selection: trim trailing spaces from block selections

The extract_*() family of functions can now optionally treat spaces as
empty cells.

Use this in selection_to_text() to trim trailing spaces from block
selections.

Closes #181

CHANGELOG.md

@@ -58,6 +58,8 @@
 
 * Blinking text now uses the foreground color, but dimmed down in its
   off state, instead of the background color.
+* Trailing spaces are trimmed when copying a block selection
+  (https://codeberg.org/dnkl/foot/issues/181).
 
 
 ### Deprecated

extract.c

@@ -15,10 +15,11 @@ struct extraction_context {
     const struct row *last_row;
     const struct cell *last_cell;
     enum selection_kind selection_kind;
+    bool trim_trailing_spaces;
 };
 
 struct extraction_context *
-extract_begin(enum selection_kind kind)
+extract_begin(enum selection_kind kind, bool trim_trailing_spaces)
 {
     struct extraction_context *ctx = malloc(sizeof(*ctx));
     if (unlikely(ctx == NULL)) {
@@ -28,6 +29,7 @@ extract_begin(enum selection_kind kind)
 
     *ctx = (struct extraction_context){
         .selection_kind = kind,
+        .trim_trailing_spaces = trim_trailing_spaces,
     };
     return ctx;
 }
@@ -143,7 +145,7 @@ extract_one(const struct terminal *term, const struct row *row,
         }
     }
 
-    if (cell->wc == 0) {
+    if (cell->wc == 0 || (ctx->trim_trailing_spaces && cell->wc == L' ')) {
         ctx->empty_count++;
         ctx->last_row = row;
         ctx->last_cell = cell;

extract.h

@@ -7,7 +7,8 @@
 
 struct extraction_context;
 
-struct extraction_context *extract_begin(enum selection_kind kind);
+struct extraction_context *extract_begin(
+    enum selection_kind kind, bool trim_trailing_spaces);
 
 bool extract_one(
     const struct terminal *term, const struct row *row, const struct cell *cell,

selection.c

@@ -224,7 +224,10 @@ selection_to_text(const struct terminal *term)
     if (term->selection.end.row == -1)
         return NULL;
 
-    struct extraction_context *ctx = extract_begin(term->selection.kind);
+    const enum selection_kind kind = term->selection.kind;
+    const bool trim_trailing_spaces = kind == SELECTION_BLOCK;
+
+    struct extraction_context *ctx = extract_begin(kind, trim_trailing_spaces);
     if (ctx == NULL)
         return NULL;
 

terminal.c

@@ -2651,7 +2651,7 @@ static bool
 rows_to_text(const struct terminal *term, int start, int end,
              char **text, size_t *len)
 {
-    struct extraction_context *ctx = extract_begin(SELECTION_NONE);
+    struct extraction_context *ctx = extract_begin(SELECTION_NONE, false);
     if (ctx == NULL)
         return false;