References ▼
This callback function is called every time a new frame(s) has/have been requested when the low memory usage feature is enabled (for more information see the LImageViewerCell::EnableCellLowMemoryUsage function).
#include "ltwrappr.h"
virtual L_INT LImageViewerCell::LowMemoryUsageCallBack(nCellIndex, puFramesRequested, uLength)
Index of the cell, which has requested the frames in puFramesRequested.
Table of uLength integers containing frames requested
Length of the frames requested array.
| Value | Meaning |
|---|---|
| SUCCESS | The function was successful. |
| < 1 | An error occurred. Refer to Return Codes. |
The low memory usage feature works by stopping the control from loading all the frames at runtime. Instead, the control will load only the frames that are currently visible on the cell. The control will send a request each time the user scrolls down or up, changes the number of visible framesetc. For example, suppose the cell layout is a 2X2 (See LImageViewerCell::SetCellProperties), and the user needs to load more than 100000 frames. The control will not load them all. This function will send a callback ([LImageViewerCell:LowMemoryUsageCallBack) when the cell is loaded requesting 4 frames (1, 2, 3 and 4) (because the cell is 2X2). Once the user scrolls down the cell to show frame number 5, frame number 1 will be disposed of because it is no longer visible, and the callback will be fired to request frame number 5. When frames are requested, the user is supposed to send them to the control using the LImageViewerCell::SetRequestedImage function.
For the callback, use the LImageViewerCell::LowMemoryUsageCallBack function, to use this callback, it must first be set by calling LImageViewerCell::EnableLowMemoryUsageCallBack function.
For an example, refer to LImageViewerCell::EnableLowMemoryUsageCallBack.