Improve label alignment docs and border case implementations.

Make clear that some alignment bit combinations are "illegal" and yield
undefined behavior that can be changed without notice.

Fix label alignment in some border cases where illegal bit combinations like
FL_ALIGN_LEFT and FL_ALIGN_RIGHT or FL_ALIGN_TOP and FL_ALIGN_BOTTOM are
both set, respectively.

Todo: There appears to be inconsistent handling WRT these "illegal" cases,
for instance with inside labels as opposed to outside labels, such that
the behavior seems to be unpredictable. See test/label.cxx.


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12181 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

FL/Enumerations.H

@@ -766,7 +766,7 @@ extern Fl_Labeltype FL_EXPORT fl_define_FL_EMBOSSED_LABEL();
 
     Flags can be or'd to achieve a combination of alignments, but there
     are some "magic values" (e.g. combinations of TOP and BOTTOM and of
-    LEFT and RIGHT) that have special meanings (see below). For instance:<BR>
+    LEFT and RIGHT) that have special meanings (see below). For instance:\n
     FL_ALIGN_TOP_LEFT == (FL_ALIGN_TOP|FL_ALIGN_LEFT) != FL_ALIGN_LEFT_TOP.
 
     \code
@@ -793,50 +793,95 @@ extern Fl_Labeltype FL_EXPORT fl_define_FL_EMBOSSED_LABEL();
                +---------------------------------+
     \endcode
     \see #FL_ALIGN_CENTER, etc.
+
+    \note
+      -# Bit positions not defined in the following constants of type
+	 \p Fl_Align are reserved for future extensions. Do not use.
+      -# The \e "magic" values (FL_ALIGN_)LEFT_TOP, RIGHT_TOP, LEFT_BOTTOM,
+	 and RIGHT_BOTTOM must not be used together with FL_ALIGN_INSIDE.
+	 Use TOP_LEFT, TOP_RIGHT, BOTTOM_LEFT, or BOTTOM_RIGHT instead.
+      -# Although bits can be or'd together there are some unused/illegal
+	 combinations, for instance:
+	- setting both FL_ALIGN_TOP and FL_ALIGN_BOTTOM in combinations other
+	  than those given in the \p Fl_Align constants below (magic values)
+	- setting both FL_ALIGN_LEFT and FL_ALIGN_RIGHT in combinations other
+	  than those given in the \p Fl_Align constants below (magic values)
+    \note
+      Using illegal bit combinations or undefined bits may yield unexpected
+      behavior, and this behavior may be changed in future FLTK versions
+      without notice.
  */
 /*@{*/
-/** FLTK type for alignment control */
+/** FLTK type for alignment control. */
 typedef unsigned Fl_Align;
+
   /** Align the label horizontally in the middle. */
-const Fl_Align FL_ALIGN_CENTER		= (Fl_Align)0;
+const Fl_Align FL_ALIGN_CENTER		= 0x0000;
+
   /** Align the label at the top of the widget. Inside labels appear below the top,
       outside labels are drawn on top of the widget. */
-const Fl_Align FL_ALIGN_TOP		= (Fl_Align)1;
+const Fl_Align FL_ALIGN_TOP		= 0x0001;
+
   /** Align the label at the bottom of the widget. */
-const Fl_Align FL_ALIGN_BOTTOM		= (Fl_Align)2;
+const Fl_Align FL_ALIGN_BOTTOM		= 0x0002;
+
   /** Align the label at the left of the widget. Inside labels appear left-justified
       starting at the left side of the widget, outside labels are right-justified and
       drawn to the left of the widget. */
-const Fl_Align FL_ALIGN_LEFT		= (Fl_Align)4;
+const Fl_Align FL_ALIGN_LEFT		= 0x0004;
+
   /** Align the label to the right of the widget. */
-const Fl_Align FL_ALIGN_RIGHT		= (Fl_Align)8;
+const Fl_Align FL_ALIGN_RIGHT		= 0x0008;
+
   /** Draw the label inside of the widget. */
-const Fl_Align FL_ALIGN_INSIDE		= (Fl_Align)16;
+const Fl_Align FL_ALIGN_INSIDE		= 0x0010;
+
   /** If the label contains an image, draw the text on top of the image. */
-const Fl_Align FL_ALIGN_TEXT_OVER_IMAGE	= (Fl_Align)0x0020;
+const Fl_Align FL_ALIGN_TEXT_OVER_IMAGE	= 0x0020;
+
   /** If the label contains an image, draw the text below the image. */
-const Fl_Align FL_ALIGN_IMAGE_OVER_TEXT	= (Fl_Align)0x0000;
-  /** All parts of the label that are lager than the widget will not be drawn . */
-const Fl_Align FL_ALIGN_CLIP		= (Fl_Align)64;
+const Fl_Align FL_ALIGN_IMAGE_OVER_TEXT	= 0x0000;
+
+  /** All parts of the label that are larger than the widget will not be drawn. */
+const Fl_Align FL_ALIGN_CLIP		= 0x0040;
+
   /** Wrap text that does not fit the width of the widget. */
-const Fl_Align FL_ALIGN_WRAP		= (Fl_Align)128;
+const Fl_Align FL_ALIGN_WRAP		= 0x0080;
+
   /** If the label contains an image, draw the text to the right of the image. */
-const Fl_Align FL_ALIGN_IMAGE_NEXT_TO_TEXT = (Fl_Align)0x0100;
+const Fl_Align FL_ALIGN_IMAGE_NEXT_TO_TEXT = 0x0100;
+
   /** If the label contains an image, draw the text to the left of the image. */
-const Fl_Align FL_ALIGN_TEXT_NEXT_TO_IMAGE = (Fl_Align)0x0120;
+const Fl_Align FL_ALIGN_TEXT_NEXT_TO_IMAGE = 0x0120;
+
 /** If the label contains an image, draw the image or deimage in the background. */
-const Fl_Align FL_ALIGN_IMAGE_BACKDROP  = (Fl_Align)0x0200;
+const Fl_Align FL_ALIGN_IMAGE_BACKDROP  = 0x0200;
+
 const Fl_Align FL_ALIGN_TOP_LEFT	= FL_ALIGN_TOP | FL_ALIGN_LEFT;
 const Fl_Align FL_ALIGN_TOP_RIGHT	= FL_ALIGN_TOP | FL_ALIGN_RIGHT;
 const Fl_Align FL_ALIGN_BOTTOM_LEFT	= FL_ALIGN_BOTTOM | FL_ALIGN_LEFT;
 const Fl_Align FL_ALIGN_BOTTOM_RIGHT	= FL_ALIGN_BOTTOM | FL_ALIGN_RIGHT;
-const Fl_Align FL_ALIGN_LEFT_TOP	= 0x0007; // magic value
-const Fl_Align FL_ALIGN_RIGHT_TOP	= 0x000b; // magic value
-const Fl_Align FL_ALIGN_LEFT_BOTTOM	= 0x000d; // magic value
-const Fl_Align FL_ALIGN_RIGHT_BOTTOM	= 0x000e; // magic value
-const Fl_Align FL_ALIGN_NOWRAP		= (Fl_Align)0; // for back compatibility
-const Fl_Align FL_ALIGN_POSITION_MASK   = 0x000f; // left, right, top, bottom
-const Fl_Align FL_ALIGN_IMAGE_MASK      = 0x0320; // l/r, t/b, backdrop
+
+/** Outside only, left of widget, top position, magic value: TOP | BOTTOM | LEFT. */
+const Fl_Align FL_ALIGN_LEFT_TOP	= 0x0007;
+
+/** Outside only, right of widget, top position, magic value: TOP | BOTTOM | RIGHT. */
+const Fl_Align FL_ALIGN_RIGHT_TOP	= 0x000b;
+
+/** Outside only, left of widget, bottom position, magic value: TOP | LEFT | RIGHT. */
+const Fl_Align FL_ALIGN_LEFT_BOTTOM	= 0x000d;
+
+/** Outside only, right of widget, bottom position, magic value: BOTTOM | LEFT | RIGHT. */
+const Fl_Align FL_ALIGN_RIGHT_BOTTOM	= 0x000e;
+
+/** Nothing, same as FL_ALIGN_CENTER, for back compatibility. */
+const Fl_Align FL_ALIGN_NOWRAP		= 0x0000;
+
+/** Mask value to test for TOP, BOTTOM, LEFT, and RIGHT flags. */
+const Fl_Align FL_ALIGN_POSITION_MASK   = 0x000f;
+
+/** Mask value to test for image alignment flags. */
+const Fl_Align FL_ALIGN_IMAGE_MASK      = 0x0320;
 /*@}*/
 
 

src/Fl_Group.cxx

@@ -793,36 +793,40 @@ void Fl_Group::draw_outside_label(const Fl_Widget& widget) const {
   } else {
     wx = x(); wy = y();
   }
-  if ( (a & 0x0f) == FL_ALIGN_LEFT_TOP ) {
-    a = (a &~0x0f ) | FL_ALIGN_TOP_RIGHT;
+  if ( (a & FL_ALIGN_POSITION_MASK) == FL_ALIGN_LEFT_TOP ) {
+    a = (a &(~FL_ALIGN_POSITION_MASK) ) | FL_ALIGN_TOP_RIGHT;
     X = wx;
     W = widget.x()-X-3;
-  } else if ( (a & 0x0f) == FL_ALIGN_LEFT_BOTTOM ) {
-    a = (a &~0x0f ) | FL_ALIGN_BOTTOM_RIGHT; 
+  } else if ( (a & FL_ALIGN_POSITION_MASK) == FL_ALIGN_LEFT_BOTTOM ) {
+    a = (a &(~FL_ALIGN_POSITION_MASK) ) | FL_ALIGN_BOTTOM_RIGHT;
     X = wx;
     W = widget.x()-X-3;
-  } else if ( (a & 0x0f) == FL_ALIGN_RIGHT_TOP ) {
-    a = (a &~0x0f ) | FL_ALIGN_TOP_LEFT; 
+  } else if ( (a & FL_ALIGN_POSITION_MASK) == FL_ALIGN_RIGHT_TOP ) {
+    a = (a &(~FL_ALIGN_POSITION_MASK) ) | FL_ALIGN_TOP_LEFT;
     X = X+W+3;
     W = wx+this->w()-X;
-  } else if ( (a & 0x0f) == FL_ALIGN_RIGHT_BOTTOM ) {
-    a = (a &~0x0f ) | FL_ALIGN_BOTTOM_LEFT; 
+  } else if ( (a & FL_ALIGN_POSITION_MASK) == FL_ALIGN_RIGHT_BOTTOM ) {
+    a = (a &(~FL_ALIGN_POSITION_MASK) ) | FL_ALIGN_BOTTOM_LEFT;
     X = X+W+3;
     W = wx+this->w()-X;
   } else if (a & FL_ALIGN_TOP) {
-    a ^= (FL_ALIGN_BOTTOM|FL_ALIGN_TOP);
+    a ^= FL_ALIGN_TOP;
+    a |= FL_ALIGN_BOTTOM;
     Y = wy;
     H = widget.y()-Y;
   } else if (a & FL_ALIGN_BOTTOM) {
-    a ^= (FL_ALIGN_BOTTOM|FL_ALIGN_TOP);
+    a ^= FL_ALIGN_BOTTOM;
+    a |= FL_ALIGN_TOP;
     Y = Y+H;
     H = wy+h()-Y;
   } else if (a & FL_ALIGN_LEFT) {
-    a ^= (FL_ALIGN_LEFT|FL_ALIGN_RIGHT);
+    a ^= FL_ALIGN_LEFT;
+    a |= FL_ALIGN_RIGHT;
     X = wx;
     W = widget.x()-X-3;
   } else if (a & FL_ALIGN_RIGHT) {
-    a ^= (FL_ALIGN_LEFT|FL_ALIGN_RIGHT);
+    a ^= FL_ALIGN_RIGHT;
+    a |= FL_ALIGN_LEFT;
     X = X+W+3;
     W = wx+this->w()-X;
   }

src/fl_labeltype.cxx

@@ -42,8 +42,16 @@ fl_normal_measure(const Fl_Label* o, int& W, int& H) {
   fl_font(o->font, o->size);
   fl_measure(o->value, W, H);
   if (o->image) {
-    if (o->image->w() > W) W = o->image->w();
-    H += o->image->h();
+    int iw = o->image->w(), ih = o->image->h();
+    if (o->align_ & FL_ALIGN_IMAGE_BACKDROP) {		// backdrop: ignore
+      // ignore backdrop image for calculation
+    } else if (o->align_ & FL_ALIGN_IMAGE_NEXT_TO_TEXT) { // text and image side by side
+      W += iw;
+      if (ih > H) H = ih;
+    } else {
+      if (iw > W) W = iw;
+      H += ih;
+    }
   }
 }