terminal-unix: support mouse escape codes

These 6-byte codes have the format of \e [ M <button> <xpos> <ypos>.
Support the first 3 mouse bottons + scroll up/down for now as
button numbers > 5 are pretty non-portable across terminals.
Pixel-based mouse position values are calculated and sent to the
input system.

osdep/terminal-unix.c

@@ -54,6 +54,12 @@ static struct termios tio_orig;
 
 static int tty_in = -1, tty_out = -1;
 
+enum entry_type {
+    ENTRY_TYPE_KEY = 0,
+    ENTRY_TYPE_MOUSE_BUTTON,
+    ENTRY_TYPE_MOUSE_MOVE,
+};
+
 struct key_entry {
     const char *seq;
     int mpkey;
@@ -61,6 +67,10 @@ struct key_entry {
     // existing sequence is replaced by the following string. Matching
     // continues normally, and mpkey is or-ed into the final result.
     const char *replace;
+    // Extend the match length by a certain length, so the contents
+    // after the match can be processed with custom logic.
+    int skip;
+    enum entry_type type;
 };
 
 static const struct key_entry keys[] = {
@@ -160,6 +170,18 @@ static const struct key_entry keys[] = {
     {"\033[29~", MP_KEY_MENU},
     {"\033[Z", MP_KEY_TAB | MP_KEY_MODIFIER_SHIFT},
 
+    // Mouse button inputs. 2 bytes of position information requires special processing.
+    {"\033[M ", MP_MBTN_LEFT | MP_KEY_STATE_DOWN, .skip = 2, .type = ENTRY_TYPE_MOUSE_BUTTON},
+    {"\033[M!", MP_MBTN_MID | MP_KEY_STATE_DOWN, .skip = 2, .type = ENTRY_TYPE_MOUSE_BUTTON},
+    {"\033[M\"", MP_MBTN_RIGHT | MP_KEY_STATE_DOWN, .skip = 2, .type = ENTRY_TYPE_MOUSE_BUTTON},
+    {"\033[M#", MP_INPUT_RELEASE_ALL, .skip = 2, .type = ENTRY_TYPE_MOUSE_BUTTON},
+    {"\033[M`", MP_WHEEL_UP, .skip = 2, .type = ENTRY_TYPE_MOUSE_BUTTON},
+    {"\033[Ma", MP_WHEEL_DOWN, .skip = 2, .type = ENTRY_TYPE_MOUSE_BUTTON},
+    // Mouse move inputs. No key events should be generated for them.
+    {"\033[M@", MP_MBTN_LEFT | MP_KEY_STATE_DOWN, .skip = 2, .type = ENTRY_TYPE_MOUSE_MOVE},
+    {"\033[MA", MP_MBTN_MID | MP_KEY_STATE_DOWN, .skip = 2, .type = ENTRY_TYPE_MOUSE_MOVE},
+    {"\033[MB", MP_MBTN_RIGHT | MP_KEY_STATE_DOWN, .skip = 2, .type = ENTRY_TYPE_MOUSE_MOVE},
+    {"\033[MC", MP_INPUT_RELEASE_ALL, .skip = 2, .type = ENTRY_TYPE_MOUSE_MOVE},
     {0}
 };
 
@@ -250,7 +272,7 @@ static void process_input(struct input_ctx *input_ctx, bool timeout)
             continue;
         }
 
-        int seq_len = strlen(match->seq);
+        int seq_len = strlen(match->seq) + match->skip;
         if (seq_len > buf.len)
             goto read_more; /* partial match */
 
@@ -264,7 +286,23 @@ static void process_input(struct input_ctx *input_ctx, bool timeout)
             continue;
         }
 
-        mp_input_put_key(input_ctx, buf.mods | match->mpkey);
+        // Parse the initially skipped mouse position information.
+        // The positions are 1-based character cell positions plus 32.
+        // Treat mouse position as the pixel values at the center of the cell.
+        if ((match->type == ENTRY_TYPE_MOUSE_BUTTON ||
+             match->type == ENTRY_TYPE_MOUSE_MOVE) && seq_len >= 6)
+        {
+            int num_rows        = 80;
+            int num_cols        = 25;
+            int total_px_width  = 0;
+            int total_px_height = 0;
+            terminal_get_size2(&num_rows, &num_cols, &total_px_width, &total_px_height);
+            mp_input_set_mouse_pos(input_ctx,
+                (buf.b[4] - 32.5) * (total_px_width / num_cols),
+                (buf.b[5] - 32.5) * (total_px_height / num_rows));
+        }
+        if (match->type != ENTRY_TYPE_MOUSE_MOVE)
+            mp_input_put_key(input_ctx, buf.mods | match->mpkey);
         skip_buf(&buf, seq_len);
     }
 

osdep/terminal.h

@@ -35,6 +35,9 @@
 #define TERM_ESC_ALT_SCREEN         "\033[?1049h"
 #define TERM_ESC_NORMAL_SCREEN      "\033[?1049l"
 
+#define TERM_ESC_ENABLE_MOUSE       "\033[?1003h"
+#define TERM_ESC_DISABLE_MOUSE      "\033[?1003l"
+
 struct input_ctx;
 
 /* Global initialization for terminal output. */