To Next Page

To Previous Page

DCAPI TR122_D_ValidateTransientTimeOffset(long *PixelOffset, char *TimeAtMidScreen);

A user application will usually involve dimensioning of a display based on the pixels as they appear to the user.

A plot of a valid transient record is initially displayed with the trigger at midscreen (offset of 0 samples). A

transient record is plotted using one sample per horizontal pixel. This routine is a service which performs no

function with the instrument or the API, but inspects the argument based on the current memory geometry and

modifies the requested pixel offset if required to comply with that geometry. The corresponding offset in pixels

(samples) is translated to a time based on the sample rate and written as a text string into the TimeAtMidScreen

argument.

DCAPI TR122_D_TransientPlot(DWORD Segment, long Offset);

This routine plots samples of a transient record from the segment indicated. The offset is the number of samples

before or after the trigger which should appear at the middle of the gradicule. The offset is automatically adjusted

internally for the limits in the current memory geometry. Therefore, typically the caller will use the validation

routine above before calling this routine. Before calling either routine the validity of a transient record in memory

must be established by calling TR122_GetTriggerInformation.

DCAPI TR122_D_SetScopeTimeOffset(long *PixelOffset, char *TimeAtMidScreen);

In the oscilloscope mode the time offset for the center of the gradicule versus the trigger location is a bit more

complicated to determine because the sample information is compressed or stretched in the plot to translate the

sample rate to a particular time per division. The offset is still given in terms of pixels and a string relating the time

at the center line of the gradicule is returned. Because the oscilloscope mode plots new information under control

of the auto thread, the time offset must be stored internally to the API for use in the plot. This function allows the

higher level software to install that offset.

DCAPI TR122_D_ScopePlot(void);

The ScopePlot routine is generally only used by the auto thread. This export is available for primitive oscilloscope

applications where the timing of data updates is controlled by the top level application. The routine automatically

manipulates the DIB, collects the trigger information, compresses samples, and plots traces based on parameters

installed elsewhere in the API. This routine does make the assumption that the memory geometry is as defined for

the oscilloscope mode.

DCAPI TR122_D_SaveBitmap(char *Filename);

This routine saves the current DIB to a 256 color Windows bitmap file. The caller must prevent any function

including the auto thread from updating the bitmap during this operation or strange results could occur.

DCAPI TR122_D_Paint(HDC hDestDC, long DestXSize, long DestYSize);

The paint routine will write the DIB to the device context specified by the handle. The size in pixels of this device

context must also be specified. If the size is not the same as the DIB, the DIB will be stretched. The aspect ratio

will be maintained as much as possible by excluding part of the destination from the write. However, it is possible

to lose image information. It is recommended that the device context have the sample pixel dimensions as the DIB.

Finally, it is important to know that the paint process will write to the foreground image of a display object. To see

the new image on a screen device it may be necessary to refresh the associated object if the object automatically

redisplays its background image.

DDC TR122 User Manual

Questions and Answers: