We have a script that dynamically generates a datawindow that has an array of icons showing the state of various data (see image below). There are up to about 20 different images that could be displayed per icon depending on the data. We are constantly trying to optimize this datawindow since we could potentially have as many as 400 different icons in a given row and we might display 20 rows at a time.
We have tried 2 different routes in terms of performance:
1) Using a computed field object with a bitmap() function to render the correct bitmap. In this case our script creates one computed field per bitmap.
2) Create 20 bitmap objects per icon and then set the visibility expressions of each one to show the correct bitmap. This means that if we build a datawindow with 400 icons we end up with 8000 bitmap objects per row.
With 1) the datawindow is created much more quickly however its performance scrolling is very slow as it appears all the computed fields end up being re-evaluated. Does anyone know a trick to suppress computed fields from recalculating in this instance?
With 2) the performance initially building the datawindow in script is slower however the performance is very good.
This is just background to the actual issue since right now we are using option 2). The real question is in terms of the look of the datawindow, we use different color detail background colors for odd/even rows, white and slighly grey. If we use .BMP files we end up with a white edge on the bmp file that looks pretty rough. If we use .PNG files with transparent edges then the datawindow looks great but again the performance degrades significantly. Note that if we use the trick where we set the transparency of the bitmaps to 1% then the edge goes away but performance degrades to about the same level as the PNG. Basically it seems that once we have any transparency going on the performance is hurt.
Please be aware that we have tried different bitmaps for odd and even rows where the even row bitmap has a white edge and the odd row has a grey edge however this then doubles the number of bitmaps being created we slows performance.
Does anyone know any tricks for dealing with this?
I think my approach is going to be see how many icons I need to create, if it is over 100 then I will use a bitmaps and if under 100 then pngs. Most of our customers are less than 100 so only the customers with longer lists of forms will see the rougher graphics.
THanks Mark
Have you considered using dummy columns to hold the filename and using a control with "display as picture" checked? This would offload most of the work when scrolling back to PB itself (instead of having to recalc all the computed objects). You would need to map the created controls to the proper column ID, but that shouldn't be a problem if you're already dynamically creating computes.