Use zoom steps instead of hard-coding levels (#92)

Co-authored-by: NRK <nrk@disroot.org>
Co-authored-by: Berke Kocaoğlu <berke.kocaoglu@metu.edu.tr>

4 files changed, 22 insertions, 63 deletions

diff --git a/commands.c b/commands.c
index 15859fa..42e78da 100644
--- a/commands.c
+++ b/commands.c
@@ -184,12 +184,8 @@ bool cg_zoom(arg_t d)
 {
 	if (mode == MODE_THUMB)
 		return tns_zoom(&tns, d);
-	else if (d > 0)
-		return img_zoom_in(&img);
-	else if (d < 0)
-		return img_zoom_out(&img);
 	else
-		return false;
+		return img_zoom(&img, d);
 }
 
 bool cg_toggle_image_mark(arg_t _)
@@ -380,7 +376,7 @@ bool ci_drag(arg_t mode)
 
 bool ci_set_zoom(arg_t zl)
 {
-	return img_zoom(&img, (prefix ? prefix : zl) / 100.0);
+	return img_zoom_to(&img, (prefix ? prefix : zl) / 100.0);
 }
 
 bool ci_fit_to_win(arg_t sm)
diff --git a/config.def.h b/config.def.h
index 0645b2b..19ea7bb 100644
--- a/config.def.h
+++ b/config.def.h
@@ -25,13 +25,10 @@ static const suffixmode_t TITLE_SUFFIXMODE = SUFFIX_BASENAME;
 #endif
 #ifdef _IMAGE_CONFIG
 
-/* levels (in percent) to use when zooming via '-' and '+':
- * (first/last value is used as min/max zoom level)
- */
-static const float zoom_levels[] = {
-	 12.5,  25.0,  50.0,  75.0,
-	100.0, 150.0, 200.0, 400.0, 800.0
-};
+/* zoom level of 1.0 means 100% */
+static const float ZOOM_MIN  = 0.01;
+static const float ZOOM_MAX  = 20.0;
+static const float ZOOM_STEP = 1.2599210498948732; /* 2^(1/3) */
 
 /* default slideshow delay (in sec, overwritten via -S option): */
 static const int SLIDESHOW_DELAY = 5;
diff --git a/image.c b/image.c
index 5e778d4..4fd1c36 100644
--- a/image.c
+++ b/image.c
@@ -42,19 +42,8 @@ enum { DEF_GIF_DELAY = 75 };
 enum { DEF_WEBP_DELAY = 75 };
 #endif
 
-float zoom_min;
-float zoom_max;
-
-static int zoomdiff(img_t *img, float z)
-{
-	return (int) ((img->w * z - img->w * img->zoom) + (img->h * z - img->h * img->zoom));
-}
-
 void img_init(img_t *img, win_t *win)
 {
-	zoom_min = zoom_levels[0] / 100.0;
-	zoom_max = zoom_levels[ARRLEN(zoom_levels) - 1] / 100.0;
-
 	imlib_context_set_display(win->env.dpy);
 	imlib_context_set_visual(win->env.vis);
 	imlib_context_set_colormap(win->env.cmap);
@@ -63,8 +52,8 @@ void img_init(img_t *img, win_t *win)
 	img->win = win;
 	img->scalemode = options->scalemode;
 	img->zoom = options->zoom;
-	img->zoom = MAX(img->zoom, zoom_min);
-	img->zoom = MIN(img->zoom, zoom_max);
+	img->zoom = MAX(img->zoom, ZOOM_MIN);
+	img->zoom = MIN(img->zoom, ZOOM_MAX);
 	img->checkpan = false;
 	img->dirty = false;
 	img->aa = ANTI_ALIAS;
@@ -569,9 +558,9 @@ bool img_fit(img_t *img)
 			z = MIN(zw, zh);
 			break;
 	}
-	z = MIN(z, img->scalemode == SCALE_DOWN ? 1.0 : zoom_max);
+	z = MIN(z, img->scalemode == SCALE_DOWN ? 1.0 : ZOOM_MAX);
 
-	if (zoomdiff(img, z) != 0) {
+	if (ABS(img->zoom - z) > 1.0/MAX(img->w, img->h)) {
 		img->zoom = z;
 		img->dirty = true;
 		return true;
@@ -687,16 +676,10 @@ bool img_fit_win(img_t *img, scalemode_t sm)
 	}
 }
 
-bool img_zoom(img_t *img, float z)
+bool img_zoom_to(img_t *img, float z)
 {
-	z = MAX(z, zoom_min);
-	z = MIN(z, zoom_max);
-
-	img->scalemode = SCALE_ZOOM;
-
-	if (zoomdiff(img, z) != 0) {
-		int x, y;
-
+	int x, y;
+	if (ZOOM_MIN <= z && z <= ZOOM_MAX) {
 		win_cursor_pos(img->win, &x, &y);
 		if (x < 0 || x >= img->win->w || y < 0 || y >= img->win->h) {
 			x = img->win->w / 2;
@@ -705,6 +688,7 @@ bool img_zoom(img_t *img, float z)
 		img->x = x - (x - img->x) * z / img->zoom;
 		img->y = y - (y - img->y) * z / img->zoom;
 		img->zoom = z;
+		img->scalemode = SCALE_ZOOM;
 		img->checkpan = true;
 		img->dirty = true;
 		return true;
@@ -713,30 +697,10 @@ bool img_zoom(img_t *img, float z)
 	}
 }
 
-bool img_zoom_in(img_t *img)
+bool img_zoom(img_t *img, int d)
 {
-	int i;
-	float z;
-
-	for (i = 0; i < ARRLEN(zoom_levels); i++) {
-		z = zoom_levels[i] / 100.0;
-		if (zoomdiff(img, z) > 0)
-			return img_zoom(img, z);
-	}
-	return false;
-}
-
-bool img_zoom_out(img_t *img)
-{
-	int i;
-	float z;
-
-	for (i = ARRLEN(zoom_levels) - 1; i >= 0; i--) {
-		z = zoom_levels[i] / 100.0;
-		if (zoomdiff(img, z) < 0)
-			return img_zoom(img, z);
-	}
-	return false;
+	const float z = img->zoom * (d > 0 ? ZOOM_STEP : 1/ZOOM_STEP);
+	return img_zoom_to(img, z);
 }
 
 bool img_pos(img_t *img, float x, float y)
diff --git a/nsxiv.h b/nsxiv.h
index be7ffe6..c148b24 100644
--- a/nsxiv.h
+++ b/nsxiv.h
@@ -39,6 +39,9 @@
 #ifndef MAX
 #define MAX(a,b) ((a) > (b) ? (a) : (b))
 #endif
+#ifndef ABS
+#define ABS(a) ((a) > 0 ? (a) : -(a))
+#endif
 
 #define ARRLEN(a) (sizeof(a) / sizeof((a)[0]))
 
@@ -246,9 +249,8 @@ bool img_load(img_t*, const fileinfo_t*);
 CLEANUP void img_close(img_t*, bool);
 void img_render(img_t*);
 bool img_fit_win(img_t*, scalemode_t);
-bool img_zoom(img_t*, float);
-bool img_zoom_in(img_t*);
-bool img_zoom_out(img_t*);
+bool img_zoom(img_t*, int);
+bool img_zoom_to(img_t*, float);
 bool img_pos(img_t*, float, float);
 bool img_move(img_t*, float, float);
 bool img_pan(img_t*, direction_t, int);