[ghex] Instead of drawing directly, invalidate the changed areas

[Kalev Lember <klember src gnome org>]

commit 70780979e7e821c3d61670147cbec537b7e2e620
Author: Kalev Lember <kalevlember gmail com>
Date:   Sat Jul 30 09:43:34 2011 +0300

    Instead of drawing directly, invalidate the changed areas
    
    This makes it possible to remove some duplicated code and also avoids
    unnecessary redraws which can cause flickering, when e.g. dragging
    cursor around.

 src/gtkhex.c |  139 ++++++++++++++++++++++++++++++++++-----------------------
 1 files changed, 83 insertions(+), 56 deletions(-)
---
diff --git a/src/gtkhex.c b/src/gtkhex.c
index 927dea8..d09b9a4 100644
--- a/src/gtkhex.c
+++ b/src/gtkhex.c
@@ -284,55 +284,35 @@ static gint get_acoords(GtkHex *gh, gint pos, gint *x, gint *y) {
 	return TRUE;
 }
 
+static void
+invalidate_xc (GtkHex *gh)
+{
+    GtkWidget *widget = gh->xdisp;
+    gint cx, cy;
 
-/*
- * renders a byte at offset pos in both displays
- */ 
-static void render_byte(GtkHex *gh, gint pos) {
-	gint cx, cy;
-	gchar buf[2];
-	cairo_t *cr;
-
-	if (!gtk_widget_get_realized (gh->xdisp) || !gtk_widget_get_realized (gh->adisp))
-		return;
-
-	if(!get_xcoords(gh, pos, &cx, &cy))
-		return;
-
-	format_xbyte(gh, pos, buf);
-
-	cr = gdk_cairo_create (gtk_widget_get_window (gh->xdisp));
-
-	gdk_cairo_set_source_color (cr, &gtk_widget_get_style (GTK_WIDGET (gh))->base[GTK_STATE_NORMAL]);
-	cairo_rectangle (cr, cx, cy, 2 * gh->char_width, gh->char_height);
-	cairo_fill (cr);
-
-	if(pos < gh->document->file_size) {
-		gdk_cairo_set_source_color (cr, &gtk_widget_get_style (GTK_WIDGET (gh))->text[GTK_STATE_NORMAL]);
-		cairo_move_to (cr, cx, cy);
-		pango_layout_set_text (gh->xlayout, buf, 2);
-		pango_cairo_show_layout (cr, gh->xlayout);
-	}
-	cairo_destroy (cr);
-	
-	if(!get_acoords(gh, pos, &cx, &cy))
-		return;
+    if (get_xcoords (gh, gh->cursor_pos, &cx, &cy)) {
+        if (gh->lower_nibble)
+            cx += gh->char_width;
 
-	cr = gdk_cairo_create (gtk_widget_get_window (gh->adisp));
+        gtk_widget_queue_draw_area (widget,
+                                    cx, cy,
+                                    gh->char_width + 1,
+                                    gh->char_height);
+    }
+}
 
-	gdk_cairo_set_source_color (cr, &gtk_widget_get_style (GTK_WIDGET (gh))->base[GTK_STATE_NORMAL]);
-	cairo_rectangle (cr, cx, cy, gh->char_width, gh->char_height);
-	cairo_fill (cr);
-	if(pos < gh->document->file_size) {
-		gdk_cairo_set_source_color (cr, &gtk_widget_get_style (GTK_WIDGET (gh))->text[GTK_STATE_NORMAL]);
-		buf[0] = gtk_hex_get_byte(gh, pos);
-		if(!is_displayable((guchar)buf[0]))
-			buf[0] = '.';
-		cairo_move_to (cr, cx, cy);
-		pango_layout_set_text (gh->alayout, buf, 1);
-		pango_cairo_show_layout (cr, gh->alayout);
-	}
-	cairo_destroy (cr);
+static void
+invalidate_ac (GtkHex *gh)
+{
+    GtkWidget *widget = gh->adisp;
+    gint cx, cy;
+
+    if (get_acoords (gh, gh->cursor_pos, &cx, &cy)) {
+        gtk_widget_queue_draw_area (widget,
+                                    cx, cy,
+                                    gh->char_width + 1,
+                                    gh->char_height);
+    }
 }
 
 /*
@@ -415,8 +395,8 @@ static void render_xc(GtkHex *gh) {
 static void show_cursor(GtkHex *gh) {
 	if(!gh->cursor_shown) {
 		if (gtk_widget_get_realized (gh->xdisp) || gtk_widget_get_realized (gh->adisp)) {
-			render_xc(gh);
-			render_ac(gh);
+			invalidate_xc (gh);
+			invalidate_ac (gh);
 		}
 		gh->cursor_shown = TRUE;
 	}
@@ -424,8 +404,10 @@ static void show_cursor(GtkHex *gh) {
 
 static void hide_cursor(GtkHex *gh) {
 	if(gh->cursor_shown) {
-		if (gtk_widget_get_realized (gh->xdisp) || gtk_widget_get_realized (gh->adisp))
-			render_byte(gh, gh->cursor_pos);
+		if (gtk_widget_get_realized (gh->xdisp) || gtk_widget_get_realized (gh->adisp)) {
+			invalidate_xc (gh);
+			invalidate_ac (gh);
+		}
 		gh->cursor_shown = FALSE;
 	}
 }
@@ -602,6 +584,51 @@ static void render_ascii_highlights(GtkHex *gh, gint cursor_line)
 }
 
 /*
+ * when calling invalidate_*_lines() the imin and imax arguments are the
+ * numbers of the first and last line TO BE INVALIDATED in the range
+ * [0 .. gh->vis_lines-1] AND NOT [0 .. gh->lines]!
+ */
+static void
+invalidate_lines (GtkHex *gh,
+                  GtkWidget *widget,
+                  gint imin,
+                  gint imax)
+{
+    GtkAllocation allocation;
+
+    gtk_widget_get_allocation (widget, &allocation);
+    gtk_widget_queue_draw_area (widget,
+                                0,
+                                imin * gh->char_height,
+                                allocation.width,
+                                (imax - imin + 1) * gh->char_height);
+}
+
+static void
+invalidate_hex_lines (GtkHex *gh,
+                      gint imin,
+                      gint imax)
+{
+    invalidate_lines (gh, gh->xdisp, imin, imax);
+}
+
+static void
+invalidate_ascii_lines (GtkHex *gh,
+                        gint imin,
+                        gint imax)
+{
+    invalidate_lines (gh, gh->adisp, imin, imax);
+}
+
+static void
+invalidate_offsets (GtkHex *gh,
+                    gint imin,
+                    gint imax)
+{
+    invalidate_lines (gh, gh->offsets, imin, imax);
+}
+
+/*
  * when calling render_*_lines() the imin and imax arguments are the
  * numbers of the first and last line TO BE DISPLAYED in the range
  * [0 .. gh->vis_lines-1] AND NOT [0 .. gh->lines]!
@@ -1222,11 +1249,11 @@ static void gtk_hex_real_data_changed(GtkHex *gh, gpointer data) {
 	else
 		end_line = MIN(end_line, gh->vis_lines);
 
-	render_hex_lines(gh, start_line, end_line);
-	render_ascii_lines(gh, start_line, end_line);
+    invalidate_hex_lines (gh, start_line, end_line);
+    invalidate_ascii_lines (gh, start_line, end_line);
     if (gh->show_offsets)
     {
-        render_offsets (gh, start_line, end_line);
+        invalidate_offsets (gh, start_line, end_line);
     }
 }
 
@@ -1241,11 +1268,11 @@ static void bytes_changed(GtkHex *gh, gint start, gint end)
 
 	start_line = MAX(start_line, 0);
 
-	render_hex_lines(gh, start_line, end_line);
-	render_ascii_lines(gh, start_line, end_line);
+    invalidate_hex_lines (gh, start_line, end_line);
+    invalidate_ascii_lines (gh, start_line, end_line);
     if (gh->show_offsets)
     {
-        render_offsets (gh, start_line, end_line);
+        invalidate_offsets (gh, start_line, end_line);
     }
 }