Add --ignore-empty command line option (close #549)

This option can be used to avoid exporting empty frames/cels.

src/app/app.cpp

@@ -210,6 +210,8 @@ void App::initialize(int argc, const char* argv[])
   // Procress options
   PRINTF("Processing options...\n");
 
+  bool ignoreEmpty = false;
+
   // Open file specified in the command line
   if (!options.values().empty()) {
     Console console;
@@ -258,6 +260,10 @@ void App::initialize(int argc, const char* argv[])
           importLayer = value.value();
           importLayerSaveAs = value.value();
         }
+        // --ignore-empty
+        else if (opt == &options.ignoreEmpty()) {
+          ignoreEmpty = true;
+        }
         // --save-as <filename>
         else if (opt == &options.saveAs()) {
           Document* doc = NULL;
@@ -380,6 +386,9 @@ void App::initialize(int argc, const char* argv[])
   if (m_exporter != NULL) {
     PRINTF("Exporting sheet...\n");
 
+    if (ignoreEmpty)
+      m_exporter->setIgnoreEmptyCels(true);
+
     m_exporter->exportSheet();
     m_exporter.reset(NULL);
   }

src/app/app_options.cpp

@@ -48,6 +48,7 @@ AppOptions::AppOptions(int argc, const char* argv[])
   , m_sheetPack(m_po.add("sheet-pack").description("Use a packing algorithm to avoid waste of space\nin the texture"))
   , m_splitLayers(m_po.add("split-layers").description("Import each layer of the next given sprite as\na separated image in the sheet"))
   , m_importLayer(m_po.add("import-layer").requiresValue("<name>").description("Import just one layer of the next given sprite"))
+  , m_ignoreEmpty(m_po.add("ignore-empty").description("Do not export empty frames/cels"))
   , m_verbose(m_po.add("verbose").description("Explain what is being done"))
   , m_help(m_po.add("help").mnemonic('?').description("Display this help and exits"))
   , m_version(m_po.add("version").description("Output version information and exit"))

src/app/app_options.h

@@ -56,6 +56,7 @@ public:
   const Option& sheetPack() const { return m_sheetPack; }
   const Option& splitLayers() const { return m_splitLayers; }
   const Option& importLayer() const { return m_importLayer; }
+  const Option& ignoreEmpty() const { return m_ignoreEmpty; }
 
   bool hasExporterParams() const;
 
@@ -82,6 +83,7 @@ private:
   Option& m_sheetPack;
   Option& m_splitLayers;
   Option& m_importLayer;
+  Option& m_ignoreEmpty;
 
   Option& m_verbose;
   Option& m_help;

src/app/document_exporter.cpp

@@ -32,6 +32,7 @@
 #include "base/unique_ptr.h"
 #include "gfx/packing_rects.h"
 #include "gfx/size.h"
+#include "raster/algorithm/shrink_bounds.h"
 #include "raster/cel.h"
 #include "raster/dithering_method.h"
 #include "raster/image.h"
@@ -205,6 +206,7 @@ DocumentExporter::DocumentExporter()
  , m_texturePack(false)
  , m_scale(1.0)
  , m_scaleMode(DefaultScaleMode)
+ , m_ignoreEmptyCels(false)
 {
 }
 
@@ -264,6 +266,7 @@ void DocumentExporter::exportSheet()
 
 void DocumentExporter::captureSamples(Samples& samples)
 {
+  ImageBufferPtr checkEmptyImageBuf;
   std::vector<char> buf(32);
 
   for (auto& item : m_documents) {
@@ -289,7 +292,35 @@ void DocumentExporter::captureSamples(Samples& samples)
             + "." + base::get_file_extension(filename));
       }
 
-      samples.addSample(Sample(doc, sprite, layer, frame, filename));
+      Sample sample(doc, sprite, layer, frame, filename);
+
+      if (m_ignoreEmptyCels) {
+        if (layer && layer->isImage() &&
+            !static_cast<LayerImage*>(layer)->getCel(frame)) {
+          // Empty cel this sample completely
+          continue;
+        }
+
+        base::UniquePtr<Image> checkEmptyImage(
+          Image::create(sprite->pixelFormat(),
+            sprite->width(),
+            sprite->height(),
+            checkEmptyImageBuf));
+
+        checkEmptyImage->setMaskColor(sprite->transparentColor());
+        clear_image(checkEmptyImage, sprite->transparentColor());
+        renderSample(sample, checkEmptyImage, 0, 0);
+
+        gfx::Rect frameBounds;
+        if (!algorithm::shrink_bounds(checkEmptyImage, frameBounds,
+            sprite->transparentColor())) {
+          // If shrink_bounds returns false, it's because the whole
+          // image is transparent (equal to the mask color).
+          continue;
+        }
+      }
+
+      samples.addSample(sample);
     }
   }
 }
@@ -355,12 +386,7 @@ void DocumentExporter::renderTexture(const Samples& samples, Image* textureImage
     int x = sample.inTextureBounds().x - sample.trimmedBounds().x;
     int y = sample.inTextureBounds().y - sample.trimmedBounds().y;
 
-    if (sample.layer()) {
-      layer_render(sample.layer(), textureImage, x, y, sample.frame());
-    }
-    else {
-      sample.sprite()->render(textureImage, x, y, sample.frame());
-    }
+    renderSample(sample, textureImage, x, y);
   }
 }
 
@@ -415,4 +441,14 @@ void DocumentExporter::createDataFile(const Samples& samples, std::ostream& os,
      << "}\n";
 }
 
+void DocumentExporter::renderSample(const Sample& sample, raster::Image* dst, int x, int y)
+{
+  if (sample.layer()) {
+    layer_render(sample.layer(), dst, x, y, sample.frame());
+  }
+  else {
+    sample.sprite()->render(dst, x, y, sample.frame());
+  }
+}
+
 } // namespace app

src/app/document_exporter.h

@@ -89,6 +89,10 @@ namespace app {
       m_scaleMode = mode;
     }
 
+    void setIgnoreEmptyCels(bool ignore) {
+      m_ignoreEmptyCels = ignore;
+    }
+
     void addDocument(Document* document, raster::Layer* layer = NULL) {
       m_documents.push_back(Item(document, layer));
     }
@@ -106,6 +110,7 @@ namespace app {
     Document* createEmptyTexture(const Samples& samples);
     void renderTexture(const Samples& samples, raster::Image* textureImage);
     void createDataFile(const Samples& samples, std::ostream& os, raster::Image* textureImage);
+    void renderSample(const Sample& sample, raster::Image* dst, int x, int y);
 
     class Item {
     public:
@@ -126,6 +131,7 @@ namespace app {
     bool m_texturePack;
     double m_scale;
     ScaleMode m_scaleMode;
+    bool m_ignoreEmptyCels;
     Items m_documents;
 
     DISABLE_COPYING(DocumentExporter);