再开新贴讨论，mdejtod 或其他熟悉Gdi+的进，解决后一起结贴给分！

孤独的行者牛 2011-12-10 09:09:51

前两贴地址：
http://topic.csdn.net/u/20111118/07/da4a9390-82df-4c23-88fc-90193b9e330b.html
(已结)
http://topic.csdn.net/u/20111129/21/2f3a8d3c-def9-4427-a505-7ccd6fbde2de.html
(未结)

一段时间没搞它了
再翻出来，我找到问题了，再次求教！

当按件被其他窗体或滚动到不可见区域，再次出现时，Windows自动发出WM_Paint消息！
这时候就有问题了！
若仅是有部分被挡住，重绘的时候，未被挡住的部分，也会再绘制一次，这样就造成同一个控件两部分不一样
（因为和透明渐变，所以效果不一样了！）
求教：
怎么样让它在重绘之前，清除其内容呢？或者说恢复控件未被重绘时的状态呢？

期待 mdejtod 再次出现……

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孤独的行者牛 2011-12-11

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网上找了好多资料，难道要自己处理 WM_ERASEBKGND 消息？？？？？
关键怎么处理呢……

孤独的行者牛 2011-12-11

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[Quote=引用 3 楼 delphiteacher 的回复:]

几点想法：
出现楼主的情况是因为滚动条滚动之后没有重绘客户区所导致,
……
[/Quote]

问题就在这里，现在是肯定重绘了，但是连有效区域也重绘了，相当于有效区域绘制了两次，不知道朋友还能不能理解我出的问题噢 …………

PS:若只重绘部分的话，因为实际绘制的比上面的效果图复杂，而且是一个渐变，所以若去度算重区域，是比较麻烦

孤独的行者牛 2011-12-11

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上面的贴图很明了，对比一下

左边的是正常绘制的

右边的，下半部分正常，因为下半部分，被滚到不可见的地方后，再滚动出来,这样，整个控件会重绘，下半部是无效域，重绘后正常！但上半部分，实际上被绘制了两次，造成效果异常！

所以，问题在于，在重绘时（WM_Paint消息处理中），怎么样强制清除原来的效果……

再次感谢……

DelphiTeacher 2011-12-10

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几点想法：
出现楼主的情况是因为滚动条滚动之后没有重绘客户区所导致,
一可能是楼主从没编写过控件，
还有一个可能是楼主没有看过TScrollBox及其父类TScrollingWinControl的代码，懒所导致，
楼主的控件在三种情况下需要重绘，一个拖动过大小，还有就是垂直和水平滚动条滚动之后，
需要在三个消息的事件处理中进行手动重绘，WM_SIZE,WM_HSCROLL,WM_WSCROLL这三个消息

我贴的最后一份是加入了双缓冲的，提高绘制效率的

DelphiTeacher 2011-12-10

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unit SkinScrollBox;



interface



uses

  Windows,SysUtils,Classes,Controls,Forms,GdiPlus,Messages,Graphics,Types;





type

  TSkinScrollBox=class(TScrollBox)

  private

    FBufferBitmap:TBitmap;

  protected

    procedure WMEraseBkGnd(var Message:TWMEraseBkGnd);message WM_ERASEBKGND;

    procedure WMHScroll(var Message: TWMHScroll); message WM_HSCROLL;

    procedure WMVScroll(var Message: TWMVScroll); message WM_VSCROLL;

    procedure WMPaint(var Message: TWMPaint); message WM_PAINT;

    procedure PaintWindow(DC: HDC); override;

    procedure WMSize(var Message: TWMSize); message WM_SIZE;

  public

    constructor Create(AOwner:TComponent);override;

    destructor Destroy;override;

  published

    property Align;

    property Anchors;

    property AutoScroll;

    property AutoSize;

    property BevelEdges;

    property BevelInner;

    property BevelOuter;

    property BevelKind;

    property BevelWidth;

    property BiDiMode;

    property BorderStyle;

    property Constraints;

    property DockSite;

    property DoubleBuffered;

    property DragCursor;

    property DragKind;

    property DragMode;

    property Enabled;

    property Color;

    property Ctl3D;

    property Font;

    property Padding;

    property ParentBiDiMode;

    property ParentBackground default False;

    property ParentColor;

    property ParentCtl3D;

    property ParentDoubleBuffered;

    property ParentFont;

    property ParentShowHint;

    property PopupMenu;

    property ShowHint;

    property TabOrder;

    property TabStop;

    property Touch;

    property Visible;

    property OnCanResize;

    property OnClick;

    property OnConstrainedResize;

    property OnContextPopup;

    property OnDblClick;

    property OnDockDrop;

    property OnDockOver;

    property OnDragDrop;

    property OnDragOver;

    property OnEndDock;

    property OnEndDrag;

    property OnEnter;

    property OnExit;

    property OnGesture;

    property OnGetSiteInfo;

    property OnMouseActivate;

    property OnMouseDown;

    property OnMouseEnter;

    property OnMouseLeave;

    property OnMouseMove;

    property OnMouseUp;

    property OnMouseWheel;

    property OnMouseWheelDown;

    property OnMouseWheelUp;

    property OnResize;

    property OnStartDock;

    property OnStartDrag;

    property OnUnDock;

  end;



procedure Register;



implementation



procedure Register;

begin

  RegisterComponents('SkinEngine',[TSkinScrollBox]);

end;



{ TSkinScrollBox }



constructor TSkinScrollBox.Create(AOwner: TComponent);

begin

  inherited;

  FBufferBitmap:=TBitmap.Create;

end;



destructor TSkinScrollBox.Destroy;

begin

  FBufferBitmap.Free;

  inherited;

end;



procedure TSkinScrollBox.PaintWindow(DC: HDC);

var

  Brush:IGpLinearGradientBrush;

  Graphics:IGPGraphics;

  ClientWidth,ClientHeight:Integer;

  GPRect:TGPRect;

begin

  if (Height=0) or (Width=0) then Exit;

  ClientWidth:=RectWidth(ClientRect);

  ClientHeight:=RectHeight(ClientRect);

  if (ClientHeight<>Self.FBufferBitmap.Height)

    or (ClientWidth<>Self.FBufferBitmap.Width) then

  begin

    Self.FBufferBitmap.SetSize(ClientWidth,ClientHeight);

    Graphics:=TGPGraphics.Create(Self.FBufferBitmap.Canvas.Handle);

    GPRect:=TGPRect.Create(ClientRect);

    Brush:=TGpLinearGradientBrush.Create(GPRect,

              TGPColor.Blue,

              TGPColor.Gray,

              TGPLinearGradientMode.LinearGradientModeVertical);

    Graphics.FillRectangle(Brush,GPRect);

  end;

  BitBlt(DC,0,0,ClientWidth,ClientHeight,

        Self.FBufferBitmap.Canvas.Handle,0,0,SRCCOPY);

end;



procedure TSkinScrollBox.WMEraseBkGnd(var Message: TWMEraseBkGnd);

begin

  Message.Result:=1;

end;



procedure TSkinScrollBox.WMHScroll(var Message: TWMHScroll);

begin

  Inherited;

  Invalidate;

end;



procedure TSkinScrollBox.WMPaint(var Message: TWMPaint);

begin

  ControlState:=ControlState+[csCustomPaint];

  inherited;

  ControlState:=ControlState-[csCustomPaint];

end;



procedure TSkinScrollBox.WMSize(var Message: TWMSize);

begin

  inherited;

  Invalidate;

end;



procedure TSkinScrollBox.WMVScroll(var Message: TWMVScroll);

begin

  Inherited;

  Invalidate;

end;



end.

DelphiTeacher 2011-12-10

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unit SkinScrollBox;

interface

uses
Windows,SysUtils,Classes,Controls,Forms,GdiPlus,Messages;

type
TSkinScrollBox=class(TScrollBox)
protected
procedure WMEraseBkGnd(var Message:TWMEraseBkGnd);message WM_ERASEBKGND;
procedure WMHScroll(var Message: TWMHScroll); message WM_HSCROLL;
procedure WMVScroll(var Message: TWMVScroll); message WM_VSCROLL;
procedure WMPaint(var Message: TWMPaint); message WM_PAINT;
procedure PaintWindow(DC: HDC); override;
procedure WMSize(var Message: TWMSize); message WM_SIZE;
public
constructor Create(AOwner:TComponent);override;
destructor Destroy;override;
published
property Align;
property Anchors;
property AutoScroll;
property AutoSize;
property BevelEdges;
property BevelInner;
property BevelOuter;
property BevelKind;
property BevelWidth;
property BiDiMode;
property BorderStyle;
property Constraints;
property DockSite;
property DoubleBuffered;
property DragCursor;
property DragKind;
property DragMode;
property Enabled;
property Color;
property Ctl3D;
property Font;
property Padding;
property ParentBiDiMode;
property ParentBackground default False;
property ParentColor;
property ParentCtl3D;
property ParentDoubleBuffered;
property ParentFont;
property ParentShowHint;
property PopupMenu;
property ShowHint;
property TabOrder;
property TabStop;
property Touch;
property Visible;
property OnCanResize;
property OnClick;
property OnConstrainedResize;
property OnContextPopup;
property OnDblClick;
property OnDockDrop;
property OnDockOver;
property OnDragDrop;
property OnDragOver;
property OnEndDock;
property OnEndDrag;
property OnEnter;
property OnExit;
property OnGesture;
property OnGetSiteInfo;
property OnMouseActivate;
property OnMouseDown;
property OnMouseEnter;
property OnMouseLeave;
property OnMouseMove;
property OnMouseUp;
property OnMouseWheel;
property OnMouseWheelDown;
property OnMouseWheelUp;
property OnResize;
property OnStartDock;
property OnStartDrag;
property OnUnDock;
end;

procedure Register;

implementation

procedure Register;
begin
RegisterComponents('SkinEngine',[TSkinScrollBox]);
end;

{ TSkinScrollBox }

constructor TSkinScrollBox.Create(AOwner: TComponent);
begin
inherited;

end;

destructor TSkinScrollBox.Destroy;
begin

inherited;
end;

procedure TSkinScrollBox.PaintWindow(DC: HDC);
var
Brush:IGpLinearGradientBrush;
Graphics:IGPGraphics;
begin
Graphics:=TGPGraphics.Create(DC);
Brush:=TGpLinearGradientBrush.Create(TGPRect.Create(ClientRect),
TGPColor.Blue,
TGPColor.Gray,
TGPLinearGradientMode.LinearGradientModeVertical);
Graphics.FillRectangle(Brush,TGPRect.Create(ClientRect));
end;

procedure TSkinScrollBox.WMEraseBkGnd(var Message: TWMEraseBkGnd);
begin
Message.Result:=1;
end;

procedure TSkinScrollBox.WMHScroll(var Message: TWMHScroll);
begin
Inherited;
Invalidate;
end;

procedure TSkinScrollBox.WMPaint(var Message: TWMPaint);
begin
ControlState:=ControlState+[csCustomPaint];
inherited;
ControlState:=ControlState-[csCustomPaint];
end;

procedure TSkinScrollBox.WMSize(var Message: TWMSize);
begin
inherited;
Invalidate;
end;

procedure TSkinScrollBox.WMVScroll(var Message: TWMVScroll);
begin
Inherited;
Invalidate;
end;

end.

DelphiTeacher 2011-12-10