7b75d0a256
By default, wxMSW overlay uses a constant alpha for the window's opacity which can be changed by the added wxOverlay::SetOpacity() function. For some applications, that's all they need. But for others, per-pixel alpha blending is a requirement. This capability can be enabled by calling SetOpacity(-1) before initializing the overlay. But the drawing must be done via a graphics context because the standard DC under MSW does not support alpha drawing. Also request that the overlay window be positioned below any floating windows on the target (if any).
91 lines
2.2 KiB
C++
91 lines
2.2 KiB
C++
/////////////////////////////////////////////////////////////////////////////
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// Name: wx/overlay.h
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// Purpose: wxOverlay class
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// Author: Stefan Csomor
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// Created: 2006-10-20
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// Copyright: (c) wxWidgets team
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// Licence: wxWindows licence
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/////////////////////////////////////////////////////////////////////////////
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#ifndef _WX_OVERLAY_H_
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#define _WX_OVERLAY_H_
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#include "wx/defs.h"
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// ----------------------------------------------------------------------------
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// creates an overlay over an existing window, allowing for manipulations like
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// rubberbanding etc. This API is not stable yet, not to be used outside wx
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// internal code
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// ----------------------------------------------------------------------------
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class WXDLLIMPEXP_FWD_CORE wxDC;
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class WXDLLIMPEXP_CORE wxOverlay
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{
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public:
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class Impl;
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wxOverlay();
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~wxOverlay();
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// clears the overlay without restoring the former state
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// to be done eg when the window content has been changed and repainted
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void Reset();
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bool IsNative() const;
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void SetOpacity(int alpha);
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private:
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friend class WXDLLIMPEXP_FWD_CORE wxDCOverlay;
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static Impl* Create();
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// returns true if it has been setup
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bool IsOk();
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void Init(wxDC* dc, int x , int y , int width , int height);
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void BeginDrawing(wxDC* dc);
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void EndDrawing(wxDC* dc);
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void Clear(wxDC* dc);
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Impl* m_impl;
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bool m_inDrawing;
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wxDECLARE_NO_COPY_CLASS(wxOverlay);
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};
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class WXDLLIMPEXP_CORE wxDCOverlay
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{
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public:
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// connects this overlay to the corresponding drawing dc, if the overlay is
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// not initialized yet this call will do so
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wxDCOverlay(wxOverlay &overlay, wxDC *dc, int x , int y , int width , int height);
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// convenience wrapper that behaves the same using the entire area of the dc
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wxDCOverlay(wxOverlay &overlay, wxDC *dc);
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// removes the connection between the overlay and the dc
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virtual ~wxDCOverlay();
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// clears the layer, restoring the state at the last init
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void Clear();
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private:
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void Init(wxDC *dc, int x , int y , int width , int height);
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wxOverlay& m_overlay;
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wxDC* m_dc;
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wxDECLARE_NO_COPY_CLASS(wxDCOverlay);
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};
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#endif // _WX_OVERLAY_H_
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