Windows program design Reading Notes-metafiles

1. Metadata File.

It is composed of a series of binary records equivalent to calling graphical functions. These records are generally used to draw straight lines, curves, areas, text, and so on.

 

Ii. "DrawingProgram"Create a bitmap, and" plotting program "Create a Metafile.

The metadata file occupies less space than the bitmap, and is more device-independent than the bitmap file.

 

Iii. Old Metafile format. The extension is. WMF.

HDC hdcmeta = createmetafile (lpctstr lpszfile // file name );

// Create a Metafile and save it in the file path. The extension is. WMF.

// If the parameter is null, it is created in the memory,

Ellipse (hdcmeta, 100,100,); // then plot with hdcmeta.

Hmetafile hmf = closemetafile (hdcmeta); // close and get the handle

Playmetafile (HDC, hmf); // draw hmf on HDC

Deletemetafile (hmf );

 

Hmf = getmetafile (filename); // read the Metafile.

Getdevicecaps (hmf, horzsize); // This type of getdevicecaps function can obtain the metadata attributes.

Henhmetafile copyenhmetafile (henhmetafileHemfsrc, LpctstrLpszfile); // CopyLpszfile,Empty to memory

 

Meta files can be used as user-defined resources: setmetafilebitsex

 

Iv. Enhanced Metadata File With the extension. EMF

HDC hdcmeta = createenhmetafile (

HDC hdcref, // handle to reference DC

Lptstr lpfilename, // file name

Const rect * lprect, // bounding rectangle

Lptstr lpdescription // description string

);

// Create a Metafile and save it in the file path. The extension is. EMF.

// If the parameter is null, it is created in the memory,

Ellipse (hdcmeta, 100,100,); // then plot with hdcmeta.

Hmetafile hmf = closeenhmetafile (hdcmeta); // close and get the handle

Playenhmetafile (HDC, hmf, & rect); // on HDC, draw the hmf and scale it to the rect range.

Deleteenhmetafile (hmf );

Getmetafile (filename); // read the Metafile.

Meta files can be used as user-defined resources: setmetafilebitsex

 

The biggest improvement of Enhanced Meta files over older meta files is the addition of file header information.

Obtain the file header information: uint getenhmetafileheader (henhmetafile hemf, // handle to Enhanced Metafile uint cbbuffer, // size of buffer lpenhmetaheader EMH // data buffer );

Cximage = EMH. rclbounds. Right-EMH. rclbounds. Left; // metadata file length
Cyimage = EMH. rclbounds. Bottom-EMH. rclbounds. Top; // Metafile width

 

Enumerate bool enumenhmetafile (HDC, // handle to DC henhmetafile hemf, // handle to Enhanced Metafile enhmfenumproc lpenhmetafunc, // callback function lpvoid lpdata, // callback-function data const rect * lprect); // bounding rectangle

// Execute the operations in the lpenhmetafunc function for each object in the Metafile.

 

V. Metadata File data format.

It is the same as a normal file. Hexadecimal: object type, type length, type content.

For the type definition, see msdn: EMR ....