File Extension APM

File type: Aldus Placeable Metafiles

About the APM file type:

If Windows cannot find the appropriate program associated with .APM files, then your registry may have errors. Check your Windows registry for errors (includes file association errors).

The APM file extension is a representation of the read mode of the Aldus Placeable Metafiles which was developed and introduced by the Aldus Corporation. This file type is used for non-standard ways of specifying the scaling and mapping of metafiles on an intended output device. The placeable metafile represented by the APM file format is not supported directly by the Application Programming Interface of Microsoft Windows. In this context, to utilize a placeable metafile with the Windows API, the header of the APM file extension must first be stripped to be accommodated directly. This process is normally done by copying the source metafile into a temporary storage file which typically begins at the file offset of 0x16. After accomplishing this process, the contents of the temporary file can then be utilized as an input source for the Windows CopyMetaFile(), PlayMetaFile(), GetMetaFile(), and similar GDI functions. The APM file extension is limited to a 64K file length. The patent to this technology is currently held by Adobe Systems.


Detailed information for file extension APM

Category: System Files
File format: Proprietary
Open with Windows: Microsoft Windows Operating System
Open with Linux: N/A
There are several important properties attributed with the APM file extension such as Handle which is related to the function of storing the associated metafile handle into the system memory. When carrying out the function of writing to the storage disk, this property is generally not utilized and constantly holds a zero value. The coordinates for the lower-right and upper-left hand corners of the image in relation to the representation to the output device is contained in the Left, Right, Top, and Bottom properties of the APM file extension. The measurements used for these properties use the unit twips which is a twentieth of a point or equivalent to 1/1440 of an inch. These fields likewise correspond to the RECT data structure, utilized by the Microsoft Windows Operating System platform and defined within the WINDOWS.H file. The Inch property therefore defines the number of twips contained per inch when representing the image. The Reserved property is never utilized and thus, always contains a zero value. The Checksum property contains the value of the previous ten words contained in the header which is also considered as an attempt to verify the integrity of the metafile to make sure that it is not corrupted by using XOR calculation.