Improve scroll bar treatment on Haiku

* src/haiku_support.cc (MessageReceived): Subtract portion from
range of scroll bar.
* src/haikuterm.c (BE_SB_MAX): Adjust values for better
rounding.
(haiku_set_scroll_bar_thumb): Round values instead of
truncating them.

2 files changed, 14 insertions, 11 deletions

diff --git a/src/haiku_support.cc b/src/haiku_support.cc
index 6f5196dc1ce..9b85cd6e0ac 100644
--- a/src/haiku_support.cc
+++ b/src/haiku_support.cc
@@ -1578,18 +1578,22 @@ public:
   MessageReceived (BMessage *msg)
   {
     int32 portion, range;
+    double proportion;
 
     if (msg->what == SCROLL_BAR_UPDATE)
       {
         old_value = msg->GetInt32 ("emacs:units", 0);
         portion = msg->GetInt32 ("emacs:portion", 0);
         range = msg->GetInt32 ("emacs:range", 0);
+        proportion = (double) portion / range;
 
         if (!msg->GetBool ("emacs:dragging", false))
           {
-            this->SetRange (0, range);
+            /* Unlike on Motif, PORTION isn't included in the total
+               range of the scroll bar.  */
+            this->SetRange (0, std::floor ((double) range - (range * proportion)));
             this->SetValue (old_value);
-            this->SetProportion ((float) portion / range);
+            this->SetProportion (proportion);
           }
       }
 
diff --git a/src/haikuterm.c b/src/haikuterm.c
index a7b971f2c1b..119c54b17ac 100644
--- a/src/haikuterm.c
+++ b/src/haikuterm.c
@@ -41,7 +41,7 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #endif
 
 /* Minimum and maximum values used for Haiku scroll bars.  */
-#define BE_SB_MAX 10000000
+#define BE_SB_MAX 12000000
 
 struct haiku_display_info *x_display_list = NULL;
 extern frame_parm_handler haiku_frame_parm_handlers[];
@@ -440,8 +440,7 @@ haiku_set_scroll_bar_thumb (struct scroll_bar *bar, int portion,
                             int position, int whole)
 {
   void *scroll_bar = bar->scroll_bar;
-  float top, shown;
-  int size, value;
+  double top, shown, size, value;
 
   if (scroll_bar_adjust_thumb_portion_p)
     {
@@ -461,8 +460,8 @@ haiku_set_scroll_bar_thumb (struct scroll_bar *bar, int portion,
         top = 0, shown = 1;
       else
         {
-          top = (float) position / whole;
-          shown = (float) portion / whole;
+          top = (double) position / whole;
+          shown = (double) portion / whole;
         }
 
       /* Slider size.  Must be in the range [1 .. MAX - MIN] where MAX
@@ -481,12 +480,12 @@ haiku_set_scroll_bar_thumb (struct scroll_bar *bar, int portion,
     {
       bar->page_size = 0;
 
-      size = (((float) portion / whole) * BE_SB_MAX);
-      value = (((float) position / whole) * BE_SB_MAX);
+      size = (((double) portion / whole) * BE_SB_MAX);
+      value = (((double) position / whole) * BE_SB_MAX);
     }
 
-  BView_scroll_bar_update (scroll_bar, size, BE_SB_MAX, value,
-                           bar->dragging);
+  BView_scroll_bar_update (scroll_bar, lrint (size),
+                           BE_SB_MAX, lrint (value), bar->dragging);
 }
 
 static void