Delphi 如何在将screen对象句柄设置为DrawFocusRect时消除屏幕闪烁
我正试图在我多年前开发的“理解屏幕捕获”组件中,围绕选定的屏幕对象绘制一个聚焦矩形。我可以通过使用句柄获取光标下对象的句柄来DrawFocusRect:=WindowFromPoint(P);但这要求我先隐藏,然后展示自我,让它发挥作用,否则自我的句柄就会返回 不幸的是,当我隐藏和显示窗体时,它会在窗体被隐藏和显示时导致闪烁 我可以毫无问题地获得所选对象的位图,只需绘制所选对象就让我抓狂 有没有人建议在选定的对象周围绘制一个FocusedRect,这样就不会闪烁?如果窗体位于屏幕上,是否有API来获取屏幕句柄 我尝试使用句柄:=WindowFromDC(ScreenDC),因此我不必隐藏和显示表单,但WindowFromDC仍然返回表单而不是屏幕 TCaptureObjectForm是透明的,位于屏幕上。我需要组件中的TCaptureObjectForm //FormMouseMove事件-于2011年8月2日添加Delphi 如何在将screen对象句柄设置为DrawFocusRect时消除屏幕闪烁,delphi,Delphi,我正试图在我多年前开发的“理解屏幕捕获”组件中,围绕选定的屏幕对象绘制一个聚焦矩形。我可以通过使用句柄获取光标下对象的句柄来DrawFocusRect:=WindowFromPoint(P);但这要求我先隐藏,然后展示自我,让它发挥作用,否则自我的句柄就会返回 不幸的是,当我隐藏和显示窗体时,它会在窗体被隐藏和显示时导致闪烁 我可以毫无问题地获得所选对象的位图,只需绘制所选对象就让我抓狂 有没有人建议在选定的对象周围绘制一个FocusedRect,这样就不会闪烁?如果窗体位于屏幕上,是否有API
procedure TCaptureObjectForm.FormMouseMove( Sender: TObject; Shift: TShiftState; X, Y: Integer );
const
crHand = -18;
var
P: TPoint;
Handles: HWND;
Rect: TRect;
ScreenDC: HDC;
begin
// hide the TCaptureObjectForm form so the screen is found by WindowFromPoint
Self.Hide;
// get the object on the screen
GetCursorPos( P );
Handles := WindowFromPoint( P );
// tried this but it returns self.handle rather than the screen handle
//ScreenDC := GetDC( 0 );
//Handles := WindowFromDC(ScreenDC);
//ReleaseDC( 0, ScreenDC );
// restore the TCaptureObjectForm
Self.Show;
// get object rect
GetWindowRect( Handles, Rect );
// draw a rect to show it is focused
Self.Canvas.DrawFocusRect( Rect );
end;
我用这个
procedure TForm1.FormCreate(Sender: TObject);
begin
Form1.DoubleBuffered:=True;
end;
是Microsoft Visual Basic中的一个示例,它所做的工作与您所需要的非常相似
他们采取以下方法:
形式捕获鼠标\u MouseDown
Form\u MouseMove
窗体中释放鼠标,并使整个屏幕无效,以擦除最后绘制的矩形
//不是全局变量,而是私有形式变量
变量
HwndLastTracked:HWND;
CapturedMouse:布尔值;
过程跟踪程序(HWND窗口:HWND);
变量
rc:TRect;
dc:HDC;
钢笔,旧钢笔:HPEN;
老布什:HBRUSH;
风格,exStyle:长型;
cx,cy:整数;
开始
GetWindowRect(hwndWindow,rc);
//窗口原点(左上角)的窗口坐标为(0,0)
偏置(rc,-rc.左,-rc.上);
//GetWindowDC返回的DC覆盖整个窗口区域,但在Windows中
//Vista/7由于以下原因,它似乎被剪裁为不包括非客户端区域
//DWM处理非客户端绘图,因此不允许在其上进行绘制。
//因此,我们需要跳过这个非客户端区域,这就是我调整
//窗口rect以匹配客户端区域。使用GetClientRect而不是
//GetWindowRect不适用于排除滚动条和子对象
//用WM_NCPAINT绘制的部件,如Windows的WS_Exeges和Delphi的
//斜面。
样式:=GetWindowLong(hwndWindow,GWL_样式);
exStyle:=GetWindowLong(hwndWindow,GWL_exStyle);
如果样式和WS_标题为0,则开始
如果exStyle和WS_EX_工具窗口为0,则
cy:=GetSystemMetrics(SM_CYSMCAPTION)
其他的
cy:=GetSystemMetrics(SM_CYCAPTION);
//丢弃标题所覆盖的区域
股份有限公司(位于西西里州的rc.Top);
结束;
如果样式和宽度为0,则开始
cx:=GetSystemMetrics(SM_CXFRAME);
cy:=GetSystemMetrics(SM_CYFRAME);
结束
否则,如果样式和WS_DLGFRAME 0,则开始
cx:=GetSystemMetrics(SM_CXDLGFRAME);
cy:=GetSystemMetrics(SM_CYDLGFRAME);
结束
否则,如果样式和WS_边框为0,则开始
cx:=GetSystemMetrics(SM_CXBORDER);
cy:=GetSystemMetrics(SM_CYBORDER);
结束
否则开始
cx:=0;
cy:=0;
结束;
如果是(cx 0)或(cy 0),则开始
//丢弃边界覆盖的区域
偏置(rc、cx、cy);
12月(右区,cx*2);
12月(钢筋混凝土底部,cy*2);
结束;
//Windows API函数不会引发异常,所以我不使用try finally
dc:=GetWindowDC(hwndWindow);
//选项1:聚焦矩形
//DrawFocusRect(dc、rc);
//选项2:倒厚边框
SetROP2(dc,R2_非);
pen:=CreatePen(PS_INSIDEFRAME,3*GetSystemMetrics(SM_CXBORDER),0);
oldPen:=选择对象(dc,笔);
oldBrush:=SelectObject(dc,GetStockObject(NULL_笔刷));
矩形(dc,rc.左,rc.上,rc.右,rc.下);
选择对象(dc、oldBrush);
选择对象(dc、oldPen);
删除对象(笔);
//结束方案2
释放dc(hwndWindow,dc);
结束;
步骤t用于m1.FormMouseDown(发送方:ToObject;按钮:TMouseButton;
移位:t移位状态;X,Y:整数);
开始
如果SetCapture(句柄)为0,则开始
CapturedMouse:=真;
HwndLastTracked:=0;
屏幕光标:=crCross;
结束;
结束;
过程TForm1.FormMouseMove(发送方:TObject;移位:TShiftState;
十、 Y:整数);
变量
HWND:HWND;
开始
如果是CapturedMouse,则开始
hwndCaptured:=WindowFromPoint(客户端到屏幕(点(X,Y));
//取消注释此跟踪根窗口而不是子窗口
//hwndCaptured:=GetSencenter(hwndCaptured,GA_根);
如果hwndCaptured HwndLastTracked,则开始
如果HWNDLAST0,则
逆变器跟踪器(HwndLastTracked);
反转跟踪器(HWNDF);
HwndLastTracked:=hwndCaptured;
结束;
结束;
结束;
程序TForm1.FormMouseUp(发送方:TObject;按钮:TMouseButton;
移位:t移位状态;X,Y:整数);
开始
如果是CapturedMouse,则开始
释放捕获;
CapturedMouse:=假;
如果为0,则开始
逆变器跟踪器(HwndLastTracked);
HwndLastTracked:=0;
结束;
Screen.Cursor:=crDefault;
结束;
结束;
下面是微软如何在VisualStudio的Spy++中使用此技术的屏幕截图。红色气球和文字是我的
我将DoubleBuffered设置为true后,闪烁的次数减少了很多,但FocusedRect当然仍然闪烁。有更好的方法吗?对不起,我没有其他想法……也许大卫·赫弗南对这个问题的回答可以帮助你。这样做的缺点是它会阻止某些组件正确渲染
// Not global variables, but private form ones
var
HwndLastTracked: HWND;
CapturedMouse: boolean;
procedure InvertTracker(hwndWindow: HWND);
var
rc: TRect;
dc: HDC;
pen, oldPen: HPEN;
oldBrush: HBRUSH;
style, exStyle: longint;
cx, cy: integer;
begin
GetWindowRect(hwndWindow, rc);
// Window coordinates of the origin (top-left corner) of a window is (0, 0)
OffsetRect(rc, -rc.Left, -rc.Top);
// DC returned by GetWindowDC covers the full window area, but in Windows
// Vista/7 it seems to be clipped excluding the nonclient region, due to
// DWM handling nonclient drawing, so it doesn't allow painting over it.
// Thus we need to skip this nonclient area and that is why I adjust the
// window rect to match the client area. Using GetClientRect instead of
// GetWindowRect is not suitable as excludes scroll bars and child
// parts drawed in WM_NCPAINT, such as Windows' WS_EXEDGEs and Delphi's
// bevels.
style := GetWindowLong(hwndWindow, GWL_STYLE);
exStyle := GetWindowLong(hwndWindow, GWL_EXSTYLE);
if style and WS_CAPTION <> 0 then begin
if exStyle and WS_EX_TOOLWINDOW <> 0 then
cy := GetSystemMetrics(SM_CYSMCAPTION)
else
cy := GetSystemMetrics(SM_CYCAPTION);
// discard area covered by caption
Inc(rc.Top, cy);
end;
if style and WS_THICKFRAME <> 0 then begin
cx := GetSystemMetrics(SM_CXFRAME);
cy := GetSystemMetrics(SM_CYFRAME);
end
else if style and WS_DLGFRAME <> 0 then begin
cx := GetSystemMetrics(SM_CXDLGFRAME);
cy := GetSystemMetrics(SM_CYDLGFRAME);
end
else if style and WS_BORDER <> 0 then begin
cx := GetSystemMetrics(SM_CXBORDER);
cy := GetSystemMetrics(SM_CYBORDER);
end
else begin
cx := 0;
cy := 0;
end;
if (cx <> 0) or (cy <> 0) then begin
// discard area covered by borders
OffsetRect(rc, cx, cy);
Dec(rc.Right, cx*2);
Dec(rc.Bottom, cy*2);
end;
// Windows API functions don't raise exceptions, so I don't use try-finally
dc := GetWindowDC(hwndWindow);
// Option 1: focused rect
//DrawFocusRect(dc, rc);
// Option 2: inverted thick border
SetROP2(dc, R2_NOT);
pen := CreatePen(PS_INSIDEFRAME, 3 * GetSystemMetrics(SM_CXBORDER), 0);
oldPen := SelectObject(dc, pen);
oldBrush := SelectObject(dc, GetStockObject(NULL_BRUSH));
Rectangle(dc, rc.Left, rc.Top, rc.Right, rc.Bottom);
SelectObject(dc, oldBrush);
SelectObject(dc, oldPen);
DeleteObject(pen);
// End option 2
ReleaseDC(hwndWindow, dc);
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if SetCapture(Handle) <> 0 then begin
CapturedMouse := true;
HwndLastTracked := 0;
Screen.Cursor := crCross;
end;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState;
X, Y: Integer);
var
hwndCaptured: HWND;
begin
if CapturedMouse then begin
hwndCaptured := WindowFromPoint(ClientToScreen(Point(X, Y)));
// Uncomment this for track root windows instead of childs
//hwndCaptured := GetAncestor(hwndCaptured, GA_ROOT);
if hwndCaptured <> HwndLastTracked then begin
if HwndLastTracked <> 0 then
InvertTracker(HwndLastTracked);
InvertTracker(hwndCaptured);
HwndLastTracked := hwndCaptured;
end;
end;
end;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if CapturedMouse then begin
ReleaseCapture;
CapturedMouse := false;
if HwndLastTracked <> 0 then begin
InvertTracker(HwndLastTracked);
HwndLastTracked := 0;
end;
Screen.Cursor := crDefault;
end;
end;