Core (LV::Video): Implement saves to PNG files

libvisual/CMakeLists.txt

@@ -82,8 +82,11 @@ IF(NOT HAVE_STDC_MATH)
   MESSAGE(FATAL_ERROR "Libvisual requires libm to build")
 ENDIF()
 
+# Check for Zlib
+FIND_PACKAGE(ZLIB 1.2 REQUIRED)
+
 # Check for libpng
-FIND_PACKAGE(PNG REQUIRED)
+FIND_PACKAGE(PNG 1.4 REQUIRED)
 
 # Internationalization
 SET(GETTEXT_PACKAGE "libvisual-${LV_VERSION_SUFFIX}")

libvisual/libvisual/CMakeLists.txt

@@ -176,6 +176,7 @@ TARGET_LINK_LIBRARIES(libvisual
   PkgConfig::ORC
   PNG::PNG
   Threads::Threads
+  ZLIB::ZLIB
 )
 
 IF(WIN32)

libvisual/libvisual/lv_video.cpp

@@ -29,26 +29,87 @@
 #include "lv_color.h"
 #include "lv_common.h"
 #include "lv_cpu.h"
+#include "private/lv_string_hash.hpp"
 #include "private/lv_video_private.hpp"
 #include "private/lv_video_blit.hpp"
 #include "private/lv_video_convert.hpp"
 #include "private/lv_video_fill.hpp"
 #include "private/lv_video_transform.hpp"
 #include "private/lv_video_bmp.hpp"
 #include "private/lv_video_png.hpp"
+#include <algorithm>
+#include <cctype>
 #include <cstring>
+#include <filesystem>
 #include <fstream>
+#include <functional>
+#include <optional>
+#include <string>
+#include <unordered_map>
+#include <vector>
 
 namespace LV {
 
+  namespace fs = std::filesystem;
+
   namespace {
 
+    using BitmapReader = std::function<VideoPtr (std::istream&)>;
+    using BitmapWriter = std::function<bool (Video const&, std::ostream&)>;
+
+    struct ImageFormatInfo
+    {
+        std::string              name;
+        BitmapReader             reader;
+        BitmapWriter             writer;
+        std::vector<std::string> extensions;
+    };
+
+    using ImageFormatExtensionLookup = std::unordered_map<
+        std::string, ImageFormat, StringHash, std::equal_to<>>;
+
+    std::unordered_map<ImageFormat, ImageFormatInfo> const supported_image_formats
+    {
+        {ImageFormat::BMP, {"BMP", bitmap_load_bmp, nullptr, {".bmp"}}},
+        {ImageFormat::PNG, {"PNG", bitmap_load_png, bitmap_save_png, {".png"}}}
+    };
+
+    ImageFormatExtensionLookup build_image_format_extension_lookup ()
+    {
+        ImageFormatExtensionLookup map;
+
+        for (auto const& entry : supported_image_formats)
+            for (auto const& extension : entry.second.extensions)
+                map.emplace (extension, entry.first);
+
+        return map;
+    }
+
+    std::optional<ImageFormat> find_image_format_by_extension (std::string_view extension)
+    {
+        static auto const lookup {build_image_format_extension_lookup ()};
+
+        auto match {lookup.find (extension)};
+        if (match == lookup.end ())
+            return std::nullopt;
+        return match->second;
+    }
+
     bool is_valid_scale_method (VisVideoScaleMethod scale_method)
     {
         return scale_method == VISUAL_VIDEO_SCALE_NEAREST
             || scale_method == VISUAL_VIDEO_SCALE_BILINEAR;
     }
 
+    // TODO: Factor this out into a string utility library
+    std::string to_lower_ascii (std::string const& s)
+    {
+        auto result {s};
+        for (auto& c : result)
+            c = std::tolower (c);
+        return result;
+    }
+
   } // anonymous namespace
 
 
@@ -191,17 +252,16 @@ namespace LV {
 
   VideoPtr Video::create_from_stream (std::istream& input)
   {
-      auto image = bitmap_load_bmp (input);
-      if (image) {
-          return image;
-      }
-
-      image = bitmap_load_png (input);
-      if (image) {
-          return image;
+      for (auto entry : supported_image_formats) {
+          if (entry.second.reader) {
+              auto image {entry.second.reader (input)};
+              if (image) {
+                  return image;
+              }
+          }
       }
 
-      return {};
+      return nullptr;
   }
 
   VideoPtr Video::create_scale_depth (VideoConstPtr const& src,
@@ -260,6 +320,43 @@ namespace LV {
       return m_impl->buffer->is_allocated ();
   }
 
+  bool Video::save_to_file (std::string const& path) const
+  {
+      auto extension {fs::path {path}.extension ()};
+      auto extension_lower (to_lower_ascii (extension.string ()));
+
+      auto format {find_image_format_by_extension (extension_lower)};
+      if (!format.has_value ()) {
+          visual_log (VISUAL_LOG_ERROR, "Could not deduce format from filename (%s)", path.c_str ());
+          return false;
+      }
+
+      std::ofstream output {path};
+      if (!output) {
+          visual_log (VISUAL_LOG_ERROR, "Could not create file '%s'", path.c_str ());
+          return false;
+      }
+
+      return save_to_stream (output, format.value ());
+  }
+
+  bool Video::save_to_stream (std::ostream& output, ImageFormat format) const
+  {
+      auto entry {supported_image_formats.find (format)};
+
+      if (entry == supported_image_formats.end ()) {
+          visual_log (VISUAL_LOG_ERROR, "Saving to unknown format (%d).", static_cast<int> (format));
+          return false;
+      }
+
+      if (!entry->second.writer) {
+          visual_log (VISUAL_LOG_ERROR, "Saving to %s is unsupported.", entry->second.name.c_str ());
+          return false;
+      }
+
+      return entry->second.writer (*this, output);
+  }
+
   void Video::copy_attrs (VideoConstPtr const& src)
   {
       set_depth (src->m_impl->depth);

libvisual/libvisual/lv_video.h

@@ -96,6 +96,14 @@ typedef enum {
     VISUAL_VIDEO_COMPOSE_TYPE_CUSTOM      /**< Custom compose function (looks up on the source VisVideo. */
 } VisVideoComposeType;
 
+/**
+ * The set of known and supported image formats.
+ */
+typedef enum {
+    VISUAL_IMAGE_FORMAT_BMP = 0,
+    VISUAL_IMAGE_FORMAT_PNG
+} VisImageFormat;
+
 typedef struct _VisVideoAttrOptions VisVideoAttrOptions;
 
 #ifdef __cplusplus
@@ -125,6 +133,15 @@ struct _VisVideoAttrOptions {
 
 namespace LV {
 
+  /**
+   * The set of known and supported image formats.
+   */
+  enum class ImageFormat
+  {
+      BMP = VISUAL_IMAGE_FORMAT_BMP,
+      PNG = VISUAL_IMAGE_FORMAT_PNG
+  };
+
   class Video;
 
   typedef IntrusivePtr<Video> VideoPtr;
@@ -259,6 +276,25 @@ namespace LV {
        */
       BufferPtr get_buffer () const;
 
+      /**
+       * Saves contents to a file.
+       *
+       * @param path Path name of file to save to. Specify the file format by using the appropriate extension.
+       *
+       * @return true if file was successfully saved, false otherwise.
+       */
+      bool save_to_file (std::string const& path) const;
+
+      /**
+       * Saves contents to a stream.
+       *
+       * @param output stream to write contents to.
+       * @param format image file format to encode contents in.
+       *
+       * @return true if file was successfully saved, false otherwise.
+       */
+      bool save_to_stream (std::ostream& output, ImageFormat format) const;
+
       /**
        * Sets all attributes.
        *
@@ -513,6 +549,8 @@ LV_NODISCARD LV_API VisVideo *visual_video_new_with_buffer (int width, int heigh
 LV_NODISCARD LV_API VisVideo *visual_video_new_wrap_buffer (void *buffer, int owner, int width, int height, VisVideoDepth depth, int pitch);
 LV_NODISCARD LV_API VisVideo *visual_video_load_from_file  (const char *path);
 
+LV_API int visual_video_save_to_file (VisVideo *video);
+
 LV_API void visual_video_ref   (VisVideo *video);
 LV_API void visual_video_unref (VisVideo *video);
 

libvisual/libvisual/lv_video_c.cpp

@@ -68,6 +68,14 @@ VisVideo *visual_video_load_from_file (const char *path)
     return self.get ();
 }
 
+int visual_video_save_to_file (VisVideo *self, const char *path)
+{
+    visual_return_val_if_fail (self != nullptr, FALSE);
+    visual_return_val_if_fail (path != nullptr, FALSE);
+
+    return self->save_to_file (path);
+}
+
 int visual_video_has_allocated_buffer (VisVideo *self)
 {
     visual_return_val_if_fail (self != nullptr, FALSE);