(svn r23791) -Fix [FS#4960]: resize text panel for parameter description if it doesn't fit in 4 lines.

If you resize the window so it's smaller than default the text might still not fit

src/gfx.cpp

@@ -821,6 +821,36 @@ Dimension GetStringMultiLineBoundingBox(StringID str, const Dimension &suggestio
 	return box;
 }
 
+
+/**
+ * Calculates height of string (in pixels). The string is changed to a multiline string if needed.
+ * @param str string to check
+ * @param maxw maximum string width
+ * @return height of pixels of string when it is drawn
+ */
+int GetStringHeight(const char *str, int maxw)
+{
+	char buffer[DRAW_STRING_BUFFER];
+
+	strecpy(buffer, str, lastof(buffer));
+
+	uint32 tmp = FormatStringLinebreaks(buffer, lastof(buffer), maxw);
+
+	return GetMultilineStringHeight(buffer, GB(tmp, 0, 16), FS_NORMAL);
+}
+
+/**
+ * Calculate string bounding box for multi-line strings.
+ * @param str        String to check.
+ * @param suggestion Suggested bounding box.
+ * @return Bounding box for the multi-line string, may be bigger than \a suggestion.
+ */
+Dimension GetStringMultiLineBoundingBox(const char *str, const Dimension &suggestion)
+{
+	Dimension box = {suggestion.width, GetStringHeight(str, suggestion.width)};
+	return box;
+}
+
 /**
  * Draw string, possibly over multiple lines.
  *

src/gfx_func.h

@@ -125,6 +125,7 @@ Dimension GetStringBoundingBox(StringID strid);
 uint32 FormatStringLinebreaks(char *str, const char *last, int maxw, FontSize start_fontsize = FS_NORMAL);
 int GetStringHeight(StringID str, int maxw);
 Dimension GetStringMultiLineBoundingBox(StringID str, const Dimension &suggestion);
+Dimension GetStringMultiLineBoundingBox(const char *str, const Dimension &suggestion);
 void LoadStringWidthTable(bool monospace = false);
 
 void DrawDirtyBlocks();

src/newgrf_gui.cpp

@@ -211,7 +211,17 @@ struct NewGRFParametersWindow : public Window {
 				break;
 
 			case WID_NP_DESCRIPTION:
-				size->height = max<uint>(size->height, FONT_HEIGHT_NORMAL * 4 + WD_TEXTPANEL_TOP + WD_TEXTPANEL_BOTTOM);
+				/* Minimum size of 4 lines. The 500 is the default size of the window. */
+				Dimension suggestion = {500 - WD_FRAMERECT_LEFT - WD_FRAMERECT_RIGHT, FONT_HEIGHT_NORMAL * 4 + WD_TEXTPANEL_TOP + WD_TEXTPANEL_BOTTOM};
+				for (uint i = 0; i < this->grf_config->param_info.Length(); i++) {
+					const GRFParameterInfo *par_info = this->grf_config->param_info[i];
+					if (par_info == NULL) continue;
+					const char *desc = GetGRFStringFromGRFText(par_info->desc);
+					if (desc == NULL) continue;
+					const Dimension d = GetStringMultiLineBoundingBox(desc, suggestion);
+					suggestion = maxdim(d, suggestion);
+				}
+				size->height = suggestion.height;
 				break;
 		}
 	}