[reactos] 01/01: [UXTHEME] Improve drawing of the scrollbars when they are too small. CORE-13513

[Giannis Adamopoulos]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=68af472a2133fb8e6859a…

commit 68af472a2133fb8e6859a7a9d5363385b995f891
Author: Giannis Adamopoulos <gadamopoulos(a)reactos.org>
AuthorDate: Thu Nov 23 21:17:03 2017 +0200

    [UXTHEME] Improve drawing of the scrollbars when they are too small. CORE-13513
---
 dll/win32/uxtheme/ncscrollbar.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/dll/win32/uxtheme/ncscrollbar.c b/dll/win32/uxtheme/ncscrollbar.c
index 27299f867d..8d6f21de69 100644
--- a/dll/win32/uxtheme/ncscrollbar.c
+++ b/dll/win32/uxtheme/ncscrollbar.c
@@ -126,6 +126,9 @@ static enum SCROLL_HITTEST SCROLL_HitTest( HWND hwnd, SCROLLBARINFO*
psbi, BOOL
 
 static void SCROLL_ThemeDrawPart(PDRAW_CONTEXT pcontext, int iPartId,int iStateId, 
SCROLLBARINFO* psbi, int htCurrent, int htDown, int htHot, RECT* r)
 {
+    if (r->right <= r->left || r->bottom <= r->top)
+        return;
+
     if(psbi->rgstate[htCurrent] & STATE_SYSTEM_UNAVAILABLE)
         iStateId += BUTTON_DISABLED - BUTTON_NORMAL;
     else if (htHot == htCurrent)
@@ -187,17 +190,22 @@ static void SCROLL_DrawInterior( PDRAW_CONTEXT pcontext,
SCROLLBARINFO* psbi,
     r = psbi->rcScrollBar;
     if (vertical)
     {
-        thumbPos += pcontext->wi.rcClient.top - pcontext->wi.rcWindow.top;
+        if (thumbPos)
+            thumbPos += pcontext->wi.rcClient.top - pcontext->wi.rcWindow.top;
         r.top    += psbi->dxyLineButton;
         r.bottom -= (psbi->dxyLineButton);
     }
     else
     {
-        thumbPos += pcontext->wi.rcClient.left - pcontext->wi.rcWindow.left;
+        if (thumbPos)
+            thumbPos += pcontext->wi.rcClient.left - pcontext->wi.rcWindow.left;
         r.left  += psbi->dxyLineButton;
         r.right -= psbi->dxyLineButton;
     }
 
+    if (r.right <= r.left || r.bottom <= r.top)
+        return;
+
     /* Draw the scroll rectangles and thumb */
 
     if (!thumbPos)  /* No thumb to draw */