Partially fix zoom mode

Does not yet work with initial zoom value != 100%

src/events.c

@@ -126,11 +126,16 @@ static void feh_event_handle_ButtonPress(XEvent * ev)
 			opt.mode = MODE_ZOOM;
 			winwid->mode = MODE_ZOOM;
 			D(3, ("click offset is %d,%d\n", ev->xbutton.x, ev->xbutton.y));
-			winwid->click_offset_x = ev->xbutton.x - winwid->im_x;
-			winwid->click_offset_y = ev->xbutton.y - winwid->im_y;
-			winwid->im_click_offset_x = winwid->click_offset_x / winwid->zoom;
-			winwid->im_click_offset_y = winwid->click_offset_y / winwid->zoom;
+			winwid->click_offset_x = ev->xbutton.x;
+			winwid->click_offset_y = ev->xbutton.y;
+			winwid->old_zoom = winwid->zoom;
 			winwid->zoom = 1.0;
+
+			/* required to adjust the image position in zoom mode */
+			winwid->orig_im_x = winwid->im_x;
+			winwid->orig_im_y = winwid->im_y;
+
+			/* center the image */
 			if (winwid->full_screen) {
 				winwid->im_x = (scr_width - winwid->im_w) >> 1;
 				winwid->im_y = (scr_height - winwid->im_h) >> 1;
@@ -146,17 +151,9 @@ static void feh_event_handle_ButtonPress(XEvent * ev)
 					winwid->im_y = 0;
 				}
 			}
-			if (winwid->im_click_offset_x < 30)
-				winwid->im_click_offset_x = 30;
-			if (winwid->im_click_offset_y < 0)
-				winwid->im_click_offset_y = 0;
-			if (winwid->im_click_offset_x > winwid->im_w)
-				winwid->im_click_offset_x = winwid->im_w;
-			if (winwid->im_click_offset_y > winwid->im_h)
-				winwid->im_click_offset_y = winwid->im_h;
-
-			if (winwid->click_offset_x < 30)
-				winwid->click_offset_x = 30;
+
+			if (winwid->click_offset_x < 0)
+				winwid->click_offset_x = 0;
 			if (winwid->click_offset_y < 0)
 				winwid->click_offset_y = 0;
 			if (winwid->click_offset_x > winwid->w)
@@ -425,21 +422,27 @@ static void feh_event_handle_MotionNotify(XEvent * ev)
 
 		winwid = winwidget_get_from_window(ev->xmotion.window);
 		if (winwid) {
-			winwid->zoom = ((double) ev->xmotion.x - (double) winwid->click_offset_x) / 64.0;
-			if (winwid->zoom < 0)
-				winwid->zoom = 1.0 + ((winwid->zoom * 64.0) / ((double)
-									       (winwid->click_offset_x + 1)));
+			if (ev->xmotion.x > winwid->click_offset_x)
+				winwid->zoom = winwid->old_zoom + (
+						((double) ev->xmotion.x - (double) winwid->click_offset_x)
+						/ 128.0);
+						/*/ ((double) (winwid->click_offset_x + 1)));*/
 			else
-				winwid->zoom += 1.0;
+				winwid->zoom = winwid->old_zoom - (
+						((double) winwid->click_offset_x - (double) ev->xmotion.x)
+						/ 128.0);
+						/*/ ((double) (winwid->click_offset_x + 1)));*/
 
 			if (winwid->zoom < 0.01)
 				winwid->zoom = 0.01;
 
-			/* calculate change in zoom and move im_x and im_y respectively to
-			   enable zooming to the clicked spot... */
-			/* for now, center around im_click_offset_x and im_click_offset_y */
-			winwid->im_x = (winwid->w / 2) - (winwid->im_click_offset_x * winwid->zoom);
-			winwid->im_y = (winwid->h / 2) - (winwid->im_click_offset_y * winwid->zoom);
+			/* center around click_offset */
+			winwid->im_x = winwid->click_offset_x
+					- (winwid->click_offset_x * winwid->zoom);
+					/*+ (winwid->orig_im_x * winwid->zoom);*/
+			winwid->im_y = winwid->click_offset_y
+					- (winwid->click_offset_y * winwid->zoom);
+					/*+ (winwid->orig_im_y * winwid->zoom);*/
 
 			winwidget_render_image(winwid, 0, 0);
 		}

src/winwidget.c

@@ -69,11 +69,10 @@ static winwidget winwidget_allocate(void)
 	ret->im_x = 0;
 	ret->im_y = 0;
 	ret->zoom = 1.0;
+	ret->old_zoom = 1.0;
 
 	ret->click_offset_x = 0;
 	ret->click_offset_y = 0;
-	ret->im_click_offset_x = 0;
-	ret->im_click_offset_y = 0;
 	ret->has_rotated = 0;
 
 	D_RETURN(4, ret);
@@ -911,14 +910,13 @@ void feh_debug_print_winwid(winwidget w)
 	       "h = %d\n" "im_w = %d\n" "im_h = %d\n" "im_angle = %f\n"
 	       "type = %d\n" "had_resize = %d\n" "im = %p\n" "GC = %p\n"
 	       "pixmap = %ld\n" "name = %s\n" "file = %p\n" "mode = %d\n"
-	       "im_x = %d\n" "im_y = %d\n" "zoom = %f\n"
+	       "im_x = %d\n" "im_y = %d\n" "zoom = %f\n" "old_zoom = %f\n"
 	       "click_offset_x = %d\n" "click_offset_y = %d\n"
-	       "im_click_offset_x = %d\n" "im_click_offset_y = %d\n"
 	       "has_rotated = %d\n", (void *)w, w->win, w->w, w->h, w->im_w,
 	       w->im_h, w->im_angle, w->type, w->had_resize, w->im, (void *)w->gc,
 	       w->bg_pmap, w->name, (void *)w->file, w->mode, w->im_x, w->im_y,
-	       w->zoom, w->click_offset_x, w->click_offset_y,
-	       w->im_click_offset_x, w->im_click_offset_y, w->has_rotated);
+	       w->zoom, w->old_zoom, w->click_offset_x, w->click_offset_y,
+	       w->has_rotated);
 }
 
 void winwidget_reset_image(winwidget winwid)

src/winwidget.h

@@ -92,20 +92,27 @@ struct __winwidget {
 	gib_list *file;
 	unsigned char visible;
 
-	/* Stuff for zooming */
+	/* panning, zooming, etc. */
 	unsigned char mode;
 
-	unsigned char caption_entry;	/* are we in caption entry mode? */
+	unsigned char caption_entry;
+
+	/* image offset from window top left */
+	int im_x;
+	int im_y;
+
+	/* same, as cache for zoom mode */
+	int orig_im_x;
+	int orig_im_y;
+
+	/* From 0 (not visible) to 1.00 (actual size)
+	 * all the way up to INT_MAX (eww)
+	 */
+	double zoom;
+	double old_zoom;
 
-	/* New stuff */
-	int im_x;		/* image offset from window top left */
-	int im_y;		/* image offset from window top left */
-	double zoom;		/* From 0 (not visible) to 1.00 (actual size)
-				   all the way up to INT_MAX (ouch) */
 	int click_offset_x;
 	int click_offset_y;
-	int im_click_offset_x;
-	int im_click_offset_y;
 
 	unsigned char has_rotated;
 };