Add support for adjusting the font scale at runtime

1 files changed, 63 insertions, 2 deletions

diff --git a/terminal.vala b/terminal.vala
index d0f9480..c6c2525 100644
--- a/terminal.vala
+++ b/terminal.vala
@@ -9,6 +9,15 @@ class Terminal : Gtk.Overlay {
 	const uint PCRE2_JIT_PARTIAL_SOFT = 0x00000002u;
 	const uint PCRE2_ERROR_JIT_BADOPTION = -45;
 
+	/* The following values were chosen to be powers of 1.2 that lie within the
+	 * range of VTE's bounds for the font scale: [0.25, 4].
+	 *
+	 * They allow for 7 steps above or below the default scale of 1.
+	 */
+	const double FONT_SCALE_MIN = 0.2790816472336535; // 1.2 ^ -7
+	const double FONT_SCALE_MAX = 3.583180799999999;  // 1.2 ^ 7
+	const double FONT_SCALE_FACTOR = 1.2;
+
 	struct PaletteEntry {
 		string name;
 		string normal;
@@ -42,6 +51,7 @@ class Terminal : Gtk.Overlay {
 	bool has_search;
 	string url_match;
 	uint? infobar_timeout_id;
+	double scroll_delta;
 
 	public Terminal(string[] args, Gtk.Container parent, Gtk.Window window) {
 		Object(parent: parent, window: window);
@@ -135,12 +145,16 @@ class Terminal : Gtk.Overlay {
 		}
 	}
 
+	bool match_modifiers(int state, Gdk.ModifierType modifiers) {
+		return (state & modifiers) == modifiers;
+	}
+
 	bool match_button(Gdk.EventButton event, Gdk.ModifierType modifiers, uint button) {
-		return (event.state & modifiers) == modifiers && event.button == button;
+		return match_modifiers(event.state, modifiers) && event.button == button;
 	}
 
 	bool match_key(Gdk.EventKey event, Gdk.ModifierType modifiers, uint key) {
-		return (event.state & modifiers) == modifiers && event.keyval == key;
+		return match_modifiers(event.state, modifiers) && event.keyval == key;
 	}
 
 	void infobar_show(string message, Gtk.MessageType level, uint? timeout = null) {
@@ -300,6 +314,18 @@ class Terminal : Gtk.Overlay {
 		clipboard.set_text(url_match, -1);
 	}
 
+	void adjust_font_scale(double scale) {
+		vte.set_font_scale(scale.clamp(FONT_SCALE_MIN, FONT_SCALE_MAX));
+	}
+
+	void increase_font_scale() {
+		adjust_font_scale(vte.get_font_scale() * FONT_SCALE_FACTOR);
+	}
+
+	void decrease_font_scale() {
+		adjust_font_scale(vte.get_font_scale() / FONT_SCALE_FACTOR);
+	}
+
 	[GtkCallback]
 	void vte_copy() {
 		if (vte.get_has_selection()) {
@@ -366,6 +392,41 @@ class Terminal : Gtk.Overlay {
 			return true;
 		}
 
+		if (match_key(event, CONTROL_MASK, Gdk.Key.@0)) {
+			vte.set_font_scale(1.0);
+			return true;
+		}
+
+		if (match_key(event, CONTROL_MASK, Gdk.Key.equal)) {
+			increase_font_scale();
+			return true;
+		}
+
+		if (match_key(event, CONTROL_MASK, Gdk.Key.minus)) {
+			decrease_font_scale();
+			return true;
+		}
+
+		return false;
+	}
+
+	[GtkCallback]
+	bool vte_scroll(Gdk.EventScroll event) {
+		if (match_modifiers(event.state, CONTROL_MASK)) {
+			scroll_delta += event.delta_y;
+
+			if (Math.fabs(scroll_delta) >= 1) {
+				if (scroll_delta < 0) {
+					increase_font_scale();
+				} else {
+					decrease_font_scale();
+				}
+				scroll_delta = 0;
+			}
+
+			return true;
+		}
+
 		return false;
 	}