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-rw-r--r--buffer.c52
-rw-r--r--util.c8
2 files changed, 56 insertions, 4 deletions
diff --git a/buffer.c b/buffer.c
index c0213ea..42c5ee3 100644
--- a/buffer.c
+++ b/buffer.c
@@ -442,18 +442,62 @@ bool buffer_pos_move_down(TextBuffer *buffer, BufferPos *pos) {
return true;
}
+// if the cursor is offscreen, this will scroll to make it onscreen.
+static void buffer_scroll_to_cursor(TextBuffer *buffer) {
+ i64 cursor_line = buffer->cursor_pos.line;
+ i64 cursor_col = buffer_index_to_column(buffer, (u32)cursor_line, buffer->cursor_pos.index);
+ i64 display_lines = buffer_display_rows(buffer);
+ i64 display_cols = buffer_display_cols(buffer);
+ double scroll_x = buffer->scroll_x, scroll_y = buffer->scroll_y;
+ i64 scroll_padding = 5;
+
+ // scroll left if cursor is off screen in that direction
+ double max_scroll_x = (double)(cursor_col - scroll_padding);
+ scroll_x = util_mind(scroll_x, max_scroll_x);
+ // scroll right
+ double min_scroll_x = (double)(cursor_col - display_cols + scroll_padding);
+ scroll_x = util_maxd(scroll_x, min_scroll_x);
+ // scroll up
+ double max_scroll_y = (double)(cursor_line - scroll_padding);
+ scroll_y = util_mind(scroll_y, max_scroll_y);
+ // scroll down
+ double min_scroll_y = (double)(cursor_line - display_lines + scroll_padding);
+ scroll_y = util_maxd(scroll_y, min_scroll_y);
+
+ buffer->scroll_x = scroll_x;
+ buffer->scroll_y = scroll_y;
+ buffer_correct_scroll(buffer); // it's possible that min/max_scroll_x/y go too far
+}
+
bool buffer_cursor_move_left(TextBuffer *buffer) {
- return buffer_pos_move_left(buffer, &buffer->cursor_pos);
+ if (buffer_pos_move_left(buffer, &buffer->cursor_pos)) {
+ buffer_scroll_to_cursor(buffer);
+ return true;
+ }
+ return false;
}
bool buffer_cursor_move_right(TextBuffer *buffer) {
- return buffer_pos_move_right(buffer, &buffer->cursor_pos);
+ if (buffer_pos_move_right(buffer, &buffer->cursor_pos)) {
+ buffer_scroll_to_cursor(buffer);
+ return true;
+ }
+ return false;
}
bool buffer_cursor_move_up(TextBuffer *buffer) {
- return buffer_pos_move_up(buffer, &buffer->cursor_pos);
+ if (buffer_pos_move_up(buffer, &buffer->cursor_pos)) {
+ buffer_scroll_to_cursor(buffer);
+ return true;
+ }
+ return false;
}
bool buffer_cursor_move_down(TextBuffer *buffer) {
- return buffer_pos_move_down(buffer, &buffer->cursor_pos);
+ if (buffer_pos_move_down(buffer, &buffer->cursor_pos)) {
+ buffer_scroll_to_cursor(buffer);
+ return true;
+ }
+ return false;
}
+
diff --git a/util.c b/util.c
index c1446a8..e183461 100644
--- a/util.c
+++ b/util.c
@@ -25,4 +25,12 @@ static void util_zero_memory(void *mem, size_t size) {
memset(mem, 0, size);
}
+static double util_maxd(double a, double b) {
+ return a > b ? a : b;
+}
+
+static double util_mind(double a, double b) {
+ return a < b ? a : b;
+}
+
#endif