From 70fbca36060e2c358a6dc54da853ba6d5ec8724d Mon Sep 17 00:00:00 2001
From: Michael Drake <tlsa@netsurf-browser.org>
Date: Fri, 22 Mar 2013 18:01:02 +0000
Subject: Reduce redraw area for selection set/change/clear.

---
 desktop/textarea.c | 50 +++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 39 insertions(+), 11 deletions(-)

(limited to 'desktop')

diff --git a/desktop/textarea.c b/desktop/textarea.c
index 2ba1c53cc..15d35e1e5 100644
--- a/desktop/textarea.c
+++ b/desktop/textarea.c
@@ -459,7 +459,6 @@ static bool textarea_select(struct textarea *ta, int b_start, int b_end,
 	int swap;
 	bool pre_existing_selection = (ta->sel_start != -1);
 	struct textarea_msg msg;
-	int line_start = 0, line_end = 0;
 
 	if (b_start == b_end) {
 		textarea_clear_selection(ta);
@@ -483,18 +482,29 @@ static bool textarea_select(struct textarea *ta, int b_start, int b_end,
 	msg.data.redraw.x1 = ta->vis_width - ta->border_width -
 			((ta->bar_y == NULL) ? 0 : SCROLLBAR_WIDTH);
 
-	if (force_redraw || !pre_existing_selection ||
-			(ta->sel_start != b_start && ta->sel_end != b_end)) {
-		/* Asked to redraw everything, or there's a new selection, or
-		 * both ends of the selection have moved */
+	if (force_redraw) {
+		/* Asked to redraw everything */
 		msg.data.redraw.y0 = ta->border_width;
 		msg.data.redraw.y1 = ta->vis_height - ta->border_width -
 				((ta->bar_x == NULL) ? 0 : SCROLLBAR_WIDTH);
 	} else {
-		/* Redraw to cover change in selection start or change in
-		 * selection end */
+		/* Try to minimise redraw region */
 		unsigned int b_low, b_high;
-		if (ta->sel_start != b_start) {
+		int line_start = 0, line_end = 0;
+
+		if (!pre_existing_selection) {
+			/* There's a new selection */
+			b_low = b_start;
+			b_high = b_end;
+
+		} else if (ta->sel_start != b_start && ta->sel_end != b_end) {
+			/* Both ends of the selection have moved */
+			b_low = (ta->sel_start < b_start) ?
+					ta->sel_start : b_start;
+			b_high = (ta->sel_end > b_end) ?
+					ta->sel_end : b_end;
+
+		} else if (ta->sel_start != b_start) {
 			/* Selection start changed */
 			if ((signed)ta->sel_start < b_start) {
 				b_low = ta->sel_start;
@@ -503,6 +513,7 @@ static bool textarea_select(struct textarea *ta, int b_start, int b_end,
 				b_low = b_start;
 				b_high = ta->sel_start;
 			}
+
 		} else {
 			/* Selection end changed */
 			if ((signed)ta->sel_end < b_end) {
@@ -514,6 +525,7 @@ static bool textarea_select(struct textarea *ta, int b_start, int b_end,
 			}
 		}
 
+		/* Find redraw start/end lines */
 		for (line_end = 0; line_end < ta->line_count - 1; line_end++)
 			if (ta->lines[line_end + 1].b_start > b_low) {
 				line_start = line_end;
@@ -523,6 +535,7 @@ static bool textarea_select(struct textarea *ta, int b_start, int b_end,
 			if (ta->lines[line_end + 1].b_start > b_high)
 				break;
 
+		/* Set vertical redraw range */
 		msg.data.redraw.y0 = max(ta->border_width,
 				ta->line_height * line_start +
 				ta->text_y_offset - ta->scroll_y);
@@ -2677,22 +2690,37 @@ textarea_mouse_status textarea_mouse_action(struct textarea *ta,
 bool textarea_clear_selection(struct textarea *ta)
 {
 	struct textarea_msg msg;
+	int line_end, line_start = 0;
 
 	if (ta->sel_start == -1)
 		/* No selection to clear */
 		return false;
 
+	/* Find selection start & end lines */
+	for (line_end = 0; line_end < ta->line_count - 1; line_end++)
+		if (ta->lines[line_end + 1].b_start > (unsigned)ta->sel_start) {
+			line_start = line_end;
+			break;
+		}
+	for (; line_end < ta->line_count - 1; line_end++)
+		if (ta->lines[line_end + 1].b_start > (unsigned)ta->sel_end)
+			break;
+
 	/* Clear selection and redraw */
 	ta->sel_start = ta->sel_end = -1;
 
 	msg.ta = ta;
 	msg.type = TEXTAREA_MSG_REDRAW_REQUEST;
 	msg.data.redraw.x0 = ta->border_width;
-	msg.data.redraw.y0 = ta->border_width;
+	msg.data.redraw.y0 = max(ta->border_width,
+			ta->line_height * line_start +
+			ta->text_y_offset - ta->scroll_y);
 	msg.data.redraw.x1 = ta->vis_width - ta->border_width -
 			((ta->bar_y == NULL) ? 0 : SCROLLBAR_WIDTH);
-	msg.data.redraw.y1 = ta->vis_height - ta->border_width -
-			((ta->bar_x == NULL) ? 0 : SCROLLBAR_WIDTH);
+	msg.data.redraw.y1 = min(ta->vis_height - ta->border_width -
+			((ta->bar_x == NULL) ? 0 : SCROLLBAR_WIDTH),
+			ta->line_height * line_end + ta->text_y_offset +
+			ta->line_height - ta->scroll_y);
 
 	ta->callback(ta->data, &msg);
 
-- 
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