using System; 
using System.Windows.Forms;  
using System.Drawing;
public class Scroll : Panel {
    public delegate void HandlerOI(object o, int arg);  
    public event HandlerOI BaseChangedAnyway, BaseChangedMechanical, BaseChangedByCode; 
    protected void OnBaseChangedAnyway(object o, int i) { 
    } // ==================================================================================== 
    protected void OnBaseChangedMechanical(object o, int i) {
    } // ==================================================================================== 
    protected void OnBaseChangedByCode(object o, int i) {
    } // ==================================================================================== 
    protected override void OnSizeChanged(EventArgs e) {
        if (this.Width < 15) {this.Width=15; }   
        if (this.Height < 15) {this.Height=15; }   
        this._setwhkernel(); 
    } // ==================================================================================== 
    protected override void OnMove(EventArgs e) { 
        base.OnMove(e); 
    } // ==================================================================================== 
    public int getbase() {
        return bas; 
    } // ==================================================================================== 
    public void setbase(double itf) { 
        bas=(int)Math.Floor(itf);  this._setcode();  
    } // ==================================================================================== 
    public void setwhole(double itf) { 
        whole=(int)(itf);  _setcode();   
    } // ==================================================================================== 
    public void setview(double itf) { 
        this.view=(int)itf; this._setcode();  
    } // ==================================================================================== 
    public void setlargeChange(double itf) { 
        this.largechange=(int)itf;  
    } // ==================================================================================== 
    public void setinverse(bool f) {  
        this.inversef=f;   this._setM(); 
    } // ==================================================================================== 
    public void setx(int itf) {
        this.Location = new Point(itf, this.Location.Y); 
    } // ==================================================================================== 
    public void sety(int itf) {
        this.Location = new Point(this.Location.X, itf); 
    } // ====================================================================================  
    public void setw(int itf) {
        this.setwh(itf, this.Height); 
    } // ==================================================================================== 
    public void seth(int itf) {
        this.setwh(this.Width, itf);  
    } // ==================================================================================== 
    // ######################################################################################
    // ################################ public <---> private ################################
    // ######################################################################################    
    private int Q, pwhole, pview;  
    private int bas=0, whole=100, view=0, largechange=10, pbase=0;
    private bool inversef = false; 
    private bool dragging=false; // , nn=typeof(xtf);  
    private int devipivot=0; 
    private Button btfrom = new Button(), btto = new Button(), btM = new Button();  
    public Scroll() {
        this.BackColor = Color.LightGray; 
        Controls.AddRange(new Control[]{ btfrom, btto, btM });
        btfrom.BackColor = btto.BackColor = btM.BackColor = Color.Azure; 
        BaseChangedAnyway += OnBaseChangedAnyway; 
        BaseChangedMechanical += OnBaseChangedMechanical; 
        BaseChangedByCode += OnBaseChangedByCode;  
        this._setwhkernel();  
        this.btfrom.Click += (o,e)=>{ this.bas--;  
            if (this.bas < 0) {this.bas=0; } this._setmechaFTG(); }; 
        this.btto.Click+= (o, e)=>{ this.bas++;  
            if (this.bas > this.whole-this.view) {this.bas=this.whole-this.view; } 
            if (this.bas < 0) {this.bas=0; }  this._setmechaFTG(); };
        this.MouseDown += (o, e) => {
            int pv;  
            if (this.Width > this.Height) {pv = e.X-Q; 
                } else {pv = e.Y-Q; } // temporary 
            if (this.inversef) {pv=this.pwhole-pv; }   
            if (pv > this.pbase) {
                this.bas += this.largechange; 
                if (this.bas > this.whole-this.view) {this.bas=this.whole-this.view; } 
            } else {
                this.bas -= this.largechange; if (this.bas < 0) {this.bas=0; } } 
            this._setmechaFTG(); }; 
        this.btM.MouseDown += (o,edummy)=>{  
            Point e=MousePosition;  
            int xy=e.X;  if (this.Width < this.Height) {xy=e.Y; }  
            if (this.inversef) { this.devipivot=-xy-this.pbase; 
                } else { this.devipivot=xy-this.pbase; }  
            this.dragging=true; }; 
        this.btfrom.MouseMove += (o,e)=>{ screen(e); this._shift(e); }; 
        this.btto.MouseMove += (o,e)=>{ screen(e); this._shift(e); };
        this.MouseMove += (o,e) => { screen(e); this._shift(e); };
        this.btM.MouseMove += (o,e)=>{ screen(e); this._shift(e); };  
        this.btM.MouseUp+= (o,e) => { this._shift(e); }; 
    } // ==================================================================================== 
    private void setwh(int wtf, int htf) { 
        this.Width=wtf; this.Height=htf;   
        if (wtf < 15) {this.Width=15; }   if (htf < 15) {this.Height=15; }  
        this._setwhkernel(); 
    } // ==================================================================================== 
    private void screen(MouseEventArgs e) {
        if (e.Button == MouseButtons.None) { this.dragging=false; } 
    } // ==================================================================================== 
    private void _shift(MouseEventArgs edummy) {
        Point e=MousePosition; 
        if (!this.dragging) { return; } 
        var pv=e.X;  if (this.Width < this.Height) {pv=e.Y; } 
        if (this.inversef) { pv=-pv; } 
        var devipivothere= pv-this.pbase;  this.pbase += devipivothere-this.devipivot; 
        if (this.pbase > this._proomtot()) {this.pbase=this._proomtot(); } 
        if (this.pbase < 0) {this.pbase=0; }
        if (this._proomtot() == 0) { this.bas=0; 
        } else {
            this.bas=this.pbase*(this.whole-this.view)/this._proomtot(); } 
        BaseChangedMechanical(this, this.bas);  BaseChangedAnyway(this, this.bas); 
        this._setM();  
    } // ==================================================================================== 
    private void _setmechaFTG() { 
        if (this.whole-this.view == 0) { this.pbase=0; 
        } else { this.pbase=this.bas*this._proomtot()/(this.whole-this.view); }  
        BaseChangedMechanical(this, bas);  BaseChangedAnyway(this, bas); 
        this._setM(); 
    } // ==================================================================================== 
    private void _setwhkernel() {  
        if (this.Width > this.Height) { 
            this.Q=this.Height;  this.pwhole=this.Width-this.Q-this.Q; 
            Button btL=this.btfrom, btR=this.btto; // temporary !!! 
            if (this.inversef) { btR=this.btfrom; btL=this.btto; }
            btL.SetBounds(0, 0, Q, Q);  
            btR.SetBounds(pwhole+Q, 0, Q, Q);    
            btL.Text="<";  btR.Text=">";  
        } else {   
            this.Q=this.Width;  this.pwhole=this.Height-this.Q-this.Q; 
            Button btT=this.btfrom, btB=this.btto; // temporary !!!  
            if (this.inversef) { btB=this.btfrom; btT=this.btto; } 
            btT.SetBounds(0, 0, Q, Q);  
            btB.SetBounds(0, pwhole+Q, Q, Q);     
            btT.Text="A";  btB.Text="V";   }  
        this._setcode(); 
    } // ==================================================================================== 
    private void _setcode() { 
        if (this.bas > this.whole-this.view) {this.bas=this.whole-this.view; } 
        if (this.bas < 0) {this.bas=0; }
        this.pview = this.pwhole * this.view / this.whole;   
        if (this.pview < 15) {this.pview=15; }  
        if (this.pview > this.pwhole) {this.pview = this.pwhole; } 
        if (this.whole-this.view == 0) { this.pbase=0; 
        } else { this.pbase=this.bas*this._proomtot()/(this.whole-this.view); } 
        BaseChangedByCode(this, this.bas); 
        BaseChangedAnyway(this, this.bas);  
        this._setM(); 
    } // ==================================================================================== 
    private void _setM() {    
        if (this.Width > this.Height) { 
            if (this.inversef) {
                btM.SetBounds(pwhole + Q - pbase - pview, 0, pview, Q); 
            } else {
                btM.SetBounds(Q + pbase, 0, pview, Q); } 
        } else {
            if (this.inversef) {
                btM.SetBounds(0, pwhole + Q - pbase - pview, Q, pview);  
            } else {
                btM.SetBounds(0, Q + pbase, Q, pview); } } 
    } // ==================================================================================== 
    private int _proomtot() { 
        int toret=this.pwhole-this.pview;  if (toret < 0) {toret=0; }  return toret; 
    } // ==================================================================================== 
} // ########################################################################################