Make textbuttons() work for transparent text boxes

Misa asked me if this should only work for non-transparent textboxes,
and it shouldn't - that was kind of an oversight.

To make it work for transparent textboxes as well, I made a little
restructuring to avoid duplicating the code - fill_buttons() is now
called textbox_line(), and it replaces the direct accessing of the
textbox lines in the printing loops. The code that checks the width
of the textbox does not need to be copied, since the text box is
naturally not drawn for transparent text boxes.

desktop_version/src/Graphics.cpp

@@ -765,8 +765,23 @@ void Graphics::drawtile3( int x, int y, int t, int off, int height_subtract /*=
     draw_texture_part(grphx.im_tiles3, x, y, x2, y2, 8, 8 - height_subtract, 1, 1);
 }
 
-static void fill_buttons(char* buffer, const size_t buffer_len, const char* line)
+const char* Graphics::textbox_line(
+    char* buffer,
+    const size_t buffer_len,
+    const size_t textbox_i,
+    const size_t line_i
+) {
+    /* Gets a line in a textbox, accounting for filling button placeholders like {b_map}.
+     * Takes a buffer as an argument, but DOESN'T ALWAYS write to that buffer.
+     * Always use the return value! ^^
+     * Does not check boundaries. */
+
+    const char* line = textboxes[textbox_i].lines[line_i].c_str();
+    if (!textboxes[textbox_i].fill_buttons)
     {
+        return line;
+    }
+
     vformat_buf(buffer, buffer_len,
         line,
         "b_act:but,"
@@ -780,6 +795,7 @@ static void fill_buttons(char* buffer, const size_t buffer_len, const char* line
         vformat_button(ActionSet_InGame, Action_InGame_Restart),
         vformat_button(ActionSet_InGame, Action_InGame_Esc)
     );
+    return buffer;
 }
 
 void Graphics::drawgui(void)
@@ -787,7 +803,6 @@ void Graphics::drawgui(void)
     int text_sign;
     int crew_yp;
     int crew_sprite;
-    size_t i;
 
     if (flipmode)
     {
@@ -803,7 +818,7 @@ void Graphics::drawgui(void)
     }
 
     //Draw all the textboxes to the screen
-    for (i = 0; i<textboxes.size(); i++)
+    for (size_t i = 0; i<textboxes.size(); i++)
     {
         int text_yoff;
         int yp;
@@ -824,6 +839,8 @@ void Graphics::drawgui(void)
             yp = SCREEN_HEIGHT_PIXELS - yp - 16 - textboxes[i].lines.size() * font_height;
         }
 
+        char buffer[SCREEN_WIDTH_CHARS + 1];
+
         if (textboxes[i].r == 0 && textboxes[i].g == 0 && textboxes[i].b == 0)
         {
             /* To avoid the outlines for different lines overlapping the text itself,
@@ -835,7 +852,7 @@ void Graphics::drawgui(void)
                     textboxes[i].print_flags | PR_CJK_LOW | PR_BOR,
                     textboxes[i].xp + 8,
                     yp + text_yoff + text_sign * (j * font_height),
-                    textboxes[i].lines[j],
+                    textbox_line(buffer, sizeof(buffer), i, j),
                     0, 0, 0
                 );
             }
@@ -845,7 +862,7 @@ void Graphics::drawgui(void)
                     textboxes[i].print_flags | PR_CJK_LOW,
                     textboxes[i].xp + 8,
                     yp + text_yoff + text_sign * (j * font_height),
-                    textboxes[i].lines[j],
+                    textbox_line(buffer, sizeof(buffer), i, j),
                     196, 196, 255 - help.glow
                 );
             }
@@ -864,11 +881,9 @@ void Graphics::drawgui(void)
                 /* If we can fill in buttons, the width of the box may change...
                  * This is Violet's fault. She decided to say a button name out loud. */
                 int max = 0;
-                char buffer[SCREEN_WIDTH_CHARS + 1];
                 for (j = 0; j < textboxes[i].lines.size(); j++)
                 {
-                    fill_buttons(buffer, sizeof(buffer), textboxes[i].lines[j].c_str());
+                    int len = font::len(textboxes[i].print_flags, textbox_line(buffer, sizeof(buffer), i, j));
-                    int len = font::len(textboxes[i].print_flags, buffer);
                     if (len > max)
                     {
                         max = len;
@@ -881,21 +896,11 @@ void Graphics::drawgui(void)
 
             for (j = 0; j < textboxes[i].lines.size(); j++)
             {
-                const char* line = textboxes[i].lines[j].c_str();
-                char buffer[SCREEN_WIDTH_CHARS + 1];
-
-                if (textboxes[i].fill_buttons)
-                {
-                    // Fill button placeholders like {b_map} in dialogue text.
-                    fill_buttons(buffer, sizeof(buffer), line);
-                    line = buffer;
-                }
-
                 font::print(
                     textboxes[i].print_flags | PR_BRIGHTNESS(tl_lerp*255) | PR_CJK_LOW,
                     textboxes[i].xp + 8,
                     yp + text_yoff + text_sign * (j * font_height),
-                    line,
+                    textbox_line(buffer, sizeof(buffer), i, j),
                     textboxes[i].r, textboxes[i].g, textboxes[i].b
                 );
             }

desktop_version/src/Graphics.h

@@ -160,6 +160,7 @@ public:
     void draw_grid_tile(SDL_Texture* texture, int t, int x, int y, int width, int height, SDL_Color color);
 
     void updatetextboxes(void);
+    const char* textbox_line(char* buffer, size_t buffer_len, size_t textbox_i, size_t line_i);
     void drawgui(void);
 
     void draw_sprite(int x, int y, int t, int r, int g, int b);