69 lines
1.7 KiB
C
69 lines
1.7 KiB
C
#include "screen.h"
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static volatile SCREEN_STRUCT* screen_list = NULL;
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static volatile SCREEN_STRUCT* screen_current = NULL;
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static volatile SCREEN_STRUCT* screen_goto = NULL;
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SCREEN_STRUCT* gui_screen_get_current() {
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return screen_current;
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}
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void gui_screen_update() {
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if(screen_goto!=NULL) { //we received the task to switch the screen
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SCREEN_STRUCT* go = screen_goto; //Backup volatile variable
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screen_goto=NULL;
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if(go->next!=NULL) { //we're going back
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if(go->next!=screen_current) return; //list corrupted?
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screen_current->on_leave(screen_current);
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go->next=NULL;
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} else { //we're going forward
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if(screen_current!=NULL) { //this is not the first screen
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screen_current->on_leave(screen_current);
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screen_current->next = go;
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} else { //first screen ever seen
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screen_list=go;
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}
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}
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go->on_enter(go);
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screen_current = go;
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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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if(screen==NULL) return false;
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screen->next = 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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if(screen_list==NULL) return false;
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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) return false; //There's only a single screen.
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if(current!=screen_current) return false; //List corrupted?
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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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