Calculate and store text offsets only when they change, rather than recalculating on every redraw and caret placement. Also ensures that caret placement and redraw get the same text offset values.

1 files changed, 37 insertions, 23 deletions

diff --git a/desktop/textarea.c b/desktop/textarea.c
index ad9c8f25a..0426b007a 100644
--- a/desktop/textarea.c
+++ b/desktop/textarea.c
@@ -80,6 +80,9 @@ struct textarea {
 	int border_width;	/**< Border width, in pixels */
 	colour border_col;	/**< Border colour */
 
+	int text_y_offset;		/**< Vertical dist to 1st line top */
+	int text_y_offset_baseline;	/**< Vertical dist to 1st baseline */
+
 	plot_font_style_t fstyle;	/**< Text style, inc. textarea bg col */
 	plot_font_style_t sel_fstyle;	/**< Selected text style */
 	int line_height;		/**< Line height obtained from style */
@@ -1044,6 +1047,32 @@ static bool textarea_drag_end(struct textarea *ta, browser_mouse_state mouse,
 }
 
 
+/**
+ * Setup text offsets after height / border / padding change
+ *
+ * \param ta	Textarea widget
+ */
+static void textarea_setup_text_offsets(struct textarea *ta)
+{
+	int text_y_offset, text_y_offset_baseline;
+
+	text_y_offset = text_y_offset_baseline = ta->border_width;
+	if (ta->flags & TEXTAREA_MULTILINE) {
+		/* Multiline textarea */
+		text_y_offset += ta->pad_top;
+		text_y_offset_baseline += (ta->line_height * 3 + 2) / 4 +
+				ta->pad_top;
+	} else {
+		/* Single line text area; text is vertically centered */
+		int vis_height = ta->vis_height - 2 * ta->border_width;
+		text_y_offset += (vis_height - ta->line_height + 1) / 2;
+		text_y_offset_baseline += (vis_height * 3 + 2) / 4;
+	}
+
+	ta->text_y_offset = text_y_offset;
+	ta->text_y_offset_baseline = text_y_offset_baseline;
+}
+
 
 
 /* exported interface, documented in textarea.h */
@@ -1146,6 +1175,7 @@ struct textarea *textarea_create(const textarea_flags flags,
 	ret->lines = NULL;
 	ret->lines_alloc_size = 0;
 
+	textarea_setup_text_offsets(ret);
 	textarea_reflow(ret, 0);
 
 	return ret;
@@ -1272,7 +1302,6 @@ bool textarea_set_caret(struct textarea *ta, int caret)
 	int index;
 	int x, y;
 	int x0, y0, x1, y1;
-	int text_y_offset;
 	int width, height;
 	struct textarea_msg msg;
 	bool scrolled;
@@ -1285,15 +1314,6 @@ bool textarea_set_caret(struct textarea *ta, int caret)
 	if (caret != -1 && caret > (signed)c_len)
 		caret = c_len;
 
-	if (ta->flags & TEXTAREA_MULTILINE) {
-		/* Multiline textarea */
-		text_y_offset = ta->border_width + ta->pad_top;
-	} else {
-		/* Single line text area; text is vertically centered */
-		text_y_offset = ta->border_width;
-		text_y_offset += (ta->vis_height - ta->line_height + 1) / 2;
-	}
-
 	/* Delete the old caret */
 	if (ta->caret_pos.char_off != -1 &&
 			ta->flags & TEXTAREA_INTERNAL_CARET) {
@@ -1355,7 +1375,7 @@ bool textarea_set_caret(struct textarea *ta, int caret)
 
 		x += ta->border_width + ta->pad_left;
 		ta->caret_x = x;
-		y = ta->line_height * ta->caret_pos.line + text_y_offset;
+		y = ta->line_height * ta->caret_pos.line + ta->text_y_offset;
 		ta->caret_y = y;
 
 		scrolled = textarea_scroll_visible(ta);
@@ -1561,18 +1581,8 @@ void textarea_redraw(struct textarea *ta, int x, int y, colour bg, float scale,
 	else
 		c_pos = 0;
 
-	text_y_offset = text_y_offset_baseline = ta->border_width;
-	if (ta->flags & TEXTAREA_MULTILINE) {
-		/* Multiline textarea */
-		text_y_offset += ta->pad_top;
-		text_y_offset_baseline += (ta->line_height * 3 + 2) / 4 +
-				ta->pad_top;
-	} else {
-		/* Single line text area; text is vertically centered */
-		int vis_height = ta->vis_height - 2 * ta->border_width;
-		text_y_offset += (vis_height - ta->line_height + 1) / 2;
-		text_y_offset_baseline += (vis_height * 3 + 2) / 4;
-	}
+	text_y_offset = ta->text_y_offset;
+	text_y_offset_baseline = ta->text_y_offset_baseline;
 
 	if (scale != 1.0) {
 		text_y_offset *= scale;
@@ -2354,6 +2364,8 @@ void textarea_set_dimensions(struct textarea *ta, int width, int height)
 {
 	ta->vis_width = width;
 	ta->vis_height = height;
+
+	textarea_setup_text_offsets(ta);
 	textarea_reflow(ta, 0);
 }
 
@@ -2368,6 +2380,8 @@ void textarea_set_layout(struct textarea *ta, int width, int height,
 	ta->pad_right = right + ((ta->bar_y == NULL) ? 0 : SCROLLBAR_WIDTH);
 	ta->pad_bottom = bottom + ((ta->bar_x == NULL) ? 0 : SCROLLBAR_WIDTH);
 	ta->pad_left = left;
+
+	textarea_setup_text_offsets(ta);
 	textarea_reflow(ta, 0);
 }