111 lines
4.6 KiB
C
111 lines
4.6 KiB
C
/**************************************************************************************************************************************
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* Project: discoverpixy
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* Website: https://github.com/t-moe/discoverpixy
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* Authors: Aaron Schmocker, Timo Lang
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* Institution: BFH Bern University of Applied Sciences
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* File: common/gui/screen.c
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*
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* Version History:
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* Date Autor Email SHA Changes
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* 2015-04-27 timolang@gmail.com cf72baa Introduced a Screen (sub) module and divided app into multiple screens.
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* 2015-04-27 timolang@gmail.com 77e6d0e Fixed screen implementation.
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* 2015-05-10 timolang@gmail.com b6ab7c8 Fixed compiler warning in tft and screen module.
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* 2015-05-17 timolang@gmail.com 2d46336 Improved comments in implementation of button, checkbox, numupdown, tft, touch and screen modules/submodules.
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* 2015-06-01 timolang@gmail.com eb573bc Finalized calibration. Fixed a bug in screen module.
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* 2015-06-06 timolang@gmail.com c06661d Fixed some outdated comments in source code. Documented Gui Module in docu.
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*
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**************************************************************************************************************************************/
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#include "screen.h"
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/* The idea is as follows:
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* We only call screen callbacks from the gui_screen_update() method, which is called from the applications main loop.
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* Instructions to switch the screen will be delayed until the gui_screen_update() method is called again.
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* This makes it safe to change the screen from an touch interrupt (e.g. button callback)
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*/
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/* Possible Improvements:
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* Ensure that you can not navigate to a screen which is already in the history (because it will corrupt the list)
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*/
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static SCREEN_STRUCT* screen_list = NULL; //Head of the linked list which stores the screen history.
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static SCREEN_STRUCT* screen_current = NULL; //Pointer to the current screen (= tail of the list)
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static volatile SCREEN_STRUCT* screen_goto = NULL; //Screen we should navigate to once we enter the gui_screen_update() method again
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SCREEN_STRUCT* gui_screen_get_current()
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{
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return screen_current;
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}
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void gui_screen_update()
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{
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if (screen_goto != NULL) { //we received the task to switch the screen
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SCREEN_STRUCT* go = (SCREEN_STRUCT*) screen_goto; //Backup volatile variable
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screen_goto = NULL; //reset the "goto instruction", since we're processing it now
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if (go->next != NULL) { //The screen is not the last in the list, so we're going back
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if (go->next != screen_current) { //this condition should always be false
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return; //list corrupted?
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}
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screen_current->on_leave(screen_current); //let the current screen free/unregister it's resources
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go->next = NULL; //remove the current screen from the list
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} else { //we're going forward (to a new screen)
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if (screen_current != NULL) { //this is not the first screen
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screen_current->on_leave(screen_current); //let the current screen free/unregister it's resources
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screen_current->next = go; //append the new screen to the end of the list
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} else { //first screen ever seen
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screen_list = go; //set the new screen as list-head
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}
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}
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go->on_enter(go); //let the new screen allocate/register it's resources
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screen_current = go; //the new screen is now the current screen. Transition done
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}
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if (screen_current != NULL) { //A screen has been set
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screen_current->on_update(screen_current); //Update current screen
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}
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}
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bool gui_screen_navigate(SCREEN_STRUCT* screen)
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{
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if (screen == NULL || screen == screen_current || screen == screen_goto) { //invalid argument passed
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return false;
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}
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screen->next = NULL; //this will become the new tail of the list, so the next pointer must be NULL
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screen_goto = screen; //"send message" to main loop, to switch the screen
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return true;
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}
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bool gui_screen_back()
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{
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if (screen_list == NULL) { //the list head is emtpy, nothing to go back to
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return false;
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}
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SCREEN_STRUCT* current = screen_list;
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SCREEN_STRUCT* last = NULL;
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//Find second last element in list
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while (current->next != NULL) {
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last = current;
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current = current->next;
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}
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if (last == NULL) {
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return false; //There's only a single screen, there's no going back here
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}
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if (current != screen_current) {
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return false; //The last entry in the list is not the current screen. List corrupted?
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}
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screen_goto = last; //"send message" to main loop, to switch the screen
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return true;
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}
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