checkbox.c

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/**************************************************************************************************************************************
* Project:       discoverpixy
* Website:       https://github.com/t-moe/discoverpixy
* Authors:       Aaron Schmocker, Timo Lang
* Institution:   BFH Bern University of Applied Sciences
* File:          common/gui/checkbox.c
*
* Version History:
* Date          Autor Email         SHA     Changes
* 2015-04-27    timolang@gmail.com  b300ac5 Added Checkbox support
* 2015-05-17    timolang@gmail.com  2d46336 Improved comments in implementation of button, checkbox, numupdown, tft, touch and screen modules/submodules.
*
**************************************************************************************************************************************/

#include "tft.h"
#include "touch.h"
#include "checkbox.h"
#include <stdio.h>

/* The idea is as follows:
 * When the user creates a checkbox we create a touch area for that region and wait for PEN_DOWN events.
 * Once the user puts the pen down in this area we'll redraw the checkbox with different shadows (feedback)
 * and we'll now wait on PEN_UP or PEN_LEAVE events.
 * If the user takes the pen away while in the area (PEN_UP), we toggle the checkbox and we call the provided user callback
 * Otherwise (PEN_LEAVE) we only restore the initial shadows
 */


#define ACTIVE_COLOR RGB(251,208,123) //shadow color (inside of border)
#define BORDER_COLOR RGB(29,82,129) //1px border color
#define BACKGROUND_COLOR WHITE //Background color

//Callback which is called when the user touches the touch-area we created for the checkbox
void checkboxes_cb(void* touchArea, TOUCH_ACTION triggeredAction)
{
    TOUCH_AREA_STRUCT* area = (TOUCH_AREA_STRUCT*)touchArea;
    CHECKBOX_STRUCT* checkbox = (CHECKBOX_STRUCT*)touchArea;

    switch (triggeredAction) {
    case PEN_DOWN:  //If the user touches the area for the "first time"
        area->hookedActions = PEN_UP | PEN_LEAVE; //for the future we only want PEN_UP and PEN_LEAVE events

        //Draw active shadows
        tft_draw_rectangle(checkbox->base.x1 + 1, checkbox->base.y1 + 1, checkbox->base.x2 - 1, checkbox->base.y2 - 1, ACTIVE_COLOR);
        tft_draw_rectangle(checkbox->base.x1 + 2, checkbox->base.y1 + 2, checkbox->base.x2 - 2, checkbox->base.y2 - 2, ACTIVE_COLOR);
        break;

    case PEN_UP: //If the user took the pen away, while in the area (=toggle checkbox!)
        checkbox->checked = !checkbox->checked; //Toggle checkbox state
        gui_checkbox_update(checkbox); //redraw/overdraw tickmark

        if (checkbox->callback != NULL) { //The user provided a callback
            checkbox->callback(checkbox, checkbox->checked); //Call the provided callback with the new checked state
        }

    // no break statement here!
    case PEN_LEAVE: //if the user "slided out" of the area
        area->hookedActions = PEN_DOWN; //for the future we only want PEN_DOWN events

        //Draw inactive shadows
        tft_draw_rectangle(checkbox->base.x1 + 1, checkbox->base.y1 + 1, checkbox->base.x2 - 1, checkbox->base.y2 - 1, BACKGROUND_COLOR);
        tft_draw_rectangle(checkbox->base.x1 + 2, checkbox->base.y1 + 2, checkbox->base.x2 - 2, checkbox->base.y2 - 2, BACKGROUND_COLOR);
        break;

    default:
        break;
    }
}

bool gui_checkbox_add(CHECKBOX_STRUCT* checkbox)
{
    if (touch_have_empty(1)) { //Check if the touch module can handle one additional area
        unsigned char size = 0;
        checkbox->base.hookedActions = PEN_DOWN; //At first we are interested in PEN_DOWN events
        checkbox->base.callback = checkboxes_cb; //Use our own callback for the touch area events

        //Check the size of the checkbox
        if (checkbox->base.x2 > checkbox->base.x1) {
            size = checkbox->base.x2 - checkbox->base.x1;    //use width a as size
        }

        if (checkbox->base.y2 > checkbox->base.y1) {
            if ((checkbox->base.y2 - checkbox->base.y1) > size) { //height is larger than size
                size = checkbox->base.y2 - checkbox->base.y1;    //use height as size
            }
        }

        if (size == 0) { //no size found (maybe swap x2 and x1 or y2 and y1 ?)
            return false; //signal error
        }

        if ((size & 0x01)) { //the size is an odd number
            size++;    //make size an even number
        }

        //Correct x2,y2 so that the checkbox is quadratic
        checkbox->base.x2 = checkbox->base.x1 + size;
        checkbox->base.y2 = checkbox->base.y1 + size;

        gui_checkbox_redraw(checkbox);//Call redraw method, which will take care of the drawing of the entire checkbox

        return touch_register_area(&checkbox->base); //Register the touch area and receive events for this checkbox, from now on
    }

    return false; //no more touch areas left
}

void gui_checkbox_redraw(CHECKBOX_STRUCT* checkbox)
{
    //Draw background and border
    tft_fill_rectangle(checkbox->base.x1 + 1, checkbox->base.y1 + 1, checkbox->base.x2 - 1, checkbox->base.y2 - 1, BACKGROUND_COLOR);
    tft_draw_rectangle(checkbox->base.x1, checkbox->base.y1, checkbox->base.x2, checkbox->base.y2, BORDER_COLOR);

    if (checkbox->checked) { //checkbox is currently checked
        gui_checkbox_update(checkbox); //Call update method which will draw the tickmark
    }
}

void gui_checkbox_remove(CHECKBOX_STRUCT* checkbox)
{
    //We only need to unregister the touch area, as we have not allocated anything else
    touch_unregister_area((TOUCH_AREA_STRUCT*)checkbox);
}

void gui_checkbox_update(CHECKBOX_STRUCT* checkbox)
{
    unsigned int c = (checkbox->checked) ? checkbox->fgcolor : BACKGROUND_COLOR; //color to use for the tickmark

    //helper points inside the checkbox
    unsigned int xcent = checkbox->base.x1 + (checkbox->base.x2 - checkbox->base.x1) * 6 / 14;
    unsigned int yleft = checkbox->base.y2 - (xcent - checkbox->base.x1) - 1 ;
    unsigned int yright = checkbox->base.y2 - (checkbox->base.x2 - xcent) - 1 ;
    unsigned int ybot = checkbox->base.y2 - 4;

    //Draw tickmark as a 3pixel wide line
    tft_draw_line(checkbox->base.x1 + 3, yleft - 1, xcent, ybot - 1, c);
    tft_draw_line(checkbox->base.x1 + 3, yleft, xcent, ybot , c);
    tft_draw_line(checkbox->base.x1 + 3, yleft + 1, xcent, ybot + 1, c);
    xcent++;
    ybot--;
    tft_draw_line(xcent, ybot - 1, checkbox->base.x2 - 3, yright - 1, c);
    tft_draw_line(xcent, ybot, checkbox->base.x2 - 3, yright + 0, c);
    tft_draw_line(xcent, ybot + 1, checkbox->base.x2 - 3, yright + 1, c);
}