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107 lines
3.3 KiB
C++
107 lines
3.3 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef MOZILLA_WIDGET_WINDOWSEMF_H
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#define MOZILLA_WIDGET_WINDOWSEMF_H
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/* include windows.h for the HDC definitions that we need. */
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#include <windows.h>
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namespace mozilla {
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namespace widget {
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/**
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* Windows Enhance Metafile: https://en.wikipedia.org/wiki/Windows_Metafile
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* A metafile, also called a vector image, is an image that is stored as a
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* sequence of drawing commands and settings. The commands and settings
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* recorded in a Metafile object can be stored in memory or saved to a file.
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*
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* The metafile device context is used for all drawing operations required to
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* create the picture. When the system processes a GDI function associated with
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* a metafile DC, it converts the function into the appropriate data and stores
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* this data in a record appended to the metafile.
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*/
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class WindowsEMF {
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public:
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WindowsEMF();
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~WindowsEMF();
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/**
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* Initializes the object with the path of a file where the EMF data stream
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* should be stored. Callers are then expected to call GetDC() to draw output
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* before going on to call Playback() or SaveToFile() to generate the EMF
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* output.
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*/
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bool InitForDrawing(const wchar_t* aMetafilePath = nullptr);
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/**
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* Initializes the object with an existing EMF file. Consumers cannot use
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* GetDC() to obtain an HDC to modify the file. They can only use Playback().
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*/
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bool InitFromFileContents(const wchar_t* aMetafilePath);
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/**
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* Creates the EMF from the specified data
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*
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* @param aByte Pointer to a buffer that contains EMF data.
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* @param aSize Specifies the size, in bytes, of aByte.
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*/
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bool InitFromFileContents(PBYTE aBytes, UINT aSize);
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/**
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* If this object was initiaziled using InitForDrawing() then this function
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* returns an HDC that can be drawn to generate the EMF output. Otherwise it
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* returns null. After finishing with the HDC, consumers could call Playback()
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* to draw EMF onto the given DC or call SaveToFile() to finish writing the
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* EMF file.
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*/
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HDC GetDC() const {
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MOZ_ASSERT(mDC,
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"GetDC can be used only after "
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"InitForDrawing/ InitFromFileContents and before"
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"Playback/ SaveToFile");
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return mDC;
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}
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/**
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* Play the EMF's drawing commands onto the given DC.
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*/
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bool Playback(HDC aDeviceContext, const RECT& aRect);
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/**
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* Called to generate the EMF file once a consumer has finished drawing to
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* the HDC returned by GetDC(), if initializes the object with the path of a
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* file.
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*/
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bool SaveToFile();
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/**
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* Return the size of the enhanced metafile, in bytes.
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*/
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UINT GetEMFContentSize();
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/**
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* Retrieves the contents of the EMF and copies them into a buffer.
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*
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* @param aByte the buffer to receive the data.
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*/
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bool GetEMFContentBits(PBYTE aBytes);
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private:
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WindowsEMF(const WindowsEMF& aEMF) = delete;
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bool FinishDocument();
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void ReleaseEMFHandle();
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void ReleaseAllResource();
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/* Compiled EMF data handle. */
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HENHMETAFILE mEmf;
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HDC mDC;
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};
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} // namespace widget
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} // namespace mozilla
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#endif /* MOZILLA_WIDGET_WINDOWSEMF_H */
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