I have just committed the removal of a the old scaling code from Kicad. This effectively means that wxDC is now used for all coordinate conversion between drawing and screen units. This transition is by no means complete as there are still some issues that need to be addressed. I learned a great deal along the way and want to share some observations into the Kicad drawing code so here it goes.
1) All coordinate conversions between logical (drawing) units and device (screen, printer, etc.) should be done using the device context. Use LogicalToDevice and DeviceToLogical methods for all coordinate conversions. In order for this to work properly, the scroll bars must be set to the correct position and DoPrepareDC must be called before using the device context. 2) All drawing and clipping should be done in drawing coordinates. There is no longer any need to convert to device coordinates before drawing. 3) Using wxBufferedDC now works properly on Windows. Using a buffer DC on GTK and OSX shouldn't be necessary as they both support double buffering natively (according to the wxWidgets documentation). Please note that wxBuffedDC can currently only be used to redraw the entire screen area. This is due to the fact that drawing when editing does not update the background. Drawing when editing is accomplish by XORing the current object to erase it and redrawing the edited object so using a buffered DC will not work. I added an INSTALL_UNBUFFER_DC for edit drawing purposes. 4) You can experiment with turning the buffered DC on and off by setting KICAD_USE_BUFFERED_PAINTDC and KICAD_USE_BUFFERED_DC to 1 or 0. I recommend reading the comments in kicad_device_context.h before changing anything. As of now, both paint and client DCs are buffered on Windows. I'm not sure this is the best combination. I'm sure if there are any performance regressions, I'll hear about it. I don't notice much of a difference on my machine. 5) I removed several places where the cursor and pointer positions (which are not always the same position) were saved in object member variables in both screen and drawing units which was extremely confusing. Please do not add another variable (object member or otherwise) to save any position information. Use the ones already stored in the base screen object. 6) I had to disable the optimized bitmap version of the grid drawing code. I'll take a look at it as soon as get some time. Although using buffer drawing on Windows should help mitigate some of the performance issues (maybe?). There is still quite a bit of work to be done but this is a good first pass. There is a lot of legacy code which I'm sure can be removed and/or simplified which I will continue to chip away at. I'm not sure the clipping is 100% correct but now that all the drawing is done in drawing units it should be a lot easier to verify. I need some help from our OSX developers to verify I didn't break anything. If anyone finds any drawing issues, please let me know and I'll do my best to fix it promptly. Thanks, Wayne _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
