Optimized and fixed canvas portion merging in final picture

src/render/software/Canvas.cpp

@@ -6,6 +6,8 @@
 #include "CanvasPreview.h"
 #include "CanvasPictureWriter.h"
 
+#define CUTTER_SIZE 800
+
 Canvas::Canvas()
 {
     horizontal_portion_count = 1;
@@ -28,8 +30,8 @@ Canvas::~Canvas()
 
 void Canvas::setSize(int width, int height)
 {
-    horizontal_portion_count = 1 + (width - 1) / 800;
-    vertical_portion_count = 1 + (height - 1) / 800;
+    horizontal_portion_count = 1 + (width - 1) / CUTTER_SIZE;
+    vertical_portion_count = 1 + (height - 1) / CUTTER_SIZE;
 
     int portion_width = width / horizontal_portion_count;
     int portion_height = height / vertical_portion_count;

src/render/software/CanvasPictureWriter.cpp

@@ -14,11 +14,19 @@ CanvasPictureWriter::CanvasPictureWriter(const Canvas *canvas):
     antialias = 1;
     width = canvas->getWidth();
     height = canvas->getHeight();
+
+    last_portion = NULL;
+    last_stream = NULL;
+    last_y = 0;
 }
 
 CanvasPictureWriter::~CanvasPictureWriter()
 {
     delete profile;
+    if (last_stream)
+    {
+        delete last_stream;
+    }
 }
 
 void CanvasPictureWriter::setAntialias(int antialias)
@@ -80,15 +88,29 @@ Color CanvasPictureWriter::getRawPixel(int x, int y)
     // Get the portion this pixel is in
     CanvasPortion *portion = canvas->atPixel(x, y);
 
-    // Get the pack stream positioned at the pixel
-    PackStream stream;
-    if (not portion->getReadStream(stream, x - portion->getXOffset(), y - portion->getYOffset()))
+    // While we stay in the same portion line, read is sequential in the stream
+    if (portion != last_portion or last_y != y)
     {
-        return COLOR_BLACK;
+        // Get the pack stream positioned at the pixel
+        if (last_stream)
+        {
+            delete last_stream;
+        }
+        last_stream = new PackStream;
+        if (portion->getReadStream(*last_stream, x - portion->getXOffset(), y - portion->getYOffset()))
+        {
+            last_portion = portion;
+            last_y = y;
+        }
+        else
+        {
+            // Portion has no stream
+            return COLOR_BLACK;
+        }
     }
 
-    // Load the pixel and apply tone mapping
+    // Load the pixel
     Color col;
-    col.load(&stream);
+    col.load(last_stream);
     return col;
 }

src/render/software/CanvasPictureWriter.h

@@ -46,6 +46,10 @@ private:
     int width;
     int height;
     ColorProfile *profile;
+
+    CanvasPortion *last_portion;
+    int last_y;
+    PackStream *last_stream;
 };
 
 }

src/render/software/CanvasPortion.cpp

@@ -108,11 +108,20 @@ bool CanvasPortion::getReadStream(PackStream &stream, int x, int y)
 {
     if (FileSystem::isFile(filepath))
     {
+        if (not stream.bindToFile(filepath))
+        {
+            return false;
+        }
+
         int unused_i;
-        double unused_d;
-        stream.bindToFile(filepath);
         stream.skip(unused_i, 2);
-        stream.skip(unused_d, (y * width + x - 1) * 4);
+
+        if (x > 0 or y > 0)
+        {
+            double unused_d;
+            stream.skip(unused_d, (y * width + x) * 4);
+        }
+
         return true;
     }
     else