Optimized output picture saving

src/render/software/Canvas.cpp

@@ -98,7 +98,19 @@ CanvasPortion *Canvas::atPixel(int x, int y) const
     int pwidth = portions[0]->getWidth();
     int pheight = portions[0]->getHeight();
 
-    return at(x / pwidth, y / pheight);
+    int px = x / pwidth;
+    int py = y / pheight;
+
+    if (px >= horizontal_portion_count)
+    {
+        px = horizontal_portion_count - 1;
+    }
+    if (py >= vertical_portion_count)
+    {
+        py = vertical_portion_count - 1;
+    }
+
+    return at(px, py);
 }
 
 bool Canvas::saveToDisk(const std::string &filepath, const ColorProfile &profile, int antialias) const

src/render/software/CanvasPictureWriter.cpp

@@ -15,18 +15,14 @@ CanvasPictureWriter::CanvasPictureWriter(const Canvas *canvas):
     width = canvas->getWidth();
     height = canvas->getHeight();
 
-    last_portion = NULL;
-    last_stream = NULL;
-    last_y = 0;
+    cache = new Color[1];
+    cache_y = -antialias;
+    cache_width = 0;
 }
 
 CanvasPictureWriter::~CanvasPictureWriter()
 {
     delete profile;
-    if (last_stream)
-    {
-        delete last_stream;
-    }
 }
 
 void CanvasPictureWriter::setAntialias(int antialias)
@@ -85,32 +81,44 @@ unsigned int CanvasPictureWriter::getPixel(int x, int y)
 
 Color CanvasPictureWriter::getRawPixel(int x, int y)
 {
-    // Get the portion this pixel is in
-    CanvasPortion *portion = canvas->atPixel(x, y);
+    if (not (y >= cache_y && y < cache_y + antialias))
+    {
+        // Load rows into cache
+        delete [] cache;
+        cache_y = y;
+        cache_width = canvas->getWidth();
+        cache = new Color[cache_width * antialias];
 
-    // While we stay in the same portion line, read is sequential in the stream
-    if (portion != last_portion or last_y != y)
+        CanvasPortion *portion = NULL;
+        PackStream *stream = new PackStream;
+
+        Color* itcolor = cache;
+        bool has_pixels = false;
+        for (int cy = cache_y; cy < cache_y + antialias; cy++)
         {
-        // Get the pack stream positioned at the pixel
-        if (last_stream)
+            for (int cx = 0; cx < cache_width; cx++)
             {
-            delete last_stream;
+                CanvasPortion *nportion = canvas->atPixel(cx, cy);
+                if (nportion != portion)
+                {
+                    portion = nportion;
+                    delete stream;
+                    stream = new PackStream;
+                    has_pixels = portion->getReadStream(*stream, cx - portion->getXOffset(), cy - portion->getYOffset());
                 }
-        last_stream = new PackStream;
-        if (portion->getReadStream(*last_stream, x - portion->getXOffset(), y - portion->getYOffset()))
+                if (has_pixels)
                 {
-            last_portion = portion;
-            last_y = y;
+                    itcolor->load(stream);
                 }
                 else
                 {
-            // Portion has no stream
-            return COLOR_BLACK;
+                    *itcolor = COLOR_BLACK;
+                }
+                itcolor++;
+            }
         }
     }
 
-    // Load the pixel
-    Color col;
-    col.load(last_stream);
-    return col;
+    // Hit the cache
+    return cache[(y - cache_y) * cache_width + x];
 }

src/render/software/CanvasPictureWriter.h

@@ -47,9 +47,9 @@ private:
     int height;
     ColorProfile *profile;
 
-    CanvasPortion *last_portion;
-    int last_y;
-    PackStream *last_stream;
+    int cache_y;
+    int cache_width;
+    Color *cache;
 };
 
 }