multiline textbox mode

src/frontend/gui/controls.h

@@ -31,7 +31,12 @@ namespace gui {
         bool multiline = false;
 
         // runtime values
+        
+        /// @brief Text Y offset relative to label position
+        /// (last calculated alignment)
         int textYOffset = 0;
+
+        /// @brief Text line height multiplied by line interval
         int totalLineHeight = 1;
     public:
         Label(std::string text, std::string fontName="normal");
@@ -43,15 +48,39 @@ namespace gui {
         virtual void setFontName(std::string name);
         virtual const std::string& getFontName() const;
 
+        /// @brief Set text vertical alignment (default value: center)
+        /// @param align Align::top / Align::center / Align::bottom
         virtual void setVerticalAlign(Align align);
         virtual Align getVerticalAlign() const;
 
+        /// @brief Get line height multiplier used for multiline labels 
+        /// (default value: 1.5)
         virtual float getLineInterval() const;
+
+        /// @brief Set line height multiplier used for multiline labels
         virtual void setLineInterval(float interval);
 
+        /// @brief Get Y position of the text relative to label position
+        /// @return Y offset
         virtual int getTextYOffset() const;
+
+        /// @brief Get Y position of the line relative to label position
+        /// @param line target line index
+        /// @return Y offset
         virtual int getLineYOffset(uint line) const;
 
+        /// @brief Get position of line start in the text
+        /// @param line target line index
+        /// @return position in the text [0..length]
+        virtual size_t getTextLineOffset(uint line) const;
+
+        /// @brief Get line index by its Y offset relative to label position
+        /// @param offset target Y offset
+        /// @return line index [0..+]
+        virtual uint getLineByYOffset(int offset) const;
+        virtual uint getLineByTextIndex(size_t index) const;
+        virtual uint getLinesNumber() const;
+
         virtual void draw(const GfxContext* pctx, Assets* assets) override;
 
         virtual void textSupplier(wstringsupplier supplier);
@@ -133,8 +162,11 @@ namespace gui {
         bool valid = true;
         /// @brief text input pointer, value may be greather than text length
         uint caret = 0;
+        /// @brief actual local (line) position of the caret on vertical move
+        uint maxLocalCaret = 0;
         uint textOffset = 0;
         int textInitX;
+        /// @brief last time of the caret was moved (used for blink animation)
         double caretLastMove = 0.0;
         Font* font = nullptr;
 
@@ -146,13 +178,20 @@ namespace gui {
 
         size_t normalizeIndex(int index);
 
-        int calcIndexAt(int x) const;
+        int calcIndexAt(int x, int y) const;
         void paste(const std::wstring& text);
         void setTextOffset(uint x);
         void erase(size_t start, size_t length);
         bool eraseSelected();
         void resetSelection();
         void extendSelection(int index);
+        size_t getLineLength(uint line) const;
+
+        /// @brief Get total length of the selection 
+        size_t getSelectionLength() const;
+
+        /// @brief Set maxLocalCaret to local (line) caret position
+        void resetMaxLocalCaret();
     public:
         TextBox(std::wstring placeholder, 
                 glm::vec4 padding=glm::vec4(4.0f));