ClassiCube/ClassicalSharp/2D/Screens/Inventory/InventoryScreen.Scrolling.cs

// ClassicalSharp copyright 2014-2016 UnknownShadow200 | Licensed under MIT
using System;
using System.Drawing;
using OpenTK.Input;

namespace ClassicalSharp.Gui {
	
	public partial class InventoryScreen : Screen {
		
		const int scrollbarWidth = 10;
		static FastColour scrollCol = new FastColour( 10, 10, 10, 220 );
		static FastColour scrollUsedCol = new FastColour( 100, 100, 100, 220 );
		float ScrollbarScale { get { return TableHeight / (float)rows; } }
		
		void DrawScrollbar() {
			api.Draw2DQuad( TableX - scrollbarWidth, TableY, scrollbarWidth, TableHeight, scrollCol );
			int y, height;
			GetScrollbarCoords( out y, out height );
			api.Draw2DQuad( TableX - scrollbarWidth, TableY + y, scrollbarWidth, height, scrollUsedCol );
		}
		
		void GetScrollbarCoords( out int y, out int height ) {
			float scale = ScrollbarScale;
			y = (int)Math.Ceiling( scrollY * scale );
			height = (int)Math.Ceiling( maxRows * scale );
			height = Math.Min(y + height, TableHeight) - y;
		}
		
		public override bool HandlesMouseScroll( int delta ) {
			bool bounds = Contains( TableX - scrollbarWidth, TableY, TableWidth + scrollbarWidth, 
			                       TableHeight, game.Mouse.X, game.Mouse.Y );
			bool hotbar = game.IsKeyDown( Key.AltLeft ) || game.IsKeyDown( Key.AltRight );
			if( !bounds || hotbar ) return false;
			
			int rowY = (selIndex / blocksPerRow) - scrollY;
			scrollY -= delta;
			ClampScrollY();
			if( selIndex == - 1 ) return true;
			
			selIndex = scrollY * blocksPerRow + (selIndex % blocksPerRow);
			for( int row = 0; row < rowY; row++ ) {
				selIndex += blocksPerRow;
			}
			
			if( selIndex >= blocksTable.Length )
				selIndex = -1;			
			RecreateBlockInfoTexture();
			return true;
		}
		int scrollY;
		
		void ClampScrollY() {
			if( scrollY >= rows - maxRows ) scrollY = rows - maxRows;
			if( scrollY < 0 ) scrollY = 0;
		}
		
		void ScrollbarClick( int mouseY ) {
			mouseY -= TableY;
			int y, height;
			GetScrollbarCoords( out y, out height );
			
			if( mouseY < y ) {
				scrollY -= maxRows;
			} else if( mouseY >= y + height ) {
				scrollY += maxRows;
			} else {
				draggingMouse = true;
				mouseOffset = mouseY - y;
			}
			ClampScrollY();
		}
		
		bool draggingMouse = false;
		int mouseOffset = 0;
		
		public override bool HandlesMouseUp( int mouseX, int mouseY, MouseButton button ) {
			draggingMouse = false;
			mouseOffset = 0;
			return true;
		}
	}
}