Adding support for WebP export.

Author: phase1geo

meson.build

@@ -42,7 +42,7 @@ cc = meson.get_compiler('c')
 math_dep = cc.find_library('m', required: false)
 
 add_project_arguments([
-  #        '--vapidir', join_paths(meson.current_source_dir(), 'vapi'),
+        '--vapidir', join_paths(meson.current_source_dir(), 'vapi'),
         '--disable-warnings'
     ],
     language: 'vala',
@@ -57,6 +57,7 @@ dependencies = [
     dependency('libxml-2.0'),
     dependency('libportal-gtk4'),
     dependency('pangocairo'),
+    dependency('libwebp'),
     math_dep
 ]
 

src/Exports.vala

@@ -38,6 +38,7 @@ public class Exports {
     add( new ExportPDF( canvas ) );
     add( new ExportPNG( canvas ) );
     add( new ExportSVG( canvas ) );
+    add( new ExportWebP( canvas ) );
 
     clipboard = new ExportClipboard( canvas );
     printer   = new ExportPrint( canvas );

src/exports/ExportWebP.vala

@@ -0,0 +1,81 @@
+/*
+* Copyright (c) 2018 (https://github.com/phase1geo/Minder)
+*
+* This program is free software; you can redistribute it and/or
+* modify it under the terms of the GNU General Public
+* License as published by the Free Software Foundation; either
+* version 2 of the License, or (at your option) any later version.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+* General Public License for more details.
+*
+* You should have received a copy of the GNU General Public
+* License along with this program; if not, write to the
+* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+* Boston, MA 02110-1301 USA
+*
+* Authored by: Trevor Williams <[email protected]>
+*/
+
+using WebP;
+using Cairo;
+using Gdk;
+using Gtk;
+
+public class ExportWebP : Export {
+
+  public ExportWebP( Canvas canvas ) {
+    base( canvas, "webp", _( "WebP" ), { ".webp" } );
+  }
+
+  /* Default constructor */
+  public override bool export( string filename, Pixbuf source ) {
+
+    var fname = repair_filename( filename );
+
+    /* Create the drawing surface */
+    var surface = new ImageSurface( Format.RGB24, source.width, source.height );
+    var context = new Context( surface );
+    canvas.draw_all( context );
+
+    /* Write the pixbuf to the file */
+    var pixbuf = pixbuf_get_from_surface( surface, 0, 0, surface.get_width(), surface.get_height() );
+
+    uint8* output_buffer = null;
+    size_t buffer_size   = 0;
+    switch( pixbuf.get_n_channels() ) {
+      case 3 :
+        buffer_size = WebP.encode_lossless_rgb( pixbuf.get_pixels(), pixbuf.get_width(), pixbuf.get_height(), pixbuf.get_rowstride(), out output_buffer );
+        break;
+      case 4 :
+        buffer_size = WebP.encode_lossless_rgb( pixbuf.get_pixels(), pixbuf.get_width(), pixbuf.get_height(), pixbuf.get_rowstride(), out output_buffer );
+        break;
+    }
+
+    if( buffer_size == 0 ) {
+      stdout.printf( "Failed to encode WebP image." );
+      return( false );
+    }
+
+    try {
+      uint8[] obuf = {};
+      for( int i=0; i<buffer_size; i++ ) {
+        obuf += output_buffer[i];
+      }
+      WebP.free( output_buffer );
+      var file = File.new_for_path( fname );
+      var output_stream = file.replace( null, false, FileCreateFlags.NONE, null );
+      output_stream.write( obuf );
+      output_stream.close();
+    } catch (IOError e) {
+      stdout.printf( "Error saving WebP file: %s", e.message );
+      return( false );
+    }
+
+    return( true );
+
+  }
+
+}

src/exports/meson.build

@@ -4,5 +4,6 @@ sources += files(
   'ExportPDF.vala',
   'ExportPNG.vala',
   'ExportPrint.vala',
-  'ExportSVG.vala'
+  'ExportSVG.vala',
+  'ExportWebP.vala',
 )

vapi/libportal-gtk4.vapi

@@ -0,0 +1,25 @@
+[CCode (cheader_filename = "webp/encode.h")]
+namespace WebP {
+
+  [CCode (cname = "WebPEncodeLosslessRGB")]
+  public extern size_t encode_lossless_rgb(
+    uint8* rgb,
+    int width,
+    int height,
+    int stride,
+    out uint8* output_buffer
+  );
+
+  [CCode (cname = "WebPEncodeLosslessRGBA")]
+  public extern size_t encode_lossless_rgba(
+    uint8* rgb,
+    int width,
+    int height,
+    int stride,
+    out uint8* output_buffer
+  );
+
+  [CCode (cname = "WebPFree")]
+  public extern void free(void* ptr);
+
+}