[gthumb: 105/129] rotate tool: removed skew algorithm, ready for affine transformation

[Paolo Bacchilega <paobac src gnome org>]

commit 7a1b478f41e34632b3396cec1943a77ea4d06efc
Author: Stefano Pettini <spettini users sourceforge net>
Date:   Thu Apr 21 12:19:01 2011 +0100

    rotate tool: removed skew algorithm, ready for affine transformation

 extensions/file_tools/gdk-pixbuf-rotate.c    |  144 +++----------------------
 extensions/file_tools/gdk-pixbuf-rotate.h    |    4 +-
 extensions/file_tools/gth-file-tool-rotate.c |   21 ++--
 3 files changed, 29 insertions(+), 140 deletions(-)
---
diff --git a/extensions/file_tools/gdk-pixbuf-rotate.c b/extensions/file_tools/gdk-pixbuf-rotate.c
index 24a6f9e..9014dfd 100644
--- a/extensions/file_tools/gdk-pixbuf-rotate.c
+++ b/extensions/file_tools/gdk-pixbuf-rotate.c
@@ -19,143 +19,35 @@
  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <math.h>
 #include <gthumb.h>
 #include "gdk-pixbuf-rotate.h"
 
 
-#define interpolate_value(v1, f1, v2, f2) (CLAMP ((f1) * (v1) + (f2) * (v2), 0, 255))
-
-
-static GdkPixbuf*
-skew(GdkPixbuf *src_pixbuf,
-     double     angle,
-     gint       auto_crop)
-{
-	GdkPixbuf *new_pixbuf;
-	double     skew;
-	int        src_rowstride, new_rowstride, n_channels;
-	int        width;
-	int        width_new;
-	int        height;
-	int        delta_max;
-	int        x;
-	int        y;
-	guchar    *p_src, *p_src2;
-	guchar    *p_new, *p_new_row;
-	guchar     r1, g1, b1;
-	guchar     r2, g2, b2;
-	double     delta;
-	double     f1, f2;
-	int        x1, x2;
-	
-	if (angle != 0.0 && angle >= -45 && angle <= 45.0) {
-
-		skew = tan (angle / 180.0 * 3.1415926535);
-
-		n_channels = gdk_pixbuf_get_n_channels (src_pixbuf);
-
-		width = gdk_pixbuf_get_width (src_pixbuf);
-		height = gdk_pixbuf_get_height (src_pixbuf);
-		delta_max = (int) floor (fabs (skew * height));
-		
-		if (auto_crop)
-			width_new = width - delta_max;
-		else
-			width_new = width + delta_max;
-
-		new_pixbuf = gdk_pixbuf_new (gdk_pixbuf_get_colorspace (src_pixbuf),
-			gdk_pixbuf_get_has_alpha (src_pixbuf),
-			gdk_pixbuf_get_bits_per_sample (src_pixbuf),
-			width_new,
-			height);
-
-		p_src = gdk_pixbuf_get_pixels (src_pixbuf);
-		p_new = gdk_pixbuf_get_pixels (new_pixbuf);
-
-		src_rowstride = gdk_pixbuf_get_rowstride (src_pixbuf);
-		new_rowstride = gdk_pixbuf_get_rowstride (new_pixbuf);
-
-		for (y = 0; y < height; y++) {
-		
-			if (skew > 0)
-				delta = skew * y;
-			else
-				delta = skew * -(height - y - 1);
-			
-			f1 = delta - floor (delta);
-			f2 = 1.0 - f1;
-			
-			p_new_row = p_new;
-
-			for (x = 0; x < width_new; x++) {
-			
-				x1 = (int) floor (x - delta);
-				x2 = (int) ceil  (x - delta);
-			
-				if (auto_crop) {
-					x1 += delta_max;
-					x2 += delta_max;
-				}
-				
-				if (x1 < 0 || x1 >= width) {
-					r1 = 0;
-					g1 = 0;
-					b1 = 0;
-				}
-				else {
-					p_src2 = p_src + x1 * n_channels;
-					
-					r1 = p_src2[RED_PIX];
-					g1 = p_src2[GREEN_PIX];
-					b1 = p_src2[BLUE_PIX];
-				}
-
-				if (x2 < 0 || x2 >= width) {
-					r2 = 0;
-					g2 = 0;
-					b2 = 0;
-				}
-				else {
-					p_src2 = p_src + x2 * n_channels;
-					
-					r2 = p_src2[RED_PIX];
-					g2 = p_src2[GREEN_PIX];
-					b2 = p_src2[BLUE_PIX];
-				}
-				
-				p_new_row[RED_PIX]   = interpolate_value(r1, f1, r2, f2);
-				p_new_row[GREEN_PIX] = interpolate_value(g1, f1, g2, f2);
-				p_new_row[BLUE_PIX]  = interpolate_value(b1, f1, b2, f2);
-
-				p_new_row += n_channels;
-			}
-
-			p_src += src_rowstride;
-			p_new += new_rowstride;
-		}
-	}
-	else {
-		g_object_ref (src_pixbuf);
-		new_pixbuf = src_pixbuf;
-	}
-	
-	return new_pixbuf;
-}
-
-
 GdkPixbuf*
 _gdk_pixbuf_rotate (GdkPixbuf *src_pixbuf,
-		    int        center_x,
-		    int        center_y,
+		    double     center_x,
+		    double     center_y,
 		    double     angle,
 		    gint       auto_crop)
 {
 	GdkPixbuf *new_pixbuf;
-
-	// TODO: implement the correct rotate algorithm
+	
+	if (angle == 0.0) {
+		new_pixbuf = src_pixbuf;
+		g_object_ref (new_pixbuf);
+	}
+	else if (angle >= 90.0) {
+		new_pixbuf = gdk_pixbuf_rotate_simple (src_pixbuf, GDK_PIXBUF_ROTATE_CLOCKWISE);
+	}
+	else if (angle <= -90.0) {
+		new_pixbuf = gdk_pixbuf_rotate_simple (src_pixbuf, GDK_PIXBUF_ROTATE_COUNTERCLOCKWISE);
+	}
+	else {
+		// TODO: implement the rotation here
 		
-	new_pixbuf = skew (src_pixbuf, angle, auto_crop);
+		new_pixbuf = src_pixbuf;
+		g_object_ref (new_pixbuf);
+	}
 
 	return new_pixbuf;
 }
diff --git a/extensions/file_tools/gdk-pixbuf-rotate.h b/extensions/file_tools/gdk-pixbuf-rotate.h
index 8749bc4..b73a4b6 100644
--- a/extensions/file_tools/gdk-pixbuf-rotate.h
+++ b/extensions/file_tools/gdk-pixbuf-rotate.h
@@ -29,8 +29,8 @@
 G_BEGIN_DECLS
 
 GdkPixbuf* _gdk_pixbuf_rotate (GdkPixbuf *src_pixbuf,
-			       int        center_x,
-			       int        center_y,
+			       double     center_x,
+			       double     center_y,
 			       double     angle,
 			       gint       auto_crop);
 
diff --git a/extensions/file_tools/gth-file-tool-rotate.c b/extensions/file_tools/gth-file-tool-rotate.c
index 1c16bb1..fc95060 100644
--- a/extensions/file_tools/gth-file-tool-rotate.c
+++ b/extensions/file_tools/gth-file-tool-rotate.c
@@ -107,8 +107,8 @@ apply_cb (gpointer user_data)
 	GtkWidget         *window;
 	GtkWidget         *viewer_page;
 	double             rotation_angle;
-	int                center_x;
-	int                center_y;
+	double             center_x;
+	double             center_y;
 	gint               auto_crop;
 
 	if (self->priv->apply_event != 0) {
@@ -120,17 +120,14 @@ apply_cb (gpointer user_data)
 	viewer_page = gth_browser_get_viewer_page (GTH_BROWSER (window));
 
 	rotation_angle = gtk_range_get_value (GTK_RANGE (self->priv->rotation_angle));
+	center_x = (self->priv->pixbuf_width - 1) / 2.0;
+	center_y = (self->priv->pixbuf_height - 1) / 2.0;
+	auto_crop = gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (self->priv->auto_crop));
 	
-	if (rotation_angle != 0.0) {
-		center_x = self->priv->pixbuf_width / 2;
-		center_y = self->priv->pixbuf_height / 2;
-		auto_crop = gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (self->priv->auto_crop));
-		
-		_g_object_unref (self->priv->dest_pixbuf);
-		self->priv->dest_pixbuf = _gdk_pixbuf_rotate (self->priv->src_pixbuf, center_x, center_y, rotation_angle, auto_crop);
-
-		gth_image_viewer_page_set_pixbuf (GTH_IMAGE_VIEWER_PAGE (viewer_page), self->priv->dest_pixbuf, FALSE);
-	}
+	_g_object_unref (self->priv->dest_pixbuf);
+	self->priv->dest_pixbuf = _gdk_pixbuf_rotate (self->priv->src_pixbuf, center_x, center_y, rotation_angle, auto_crop);
+
+	gth_image_viewer_page_set_pixbuf (GTH_IMAGE_VIEWER_PAGE (viewer_page), self->priv->dest_pixbuf, FALSE);
 	
 	return FALSE;
 }