Comment; fix up UI for subtitle scaling.

diff --git a/src/lib/subtitle.cc b/src/lib/subtitle.cc
index 3559197a04b9e77f22f93d3ccfc762cf8feb22a1..040a057fcf3ee040af1767db95eadfa519de2e88 100644 (file)
--- a/src/lib/subtitle.cc
+++ b/src/lib/subtitle.cc
@@ -80,25 +80,44 @@ subtitle_transform (
 {
        SubtitleTransform tx;
 
+       /* The area of the original subtitle, in the coordinate space of the source video frame */
        Rectangle sub_area (sub_pos.x, sub_pos.y + fs->subtitle_offset, sub_width, sub_height);
-       
+
+       /* The cropped area of the source video frame, in the same coordinate space */
        Rectangle cropped_target_area (
                fs->crop.left,
                fs->crop.top,
                target_base_width - (fs->crop.left + fs->crop.right),
                target_base_height - (fs->crop.top + fs->crop.bottom)
                );
-       
+
+       /* Hence the area of the cropped subtitle, in the same coordinate space */
        Rectangle cropped_sub_area = sub_area.intersection (cropped_target_area);
-       
+
+       /* The crop that should be applied to the subtitle, in its coordinate space */
        tx.crop.x = cropped_sub_area.x - sub_area.x;
        tx.crop.y = cropped_sub_area.y - sub_area.y;
        tx.crop.w = cropped_sub_area.w;
        tx.crop.h = cropped_sub_area.h;
 
+       /* We will scale the subtitle by the same amount as the video frame, and also by the additional
+          subtitle_scale
+       */
        tx.transformed.w = cropped_sub_area.w * target_x_scale * fs->subtitle_scale;
        tx.transformed.h = cropped_sub_area.h * target_y_scale * fs->subtitle_scale;
 
+       /* Then we need a corrective translation, consisting of two parts:
+        *
+        * 1.  that which is the result of the scaling of the subtitle by target_x_scale and target_y_scale; this will be
+        *     (sub_area.x - fs->crop_left) * target_x_scale and (sub_area.y - fs->crop_top) * target_y_scale.
+        *
+        * 2.  that to shift the origin of the scale by fs->subtitle_scale to the centre of the subtitle; this will be
+        *     (width_before_subtitle_scale * (1 - fs->subtitle_scale) / 2) and
+        *     (height_before_subtitle_scale * (1 - fs->subtitle_scale) / 2).
+        *
+        * Combining these two translations gives these expressions.
+        */
+       
        tx.transformed.x = target_x_scale * ((sub_area.x - fs->crop.left) + (cropped_sub_area.w * (1 - fs->subtitle_scale) / 2));
        tx.transformed.y = target_y_scale * ((sub_area.y - fs->crop.top) + (cropped_sub_area.h * (1 - fs->subtitle_scale) / 2));
 

diff --git a/src/wx/film_editor.cc b/src/wx/film_editor.cc
index ae1557c3e892a97f67a44d3b46ebc272c36acde0..143b058b1fba2c7995c45df5abb571dbf31c9df3 100644 (file)
--- a/src/wx/film_editor.cc
+++ b/src/wx/film_editor.cc
@@ -139,9 +139,14 @@ FilmEditor::FilmEditor (Film* f, wxWindow* parent)
        _subtitle_offset = new wxSpinCtrl (this);
        _sizer->Add (video_control (_subtitle_offset), 1);
 
-       video_control (add_label_to_sizer (_sizer, this, "Subtitle Scale"));
-       _subtitle_scale = new wxSpinCtrl (this);
-       _sizer->Add (video_control (_subtitle_scale), 1);
+       {
+               video_control (add_label_to_sizer (_sizer, this, "Subtitle Scale"));
+               wxBoxSizer* s = new wxBoxSizer (wxHORIZONTAL);
+               _subtitle_scale = new wxSpinCtrl (this);
+               s->Add (video_control (_subtitle_scale));
+               video_control (add_label_to_sizer (s, this, "%"));
+               _sizer->Add (s);
+       }
        
        video_control (add_label_to_sizer (_sizer, this, "Frames Per Second"));
        _frames_per_second = new wxStaticText (this, wxID_ANY, wxT (""));
@@ -195,6 +200,7 @@ FilmEditor::FilmEditor (Film* f, wxWindow* parent)
        _audio_delay->SetRange (-1000, 1000);
        _still_duration->SetRange (0, 60 * 60);
        _subtitle_offset->SetRange (-1024, 1024);
+       _subtitle_scale->SetRange (1, 1000);
 
        vector<DCPContentType const *> const ct = DCPContentType::all ();
        for (vector<DCPContentType const *>::const_iterator i = ct.begin(); i != ct.end(); ++i) {
@@ -358,7 +364,7 @@ FilmEditor::subtitle_scale_changed (wxCommandEvent &)
        }
 
        _ignore_changes = Film::SUBTITLE_OFFSET;
-       _film->set_subtitle_scale (_subtitle_scale->GetValue ());
+       _film->set_subtitle_scale (_subtitle_scale->GetValue() / 100.0);
        _ignore_changes = Film::NONE;
 }
 
@@ -490,7 +496,7 @@ FilmEditor::film_changed (Film::Property p)
                _subtitle_offset->SetValue (_film->subtitle_offset ());
                break;
        case Film::SUBTITLE_SCALE:
-               _subtitle_scale->SetValue (_film->subtitle_scale ());
+               _subtitle_scale->SetValue (_film->subtitle_scale() * 100);
                break;
        }
 }