screen: extract selection code

The screen-selection code is horrible and just hacked together. It works
and seems to have no bugs, but we definitely need to rework it. Lets move
it into a separate file to make it mostly independent of the core screen
code.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

3 files changed, 358 insertions, 322 deletions

diff --git a/Makefile.am b/Makefile.am
index 64e538a..a052755 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -118,6 +118,7 @@ libtsm_la_SOURCES = \
 	src/libtsm_int.h \
 	src/tsm_unicode.c \
 	src/tsm_screen.c \
+	src/tsm_selection.c \
 	src/tsm_vte.c \
 	src/tsm_vte_charsets.c \
 	external/wcwidth.h \
diff --git a/src/tsm_screen.c b/src/tsm_screen.c
index 4e25083..ed84718 100644
--- a/src/tsm_screen.c
+++ b/src/tsm_screen.c
@@ -1605,328 +1605,6 @@ void tsm_screen_erase_screen(struct tsm_screen *con, bool protect)
 			     protect);
 }
 
-/*
- * Selection Code
- * If a running pty-client does not support mouse-tracking extensions, a
- * terminal can manually mark selected areas if it does mouse-tracking itself.
- * This tracking is slightly different than the integrated client-tracking:
- *
- * Initial state is no-selection. At any time selection_reset() can be called to
- * clear the selection and go back to initial state.
- * If the user presses a mouse-button, the terminal can calculate the selected
- * cell and call selection_start() to notify the terminal that the user started
- * the selection. While the mouse-button is held down, the terminal should call
- * selection_target() whenever a mouse-event occurs. This will tell the screen
- * layer to draw the selection from the initial start up to the last given
- * target.
- * Please note that the selection-start cannot be modified by the terminal
- * during a selection. Instead, the screen-layer automatically moves it along
- * with any scroll-operations or inserts/deletes. This also means, the terminal
- * must _not_ cache the start-position itself as it may change under the hood.
- * This selection takes also care of scrollback-buffer selections and correctly
- * moves selection state along.
- *
- * Please note that this is not the kind of selection that some PTY applications
- * support. If the client supports the mouse-protocol, then it can also control
- * a separate screen-selection which is always inside of the actual screen. This
- * is a totally different selection.
- */
-
-static void selection_set(struct tsm_screen *con, struct selection_pos *sel,
-			  unsigned int x, unsigned int y)
-{
-	struct line *pos;
-
-	sel->line = NULL;
-	pos = con->sb_pos;
-
-	while (y && pos) {
-		--y;
-		pos = pos->next;
-	}
-
-	if (pos)
-		sel->line = pos;
-
-	sel->x = x;
-	sel->y = y;
-}
-
-SHL_EXPORT
-void tsm_screen_selection_reset(struct tsm_screen *con)
-{
-	if (!con)
-		return;
-
-	screen_inc_age(con);
-	/* TODO: more sophisticated ageing */
-	con->age = con->age_cnt;
-
-	con->sel_active = false;
-}
-
-SHL_EXPORT
-void tsm_screen_selection_start(struct tsm_screen *con,
-				unsigned int posx,
-				unsigned int posy)
-{
-	if (!con)
-		return;
-
-	screen_inc_age(con);
-	/* TODO: more sophisticated ageing */
-	con->age = con->age_cnt;
-
-	con->sel_active = true;
-	selection_set(con, &con->sel_start, posx, posy);
-	memcpy(&con->sel_end, &con->sel_start, sizeof(con->sel_end));
-}
-
-SHL_EXPORT
-void tsm_screen_selection_target(struct tsm_screen *con,
-				 unsigned int posx,
-				 unsigned int posy)
-{
-	if (!con || !con->sel_active)
-		return;
-
-	screen_inc_age(con);
-	/* TODO: more sophisticated ageing */
-	con->age = con->age_cnt;
-
-	selection_set(con, &con->sel_end, posx, posy);
-}
-
-/* TODO: tsm_ucs4_to_utf8 expects UCS4 characters, but a cell contains a
- * tsm-symbol (which can contain multiple UCS4 chars). Fix this when introducing
- * support for combining characters. */
-static unsigned int copy_line(struct line *line, char *buf,
-			      unsigned int start, unsigned int len)
-{
-	unsigned int i, end;
-	char *pos = buf;
-
-	end = start + len;
-	for (i = start; i < line->size && i < end; ++i) {
-		if (i < line->size || !line->cells[i].ch)
-			pos += tsm_ucs4_to_utf8(line->cells[i].ch, pos);
-		else
-			pos += tsm_ucs4_to_utf8(' ', pos);
-	}
-
-	return pos - buf;
-}
-
-/* TODO: This beast definitely needs some "beautification", however, it's meant
- * as a "proof-of-concept" so its enough for now. */
-SHL_EXPORT
-int tsm_screen_selection_copy(struct tsm_screen *con, char **out)
-{
-	unsigned int len, i;
-	struct selection_pos *start, *end;
-	struct line *iter;
-	char *str, *pos;
-
-	if (!con || !out)
-		return -EINVAL;
-
-	if (!con->sel_active)
-		return -ENOENT;
-
-	/* check whether sel_start or sel_end comes first */
-	if (!con->sel_start.line && con->sel_start.y == SELECTION_TOP) {
-		if (!con->sel_end.line && con->sel_end.y == SELECTION_TOP) {
-			str = strdup("");
-			if (!str)
-				return -ENOMEM;
-			*out = str;
-			return 0;
-		}
-		start = &con->sel_start;
-		end = &con->sel_end;
-	} else if (!con->sel_end.line && con->sel_end.y == SELECTION_TOP) {
-		start = &con->sel_end;
-		end = &con->sel_start;
-	} else if (con->sel_start.line && con->sel_end.line) {
-		if (con->sel_start.line->sb_id < con->sel_end.line->sb_id) {
-			start = &con->sel_start;
-			end = &con->sel_end;
-		} else if (con->sel_start.line->sb_id > con->sel_end.line->sb_id) {
-			start = &con->sel_end;
-			end = &con->sel_start;
-		} else if (con->sel_start.x < con->sel_end.x) {
-			start = &con->sel_start;
-			end = &con->sel_end;
-		} else {
-			start = &con->sel_end;
-			end = &con->sel_start;
-		}
-	} else if (con->sel_start.line) {
-		start = &con->sel_start;
-		end = &con->sel_end;
-	} else if (con->sel_end.line) {
-		start = &con->sel_end;
-		end = &con->sel_start;
-	} else if (con->sel_start.y < con->sel_end.y) {
-		start = &con->sel_start;
-		end = &con->sel_end;
-	} else if (con->sel_start.y > con->sel_end.y) {
-		start = &con->sel_end;
-		end = &con->sel_start;
-	} else if (con->sel_start.x < con->sel_end.x) {
-		start = &con->sel_start;
-		end = &con->sel_end;
-	} else {
-		start = &con->sel_end;
-		end = &con->sel_start;
-	}
-
-	/* calculate size of buffer */
-	len = 0;
-	iter = start->line;
-	if (!iter && start->y == SELECTION_TOP)
-		iter = con->sb_first;
-
-	while (iter) {
-		if (iter == start->line && iter == end->line) {
-			if (iter->size > start->x) {
-				if (iter->size > end->x)
-					len += end->x - start->x + 1;
-				else
-					len += iter->size - start->x;
-			}
-			break;
-		} else if (iter == start->line) {
-			if (iter->size > start->x)
-				len += iter->size - start->x;
-		} else if (iter == end->line) {
-			if (iter->size > end->x)
-				len += end->x + 1;
-			else
-				len += iter->size;
-			break;
-		} else {
-			len += iter->size;
-		}
-
-		++len;
-		iter = iter->next;
-	}
-
-	if (!end->line) {
-		if (start->line || start->y == SELECTION_TOP)
-			i = 0;
-		else
-			i = start->y;
-		for ( ; i < con->size_y; ++i) {
-			if (!start->line && start->y == i && end->y == i) {
-				if (con->size_x > start->x) {
-					if (con->size_x > end->x)
-						len += end->x - start->x + 1;
-					else
-						len += con->size_x - start->x;
-				}
-				break;
-			} else if (!start->line && start->y == i) {
-				if (con->size_x > start->x)
-					len += con->size_x - start->x;
-			} else if (end->y == i) {
-				if (con->size_x > end->x)
-					len += end->x + 1;
-				else
-					len += con->size_x;
-				break;
-			} else {
-				len += con->size_x;
-			}
-
-			++len;
-		}
-	}
-
-	/* allocate buffer */
-	len *= 4;
-	++len;
-	str = malloc(len);
-	if (!str)
-		return -ENOMEM;
-	pos = str;
-
-	/* copy data into buffer */
-	iter = start->line;
-	if (!iter && start->y == SELECTION_TOP)
-		iter = con->sb_first;
-
-	while (iter) {
-		if (iter == start->line && iter == end->line) {
-			if (iter->size > start->x) {
-				if (iter->size > end->x)
-					len = end->x - start->x + 1;
-				else
-					len = iter->size - start->x;
-				pos += copy_line(iter, pos, start->x, len);
-			}
-			break;
-		} else if (iter == start->line) {
-			if (iter->size > start->x)
-				pos += copy_line(iter, pos, start->x,
-						 iter->size - start->x);
-		} else if (iter == end->line) {
-			if (iter->size > end->x)
-				len = end->x + 1;
-			else
-				len = iter->size;
-			pos += copy_line(iter, pos, 0, len);
-			break;
-		} else {
-			pos += copy_line(iter, pos, 0, iter->size);
-		}
-
-		*pos++ = '\n';
-		iter = iter->next;
-	}
-
-	if (!end->line) {
-		if (start->line || start->y == SELECTION_TOP)
-			i = 0;
-		else
-			i = start->y;
-		for ( ; i < con->size_y; ++i) {
-			iter = con->lines[i];
-			if (!start->line && start->y == i && end->y == i) {
-				if (con->size_x > start->x) {
-					if (con->size_x > end->x)
-						len = end->x - start->x + 1;
-					else
-						len = con->size_x - start->x;
-					pos += copy_line(iter, pos, start->x, len);
-				}
-				break;
-			} else if (!start->line && start->y == i) {
-				if (con->size_x > start->x)
-					pos += copy_line(iter, pos, start->x,
-							 con->size_x - start->x);
-			} else if (end->y == i) {
-				if (con->size_x > end->x)
-					len = end->x + 1;
-				else
-					len = con->size_x;
-				pos += copy_line(iter, pos, 0, len);
-				break;
-			} else {
-				pos += copy_line(iter, pos, 0, con->size_x);
-			}
-
-			*pos++ = '\n';
-		}
-	}
-
-	/* return buffer */
-	*pos = 0;
-	*out = str;
-	return pos - str;
-}
-
 SHL_EXPORT
 tsm_age_t tsm_screen_draw(struct tsm_screen *con, tsm_screen_draw_cb draw_cb,
 			  void *data)
diff --git a/src/tsm_selection.c b/src/tsm_selection.c
new file mode 100644
index 0000000..2157480
--- /dev/null
+++ b/src/tsm_selection.c
@@ -0,0 +1,357 @@
+/*
+ * libtsm - Screen Selections
+ *
+ * Copyright (c) 2011-2013 David Herrmann <dh.herrmann@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * Screen Selections
+ * If a running pty-client does not support mouse-tracking extensions, a
+ * terminal can manually mark selected areas if it does mouse-tracking itself.
+ * This tracking is slightly different than the integrated client-tracking:
+ *
+ * Initial state is no-selection. At any time selection_reset() can be called to
+ * clear the selection and go back to initial state.
+ * If the user presses a mouse-button, the terminal can calculate the selected
+ * cell and call selection_start() to notify the terminal that the user started
+ * the selection. While the mouse-button is held down, the terminal should call
+ * selection_target() whenever a mouse-event occurs. This will tell the screen
+ * layer to draw the selection from the initial start up to the last given
+ * target.
+ * Please note that the selection-start cannot be modified by the terminal
+ * during a selection. Instead, the screen-layer automatically moves it along
+ * with any scroll-operations or inserts/deletes. This also means, the terminal
+ * must _not_ cache the start-position itself as it may change under the hood.
+ * This selection takes also care of scrollback-buffer selections and correctly
+ * moves selection state along.
+ *
+ * Please note that this is not the kind of selection that some PTY applications
+ * support. If the client supports the mouse-protocol, then it can also control
+ * a separate screen-selection which is always inside of the actual screen. This
+ * is a totally different selection.
+ */
+
+#include <errno.h>
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include "libtsm.h"
+#include "libtsm_int.h"
+#include "shl_llog.h"
+
+#define LLOG_SUBSYSTEM "tsm_selection"
+
+static void selection_set(struct tsm_screen *con, struct selection_pos *sel,
+			  unsigned int x, unsigned int y)
+{
+	struct line *pos;
+
+	sel->line = NULL;
+	pos = con->sb_pos;
+
+	while (y && pos) {
+		--y;
+		pos = pos->next;
+	}
+
+	if (pos)
+		sel->line = pos;
+
+	sel->x = x;
+	sel->y = y;
+}
+
+SHL_EXPORT
+void tsm_screen_selection_reset(struct tsm_screen *con)
+{
+	if (!con)
+		return;
+
+	screen_inc_age(con);
+	/* TODO: more sophisticated ageing */
+	con->age = con->age_cnt;
+
+	con->sel_active = false;
+}
+
+SHL_EXPORT
+void tsm_screen_selection_start(struct tsm_screen *con,
+				unsigned int posx,
+				unsigned int posy)
+{
+	if (!con)
+		return;
+
+	screen_inc_age(con);
+	/* TODO: more sophisticated ageing */
+	con->age = con->age_cnt;
+
+	con->sel_active = true;
+	selection_set(con, &con->sel_start, posx, posy);
+	memcpy(&con->sel_end, &con->sel_start, sizeof(con->sel_end));
+}
+
+SHL_EXPORT
+void tsm_screen_selection_target(struct tsm_screen *con,
+				 unsigned int posx,
+				 unsigned int posy)
+{
+	if (!con || !con->sel_active)
+		return;
+
+	screen_inc_age(con);
+	/* TODO: more sophisticated ageing */
+	con->age = con->age_cnt;
+
+	selection_set(con, &con->sel_end, posx, posy);
+}
+
+/* TODO: tsm_ucs4_to_utf8 expects UCS4 characters, but a cell contains a
+ * tsm-symbol (which can contain multiple UCS4 chars). Fix this when introducing
+ * support for combining characters. */
+static unsigned int copy_line(struct line *line, char *buf,
+			      unsigned int start, unsigned int len)
+{
+	unsigned int i, end;
+	char *pos = buf;
+
+	end = start + len;
+	for (i = start; i < line->size && i < end; ++i) {
+		if (i < line->size || !line->cells[i].ch)
+			pos += tsm_ucs4_to_utf8(line->cells[i].ch, pos);
+		else
+			pos += tsm_ucs4_to_utf8(' ', pos);
+	}
+
+	return pos - buf;
+}
+
+/* TODO: This beast definitely needs some "beautification", however, it's meant
+ * as a "proof-of-concept" so its enough for now. */
+SHL_EXPORT
+int tsm_screen_selection_copy(struct tsm_screen *con, char **out)
+{
+	unsigned int len, i;
+	struct selection_pos *start, *end;
+	struct line *iter;
+	char *str, *pos;
+
+	if (!con || !out)
+		return -EINVAL;
+
+	if (!con->sel_active)
+		return -ENOENT;
+
+	/* check whether sel_start or sel_end comes first */
+	if (!con->sel_start.line && con->sel_start.y == SELECTION_TOP) {
+		if (!con->sel_end.line && con->sel_end.y == SELECTION_TOP) {
+			str = strdup("");
+			if (!str)
+				return -ENOMEM;
+			*out = str;
+			return 0;
+		}
+		start = &con->sel_start;
+		end = &con->sel_end;
+	} else if (!con->sel_end.line && con->sel_end.y == SELECTION_TOP) {
+		start = &con->sel_end;
+		end = &con->sel_start;
+	} else if (con->sel_start.line && con->sel_end.line) {
+		if (con->sel_start.line->sb_id < con->sel_end.line->sb_id) {
+			start = &con->sel_start;
+			end = &con->sel_end;
+		} else if (con->sel_start.line->sb_id > con->sel_end.line->sb_id) {
+			start = &con->sel_end;
+			end = &con->sel_start;
+		} else if (con->sel_start.x < con->sel_end.x) {
+			start = &con->sel_start;
+			end = &con->sel_end;
+		} else {
+			start = &con->sel_end;
+			end = &con->sel_start;
+		}
+	} else if (con->sel_start.line) {
+		start = &con->sel_start;
+		end = &con->sel_end;
+	} else if (con->sel_end.line) {
+		start = &con->sel_end;
+		end = &con->sel_start;
+	} else if (con->sel_start.y < con->sel_end.y) {
+		start = &con->sel_start;
+		end = &con->sel_end;
+	} else if (con->sel_start.y > con->sel_end.y) {
+		start = &con->sel_end;
+		end = &con->sel_start;
+	} else if (con->sel_start.x < con->sel_end.x) {
+		start = &con->sel_start;
+		end = &con->sel_end;
+	} else {
+		start = &con->sel_end;
+		end = &con->sel_start;
+	}
+
+	/* calculate size of buffer */
+	len = 0;
+	iter = start->line;
+	if (!iter && start->y == SELECTION_TOP)
+		iter = con->sb_first;
+
+	while (iter) {
+		if (iter == start->line && iter == end->line) {
+			if (iter->size > start->x) {
+				if (iter->size > end->x)
+					len += end->x - start->x + 1;
+				else
+					len += iter->size - start->x;
+			}
+			break;
+		} else if (iter == start->line) {
+			if (iter->size > start->x)
+				len += iter->size - start->x;
+		} else if (iter == end->line) {
+			if (iter->size > end->x)
+				len += end->x + 1;
+			else
+				len += iter->size;
+			break;
+		} else {
+			len += iter->size;
+		}
+
+		++len;
+		iter = iter->next;
+	}
+
+	if (!end->line) {
+		if (start->line || start->y == SELECTION_TOP)
+			i = 0;
+		else
+			i = start->y;
+		for ( ; i < con->size_y; ++i) {
+			if (!start->line && start->y == i && end->y == i) {
+				if (con->size_x > start->x) {
+					if (con->size_x > end->x)
+						len += end->x - start->x + 1;
+					else
+						len += con->size_x - start->x;
+				}
+				break;
+			} else if (!start->line && start->y == i) {
+				if (con->size_x > start->x)
+					len += con->size_x - start->x;
+			} else if (end->y == i) {
+				if (con->size_x > end->x)
+					len += end->x + 1;
+				else
+					len += con->size_x;
+				break;
+			} else {
+				len += con->size_x;
+			}
+
+			++len;
+		}
+	}
+
+	/* allocate buffer */
+	len *= 4;
+	++len;
+	str = malloc(len);
+	if (!str)
+		return -ENOMEM;
+	pos = str;
+
+	/* copy data into buffer */
+	iter = start->line;
+	if (!iter && start->y == SELECTION_TOP)
+		iter = con->sb_first;
+
+	while (iter) {
+		if (iter == start->line && iter == end->line) {
+			if (iter->size > start->x) {
+				if (iter->size > end->x)
+					len = end->x - start->x + 1;
+				else
+					len = iter->size - start->x;
+				pos += copy_line(iter, pos, start->x, len);
+			}
+			break;
+		} else if (iter == start->line) {
+			if (iter->size > start->x)
+				pos += copy_line(iter, pos, start->x,
+						 iter->size - start->x);
+		} else if (iter == end->line) {
+			if (iter->size > end->x)
+				len = end->x + 1;
+			else
+				len = iter->size;
+			pos += copy_line(iter, pos, 0, len);
+			break;
+		} else {
+			pos += copy_line(iter, pos, 0, iter->size);
+		}
+
+		*pos++ = '\n';
+		iter = iter->next;
+	}
+
+	if (!end->line) {
+		if (start->line || start->y == SELECTION_TOP)
+			i = 0;
+		else
+			i = start->y;
+		for ( ; i < con->size_y; ++i) {
+			iter = con->lines[i];
+			if (!start->line && start->y == i && end->y == i) {
+				if (con->size_x > start->x) {
+					if (con->size_x > end->x)
+						len = end->x - start->x + 1;
+					else
+						len = con->size_x - start->x;
+					pos += copy_line(iter, pos, start->x, len);
+				}
+				break;
+			} else if (!start->line && start->y == i) {
+				if (con->size_x > start->x)
+					pos += copy_line(iter, pos, start->x,
+							 con->size_x - start->x);
+			} else if (end->y == i) {
+				if (con->size_x > end->x)
+					len = end->x + 1;
+				else
+					len = con->size_x;
+				pos += copy_line(iter, pos, 0, len);
+				break;
+			} else {
+				pos += copy_line(iter, pos, 0, con->size_x);
+			}
+
+			*pos++ = '\n';
+		}
+	}
+
+	/* return buffer */
+	*pos = 0;
+	*out = str;
+	return pos - str;
+}