9 @@ class AggDeviceCapture : public AggDevice<PIXFMT> {
     INTEGER(dims)[0] = this->height;
     INTEGER(dims)[1] = this->width;
     Rf_setAttrib(raster, R_DimSymbol, dims);
+    Rf_setAttrib(raster, Rf_mkString("page"), Rf_ScalarInteger(this->pageno));
+    Rf_setAttrib(raster, Rf_mkString("changed"), Rf_ScalarLogical(this->changed));
+    this->changed = false;
     UNPROTECT(2);
     return raster;
   }