From ccd39b8804cba58206d254944c8e7c3bb8e02cdf Mon Sep 17 00:00:00 2001
From: Jorge Arellano Cid <jcid@dillo.org>
Date: Fri, 29 Jul 2011 15:45:45 -0400
Subject: avoid double draw after scrollIdle()

After going back or forward to any page, there were two redraws: one from
the origin and another from the scroll position. This patch avoids flicker,
and makes rendering 100% faster in this case.
---
 dw/layout.cc | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

(limited to 'dw/layout.cc')

diff --git a/dw/layout.cc b/dw/layout.cc
index cf19df37..170ec20e 100644
--- a/dw/layout.cc
+++ b/dw/layout.cc
@@ -194,6 +194,7 @@ Layout::Layout (Platform *platform)
    canvasWidth = canvasAscent = canvasDescent = 0;
 
    usesViewport = false;
+   drawAfterScrollReq = false;
    scrollX = scrollY = 0;
    viewportWidth = viewportHeight = 0;
    hScrollbarThickness = vScrollbarThickness = 0;
@@ -456,6 +457,11 @@ void Layout::scrollIdle ()
    if (xChanged || yChanged) {
       adjustScrollPos ();
       view->scrollTo (scrollX, scrollY);
+      if (drawAfterScrollReq) {
+         drawAfterScrollReq = false;
+         view->queueDrawTotal ();
+         MSG("Layout::scrollIdle: view->queueDrawTotal()\n");
+      }
    }
 
    scrollIdleId = -1;
@@ -503,7 +509,11 @@ void Layout::draw (View *view, Rectangle *area)
 {
    Rectangle widgetArea, intersection, widgetDrawArea;
 
-   if (topLevel) {
+   if (scrollIdleId != -1) {
+      /* scroll is pending, defer draw until after scrollIdle() */
+      drawAfterScrollReq = true;
+
+   } else if (topLevel) {
       /* Draw the top level widget. */
       widgetArea.x = topLevel->allocation.x;
       widgetArea.y = topLevel->allocation.y;
-- 
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