issue 8: Scrollbar not shown in text widgetHEADmaster

Creating a text widget with a string that does not fit into the
allocated width does not show a scrollbar.  The same code when linked to
Xaw3d does show a scrollbar.

Investigation shows this difference came from

    Author: dawes <dawes>
    Date:   Sun Jun 28 12:56:14 1998 +0000

        #1738

and probably was done to improve performance (by eliminating the use of
floating point).

Signed-off-by: Thomas E. Dickey <dickey@invisible-island.net>

1 files changed, 89 insertions, 31 deletions

diff --git a/src/Text.c b/src/Text.c
index 14cf0c3..0f7e831 100644
--- a/src/Text.c
+++ b/src/Text.c
@@ -1476,6 +1476,58 @@ GetWidestLine(TextWidget ctx)
     return (widest);
 }
 
+static void
+CheckVBarScrolling(TextWidget ctx)
+{
+  float first, last;
+  Boolean temp = (ctx->text.vbar == NULL);
+
+  if (ctx->text.scroll_vert == XawtextScrollNever) return;
+
+  if ( (ctx->text.lastPos > 0) && (ctx->text.lt.lines > 0)) {
+    first = (float) ctx->text.lt.top;
+    first /= (float) ctx->text.lastPos;
+    last = (float) ctx->text.lt.info[ctx->text.lt.lines].position;
+    if ( ctx->text.lt.info[ctx->text.lt.lines].position < ctx->text.lastPos )
+      last /= (float) ctx->text.lastPos;
+    else
+      last = 1.0;
+
+    if (ctx->text.scroll_vert == XawtextScrollWhenNeeded) {
+      int line;
+      XawTextPosition last_pos;
+      Position y = (Position) (ctx->core.height - ctx->text.margin.bottom);
+
+      if (ctx->text.hbar != NULL)
+	y -= (Position) (ctx->text.hbar->core.height +
+	      2 * ctx->text.hbar->core.border_width);
+
+      last_pos = PositionForXY(ctx, (Position) ctx->core.width, y);
+      line = LineForPosition(ctx, last_pos);
+
+      if ( (y < ctx->text.lt.info[line + 1].y) || ((last - first) < 1.0) )
+	CreateVScrollBar(ctx);
+      else
+	DestroyVScrollBar(ctx);
+    }
+
+    if (ctx->text.vbar != NULL)
+      XawScrollbarSetThumb(ctx->text.vbar, first, last - first);
+
+    if ( (ctx->text.vbar == NULL) != temp) {
+      _XawTextNeedsUpdating(ctx, zeroPosition, ctx->text.lastPos);
+      if (ctx->text.vbar == NULL)
+	_XawTextBuildLineTable (ctx, zeroPosition, FALSE);
+    }
+  }
+  else if (ctx->text.vbar != NULL) {
+    if (ctx->text.scroll_vert == XawtextScrollWhenNeeded)
+      DestroyVScrollBar(ctx);
+    else if (ctx->text.scroll_vert == XawtextScrollAlways)
+      XawScrollbarSetThumb(ctx->text.vbar, 0.0, 1.0);
+  }
+}
+
 /*
  * This routine is used by Text to notify an associated scrollbar of the
  * correct metrics (position and shown fraction) for the text being currently
@@ -1484,40 +1536,46 @@ GetWidestLine(TextWidget ctx)
 void
 _XawTextSetScrollBars(TextWidget ctx)
 {
-    float first;
-
-    if (ctx->text.scroll_vert == XawtextScrollAlways) {
-	float last;
-
-	if (ctx->text.lastPos == 0)
-	    first = 0.0;
-	else
-	    first = (float)ctx->text.lt.top / (float)ctx->text.lastPos;
-
-	if (ctx->text.lt.info[ctx->text.lt.lines].position < ctx->text.lastPos)
-	    last = (float)ctx->text.lt.info[ctx->text.lt.lines].position /
-		   (float)ctx->text.lastPos;
-	else
-	    last = 1.0;
-
-	XawScrollbarSetThumb(ctx->text.vbar, first, last - first);
-    }
+  float first, last, widest;
+  Boolean temp = (ctx->text.hbar == NULL);
+  Boolean vtemp = (ctx->text.vbar == NULL);
+
+  CheckVBarScrolling(ctx);
+
+  if (ctx->text.scroll_horiz == XawtextScrollNever) return;
+
+  if (ctx->text.vbar != NULL)
+    widest = (float)(int)(ctx->core.width - ctx->text.vbar->core.width);
+  else
+    widest = (float) (ctx->core.width);
+  widest /= (last = GetWidestLine(ctx));
+  if (ctx->text.scroll_horiz == XawtextScrollWhenNeeded) {
+    if (widest < 1.0)
+      CreateHScrollBar(ctx);
+    else
+      DestroyHScrollBar(ctx);
+  }
 
-    if (ctx->text.scroll_horiz == XawtextScrollAlways) {
-	unsigned value = GetWidestLine(ctx);
-	float denom = (float)value;
-	float widest;
+  if ( (ctx->text.hbar == NULL) != temp ) {
+    _XawTextBuildLineTable (ctx, ctx->text.lt.top, TRUE);
+    CheckVBarScrolling(ctx);	/* Recheck need for vbar, now that we added
+				   or removed the hbar.*/
+  }
 
-	if (denom <= 0)
-	    denom = (float)((int)XtWidth(ctx) - RHMargins(ctx));
-	if (denom <= 0)
-	    denom = 1;
-	widest = (float)((int)XtWidth(ctx) - RHMargins(ctx)) / denom;
-	first = (float)(ctx->text.r_margin.left - ctx->text.left_margin);
-	first /= denom;
+  if (ctx->text.hbar != NULL) {
+    first = ctx->text.r_margin.left - ctx->text.margin.left;
+    first /= last;
+    XawScrollbarSetThumb(ctx->text.hbar, first, widest);
+  }
 
-	XawScrollbarSetThumb(ctx->text.hbar, first, widest);
-    }
+  if (((ctx->text.hbar == NULL) && (ctx->text.margin.left !=
+				   ctx->text.r_margin.left)) ||
+      (ctx->text.vbar == NULL) != vtemp)
+  {
+    ctx->text.margin.left = ctx->text.r_margin.left;
+    _XawTextNeedsUpdating(ctx, zeroPosition, ctx->text.lastPos);
+    FlushUpdate(ctx);
+  }
 }
 
 static void