tdf#95173 vcl: fix not drawn progressbar widget from UNO

Commit e6c2951f1957224aa0e7dc97b33b0450c41f92f7 (delegate RenderContext,
invalidate - prgsbar, scrbar, 2015-04-29) switched ProgressBar::SetValue() from
direct partial paint to invalidate + paint later, which means setting a
progressbar value, then using an external sleep (such as Python's time.sleep())
no longer results in an updated progressbar.

Solve the problem by explicitly processing all events with at least
TaskPriority::REPAINT priority after the invalidate in ProgressBar::SetValue(),
which is similar to what the Wait implementation in the basic runtime does.

Change-Id: I86475fb899f16b72ebefe9d3056c92cedeff4439
Reviewed-on: https://gerrit.libreoffice.org/73941
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

1 files changed, 12 insertions, 0 deletions

diff --git a/vcl/source/control/prgsbar.cxx b/vcl/source/control/prgsbar.cxx
index 376ed91cfcdd..2531423a922f 100644
--- a/vcl/source/control/prgsbar.cxx
+++ b/vcl/source/control/prgsbar.cxx
@@ -22,6 +22,8 @@
 #include <vcl/prgsbar.hxx>
 #include <vcl/settings.hxx>
 #include <sal/log.hxx>
+#include <vcl/svapp.hxx>
+#include <vcl/idle.hxx>
 
 #define PROGRESSBAR_OFFSET          3
 #define PROGRESSBAR_WIN_OFFSET      2
@@ -174,6 +176,16 @@ void ProgressBar::SetValue( sal_uInt16 nNewPercent )
     {
         mnPercent = nNewPercent;
         Invalidate();
+
+        // Make sure the progressbar is actually painted even if the caller is busy with its task,
+        // so the main loop would not be invoked.
+        Idle aIdle("ProgressBar::SetValue aIdle");
+        aIdle.SetPriority(TaskPriority::POST_PAINT);
+        aIdle.Start();
+        while (aIdle.IsActive())
+        {
+            Application::Yield();
+        }
     }
 }