Delphi的Hint(2)
上一篇介绍了Hint的简单应用,这一篇将给出一个定制Hint窗口的例子。这个自定义Hint窗口的效果不错,以玻璃为边框,并且有阴影的效果。 不过这之前,我们必须介绍一个如何定制,Hint的父类为THintWindow,在Controls单元中定义。我们看看几个虚拟方法,CreateParams设定窗口的风格,我们要覆盖掉它,使其没有边框。NCPaint画窗口的边框,我们也要覆盖它,因为我们不需要边框吗。Paint比较重要,为画Hint窗口客户区内容,当然要覆盖。不过最重要的当属ActivateHint,它会设定好窗口的大小,并显示它,我们就在这里定制一个类玻璃的窗口效果。下面给出该类的实现: unit wdHintWnd; interface uses Windows, Classes, Controls, Graphics, Forms, SysUtils, ExtCtrls; type TwdHintWnd = class(THintWindow) private FWndBmp: TBitmap; //窗口位图 FHintBmp: TBitmap; //提示信息位图 protected procedure CreateParams(var Params: TCreateParams); override; procedure Paint; override; procedure NCPaint(DC: HDC); override; {画提示的图象} procedure DrawHintImg(Bmp:TBitmap; AHint: string); {取得提示窗口对应的桌面区域的图象} procedure GetDesktopImg(Bmp: TBitmap; R: TRect); {对桌面区域图象作处理,使其看起来像一块玻璃且带有一点阴影} procedure EffectHandle(WndBmp, HintBmp: TBitmap); public constructor Create(Aowner: TComponent); override; destructor Destroy; override; procedure ActivateHint(Rect: TRect; const AHint: string); override; end; implementation { TwdHintWnd } procedure TwdHintWnd.ActivateHint(Rect: TRect; const AHint: string); var P: TPoint; begin //在这里取得一个适当的尺寸显示文字 FHintBmp.Width := Rect.Right - Rect.Left; FHintBmp.Height := Rect.Bottom - Rect.Top + 4; DrawHintImg(FHintBmp, AHint); FWndBmp.Width := Rect.Right - Rect.Left + 23; FWndBmp.Height := Rect.Bottom - Rect.Top + 27; Inc(Rect.Right, 23); Inc(Rect.Bottom, 27); BoundsRect := Rect; if Left < Screen.DesktopLeft then Left := Screen.DesktopLeft; if Top < Screen.DesktopTop then Top := Screen.DesktopTop; if Left + Width > Screen.DesktopWidth then Left := Screen.DesktopWidth - Width; if Top + Height > Screen.DesktopHeight then Top := Screen.DesktopHeight - Height; GetDesktopImg(FWndBmp, BoundsRect); EffectHandle(FWndBmp, FHintBmp); P := ClientToScreen(Point(0, 0)); SetWindowPos(Handle, HWND_TOPMOST, P.X, P.Y, 0, 0, SWP_SHOWWINDOW or SWP_NOACTIVATE or SWP_NOSIZE); end; constructor TwdHintWnd.Create(Aowner: TComponent); begin inherited; FWndBmp := TBitmap.Create; FWndBmp.PixelFormat := pf24bit; FHintBmp := TBitmap.Create; end; procedure TwdHintWnd.CreateParams(var Params: TCreateParams); begin inherited; //去掉窗口边框 Params.Style := Params.Style and not WS_BORDER; end; destructor TwdHintWnd.Destroy; begin FWndBmp.Free; FHintBmp.Free; inherited; end; procedure TwdHintWnd.GetDesktopImg(Bmp: TBitmap; R: TRect); var C: TCanvas; begin C:= TCanvas.Create; try C.Handle := GetDC(0); Bmp.Canvas.CopyRect(Rect(0, 0, Bmp.Width, Bmp.Height), C, R); finally C.Free; end; end; procedure TwdHintWnd.EffectHandle(WndBmp, HintBmp: TBitmap); var R: TRect; i, j: Integer; P: PByteArray; Transt, TranstAngle: Integer; begin R := Rect(0, 0, WndBmp.Width - 4, WndBmp.Height - 4); Frame3D(WndBmp.Canvas, R, clMedGray, clBtnShadow, 1); //作窗口底下的阴影效果 Transt := 60; for j:= WndBmp.Height - 4 to WndBmp.Height - 1 do begin P := WndBmp.ScanLine[j]; TranstAngle := Transt; for i:= 3 to WndBmp.Width - 1 do begin //如果正处于右下角 if i > WndBmp.Width - 5 then begin P[3*i] := P[3*i] * TranstAngle div 100; P[3*i + 1] := P[3*i + 1] * TranstAngle div 100; P[3*i + 2] := P[3*i + 2] * TranstAngle div 100; TranstAngle := TranstAngle + 10; if TranstAngle > 90 then TranstAngle := 90; end else begin P[3*i] := P[3*i] * Transt div 100; P[3*i + 1] := P[3*i + 1] * Transt div 100; P[3*i + 2] := P[3*i + 2] * Transt div 100; end; end; Transt := Transt + 10; end; //作窗口右边的阴影效果 for j := 3 to WndBmp.Height - 5 do begin P := WndBmp.ScanLine[j]; Transt := 60; for i:= WndBmp.Width - 4 to WndBmp.Width -1 do begin P[3*i] := P[3*i] * Transt div 100; P[3*i + 1] := P[3*i + 1] * Transt div 100; P[3*i + 2] := P[3*i + 2] * Transt div 100; Transt := Transt + 10; end; end; WndBmp.Canvas.Draw(10, 10, HintBmp); end; procedure TwdHintWnd.NCPaint; begin //重载不让画边框 end; procedure TwdHintWnd.Paint; begin Canvas.CopyRect(ClientRect, FWndBmp.Canvas, ClientRect); end; procedure TwdHintWnd.DrawHintImg(Bmp: TBitmap; AHint: string); var R: TRect; begin Bmp.Canvas.Brush.Color := Application.HintColor; Bmp.Canvas.Pen.Color := Application.HintColor; Bmp.Canvas.Rectangle(0, 0, Bmp.Width, Bmp.Height); Bmp.Canvas.Font.Color := Screen.HintFont.Color; R := Rect(0, 0, Bmp.Width, Bmp.Height); Inc(R.Left, 2); Inc(R.Top, 2); DrawText(Bmp.Canvas.Handle, PChar(AHint), -1, R, DT_LEFT or DT_NOPREFIX or DT_WORDBREAK or DrawTextBiDiModeFlagsReadingOnly); end; initialization Application.ShowHint := False; HintWindowClass := TwdHintWnd; Application.ShowHint := True; end. 只需将该单元加入你的工程当中,然后运行程序,便可看到效果了,试试看,漂亮吧。 程序中重要部分已经作了注释,这里只说明几个重要的地方,首先是initialization 部分,这里将Application的ShowHint设为False,看一下VCL源码,知道Application将一个HintWindow给消毁了,而HintWindowClass定义如下: THintWindowClass = class of THintWindow;它是THintWindow的类引用,在Forms单元中它初始化为THintWindow: HintWindowClass: THintWindowClass = THintWindow; 在这里我们将其替换为TwdHintWnd,最后将ShowHint设为True,Application便用HintWindowClass创建一个Hint窗口,此时创建的便是我们定制的类了,以后的提示窗口就将用我们上面的窗口来显示。 在ActivateHint方法,我们将作效果的处理,原理是取得提示窗口在桌面上的位置对应的位图,然后画到提示窗口上,再将提示信息的位置拷贝到提示窗口中间,这样就有了透明的效果了。其次画出玻璃的边,最后在窗口右边和下边作阴影效果。 关于阴影效果的实现,用到的是图像的Alpha技术,可以到网上找一找,这里就不多说了,只给出图像透明度的公式: Dst.Red = Src.Red * alpha + (1-alpha) * Dst.Red; Dst.Green = Src.Green * alpha + (1-alpha) * Dst.Green; Dst.Blue = Src.Blue * alpha + (1-alpha) * Dst.Blue; Alpha的值为0到1之间,为1时表示完全不透明,不过我们将用于混合的颜色为黑色,即0,所以上面代码看到的是如下的样子: P[3*i] := P[3*i] * TranstAngle div 100; 玻璃提示窗口的原理大概如此,当然其透明效果是一个假象,遇到后有动的物体就暴露无疑了。不过作为一个提示窗口,我想已经足够了。