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