From 52915ba4bcb8f82a7d8249df07130e4fc0e5bd32 Mon Sep 17 00:00:00 2001
From: Jeffrey Armstrong <jeff@approximatrix.com>
Date: Mon, 8 Jun 2020 14:36:34 -0400
Subject: Line wrapping now computed only once for proportional text unless
 requested by the renderer, providing better performance.

---
 render.f90 | 122 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 118 insertions(+), 4 deletions(-)

(limited to 'render.f90')

diff --git a/render.f90 b/render.f90
index ff9ed7f..335cbcb 100644
--- a/render.f90
+++ b/render.f90
@@ -27,7 +27,10 @@ implicit none
     integer, parameter::render_action_goto   = 2
     integer, parameter::render_action_layout = 3
     integer, parameter::render_action_back   = 4
-    integer, parameter::render_action_quit   = 5
+    integer, parameter::render_action_rewrap = 5
+    integer, parameter::render_action_quit   = 6
+    
+    integer, parameter::last_break = -1
 
     character(11), dimension(2)::base_supported_types = &
         ["text/plain ", &
@@ -316,16 +319,115 @@ contains
         
     end function wrap_line
     
-    subroutine render_proportional(r, text)
+    function calculate_wrapping(r, text) result(breaks)
+    implicit none
+    
+        class(renderer)::r
+        character(*), intent(in)::text
+        integer, dimension(:), pointer::breaks
+        
+        integer::startpos, endpos
+        integer::heading_level
+        logical::list_item
+        
+        integer::current_allocation
+        integer::break_count
+        integer, dimension(:), pointer::realloc
+        
+        current_allocation = 16
+        break_count = 0
+        allocate(breaks(current_allocation))
+        
+        if(len_trim(text) > 0) then
+            
+            startpos = 1
+            
+            ! Check for headings first
+            heading_level = 0
+            do while(text(startpos:startpos) == '#') 
+                heading_level = heading_level + 1
+                startpos = startpos + 1
+            end do
+            
+            ! Or a list item
+            list_item = .FALSE.
+            if(heading_level == 0) then
+                list_item = (text(1:1) == '*') 
+                if(list_item) then
+                    startpos = startpos + 1
+                end if
+            end if
+            
+            ! If either occurred, advance past whitespace
+            if(heading_level > 0 .or. list_item) then
+                do while(text(startpos:startpos) == ' ' .or. text(startpos:startpos) == char(9))
+                    startpos = startpos + 1
+                end do
+            end if
+            
+            endpos = wrap_line(r, text, startpos, heading_level, list_item)
+            do while(endpos > startpos)
+                
+                ! Save this break
+                break_count = break_count + 1
+                
+                ! Messy memory handling...
+                if(break_count > current_allocation) then
+                    realloc => breaks
+                    breaks => null()
+                    
+                    allocate(breaks(current_allocation + 16))
+                    breaks(1:current_allocation) = realloc
+                    current_allocation = current_allocation + 16
+                    deallocate(realloc)
+                end if
+                
+                ! Now actually save it
+                breaks(break_count) = endpos
+                
+                ! Advance string positions
+                startpos = endpos+1
+                do while(text(startpos:startpos) == ' ')
+                    startpos = startpos + 1
+                end do
+        
+                ! Do not mark as a list item for subsequent lines
+                list_item = .FALSE.
+                endpos = wrap_line(r, text, startpos, heading_level, list_item)
+            end do
+        end if
+        
+        break_count = break_count + 1
+        
+        ! Messy memory handling...
+        if(break_count > current_allocation) then
+            realloc => breaks
+            breaks => null()
+            
+            allocate(breaks(current_allocation + 16))
+            breaks(1:current_allocation) = realloc
+            current_allocation = current_allocation + 16
+            deallocate(realloc)
+        end if
+        
+        ! Save an ending indicator
+        breaks(break_count) = last_break
+    
+    end function calculate_wrapping
+    
+    subroutine render_proportional(r, text, breaks)
     implicit none
     
         class(renderer)::r
         character(*)::text
+        integer, dimension(:)::breaks
         
         integer::startpos, endpos
         integer::heading_level
         logical::list_item
         
+        integer::break_index
+        
         if(len_trim(text) == 0) then 
         
             if(r%is_text_visible(" ")) then
@@ -360,7 +462,12 @@ contains
                 end do
             end if
             
-            endpos = wrap_line(r, text, startpos, heading_level, list_item)
+            break_index = 1
+            endpos = breaks(break_index)
+            if(endpos == last_break) then
+                endpos = len_trim(text)
+            end if
+            
             do while(endpos > startpos)
                 if(r%is_text_visible(text(startpos:endpos))) then
                     call r%draw_porportional(text(startpos:endpos), &
@@ -380,7 +487,14 @@ contains
                 ! Do not mark as a list item for subsequent lines
                 list_item = .FALSE.
                 
-                endpos = wrap_line(r, text, startpos, heading_level, list_item)
+                if(breaks(break_index) /= last_break) then
+                    break_index = break_index + 1
+                    endpos = breaks(break_index)
+                    if(endpos == last_break) then
+                        endpos = len_trim(text)
+                    end if
+                end if
+                
             end do
         end if
     
-- 
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