如何使用矩陣和滾動條翻譯偏移量以繪製

Question

我正在使用Matrix在OnPaint期間在我的Graphics對象上設置轉換。我希望滾動條在滾動時翻譯矩陣;這樣的事情在OnScroll：

float offset = se.NewValue - se.OldValue; 

if (offset == 0) 
{ 
    return; 
} 

if (se.ScrollOrientation == ScrollOrientation.HorizontalScroll) 
{ 
    this.TransformMatrix.Translate(-offset, 0); 
} 
else 
{ 
    this.TransformMatrix.Translate(0, -offset); 
} 

我敢肯定，這兩個WM_VSCROLL和WM_HSCROLL發送WM_PAINT因爲重繪控件沒有我實際調用Refresh()。我發現這幅畫不是很流暢，而且很緊張，並沒有畫出正確的轉變。我應該攔截WM_V/HSCROLL消息和手動設置滾動條的屬性（如位置等）SetScrollInfo？如果不是，我該怎麼辦？

Answer 1

我最終抓到了WM_V/HSROLL並自己做了這幅畫。它很棒！

下面是我使用的是什麼，如果有人想它：

protected override CreateParams CreateParams 
    { 
     get 
     { 
      var p = base.CreateParams; 
      p.Style |= NativeMethods.WindowStyles.WS_BORDER; 
      p.Style |= NativeMethods.WindowStyles.WS_HSCROLL; 
      p.Style |= NativeMethods.WindowStyles.WS_VSCROLL; 

      return p; 
     } 
    } 

    private Point ScrollPosition 
    { 
     get 
     { 
      var info = new NativeMethods.ScrollInfo(); 
      info.cbSize = (uint)Marshal.SizeOf(info); 
      info.fMask = NativeMethods.ScrollInfoMask.SIF_POS; 

      NativeMethods.GetScrollInfo(this.Handle, NativeMethods.SBFlags.SB_HORZ, out info); 
      int x = info.nPos; 

      NativeMethods.GetScrollInfo(this.Handle, NativeMethods.SBFlags.SB_VERT, out info); 
      int y = info.nPos; 

      return new Point(x, y); 
     } 
     set 
     { 
      var info = new NativeMethods.ScrollInfo(); 
      info.cbSize = (uint)Marshal.SizeOf(info); 
      info.fMask = NativeMethods.ScrollInfoMask.SIF_POS; 
      info.nPos = value.X; 
      NativeMethods.SetScrollInfo(this.Handle, NativeMethods.SBFlags.SB_HORZ, ref info, true); 

      info.nPos = value.Y; 
      NativeMethods.SetScrollInfo(this.Handle, NativeMethods.SBFlags.SB_VERT, ref info, true); 
     } 
    } 

    protected override void OnPaint(PaintEventArgs e) 
    { 
     // Clear the background color. 
     e.Graphics.Clear(Color.White); 

     e.Graphics.Transform = this.TransformMatrix.Clone(); 

     // Do drawing here. 
    } 

    protected override void OnPaintBackground(PaintEventArgs e) 
    { 
     // Do nothing. 
    } 

    private void OnScroll(ScrollEventArgs se) 
    { 

     float offset = se.NewValue - se.OldValue; 

     if (se.ScrollOrientation == ScrollOrientation.HorizontalScroll) 
     { 
      this.TransformMatrix.Translate(-offset, 0); 
     } 
     else 
     { 
      this.TransformMatrix.Translate(0, -offset); 
     } 

     this.Refresh(); 

    } 

    protected override void WndProc(ref Message m) 
    { 
     switch (m.Msg) 
     { 
      case NativeMethods.WindowMessages.WM_HSCROLL: 
      case NativeMethods.WindowMessages.WM_VSCROLL: 
       this.WmScroll(ref m); 
       m.Result = IntPtr.Zero; 
       break; 

      default: 
       base.WndProc(ref m); 
       break; 
     } 
    } 

    private void WmScroll(ref Message m) 
    { 

     int smallChange = 20; 

     uint sb = NativeMethods.SBFlags.SB_HORZ; 
     var orientation = ScrollOrientation.HorizontalScroll; 

     if(m.Msg == NativeMethods.WindowMessages.WM_VSCROLL) 
     { 
      sb = NativeMethods.SBFlags.SB_VERT; 
      orientation = ScrollOrientation.VerticalScroll; 
     } 

     // Get current scroll Page and Range. 
     var info = new NativeMethods.ScrollInfo(); 
     info.cbSize = (uint)Marshal.SizeOf(info); 
     info.fMask = NativeMethods.ScrollInfoMask.SIF_PAGE | NativeMethods.ScrollInfoMask.SIF_POS; 
     NativeMethods.GetScrollInfo(this.Handle, sb, out info); 

     int newValue = info.nPos; 
     var type = ScrollEventType.SmallDecrement; 

     switch (Unmanaged.LoWord(m.WParam)) 
     { 
      case NativeMethods.SBCommands.SB_BOTTOM: 
       type = ScrollEventType.Last; 
       break; 

      case NativeMethods.SBCommands.SB_ENDSCROLL: 
       type = ScrollEventType.EndScroll; 
       break; 

      case NativeMethods.SBCommands.SB_LINEDOWN: 
       newValue += smallChange; 
       type = ScrollEventType.SmallIncrement; 
       break; 

      case NativeMethods.SBCommands.SB_LINEUP: 
       newValue -= smallChange; 
       type = ScrollEventType.SmallDecrement; 
       break; 

      case NativeMethods.SBCommands.SB_PAGEDOWN: 
       newValue += (int)info.nPage; 
       type = ScrollEventType.LargeIncrement; 
       break; 

      case NativeMethods.SBCommands.SB_PAGEUP: 
       newValue -= (int)info.nPage; 
       type = ScrollEventType.LargeDecrement; 
       break; 

      case NativeMethods.SBCommands.SB_THUMBPOSITION: 
       type = ScrollEventType.ThumbPosition; 
       break; 

      case NativeMethods.SBCommands.SB_THUMBTRACK: 
       newValue = Unmanaged.HiWord(m.WParam); 
       type = ScrollEventType.ThumbTrack; 
       break; 

      case NativeMethods.SBCommands.SB_TOP: 
       type = ScrollEventType.First; 
       break; 
     } 

     var newInfo = new NativeMethods.ScrollInfo(); 
     newInfo.cbSize = (uint)Marshal.SizeOf(newInfo); 
     newInfo.fMask = NativeMethods.ScrollInfoMask.SIF_POS; 
     newInfo.nPos = newValue; 

     NativeMethods.SetScrollInfo(this.Handle, sb, ref newInfo, false); 

     int realNewValue = (orientation == ScrollOrientation.HorizontalScroll) ? this.ScrollPosition.X : this.ScrollPosition.Y; 

     // Fire the scroll event. 
     // TODO - Create a Scroll event. 
     this.OnScroll(new ScrollEventArgs(type, info.nPos, realNewValue, orientation)); 
    }