adding scale and bounds methods to track - closes #1

ext/track.c

@@ -246,6 +246,43 @@ static VALUE track_enable_alpha(VALUE obj)
   return obj;
 }
 
+/*
+  call-seq: scale
+  
+  Scale the track's size by width and height respectively.
+  
+  The value passed is a relative float where "1" is the current size.
+*/
+static VALUE track_scale(VALUE obj, VALUE width, VALUE height)
+{
+  MatrixRecord matrix;
+  GetTrackMatrix(TRACK(obj), &matrix);
+  ScaleMatrix(&matrix, FloatToFixed(NUM2DBL(width)), FloatToFixed(NUM2DBL(height)), 0, 0);
+  SetTrackMatrix(TRACK(obj), &matrix);
+  return obj;
+}
+
+/*
+  call-seq: bounds() -> bounds_hash
+  
+  Returns a hash of boundaries. The hash contains four keys: :left, :top, 
+  :right, :bottom. Each holds an integer representing the pixel value.
+*/
+static VALUE track_bounds(VALUE obj)
+{
+  VALUE bounds_hash = rb_hash_new();
+  RgnHandle region;
+  Rect bounds;
+  region = GetTrackDisplayBoundsRgn(TRACK(obj));
+  GetRegionBounds(region, &bounds);
+  DisposeRgn(region);
+  rb_hash_aset(bounds_hash, ID2SYM(rb_intern("left")), INT2NUM(bounds.left));
+  rb_hash_aset(bounds_hash, ID2SYM(rb_intern("top")), INT2NUM(bounds.top));
+  rb_hash_aset(bounds_hash, ID2SYM(rb_intern("right")), INT2NUM(bounds.right));
+  rb_hash_aset(bounds_hash, ID2SYM(rb_intern("bottom")), INT2NUM(bounds.bottom));
+  return bounds_hash;
+}
+
 void Init_quicktime_track()
 {
   VALUE mQuickTime;
@@ -270,4 +307,6 @@ void Init_quicktime_track()
   rb_define_method(cTrack, "new_audio_media", track_new_audio_media, 0);
   rb_define_method(cTrack, "new_text_media", track_new_text_media, 0);
   rb_define_method(cTrack, "enable_alpha", track_enable_alpha, 0);
+  rb_define_method(cTrack, "scale", track_scale, 2);
+  rb_define_method(cTrack, "bounds", track_bounds, 0);
 }

lib/quicktime/track.rb

@@ -26,5 +26,15 @@ def video?
     def text?
       media_type == :text
     end
+
+    # Returns the bounding width of this track in number of pixels.
+    def width
+      bounds[:right] - bounds[:left]
+    end
+
+    # Returns the bounding height of this track in number of pixels.
+    def height
+      bounds[:bottom] - bounds[:top]
+    end
   end
 end

spec/quicktime/track_spec.rb

@@ -6,7 +6,7 @@
       @movie = QuickTime::Movie.open(File.dirname(__FILE__) + '/../fixtures/example.mov')
     end
 
-    describe "example.mov video track" do
+    describe "video track" do
       before(:each) do
         @track = @movie.video_tracks.first
       end
@@ -49,9 +49,15 @@
         @track.offset = 2.5
         @track.offset.should == 2.5
       end
+
+      it "should be able to scale size of track" do
+        @track.scale(0.5, 0.5)
+        @track.width.should == 30
+        @track.height.should == 25
+      end
     end
-
-    describe "example.mov audio track" do
+    
+    describe "audio track" do
       before(:each) do
         @track = @movie.audio_tracks.first
       end