Reduce memory usage by cleaning up text not visible on the screen

As a text, memory usage decreased from 150mb to 20mb

2 files changed, 85 insertions, 71 deletions

diff --git a/src/Body.cpp b/src/Body.cpp
index 812840d..08ef690 100644
--- a/src/Body.cpp
+++ b/src/Body.cpp
@@ -23,7 +23,8 @@ namespace QuickMedia {
         thumbnail_is_local(false),
         title_color(sf::Color::White),
         author_color(sf::Color::White),
-        userdata(nullptr)
+        userdata(nullptr),
+        last_drawn_time(0)
     {
         if(!_title.empty())
             set_title(std::move(_title));
@@ -58,6 +59,7 @@ namespace QuickMedia {
         title_color = other.title_color;
         author_color = other.author_color;
         userdata = other.userdata;
+        last_drawn_time = other.last_drawn_time;
     }
 
     Body::Body(Program *program, sf::Font *font, sf::Font *bold_font, sf::Font *cjk_font) :
@@ -279,6 +281,8 @@ namespace QuickMedia {
         sf::Vector2f scissor_size = size;
         const float start_y = pos.y;
 
+        const sf::Int32 elapsed_time = draw_timer.getElapsedTime().asMilliseconds();
+
         if(thumbnail_resize_target_size.x != 0 && thumbnail_resize_target_size.y != 0) {
             image_max_height = thumbnail_resize_target_size.y;
         }
@@ -294,11 +298,9 @@ namespace QuickMedia {
 
         int num_items = items.size();
         if(num_items == 0 || size.y <= 0.0f) {
-            for(auto it = item_thumbnail_textures.begin(); it != item_thumbnail_textures.end();) {
-                if(!it->second->referenced)
-                    it = item_thumbnail_textures.erase(it);
-                else
-                    ++it;
+            item_thumbnail_textures.clear();
+            for(auto &body_item : items) {
+                clear_body_item_cache(body_item.get());
             }
             return;
         }
@@ -307,41 +309,6 @@ namespace QuickMedia {
             thumbnail_it.second->referenced = false;
         }
 
-        for(auto &body_item : items) {
-            if(body_item->dirty) {
-                body_item->dirty = false;
-                // TODO: Find a way to optimize fromUtf8
-                sf::String str = sf::String::fromUtf8(body_item->get_title().data(), body_item->get_title().data() + body_item->get_title().size());
-                if(body_item->title_text)
-                    body_item->title_text->setString(std::move(str));
-                else
-                    body_item->title_text = std::make_unique<Text>(std::move(str), font, cjk_font, 16, size.x - 50 - image_padding_x * 2.0f);
-                body_item->title_text->setFillColor(body_item->title_color);
-                body_item->title_text->updateGeometry();
-            }
-
-            if(body_item->dirty_description) {
-                body_item->dirty_description = false;
-                sf::String str = sf::String::fromUtf8(body_item->get_description().data(), body_item->get_description().data() + body_item->get_description().size());
-                if(body_item->description_text)
-                    body_item->description_text->setString(std::move(str));
-                else
-                    body_item->description_text = std::make_unique<Text>(std::move(str), font, cjk_font, 14, size.x - 50 - image_padding_x * 2.0f);
-                body_item->description_text->updateGeometry();
-            }
-
-            if(body_item->dirty_author) {
-                body_item->dirty_author = false;
-                sf::String str = sf::String::fromUtf8(body_item->get_author().data(), body_item->get_author().data() + body_item->get_author().size());
-                if(body_item->author_text)
-                    body_item->author_text->setString(std::move(str));
-                else
-                    body_item->author_text = std::make_unique<Text>(std::move(str), bold_font, cjk_font, 14, size.x - 50 - image_padding_x * 2.0f);
-                body_item->author_text->setFillColor(body_item->author_color);
-                body_item->author_text->updateGeometry();
-            }
-        }
-
         if(prev_selected_item < 0 || prev_selected_item >= (int)items.size()) {
             prev_selected_item = selected_item;
         }
@@ -384,8 +351,6 @@ namespace QuickMedia {
         pos.y += page_scroll;
 
         sf::Vector2u window_size = window.getSize();
-        glEnable(GL_SCISSOR_TEST);
-        glScissor(scissor_pos.x, (int)window_size.y - (int)scissor_pos.y - (int)scissor_size.y, scissor_size.x, scissor_size.y);
 
         sf::Vector2f prev_pos = pos;
         for(int i = selected_item - 1; i >= 0; --i) {
@@ -395,13 +360,20 @@ namespace QuickMedia {
             if(!item->visible)
                 continue;
 
+            update_dirty_state(item.get(), size);
+
             float item_height = get_item_height(item.get());
             prev_pos.y -= (item_height + spacing_y);
 
             if(prev_pos.y + item_height + spacing_y < start_y)
                 break;
 
+            item->last_drawn_time = elapsed_time;
+            // This is needed here rather than above the loop, since update_dirty_text cant be called inside scissor because it corrupts the text for some reason
+            glEnable(GL_SCISSOR_TEST);
+            glScissor(scissor_pos.x, (int)window_size.y - (int)scissor_pos.y - (int)scissor_size.y, scissor_size.x, scissor_size.y);
             draw_item(window, item.get(), prev_pos, size, item_height, i, content_progress);
+            glDisable(GL_SCISSOR_TEST);
             ++num_visible_items;
         }
 
@@ -413,6 +385,8 @@ namespace QuickMedia {
             if(!item->visible)
                 continue;
 
+            update_dirty_state(item.get(), size);
+
             float item_height = get_item_height(item.get());
 
             if((after_pos.y - start_y) + item_height + spacing_y > size.y)
@@ -423,7 +397,12 @@ namespace QuickMedia {
             if(after_pos.y - start_y >= size.y)
                 break;
 
+            item->last_drawn_time = elapsed_time;
+            // This is needed here rather than above the loop, since update_dirty_text cant be called inside scissor because it corrupts the text for some reason
+            glEnable(GL_SCISSOR_TEST);
+            glScissor(scissor_pos.x, (int)window_size.y - (int)scissor_pos.y - (int)scissor_size.y, scissor_size.x, scissor_size.y);
             draw_item(window, item.get(), after_pos, size, item_height, i, content_progress);
+            glDisable(GL_SCISSOR_TEST);
             after_pos.y += item_height + spacing_y;
             ++num_visible_items;
         }
@@ -431,17 +410,76 @@ namespace QuickMedia {
         if(last_fully_visible_item == -1)
             last_fully_visible_item = selected_item;
 
-        glDisable(GL_SCISSOR_TEST);
-
         for(auto it = item_thumbnail_textures.begin(); it != item_thumbnail_textures.end();) {
             if(!it->second->referenced)
                 it = item_thumbnail_textures.erase(it);
             else
                 ++it;
         }
+
+        // TODO: Only do this for items that are not visible, do not loop all items.
+        // TODO: Verify if this only runs for items that are not visible, and only once
+        // TODO: Improve performance! right now it can use up to 5-7% cpu with a lot of items!
+        for(auto &body_item : items) {
+            if(elapsed_time - body_item->last_drawn_time >= 1500) {
+                clear_body_item_cache(body_item.get());
+            }
+        }
+    }
+
+    void Body::update_dirty_state(BodyItem *body_item, sf::Vector2f size) {
+        if(body_item->dirty) {
+            body_item->dirty = false;
+            // TODO: Find a way to optimize fromUtf8
+            sf::String str = sf::String::fromUtf8(body_item->get_title().data(), body_item->get_title().data() + body_item->get_title().size());
+            if(body_item->title_text)
+                body_item->title_text->setString(std::move(str));
+            else
+                body_item->title_text = std::make_unique<Text>(std::move(str), font, cjk_font, 16, size.x - 50 - image_padding_x * 2.0f);
+            body_item->title_text->setFillColor(body_item->title_color);
+            body_item->title_text->updateGeometry();
+        }
+
+        if(body_item->dirty_description) {
+            body_item->dirty_description = false;
+            sf::String str = sf::String::fromUtf8(body_item->get_description().data(), body_item->get_description().data() + body_item->get_description().size());
+            if(body_item->description_text)
+                body_item->description_text->setString(std::move(str));
+            else
+                body_item->description_text = std::make_unique<Text>(std::move(str), font, cjk_font, 14, size.x - 50 - image_padding_x * 2.0f);
+            body_item->description_text->updateGeometry();
+        }
+
+        if(body_item->dirty_author) {
+            body_item->dirty_author = false;
+            sf::String str = sf::String::fromUtf8(body_item->get_author().data(), body_item->get_author().data() + body_item->get_author().size());
+            if(body_item->author_text)
+                body_item->author_text->setString(std::move(str));
+            else
+                body_item->author_text = std::make_unique<Text>(std::move(str), bold_font, cjk_font, 14, size.x - 50 - image_padding_x * 2.0f);
+            body_item->author_text->setFillColor(body_item->author_color);
+            body_item->author_text->updateGeometry();
+        }
+    }
+
+    void Body::clear_body_item_cache(BodyItem *body_item) {
+        if(body_item->title_text) {
+            body_item->title_text.reset();
+            body_item->dirty = true;
+        }
+        if(body_item->description_text) {
+            body_item->description_text.reset();
+            body_item->dirty_description = true;
+        }
+        if(body_item->author_text) {
+            body_item->author_text.reset();
+            body_item->dirty_author = true;
+        }
     }
 
     void Body::draw_item(sf::RenderWindow &window, BodyItem *item, sf::Vector2f pos, sf::Vector2f size) {
+        update_dirty_state(item, size);
+        item->last_drawn_time = draw_timer.getElapsedTime().asMilliseconds();
         sf::Vector2u window_size = window.getSize();
         glEnable(GL_SCISSOR_TEST);
         glScissor(pos.x, (int)window_size.y - (int)pos.y - (int)size.y, size.x, size.y);
@@ -574,10 +612,10 @@ namespace QuickMedia {
 
     float Body::get_item_height(BodyItem *item) {
         float item_height = 0.0f;
-        if(!item->get_title().empty()) {
+        if(item->title_text) {
             item_height += item->title_text->getHeight() - 2.0f;
         }
-        if(!item->get_author().empty()) {
+        if(item->author_text) {
             item_height += item->author_text->getHeight() - 2.0f;
         }
         if(item->description_text) {
diff --git a/src/Text.cpp b/src/Text.cpp
index 2165037..e311f14 100644
--- a/src/Text.cpp
+++ b/src/Text.cpp
@@ -37,7 +37,6 @@ namespace QuickMedia
         dirtyText(false),
         dirtyCaret(false),
         editable(false),
-        visible(true),
         caretMoveDirection(CaretMoveDirection::NONE),
         lineSpacing(0.0f),
         characterSpacing(0.0f),
@@ -707,32 +706,10 @@ namespace QuickMedia
         }
         
         sf::Vector2f pos = position;
-        
-        // TODO: Do not use maxWidth here. Max width might be set to 99999 and actual text width might be 200. Text width should be calculated instead
-        //sf::FloatRect targetRect(0.0f, 0.0f, maxWidth, target.getSize().y);
-        //sf::FloatRect textRect(pos.x, pos.y, maxWidth, )
-        //colRect.contains()
-        //if(pos.x + maxWidth <= 0.0f || pos.x >= maxWidth || pos.y + totalHeight <= 0.0f || pos.y >= target.getSize().y) return;
-        renderTargetSize = target.getSize();
-        if(pos.y + getHeight() <= 0.0f || pos.y >= renderTargetSize.y)
-        {
-            if(!editable && visible && lastSeenTimer.getElapsedTime().asMilliseconds() > 3000)
-            {
-                visible = false;
-                vertices[0].resize(0);
-                vertices[1].resize(0);
-            }
-            return false;
-        }
 
         const float vspace = font->getLineSpacing(characterSize);
         pos.y += floor(vspace); // Origin is at bottom left, we want it to be at top left
         
-        if(!visible) {
-            visible = true;
-            updateGeometry(true);
-        }
-        
         const sf::Font *fonts[] = { font, cjk_font };
         for(size_t i = 0; i < 2; ++i) {
             sf::RenderStates states;
@@ -740,7 +717,6 @@ namespace QuickMedia
             states.texture = &fonts[i]->getTexture(characterSize);
             target.draw(vertices[i], states);
         }
-        lastSeenTimer.restart();
         
         if(!editable) return true;
         pos.y -= floor(vspace * 2.0f);