comparison src/textabbrev.cpp @ 463:3d7070aa959e

Fix extremely slow Text::Abbrev:abbreviate for long texts (was making history scrolling very laggy with long changelogs)

     License, or (at your option) any later version.  See the file
     COPYING included with this distribution for more information.
 */
 
 #include "textabbrev.h"
+#include "debug.h"
 
 #include <QFontMetrics>
 #include <QApplication>
 
 #include <iostream>

                        const QFontMetrics &metrics, int &maxWidth,
                        Policy policy, QString ellipsis, int wrapLines)
 {
     if (ellipsis == "") ellipsis = getDefaultEllipsis();
 
+//    std::cerr << "TextAbbrev::abbreviate: text = " << text << std::endl;
+
     int tw = metrics.width(text);
+    int tl = text.length();
+
+//    std::cerr << "\n*** TextAbbrev::abbreviate: tw = " << tw << "\n***\n" << std::endl;
 
     if (tw <= maxWidth) {
         maxWidth = tw;
         return text;
     }
 
-    int truncated = text.length();
     QString original = text;
 
+    int acw = metrics.averageCharWidth();
+
     if (wrapLines < 2) {
 
-        while (tw > maxWidth && truncated > 1) {
-
-            truncated--;
+//        std::cerr << "only " << wrapLines << " line(s) remaining, going by character..." << std::endl;
+
+        int truncateTo = tl;
+
+        while (tw > maxWidth && truncateTo > 1) {
+
+            if (tw > maxWidth + acw * 10) {
+                float ratio = float(maxWidth) / float(tw);
+                truncateTo = int(truncateTo * ratio * 1.2) + 10;
+                if (truncateTo >= tl) truncateTo = tl - 1;
+            } else {
+                truncateTo--;
+            }
             
-            if (truncated > ellipsis.length()) {
-                text = abbreviateTo(original, truncated, policy, ellipsis);
+//            std::cerr << "truncating from " << tl << " to " << truncateTo << std::endl;
+
+            if (truncateTo > ellipsis.length()) {
+                text = abbreviateTo(original, truncateTo, policy, ellipsis);
             } else {
                 break;
             }
             
             tw = metrics.width(text);
-        }
+            tl = text.length() - ellipsis.length();
+        }
+
+//        std::cerr << "done, final tw = " << tw << std::endl;
         
         maxWidth = tw;
         return text;
 
     } else {

 
         tw = 0;
         int i = 0;
         QString good = "";
         int lastUsed = 0;
+
+//        std::cerr << "have " << wrapLines << " lines remaining, going by word..." << std::endl;
+
         while (tw < maxWidth && i < words.size()) {
             if (text != "") text += " ";
             text += words[i++];
             tw = metrics.width(text);
             if (tw < maxWidth) {
                 good = text;
                 lastUsed = i;
             }
         }
+
+//        std::cerr << "done" << std::endl;
             
         if (tw < maxWidth) {
             maxWidth = tw;
             return text;
         }