[evince] libview: Add new zoom mode that optimizes for readability

[Carlos Garcia Campos <carlosgc src gnome org>]

commit 0cad8758e9d96a1cf3b8a07776e64b6ae602b4e7
Author: William Jon McCann <jmccann redhat com>
Date:   Sat Dec 29 16:04:13 2012 +0100

    libview: Add new zoom mode that optimizes for readability
    
    This "Automatic" zoom mode will use fit width when
    the window is smaller than 100% of the actual page size
    and then use the actual page size up to the point the
    window is large enough to hold two entire pages side
    by side.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=689468

 libview/ev-document-model.h |    1 +
 libview/ev-view.c           |  107 +++++++++++++++++++++++++++++++++++--------
 2 files changed, 89 insertions(+), 19 deletions(-)
---
diff --git a/libview/ev-document-model.h b/libview/ev-document-model.h
index c91478b..b371d8b 100644
--- a/libview/ev-document-model.h
+++ b/libview/ev-document-model.h
@@ -38,6 +38,7 @@ typedef enum {
 	EV_SIZING_BEST_FIT = EV_SIZING_FIT_PAGE, /* Deprecated */
 	EV_SIZING_FIT_WIDTH,
 	EV_SIZING_FREE,
+        EV_SIZING_AUTOMATIC,
 } EvSizingMode;
 
 typedef struct _EvDocumentModel        EvDocumentModel;
diff --git a/libview/ev-view.c b/libview/ev-view.c
index 3e4822b..1aa3b41 100644
--- a/libview/ev-view.c
+++ b/libview/ev-view.c
@@ -246,6 +246,11 @@ static double	zoom_for_size_fit_page 			     (gdouble doc_width,
 							      gdouble doc_height,
 							      int     target_width,
 							      int     target_height);
+static double   zoom_for_size_automatic                      (GdkScreen *screen,
+							      gdouble    doc_width,
+							      gdouble    doc_height,
+							      int        target_width,
+							      int        target_height);
 static void     ev_view_zoom                                 (EvView *view,
                                                               gdouble factor);
 static void     ev_view_zoom_for_size                        (EvView *view,
@@ -3040,6 +3045,7 @@ ev_view_size_request_continuous_dual_page (EvView         *view,
 	switch (view->sizing_mode) {
 	        case EV_SIZING_FIT_WIDTH:
 	        case EV_SIZING_FIT_PAGE:
+	        case EV_SIZING_AUTOMATIC:
 			requisition->width = 1;
 
 			break;
@@ -3069,6 +3075,7 @@ ev_view_size_request_continuous (EvView         *view,
 	switch (view->sizing_mode) {
 	        case EV_SIZING_FIT_WIDTH:
 	        case EV_SIZING_FIT_PAGE:
+	        case EV_SIZING_AUTOMATIC:
 			requisition->width = 1;
 
 			break;
@@ -3163,7 +3170,8 @@ ev_view_size_request (GtkWidget      *widget,
 	 */
 	if (!view->internal_size_request &&
 	    (view->sizing_mode == EV_SIZING_FIT_WIDTH ||
-	     view->sizing_mode == EV_SIZING_FIT_PAGE)) {
+	     view->sizing_mode == EV_SIZING_FIT_PAGE ||
+	     view->sizing_mode == EV_SIZING_AUTOMATIC)) {
 		GtkAllocation allocation;
 
 		gtk_widget_get_allocation (widget, &allocation);
@@ -3229,7 +3237,8 @@ ev_view_size_allocate (GtkWidget      *widget,
 		return;
 
 	if (view->sizing_mode == EV_SIZING_FIT_WIDTH ||
-	    view->sizing_mode == EV_SIZING_FIT_PAGE) {
+	    view->sizing_mode == EV_SIZING_FIT_PAGE ||
+	    view->sizing_mode == EV_SIZING_AUTOMATIC) {
 		GtkRequisition req;
 
 		ev_view_zoom_for_size (view,
@@ -5590,6 +5599,33 @@ zoom_for_size_fit_page (gdouble doc_width,
 	return MIN (w_scale, h_scale);
 }
 
+static double
+zoom_for_size_automatic (GdkScreen *screen,
+			 gdouble    doc_width,
+			 gdouble    doc_height,
+			 int        target_width,
+			 int        target_height)
+{
+	double fit_width_scale;
+	double scale;
+
+	fit_width_scale = zoom_for_size_fit_width (doc_width, doc_height, target_width, target_height);
+
+	if (doc_height < doc_width) {
+		double fit_height_scale;
+
+		fit_height_scale = zoom_for_size_fit_height (doc_width, doc_height, target_width, target_height);
+		scale = MIN (fit_width_scale, fit_height_scale);
+	} else {
+		double actual_scale;
+
+		actual_scale = ev_document_misc_get_screen_dpi (screen) / 72.0;
+		scale = MIN (fit_width_scale, actual_scale);
+	}
+
+	return scale;
+}
+
 static void
 ev_view_zoom_for_size_continuous_and_dual_page (EvView *view,
 						int     width,
@@ -5617,12 +5653,20 @@ ev_view_zoom_for_size_continuous_and_dual_page (EvView *view,
 
 	sb_size = ev_view_get_scrollbar_size (view, GTK_ORIENTATION_VERTICAL);
 
-	if (view->sizing_mode == EV_SIZING_FIT_WIDTH) {
+	switch (view->sizing_mode) {
+	case EV_SIZING_FIT_WIDTH:
 		scale = zoom_for_size_fit_width (doc_width, doc_height, width - sb_size, height);
-	} else if (view->sizing_mode == EV_SIZING_FIT_PAGE)
+		break;
+	case EV_SIZING_FIT_PAGE:
 		scale = zoom_for_size_fit_page (doc_width, doc_height, width - sb_size, height);
-	else
+		break;
+	case EV_SIZING_AUTOMATIC:
+		scale = zoom_for_size_automatic (gtk_widget_get_screen (GTK_WIDGET (view)),
+						 doc_width, doc_height, width - sb_size, height);
+		break;
+	default:
 		g_assert_not_reached ();
+	}
 
 	ev_document_model_set_scale (view->model, scale);
 }
@@ -5653,12 +5697,20 @@ ev_view_zoom_for_size_continuous (EvView *view,
 
 	sb_size = ev_view_get_scrollbar_size (view, GTK_ORIENTATION_VERTICAL);
 
-	if (view->sizing_mode == EV_SIZING_FIT_WIDTH) {
+	switch (view->sizing_mode) {
+	case EV_SIZING_FIT_WIDTH:
 		scale = zoom_for_size_fit_width (doc_width, doc_height, width - sb_size, height);
-	} else if (view->sizing_mode == EV_SIZING_FIT_PAGE)
+		break;
+	case EV_SIZING_FIT_PAGE:
 		scale = zoom_for_size_fit_page (doc_width, doc_height, width - sb_size, height);
-	else
+		break;
+	case EV_SIZING_AUTOMATIC:
+		scale = zoom_for_size_automatic (gtk_widget_get_screen (GTK_WIDGET (view)),
+						 doc_width, doc_height, width - sb_size, height);
+		break;
+	default:
 		g_assert_not_reached ();
+	}
 
 	ev_document_model_set_scale (view->model, scale);
 }
@@ -5672,6 +5724,7 @@ ev_view_zoom_for_size_dual_page (EvView *view,
 	gdouble doc_width, doc_height;
 	gdouble scale;
 	gint other_page;
+	gint sb_size;
 
 	other_page = view->current_page ^ 1;
 
@@ -5692,15 +5745,22 @@ ev_view_zoom_for_size_dual_page (EvView *view,
 	width -= ((border.left + border.right)* 2 + 3 * view->spacing);
 	height -= (border.top + border.bottom + 2 * view->spacing);
 
-	if (view->sizing_mode == EV_SIZING_FIT_WIDTH) {
-		gint sb_size;
-
+	switch (view->sizing_mode) {
+	case EV_SIZING_FIT_WIDTH:
 		sb_size = ev_view_get_scrollbar_size (view, GTK_ORIENTATION_VERTICAL);
 		scale = zoom_for_size_fit_width (doc_width, doc_height, width - sb_size, height);
-	} else if (view->sizing_mode == EV_SIZING_FIT_PAGE)
+		break;
+	case EV_SIZING_FIT_PAGE:
 		scale = zoom_for_size_fit_page (doc_width, doc_height, width, height);
-	else
+		break;
+	case EV_SIZING_AUTOMATIC:
+		sb_size = ev_view_get_scrollbar_size (view, GTK_ORIENTATION_VERTICAL);
+		scale = zoom_for_size_automatic (gtk_widget_get_screen (GTK_WIDGET (view)),
+						 doc_width, doc_height, width - sb_size, height);
+		break;
+	default:
 		g_assert_not_reached ();
+	}
 
 	ev_document_model_set_scale (view->model, scale);
 }
@@ -5713,6 +5773,7 @@ ev_view_zoom_for_size_single_page (EvView *view,
 	gdouble doc_width, doc_height;
 	GtkBorder border;
 	gdouble scale;
+	gint sb_size;
 
 	get_doc_page_size (view, view->current_page, &doc_width, &doc_height);
 
@@ -5722,15 +5783,22 @@ ev_view_zoom_for_size_single_page (EvView *view,
 	width -= (border.left + border.right + 2 * view->spacing);
 	height -= (border.top + border.bottom + 2 * view->spacing);
 
-	if (view->sizing_mode == EV_SIZING_FIT_WIDTH) {
-		gint sb_size;
-
+	switch (view->sizing_mode) {
+	case EV_SIZING_FIT_WIDTH:
 		sb_size = ev_view_get_scrollbar_size (view, GTK_ORIENTATION_VERTICAL);
 		scale = zoom_for_size_fit_width (doc_width, doc_height, width - sb_size, height);
-	} else if (view->sizing_mode == EV_SIZING_FIT_PAGE)
+		break;
+	case EV_SIZING_FIT_PAGE:
 		scale = zoom_for_size_fit_page (doc_width, doc_height, width, height);
-	else
+		break;
+	case EV_SIZING_AUTOMATIC:
+		sb_size = ev_view_get_scrollbar_size (view, GTK_ORIENTATION_VERTICAL);
+		scale = zoom_for_size_automatic (gtk_widget_get_screen (GTK_WIDGET (view)),
+						 doc_width, doc_height, width - sb_size, height);
+		break;
+	default:
 		g_assert_not_reached ();
+	}
 
 	ev_document_model_set_scale (view->model, scale);
 }
@@ -5742,7 +5810,8 @@ ev_view_zoom_for_size (EvView *view,
 {
 	g_return_if_fail (EV_IS_VIEW (view));
 	g_return_if_fail (view->sizing_mode == EV_SIZING_FIT_WIDTH ||
-			  view->sizing_mode == EV_SIZING_FIT_PAGE);
+			  view->sizing_mode == EV_SIZING_FIT_PAGE ||
+			  view->sizing_mode == EV_SIZING_AUTOMATIC);
 	g_return_if_fail (width >= 0);
 	g_return_if_fail (height >= 0);